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Manigart O, Trotter C, Findlow H, Assefa A, Mihret W, Moti Demisse T, Yeshitela B, Osei I, Hodgson A, Quaye SL, Sow S, Coulibaly M, Diallo K, Traore A, Collard JM, Moustapha Boukary R, Djermakoye O, Mahamane AE, Jusot JF, Sokhna C, Alavo S, Doucoure S, Ba EH, Dieng M, Diallo A, Daugla DM, Omotara B, Chandramohan D, Hassan-King M, Nascimento M, Woukeu A, Borrow R, Stuart JM, Greenwood B. A Seroepidemiological Study of Serogroup A Meningococcal Infection in the African Meningitis Belt. PLoS One 2016; 11:e0147928. [PMID: 26872255 PMCID: PMC4752490 DOI: 10.1371/journal.pone.0147928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 01/11/2016] [Indexed: 12/31/2022] Open
Abstract
The pattern of epidemic meningococcal disease in the African meningitis belt may be influenced by the background level of population immunity but this has been measured infrequently. A standardised enzyme-linked immunosorbent assay (ELISA) for measuring meningococcal serogroup A IgG antibodies was established at five centres within the meningitis belt. Antibody concentrations were then measured in 3930 individuals stratified by age and residence from six countries. Seroprevalence by age was used in a catalytic model to determine the force of infection. Meningococcal serogroup A IgG antibody concentrations were high in each country but showed heterogeneity across the meningitis belt. The geometric mean concentration (GMC) was highest in Ghana (9.09 μg/mL [95% CI 8.29, 9.97]) and lowest in Ethiopia (1.43 μg/mL [95% CI 1.31, 1.57]) on the margins of the belt. The force of infection was lowest in Ethiopia (λ = 0.028). Variables associated with a concentration above the putative protective level of 2 μg/mL were age, urban residence and a history of recent vaccination with a meningococcal vaccine. Prior to vaccination with the serogroup A meningococcal conjugate vaccine, meningococcal serogroup A IgG antibody concentrations were high across the African meningitis belt and yet the region remained susceptible to epidemics.
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Affiliation(s)
- Olivier Manigart
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Medical Research Council Unit, Fajara, The Gambia
| | - Caroline Trotter
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Helen Findlow
- Public Health England Vaccine Evaluation Unit, Manchester, United Kingdom
| | - Abraham Assefa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Wude Mihret
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | | | - Isaac Osei
- Navrongo Health Research Centre, Navrongo, Ghana
| | | | | | - Samba Sow
- Centre pour les Vaccins en Développement, Bamako, Mali
| | | | - Kanny Diallo
- Centre pour les Vaccins en Développement, Bamako, Mali
| | - Awa Traore
- Centre pour les Vaccins en Développement, Bamako, Mali
| | | | | | | | | | | | - Cheikh Sokhna
- Institut de Recherche pour le Développement, Dakar, Senegal
| | - Serge Alavo
- Institut de Recherche pour le Développement, Dakar, Senegal
| | | | - El Hadj Ba
- Institut de Recherche pour le Développement, Dakar, Senegal
| | - Mariétou Dieng
- Institut de Recherche pour le Développement, Dakar, Senegal
| | | | | | - Babatunji Omotara
- Department of Community Medicine, University of Maiduguri, Maiduguri, Nigeria
| | - Daniel Chandramohan
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Musa Hassan-King
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Maria Nascimento
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Arouna Woukeu
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Ray Borrow
- Public Health England Vaccine Evaluation Unit, Manchester, United Kingdom
| | - James M. Stuart
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Brian Greenwood
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- * E-mail:
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202
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Pothin E, Ferguson NM, Drakeley CJ, Ghani AC. Estimating malaria transmission intensity from Plasmodium falciparum serological data using antibody density models. Malar J 2016; 15:79. [PMID: 26861862 PMCID: PMC4748547 DOI: 10.1186/s12936-016-1121-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/22/2016] [Indexed: 12/21/2022] Open
Abstract
Background Serological data are increasingly being used to monitor malaria transmission intensity and have been demonstrated to be particularly useful in areas of low transmission where traditional measures such as EIR and parasite prevalence are limited. The seroconversion rate (SCR) is usually estimated using catalytic models in which the measured antibody levels are used to categorize individuals as seropositive or seronegative. One limitation of this approach is the requirement to impose a fixed cut-off to distinguish seropositive and negative individuals. Furthermore, the continuous variation in antibody levels is ignored thereby potentially reducing the precision of the estimate. Methods An age-specific density model which mimics antibody acquisition and loss was developed to make full use of the information provided by serological measures of antibody levels. This was fitted to blood-stage antibody density data from 12 villages at varying transmission intensity in Northern Tanzania to estimate the exposure rate as an alternative measure of transmission intensity. Results The results show a high correlation between the exposure rate estimates obtained and the estimated SCR obtained from a catalytic model (r = 0.95) and with two derived measures of EIR (r = 0.74 and r = 0.81). Estimates of exposure rate obtained with the density model were also more precise than those derived from catalytic models. Conclusion This approach, if validated across different epidemiological settings, could be a useful alternative framework for quantifying transmission intensity, which makes more complete use of serological data.
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Affiliation(s)
- Emilie Pothin
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK. .,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Neil M Ferguson
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK.
| | - Chris J Drakeley
- Department of Immunology, London School of Hygiene and Tropical Medicine, London, UK.
| | - Azra C Ghani
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK.
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203
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Yman V, White MT, Rono J, Arcà B, Osier FH, Troye-Blomberg M, Boström S, Ronca R, Rooth I, Färnert A. Antibody acquisition models: A new tool for serological surveillance of malaria transmission intensity. Sci Rep 2016; 6:19472. [PMID: 26846726 PMCID: PMC4984902 DOI: 10.1038/srep19472] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/09/2015] [Indexed: 11/13/2022] Open
Abstract
Serology has become an increasingly important tool for the surveillance of a wide range of infectious diseases. It has been particularly useful to monitor malaria transmission in elimination settings where existing metrics such as parasite prevalence and incidence of clinical cases are less sensitive. Seroconversion rates, based on antibody prevalence to Plasmodium falciparum asexual blood-stage antigens, provide estimates of transmission intensity that correlate with entomological inoculation rates but lack precision in settings where seroprevalence is still high. Here we present a new and widely applicable method, based on cross-sectional data on individual antibody levels. We evaluate its use as a sero-surveillance tool in a Tanzanian setting with declining malaria prevalence. We find that the newly developed mathematical models produce more precise estimates of transmission patterns, are robust in high transmission settings and when sample sizes are small, and provide a powerful tool for serological evaluation of malaria transmission intensity.
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Affiliation(s)
- Victor Yman
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Michael T White
- MRC Centre for Outbreak Analysis &Modelling, Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Josea Rono
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.,KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Bruno Arcà
- Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Italy
| | - Faith H Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Marita Troye-Blomberg
- Department of Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Sweden
| | - Stéphanie Boström
- Department of Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Sweden
| | - Raffaele Ronca
- Department of Biology, Federico II University, Naples, Italy
| | | | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
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Abstract
With increasing malaria control and goals of malaria elimination, many endemic areas are transitioning from high-to-low-to-no malaria transmission. Reductions in transmission will impact on the development of naturally acquired immunity to malaria, which develops after repeated exposure to Plasmodium spp. However, it is currently unclear how declining transmission and malaria exposure will affect the development and maintenance of naturally acquired immunity. Here we review the key processes which underpin this knowledge; the amount of Plasmodium spp. exposure required to generate effective immune responses, the longevity of antibody responses and the ability to mount an effective response upon re-exposure through memory responses. Lastly we identify research priorities which will increase our understanding of how changing transmission will impact on malarial immunity.
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205
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Sepúlveda N, Paulino CD, Drakeley C. Sample size and power calculations for detecting changes in malaria transmission using antibody seroconversion rate. Malar J 2015; 14:529. [PMID: 26715538 PMCID: PMC4696297 DOI: 10.1186/s12936-015-1050-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 12/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Several studies have highlighted the use of serological data in detecting a reduction in malaria transmission intensity. These studies have typically used serology as an adjunct measure and no formal examination of sample size calculations for this approach has been conducted. METHODS A sample size calculator is proposed for cross-sectional surveys using data simulation from a reverse catalytic model assuming a reduction in seroconversion rate (SCR) at a given change point before sampling. This calculator is based on logistic approximations for the underlying power curves to detect a reduction in SCR in relation to the hypothesis of a stable SCR for the same data. Sample sizes are illustrated for a hypothetical cross-sectional survey from an African population assuming a known or unknown change point. RESULTS Overall, data simulation demonstrates that power is strongly affected by assuming a known or unknown change point. Small sample sizes are sufficient to detect strong reductions in SCR, but invariantly lead to poor precision of estimates for current SCR. In this situation, sample size is better determined by controlling the precision of SCR estimates. Conversely larger sample sizes are required for detecting more subtle reductions in malaria transmission but those invariantly increase precision whilst reducing putative estimation bias. CONCLUSIONS The proposed sample size calculator, although based on data simulation, shows promise of being easily applicable to a range of populations and survey types. Since the change point is a major source of uncertainty, obtaining or assuming prior information about this parameter might reduce both the sample size and the chance of generating biased SCR estimates.
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Affiliation(s)
- Nuno Sepúlveda
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. .,Center of Statistics and Applications of University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Bloco C6-Piso 4, 1749-1016, Lisbon, Portugal.
| | - Carlos Daniel Paulino
- Center of Statistics and Applications of University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Bloco C6-Piso 4, 1749-1016, Lisbon, Portugal. .,Instituto Superior Técnico, Universidade Técnica de Lisboa, Avenida Rovisco Pais, 1049-001, Lisbonn, Portugal.
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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206
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Current Mathematical Models for Analyzing Anti-Malarial Antibody Data with an Eye to Malaria Elimination and Eradication. J Immunol Res 2015; 2015:738030. [PMID: 26770994 PMCID: PMC4684866 DOI: 10.1155/2015/738030] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/19/2015] [Indexed: 11/17/2022] Open
Abstract
The last decade has witnessed a steady reduction of the malaria burden worldwide. With various countries targeting disease elimination in the near future, the popular parasite infection or entomological inoculation rates are becoming less and less informative of the underlying malaria burden due to a reduced number of infected individuals or mosquitoes at the time of sampling. To overcome such problem, alternative measures based on antibodies against specific malaria antigens have gained recent interest in malaria epidemiology due to the possibility of estimating past disease exposure in absence of infected individuals. This paper aims then to review current mathematical models and corresponding statistical approaches used in antibody data analysis. The application of these models is illustrated with three data sets from Equatorial Guinea, Brazilian Amazonia region, and western Kenyan highlands. A brief discussion is also carried out on the future challenges of using these models in the context of malaria elimination.
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207
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A Venue-Based Survey of Malaria, Anemia and Mobility Patterns among Migrant Farm Workers in Amhara Region, Ethiopia. PLoS One 2015; 10:e0143829. [PMID: 26619114 PMCID: PMC4664424 DOI: 10.1371/journal.pone.0143829] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 11/10/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mobile populations present unique challenges to malaria control and elimination efforts. Each year, a large number of individuals travel to northwest Amhara Region, Ethiopia to seek seasonal employment on large-scale farms. Agricultural areas typically report the heaviest malaria burden within Amhara thereby placing migrants at high risk of infection. Yet little is known about these seasonal migrants and their malaria-related risk factors. METHODS AND FINDINGS In July 2013, a venue-based survey of 605 migrant laborers 18 years or older was conducted in two districts of North Gondar zone, Amhara. The study population was predominantly male (97.7%) and young (mean age 22.8 years). Plasmodium prevalence by rapid diagnostic test (RDT) was 12.0%; One quarter (28.3%) of individuals were anemic (hemoglobin <13 g/dl). Nearly all participants (95.6%) originated from within Amhara Region, with half (51.6%) coming from within North Gondar zone. Around half (51.2%) slept in temporary shelters, while 20.5% regularly slept outside. Only 11.9% of participants had access to a long lasting insecticidal net (LLIN). Reported net use the previous night was 8.8% overall but 74.6% among those with LLIN access. Nearly one-third (30.1%) reported having fever within the past two weeks, of whom 31.3% sought care. Cost and distance were the main reported barriers to seeking care. LLIN access (odds ratio [OR] = 0.30, P = 0.04) and malaria knowledge (OR = 0.50, P = 0.02) were significantly associated with reduced Plasmodium infection among migrants, with a similar but non-significant trend observed for reported net use the previous night (OR = 0.16, P = 0.14). CONCLUSIONS High prevalence of malaria and anemia were observed among a young population that originated from relatively proximate areas. Low access to care and low IRS and LLIN coverage likely place migrant workers at significant risk of malaria in this area and their return home may facilitate parasite transport to other areas. Strategies specifically tailored to migrant farm workers are needed to support malaria control and elimination activities in Ethiopia.
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208
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Doucoure S, Drame PM. Salivary Biomarkers in the Control of Mosquito-Borne Diseases. INSECTS 2015; 6:961-76. [PMID: 26593952 PMCID: PMC4693181 DOI: 10.3390/insects6040961] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 06/15/2015] [Accepted: 09/14/2015] [Indexed: 11/26/2022]
Abstract
Vector control remains the most effective measure to prevent the transmission of mosquito-borne diseases. However, the classical entomo-parasitological methods used to evaluate the human exposure to mosquito bites and the effectiveness of control strategies are indirect, labor intensive, and lack sensitivity in low exposure/transmission areas. Therefore, they are limited in their accuracy and widespread use. Studying the human antibody response against the mosquito salivary proteins has provided new biomarkers for a direct and accurate evaluation of the human exposure to mosquito bites, at community and individual levels. In this review, we discuss the development, applications and limits of these biomarkers applied to Aedes- and Anopheles-borne diseases.
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Affiliation(s)
- Souleymane Doucoure
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses Tropicales Emergentes (URMITE) UM63: CNRS7278-IRD 198-INSERM U1095 Campus IRD-UCAD, BP 1386, Dakar 18524, Sénégal.
| | - Papa Makhtar Drame
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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209
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Rogier E, Wiegand R, Moss D, Priest J, Angov E, Dutta S, Journel I, Jean SE, Mace K, Chang M, Lemoine JF, Udhayakumar V, Barnwell JW. Multiple comparisons analysis of serological data from an area of low Plasmodium falciparum transmission. Malar J 2015; 14:436. [PMID: 26537125 PMCID: PMC4634594 DOI: 10.1186/s12936-015-0955-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/21/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND As a nation reduces the burden of falciparum malaria, identifying areas of transmission becomes increasingly difficult. Over the past decade, the field of utilizing malaria serological assays to measure exposure has grown rapidly, and a variety of serological methods for data acquisition and analysis of human IgG against falciparum antigens are available. Here, different immunoassays and statistical methods are utilized to analyse samples from a low transmission setting and directly compare the estimates generated. METHODS A subset of samples (n = 580) from a 2012 Haitian nationwide malaria survey was employed as sample population of low falciparum endemicity. In addition to the Haitian samples, samples from 247 US residents were used as a reference population of 'true seronegatives'. Data acquisition was performed through standard ELISA and bead-based multiplex assays assaying for IgG antibodies to the Plasmodium falciparum antigens MSP-1p19, MSP-1p42(D), MSP-1p42(F), and AMA-1. Appropriate parametric distributions and seropositivity cutoff values were determined by statistical measures. RESULTS Data from both assays showed a strong positive skew, and the lognormal distribution was found to be an appropriate statistical fit to the Haitian and American populations. The American samples served as a good serological true negative population for the multiplex assay, but not for ELISA-based data. Mixture model approaches to determine seronegative and seropositive populations from the Haitian data showed a high degree of distribution overlap-likely due to the historical low falciparum transmission in this nation. Different fittings to the reversible catalytic model resulted depending upon the immunoassay utilized and seropositivity cutoff method employed. Data were also analysed through fitting to penalized B-splines, presenting another possible analytical tool for the analysis of malaria serological data. CONCLUSIONS Standardization of serological techniques and analyses may prove difficult as some tools can prove to be more useful depending on the area and parasite in question, making clear interpretation a vital pursuit. The presented analysis in the low-endemic nation of Haiti found malaria-naive US residents to be an appropriate seronegative reference population for the multiplex assay, and this assay providing consistent estimates between MSP-1 and AMA-1 antigens of percent seropositives for this low-endemic population.
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Affiliation(s)
- Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - Ryan Wiegand
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - Delynn Moss
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - Jeff Priest
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - Evelina Angov
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - Ito Journel
- Laboratoire National de Santé Publique (LNSP)/Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti.
| | - Samuel E Jean
- Population Services International/Organisation Haïtienne de Marketing Social pour la Santé, Port-au-Prince, Haiti.
| | - Kimberly Mace
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - Michelle Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | | | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
| | - John W Barnwell
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA.
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210
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Stevenson JC, Stresman GH, Baidjoe A, Okoth A, Oriango R, Owaga C, Marube E, Bousema T, Cox J, Drakeley C. Use of different transmission metrics to describe malaria epidemiology in the highlands of western Kenya. Malar J 2015; 14:418. [PMID: 26502920 PMCID: PMC4624380 DOI: 10.1186/s12936-015-0944-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 10/13/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Monitoring and evaluation of malaria programmes may require a combination of approaches to detect any effects of control. This is particularly true at lower transmission levels where detecting both infection and exposure to infection will provide additional evidence of any change. This paper describes use of three transmission metrics to explore the malaria epidemiology in the highlands of western Kenya. METHODS A malariometric survey was conducted in June 2009 in two highland districts, Kisii and Rachuonyo South, Nyanza Province, Kenya using a cluster design. Enumeration areas were used to sample 46 clusters from which 12 compounds were randomly sampled. Individuals provided a finger-blood sample to assess malaria infection (rapid diagnostic test, PCR) and exposure (anti-Plasmodium falciparum MSP-1 antibodies) and a questionnaire was administered to record household factors and assess use of vector control interventions. RESULTS Malaria prevalence infection rates were 3.0 % (95 % CI 2.2-4.2 %) by rapid diagnostic test (RDT) and 8.5 % (95 % CI 7.0-10.4 %) by PCR and these ranged from 0-13.1 to 0-14.8 % between clusters for RDT and PCR, respectively. Seroprevalence was 36.8 % (95 % CI 33.9-39.8) ranging from 18.6 to 65.8 %. Both RDT and PCR prevalences were highest in children aged 5-10 years but the proportion of infections that were sub-patent was highest in those between 15 and 20 years of age (78.1 %, 95 % CI 63.0-93.3 %) and those greater than 20 years (73.3 %, 95 % CI 64.5-81.9 %). Those reporting both indoor residual spraying (IRS) in their home and use of bed nets had lower exposure to malaria compared to those who reported using IRS or bed nets alone. CONCLUSIONS In this highland site in western Kenya malaria transmission was low, but highly heterogeneous. To accurately characterize the true extent of malaria transmission, more sensitive and complementary metrics such as PCR or serology are required in addition to the standard microscopy and/or RDTs that are routinely used. This is likely to be the case in other low endemicity settings.
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Affiliation(s)
- Jennifer C Stevenson
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. .,Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe St, Baltimore, MD, 21205, USA.
| | - Gillian H Stresman
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Amrish Baidjoe
- Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
| | - Albert Okoth
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya.
| | - Robin Oriango
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya.
| | - Chrispin Owaga
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya.
| | - Elizabeth Marube
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya.
| | - Teun Bousema
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. .,Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
| | - Jonathan Cox
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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Serology describes a profile of declining malaria transmission in Farafenni, The Gambia. Malar J 2015; 14:416. [PMID: 26492873 PMCID: PMC4618886 DOI: 10.1186/s12936-015-0939-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/09/2015] [Indexed: 11/23/2022] Open
Abstract
Background Malaria morbidity and mortality has declined in recent years in a number of settings. The ability to describe changes in malaria transmission associated with these declines is important in terms of assessing the potential effects of control interventions, and for monitoring and evaluation purposes. Methods Data from five cross-sectional surveys conducted in Farafenni and surrounding villages on the north bank of River Gambia between 1988 and 2011 were compiled. Antibody responses to MSP-119 were measured in samples from all surveys, data were normalized and expressed as seroprevalence and seroconversion rates (SCR) using different mathematical models. Results Results showed declines in serological metrics with seroprevalence in children aged one to 5 years dropping from 19 % (95 % CI 15–23 %) in 1988 to 1 % (0–2 %) in 2011 (p value for trend in proportions < 0.001) and the SCR dropping from 0.069 year−1 (0.059–0.080) to 0.022 year−1 (0.017–0.028; p = 0.004). The serological data were consistent with previously described drops in both parasite prevalence in children aged 1–5 years (62 %, 57–66 %, in 1988 to 2 %, 0–4 %, in 2011; p < 0.001), and all-cause under five mortality rates (37 per 1000 person-years, 34–41, in 1990 to 17, 15–19, in 2006; p = 0.059). Conclusions This analysis shows accurate reconstruction of historical malaria transmission patterns in the Farafenni area using anti-malarial antibody responses. Demonstrating congruence between serological measures, and conventional clinical and parasitological measures suggests broader utility for serology in monitoring and evaluation of malaria transmission. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0939-1) contains supplementary material, which is available to authorized users.
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Lugaajju A, Reddy SB, Rönnberg C, Wahlgren M, Kironde F, Persson KEM. Novel flow cytometry technique for detection of Plasmodium falciparum specific B-cells in humans: increased levels of specific B-cells in ongoing infection. Malar J 2015; 14:370. [PMID: 26410225 PMCID: PMC4583755 DOI: 10.1186/s12936-015-0911-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/15/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria caused by Plasmodium falciparum is still a major health threat in endemic areas especially for children below 5 years of age. While it is recognized that antibody immunity plays an important role in controlling the disease, knowledge of the mechanisms of sustenance and natural boosting of immunity is very limited. Before, it has not been possible to investigate malaria specific B-cells directly in flow cytometry, making it difficult to know how much of a B cell response is due to malaria, or how much is due to other immunological stimulators. METHODS This study developed a technique using quantum dots and schizont extract made from ghosts of infected erythrocytes, to be able to investigate P. falciparum specific B-cells, something that has never been done before. RESULTS Major differences in P. falciparum specific B-cells were found between samples from immune (22.3 %) and non-immune (1.7 %) individuals. Samples from parasite positive individuals had the highest proportions of specific B-cells (27.9 %). CONCLUSION The study showed increased levels of P. falciparum-specific B-cells in immune individuals, with the highest levels in active malaria infections, using a new technique that opens up new possibilities to study how these cells are sustained in vivo after natural infections. It will also be useful in vaccine studies.
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Affiliation(s)
- Allan Lugaajju
- School of Biomedical Sciences, College of Health Sciences, Makerere University, Kampala, Uganda. .,Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Solna, Sweden.
| | | | - Caroline Rönnberg
- Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Solna, Sweden.
| | - Mats Wahlgren
- Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Solna, Sweden.
| | - Fred Kironde
- School of Biomedical Sciences, College of Health Sciences, Makerere University, Kampala, Uganda. .,Habib Medical School, Islamic University in Uganda, Kampala, Uganda.
| | - Kristina E M Persson
- Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Solna, Sweden. .,Department of Laboratory Medicine, Lund University, Lund, Sweden.
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Hotspots of Malaria Transmission in the Peruvian Amazon: Rapid Assessment through a Parasitological and Serological Survey. PLoS One 2015; 10:e0137458. [PMID: 26356311 PMCID: PMC4565712 DOI: 10.1371/journal.pone.0137458] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/17/2015] [Indexed: 11/29/2022] Open
Abstract
Background With low and markedly seasonal malaria transmission, increasingly sensitive tools for better stratifying the risk of infection and targeting control interventions are needed. A cross-sectional survey to characterize the current malaria transmission patterns, identify hotspots, and detect recent changes using parasitological and serological measures was conducted in three sites of the Peruvian Amazon. Material and Methods After full census of the study population, 651 participants were interviewed, clinically examined and had a blood sample taken for the detection of malaria parasites (microscopy and PCR) and antibodies against P. vivax (PvMSP119, PvAMA1) and P. falciparum (PfGLURP, PfAMA1) antigens by ELISA. Risk factors for malaria infection (positive PCR) and malaria exposure (seropositivity) were assessed by multivariate survey logistic regression models. Age-specific seroprevalence was analyzed using a reversible catalytic conversion model based on maximum likelihood for generating seroconversion rates (SCR, λ). SaTScan was used to detect spatial clusters of serology-positive individuals within each site. Results The overall parasite prevalence by PCR was low, i.e. 3.9% for P. vivax and 6.7% for P. falciparum, while the seroprevalence was substantially higher, 33.6% for P. vivax and 22.0% for P. falciparum, with major differences between study sites. Age and location (site) were significantly associated with P. vivax exposure; while location, age and outdoor occupation were associated with P. falciparum exposure. P. falciparum seroprevalence curves showed a stable transmission throughout time, while for P. vivax transmission was better described by a model with two SCRs. The spatial analysis identified well-defined clusters of P. falciparum seropositive individuals in two sites, while it detected only a very small cluster of P. vivax exposure. Conclusion The use of a single parasitological and serological malaria survey has proven to be an efficient and accurate method to characterize the species specific heterogeneity in malaria transmission at micro-geographical level as well as to identify recent changes in transmission.
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214
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Kerkhof K, Canier L, Kim S, Heng S, Sochantha T, Sovannaroth S, Vigan-Womas I, Coosemans M, Sluydts V, Ménard D, Durnez L. Implementation and application of a multiplex assay to detect malaria-specific antibodies: a promising tool for assessing malaria transmission in Southeast Asian pre-elimination areas. Malar J 2015; 14:338. [PMID: 26337785 PMCID: PMC4558921 DOI: 10.1186/s12936-015-0868-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 08/24/2015] [Indexed: 11/10/2022] Open
Abstract
Background Epidemiological surveillance is a key activity in malaria control and elimination in low-transmission and pre-elimination settings. Hence, sensitive tools for estimating malaria force of infection are crucial. Serological markers might provide additional information in estimating force of infection in low-endemic areas along with classical parasite detection methods. Serological markers can be used to estimate recent, past or present malaria exposure, depending on the used markers and their half-life. Methods An assay based on 14 Plasmodium-specific peptides, one peptide specific for Anopheles gambiae saliva protein and five Plasmodium-specific recombinant proteins was developed for the MAGPIX system, assessed for its performance, and applied on blood spots from 2000 individuals collected in the Ratanakiri Province, Cambodia. Results A significant correlation for the use of 1000 and 2000 beads/antigen/well as well as for the monoplex versus multiplex assay was observed for all antigens (p < 0.05). For the majority of antigens, antigen-coupled beads were stable for at least 2 months. The assay was very reproducible with limited intercoupling, interplate and intraplate variability (mean RSD <15 %). Estimating seroconversion and seroreversion per antigen using reversible catalytic models and models allowing two seroconversion rates showed higher seroconversion rates in adults. Conclusion The multiplex bead-based immunoassay was successfully implemented and analysis of field blood samples shows that changes detected in force of malaria infection vary according to the serological markers used. Multivariate analysis of the antibody responses and insights into the half-life of antibodies are crucial for improving the interpretation of these results and for identifying the most useful serological markers of past and recent malaria infection. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0868-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Karen Kerkhof
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. .,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
| | - Lydie Canier
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
| | - Saorin Kim
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
| | - Somony Heng
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
| | - Tho Sochantha
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
| | - Siv Sovannaroth
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
| | - Inès Vigan-Womas
- Infectious Diseases Immunology, Institut Pasteur de Madagascar, Antananarivo, Madagascar.
| | - Marc Coosemans
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. .,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
| | - Vincent Sluydts
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. .,Department of Biology, University of Antwerp, Antwerp, Belgium.
| | - Didier Ménard
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
| | - Lies Durnez
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
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215
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Abeku TA, Helinski MEH, Kirby MJ, Kefyalew T, Awano T, Batisso E, Tesfaye G, Ssekitooleko J, Nicholas S, Erdmanis L, Nalwoga A, Bass C, Cose S, Assefa A, Kebede Z, Habte T, Katamba V, Nuwa A, Bakeera-Ssali S, Akiror SC, Kyomuhangi I, Tekalegne A, Magumba G, Meek SR. Monitoring changes in malaria epidemiology and effectiveness of interventions in Ethiopia and Uganda: Beyond Garki Project baseline survey. Malar J 2015; 14:337. [PMID: 26337671 PMCID: PMC4559172 DOI: 10.1186/s12936-015-0852-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 08/16/2015] [Indexed: 11/10/2022] Open
Abstract
Background Scale-up of malaria interventions seems to have contributed to a decline in the disease but other factors may also have had some role. Understanding changes in transmission and determinant factors will help to adapt control strategies accordingly. Methods Four sites in Ethiopia and Uganda were set up to monitor epidemiological changes and effectiveness of interventions over time. Here, results of a survey during the peak transmission season of 2012 are reported, which will be used as baseline for subsequent surveys and may support adaptation of control strategies. Data on malariometric and entomological variables, socio-economic status (SES) and control coverage were collected. Results Malaria prevalence varied from 1.4 % in Guba (Ethiopia) to 9.9 % in Butemba (Uganda). The most dominant species was Plasmodium vivax in Ethiopia and Plasmodium falciparum in Uganda. The majority of human-vector contact occurred indoors in Uganda, ranging from 83 % (Anopheles funestus sensu lato) to 93 % (Anopheles gambiae s.l.), which is an important factor for the effectiveness of insecticide-treated nets (ITNs) or indoor residual spraying (IRS). High kdr-L1014S (resistance genotype) frequency was observed in A. gambiae sensu stricto in Uganda. Too few mosquitoes were collected in Ethiopia, so it was not possible to assess vector habits and insecticide resistance levels. ITN ownership did not vary by SES and 56–98 % and 68–78 % of households owned at least one ITN in Ethiopia and Uganda, respectively. In Uganda, 7 % of nets were purchased by households, but the nets were untreated. In three of the four sites, 69–76 % of people with access to ITNs used them. IRS coverage ranged from 84 to 96 % in the three sprayed sites. Half of febrile children in Uganda and three-quarters in Ethiopia for whom treatment was sought received diagnostic tests. High levels of child undernutrition were detected in both countries carrying important implications on child development. In Uganda, 7–8 % of pregnant women took the recommended minimum three doses of intermittent preventive treatment. Conclusion Malaria epidemiology seems to be changing compared to earlier published data, and it is essential to have more data to understand how much of the changes are attributable to interventions and other factors. Regular monitoring will help to better interpret changes, identify determinants, modify strategies and improve targeting to address transmission heterogeneity.
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Affiliation(s)
| | | | - Matthew J Kirby
- Malaria Consortium, London, UK. .,London School of Hygiene & Tropical Medicine, London, UK.
| | | | | | | | | | | | | | - Laura Erdmanis
- Malaria Consortium, London, UK. .,Rothamsted Research, Harpenden, UK.
| | - Angela Nalwoga
- Medical Research Council/Uganda Virus Research Institute, Uganda Research Unit on AIDS, Entebbe, Uganda.
| | | | - Stephen Cose
- Medical Research Council/Uganda Virus Research Institute, Uganda Research Unit on AIDS, Entebbe, Uganda. .,London School of Hygiene & Tropical Medicine, London, UK.
| | | | | | - Tedila Habte
- Malaria Consortium, Addis Ababa, Ethiopia. .,South Nations, Nationalities and Peoples Regional Health Bureaux, Hawassa, Ethiopia.
| | - Vincent Katamba
- National Malaria Control Programme, Ministry of Health, Kampala, Uganda.
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216
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Helb DA, Tetteh KKA, Felgner PL, Skinner J, Hubbard A, Arinaitwe E, Mayanja-Kizza H, Ssewanyana I, Kamya MR, Beeson JG, Tappero J, Smith DL, Crompton PD, Rosenthal PJ, Dorsey G, Drakeley CJ, Greenhouse B. Novel serologic biomarkers provide accurate estimates of recent Plasmodium falciparum exposure for individuals and communities. Proc Natl Acad Sci U S A 2015; 112:E4438-47. [PMID: 26216993 PMCID: PMC4538641 DOI: 10.1073/pnas.1501705112] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Tools to reliably measure Plasmodium falciparum (Pf) exposure in individuals and communities are needed to guide and evaluate malaria control interventions. Serologic assays can potentially produce precise exposure estimates at low cost; however, current approaches based on responses to a few characterized antigens are not designed to estimate exposure in individuals. Pf-specific antibody responses differ by antigen, suggesting that selection of antigens with defined kinetic profiles will improve estimates of Pf exposure. To identify novel serologic biomarkers of malaria exposure, we evaluated responses to 856 Pf antigens by protein microarray in 186 Ugandan children, for whom detailed Pf exposure data were available. Using data-adaptive statistical methods, we identified combinations of antibody responses that maximized information on an individual's recent exposure. Responses to three novel Pf antigens accurately classified whether an individual had been infected within the last 30, 90, or 365 d (cross-validated area under the curve = 0.86-0.93), whereas responses to six antigens accurately estimated an individual's malaria incidence in the prior year. Cross-validated incidence predictions for individuals in different communities provided accurate stratification of exposure between populations and suggest that precise estimates of community exposure can be obtained from sampling a small subset of that community. In addition, serologic incidence predictions from cross-sectional samples characterized heterogeneity within a community similarly to 1 y of continuous passive surveillance. Development of simple ELISA-based assays derived from the successful selection strategy outlined here offers the potential to generate rich epidemiologic surveillance data that will be widely accessible to malaria control programs.
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Affiliation(s)
- Danica A Helb
- Department of Medicine, University of California, San Francisco, CA 94110; Division of Infectious Diseases, School of Public Health, University of California, Berkeley, CA 94720; Global Health Group, University of California, San Francisco, CA 94158
| | - Kevin K A Tetteh
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Philip L Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA 92697
| | - Jeff Skinner
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20852
| | - Alan Hubbard
- Division of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720
| | | | - Harriet Mayanja-Kizza
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Moses R Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - James G Beeson
- Center for Biomedical Research, Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Canada 3004
| | - Jordan Tappero
- Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30333
| | - David L Smith
- Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom; Sanaria Institute for Global Health and Tropical Medicine, Rockville, MD 20850
| | - Peter D Crompton
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20852
| | - Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, CA 94110
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA 94110
| | - Christopher J Drakeley
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, CA 94110;
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217
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Drame PM, Poinsignon A, Dechavanne C, Cottrell G, Farce M, Ladekpo R, Massougbodji A, Cornélie S, Courtin D, Migot-Nabias F, Garcia A, Remoué F. Specific antibodies to Anopheles gSG6-P1 salivary peptide to assess early childhood exposure to malaria vector bites. Malar J 2015. [PMID: 26198354 PMCID: PMC4511589 DOI: 10.1186/s12936-015-0800-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Background The estimates of risk of malaria in early childhood are imprecise given the current entomologic and parasitological tools. Thus, the utility of anti-Anopheles salivary gSG6-P1 peptide antibody responses in measuring exposure to Anopheles bites during early infancy has been assessed. Methods Anti-gSG6-P1 IgG and IgM levels were evaluated in 133 infants (in Benin) at three (M3), six (M6), nine (M9) and 12 (M12) months of age. Specific IgG levels were also assessed in their respective umbilical cord blood (IUCB) and maternal blood (MPB). Results At M3, 93.98 and 41.35% of infants had anti-gSG6-P1 IgG and IgM Ab, respectively. Specific median IgG and IgM levels gradually increased between M3 and M6 (p < 0.0001 and p < 0.001), M6–M9 (p < 0.0001 and p = 0.085) and M9–M12 (p = 0.002 and p = 0.03). These levels were positively associated with the Plasmodium falciparum infection intensity (p = 0.006 and 0.003), and inversely with the use of insecticide-treated bed nets (p = 0.003 and 0.3). Levels of specific IgG in the MPB were positively correlated to those in the IUCB (R = 0.73; p < 0.0001) and those at M3 (R = 0.34; p < 0.0001). Conclusion The exposure level to Anopheles bites, and then the risk of malaria infection, can be evaluated in young infants by assessing anti-gSG6-P1 IgM and IgG responses before and after 6-months of age, respectively. This tool can be useful in epidemiological evaluation and surveillance of malaria risk during the first year of life.
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Affiliation(s)
- Papa M Drame
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), BP64501, 34394, Montpellier, France. .,IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), 01 BP 4414RP, Cotonou, Benin. .,Laboratory of Parasitic Diseases, NIAID, NIH, 4 Center Dr, Bethesda, MD, 20892-0425, USA.
| | - Anne Poinsignon
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), BP64501, 34394, Montpellier, France.
| | - Célia Dechavanne
- IRD UMR 216 Mère et enfant face aux infections tropicales, 75006, Paris, France. .,Faculté de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France.
| | - Gilles Cottrell
- IRD UMR 216 Mère et enfant face aux infections tropicales, 75006, Paris, France. .,Laboratoire de Mathématiques Appliquées, Université Paris Descartes, 75006, Paris, France.
| | - Manon Farce
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), BP64501, 34394, Montpellier, France.
| | - Rodolphe Ladekpo
- Centre d'Etudes et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfant (CERPAGE), Cotonou, Benin.
| | - Achille Massougbodji
- Centre d'Etudes et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfant (CERPAGE), Cotonou, Benin. .,Faculté des Sciences de la Santé, Université d'Abomey-Calavi, 01 BP 188, Cotonou, Benin.
| | - Sylvie Cornélie
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), BP64501, 34394, Montpellier, France.
| | - David Courtin
- IRD UMR 216 Mère et enfant face aux infections tropicales, 75006, Paris, France. .,Faculté de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France. .,Centre d'Etudes et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfant (CERPAGE), Cotonou, Benin.
| | - Florence Migot-Nabias
- IRD UMR 216 Mère et enfant face aux infections tropicales, 75006, Paris, France. .,Faculté de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France.
| | - André Garcia
- IRD UMR 216 Mère et enfant face aux infections tropicales, 75006, Paris, France. .,Faculté de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, 75006, Paris, France.
| | - Franck Remoué
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), BP64501, 34394, Montpellier, France. .,IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), 01 BP 4414RP, Cotonou, Benin.
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Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal. Malar J 2015; 14:275. [PMID: 26173958 PMCID: PMC4502940 DOI: 10.1186/s12936-015-0789-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 07/01/2015] [Indexed: 11/13/2022] Open
Abstract
Background In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. Methods Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. Results A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. Conclusion The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate intervention efforts. Trial registration number: PACTR201305000551876 (http://www.pactr.org).
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219
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Chitunhu S, Musenge E. Direct and indirect determinants of childhood malaria morbidity in Malawi: a survey cross-sectional analysis based on malaria indicator survey data for 2012. Malar J 2015; 14:265. [PMID: 26152223 PMCID: PMC4495946 DOI: 10.1186/s12936-015-0777-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/29/2015] [Indexed: 01/06/2023] Open
Abstract
Background Children under the age of five are most vulnerable to malaria (malaria is a major health challenge in sub-Saharan Africa) with a child dying every 30 s from malaria. Hampered socio-economic development, poverty, diseconomies of scale, marginalization, and exploitation are associated with malaria. Therefore establishing determinants of malaria in affected sub-Saharan populations is important in order to come up with informed interventions that will be effective in malaria control. Methods The study was a cross-sectional survey design based on data from the Malawi 2012 Malaria indicator Survey obtained from Demographic and Health Survey (DHS) programme website. The outcome variable was positive laboratory-based blood smear result for malaria in children less than 5 years, after an initial positive rapid malaria diagnostic test done at the homestead. Statistical modelling was done using survey logistic regression as well as generalized structural equation modelling (G-SEM) to analyse direct and indirect effects of malaria. Results The propensity score matched data had 1 325 children with 367 (27.7%) having blood smear positive malaria. Female children made up approximately 53% of the total study participants. Child related variables (age, haemoglobin and position in household) and household wealth index were significant directly and indirectly. Further on G-SEM based multivariable analysis showed socio-economic status (SES) [Odds ratio (OR) = 0.96, 95% Confidence interval (CI) = 0.92, 0.99] and primary level of education [OR = 0.50, 95% CI = 0.32, 0.77] were important direct and indirect determinants of malaria morbidity. Conclusion Socio-economic status and education are important factors that influence malaria control. These factors need to be taken into consideration when planning malaria control programmes in order to have effective programmes. Direct and indirect effect modelling can also provide an alternative modelling technique that incorporates surrogate confounders that may not be significant when modelled directly. This holistic approach is useful and will help in improving malaria control.
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Affiliation(s)
- Simangaliso Chitunhu
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg, 2193, South Africa.
| | - Eustasius Musenge
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg, 2193, South Africa.
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McLEAN ARD, ATAIDE R, SIMPSON JA, BEESON JG, FOWKES FJI. Malaria and immunity during pregnancy and postpartum: a tale of two species. Parasitology 2015; 142:999-1015. [PMID: 25731914 PMCID: PMC4453920 DOI: 10.1017/s0031182015000074] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/19/2014] [Accepted: 01/16/2015] [Indexed: 11/07/2022]
Abstract
It is well established that pregnant women are at an increased risk of Plasmodium falciparum infection when compared to non-pregnant individuals and limited epidemiological data suggest Plasmodium vivax risk also increases with pregnancy. The risk of P. falciparum declines with successive pregnancies due to the acquisition of immunity to pregnancy-specific P. falciparum variants. However, despite similar declines in P. vivax risk with successive pregnancies, there is a paucity of evidence P. vivax-specific immunity. Cross-species immunity, as well as immunological and physiological changes that occur during pregnancy may influence the susceptibility to both P. vivax and P. falciparum. The period following delivery, the postpartum period, is relatively understudied and available epidemiological data suggests that it may also be a period of increased risk of infection to Plasmodium spp. Here we review the literature and directly compare and contrast the epidemiology, clinical pathogenesis and immunological features of P. vivax and P. falciparum in pregnancy, with a particular focus on studies performed in areas co-endemic for both species. Furthermore, we review the intriguing epidemiology literature of both P. falciparum and P. vivax postpartum and relate observations to the growing literature pertaining to malaria immunology in the postpartum period.
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Affiliation(s)
- A. R. D. McLEAN
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - R. ATAIDE
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
| | - J. A. SIMPSON
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - J. G. BEESON
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - F. J. I. FOWKES
- Macfarlane Burnet Institute of Medical Research, 85 Commercial Road, Melbourne, Victoria 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Epidemiology and Preventive Medicine and Department of Infectious Diseases, Monash University, Commercial Road, Melbourne, Victoria 3004, Australia
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Ceesay SJ, Koivogui L, Nahum A, Taal MA, Okebe J, Affara M, Kaman LE, Bohissou F, Agbowai C, Tolno BG, Amambua-Ngwa A, Bangoura NF, Ahounou D, Muhammad AK, Duparc S, Hamed K, Ubben D, Bojang K, Achan J, D'Alessandro U. Malaria Prevalence among Young Infants in Different Transmission Settings, Africa. Emerg Infect Dis 2015; 21:1114-21. [PMID: 26079062 PMCID: PMC4480393 DOI: 10.3201/eid2107.142036] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The prevalence and consequences of malaria among infants are not well characterized and may be underestimated. A better understanding of the risk for malaria in early infancy is critical for drug development and informed decision making. In a cross-sectional survey in Guinea, The Gambia, and Benin, countries with different malaria transmission intensities, the overall prevalence of malaria among infants <6 months of age was 11.8% (Guinea, 21.7%; The Gambia, 3.7%; and Benin, 10.2%). Seroprevalence ranged from 5.7% in The Gambia to 41.6% in Guinea. Mean parasite densities in infants were significantly lower than those in children 1-9 years of age in The Gambia (p<0.0001) and Benin (p = 0.0021). Malaria in infants was significantly associated with fever or recent history of fever (p = 0.007) and anemia (p = 0.001). Targeted preventive interventions, adequate drug formulations, and treatment guidelines are needed to address the sizeable prevalence of malaria among young infants in malaria-endemic countries.
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Affiliation(s)
- Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, CA 94143;
| | - David L Smith
- Sanaria Institute for Global Health and Tropical Medicine, Rockville, MD 20850; and Spatial Ecology and Epidemiology Group, Department of Zoology, Oxford University, Oxford OX1 3PS, United Kingdom
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223
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Stresman GH, Baidjoe AY, Stevenson J, Grignard L, Odongo W, Owaga C, Osoti V, Makori E, Shagari S, Marube E, Cox J, Drakeley C, Bousema T. Focal Screening to Identify the Subpatent Parasite Reservoir in an Area of Low and Heterogeneous Transmission in the Kenya Highlands. J Infect Dis 2015; 212:1768-77. [PMID: 26019285 DOI: 10.1093/infdis/jiv302] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/14/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Mass screening and treatment currently fails to identify a considerable fraction of low parasite density infections, while mass treatment exposes many uninfected individuals to antimalarial drugs. Here we test a hybrid approach to screen a sentinel population to identify clusters of subpatent infections in the Kenya highlands with low, heterogeneous malaria transmission. METHODS Two thousand eighty-two inhabitants were screened for parasitemia by nested polymerase chain reaction (nPCR). Children aged ≤ 15 years and febrile adults were also tested for malaria by rapid diagnostic test (RDT) and served as sentinel members to identify subpatent infections within the household. All parasitemic individuals were assessed for multiplicity of infections by nPCR and gametocyte carriage by nucleic acid sequence-based amplification. RESULTS Households with RDT-positive individuals in the sentinel population were more likely to have nPCR-positive individuals (odds ratio: 1.71, 95% confidence interval, 1.60-1.84). The sentinel population identified 64.5% (locality range: 31.6%-81.2%) of nPCR-positive households and 77.3% (locality range: 24.2%-91.0%) of nPCR-positive individuals. The sensitivity of the sentinel screening approach was positively associated with transmission intensity (P = .037). CONCLUSIONS In this low endemic area, a focal screening approach with RDTs prior to the high transmission season was able to identify the majority of the subpatent parasite reservoirs.
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Affiliation(s)
- Gillian H Stresman
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | | | - Jennifer Stevenson
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Lynn Grignard
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Wycliffe Odongo
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Chrispin Owaga
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Victor Osoti
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Euniah Makori
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Shehu Shagari
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Elisabeth Marube
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Jonathan Cox
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Chris Drakeley
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Teun Bousema
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom Radboud University Nijmegen Medical Centre, The Netherlands
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Piperaki ET, Mavrouli M, Tseroni M, Routsias J, Kallimani A, Veneti L, Georgitsou M, Chania M, Georgakopoulou T, Hadjichristodoulou C, Tsakris A. Assessment of antibody responses in local and immigrant residents of areas with autochthonous malaria transmission in Greece. Am J Trop Med Hyg 2015; 93:153-8. [PMID: 26013377 DOI: 10.4269/ajtmh.14-0420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 02/01/2015] [Indexed: 11/07/2022] Open
Abstract
Greece has been officially malaria free since 1974. However, from 2009 to 2012, several locally acquired, cases of Plasmodium vivax malaria were detected, in immigrants and in Greek citizens. In this study, the antibody (Ab) response of Greeks and immigrants with documented malaria was initially assessed, followed by an Ab screening of Greeks and immigrant residents of local transmission areas. Of the 38 patients tested, 10.5% of Greeks and 15.7% of immigrants were positive 5-7 months after infection. Of the 1,019 individuals from various areas of Greece, including those of autochthonous transmission, 85 of the 721 (11.8%) immigrants were positive, whereas all 298 Greeks were negative. The rapid Ab titer decline observed is reasonable, given the non-endemic epidemiological setting. The seroepidemiological findings indicate that the local Greek population remains malaria naive and that at this point Greeks are unlikely to serve as reservoir for the infection of local mosquitoes.
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Affiliation(s)
- Evangelia-Theofano Piperaki
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Maria Mavrouli
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Maria Tseroni
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - John Routsias
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Athina Kallimani
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Lamprini Veneti
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Maria Georgitsou
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Maria Chania
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Theano Georgakopoulou
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Christos Hadjichristodoulou
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
| | - Athanassios Tsakris
- Department of Microbiology, Medical School, University of Athens, Athens, Greece; Hellenic Center for Disease Control and Prevention (HCDCP), Athens, Greece; General Hospital of Sparti, Sparti, Greece; Department of Hygiene and Epidemiology, Medical School, University of Thessaly, Larissa, Greece
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225
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Immunoprofiling of the tryptophan-rich antigen family in Plasmodium vivax. Infect Immun 2015; 83:3083-95. [PMID: 25987709 DOI: 10.1128/iai.03067-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/12/2015] [Indexed: 11/20/2022] Open
Abstract
Tryptophan-rich antigens (TRAgs) are an antigen family that has been identified in human and rodent malaria parasites. TRAgs have been proposed as candidate antigens for potential vaccines. The Plasmodium vivax TRAg (PvTRAg) family includes 36 members. Each PvTRAg contains a tryptophan-rich (TR) domain in the C-terminal region. In this study, we recombinantly expressed all 36 PvTRAgs using a cell-free expression system, and, for the first time, profiled the IgG antibody responses against all PvTRAgs in the sera from 96 vivax malaria patients and 40 healthy individuals using protein microarray technology. The mean seropositive rate for all PvTRAgs was 60.3%. Among them, nine PvTRAgs were newly identified in this study and showed a seropositive rate of >50%. Five of them, PvTRAg_13, PvTRAg_15, PvTRAg_16, PvTRAg_26, and PvTRAg_29, produced higher levels of IgG antibody, even in low-endemicity countries. In addition, the results of an immunofluorescence analysis suggest that PvTRAgs are, at least in part, associated with caveola-vesicle complexes, a unique structure of P. vivax-infected erythrocytes. The mechanism of formation and the function of these abundant membrane structures are not known. Further investigation aimed at determining the functions of these proteins would lead to a better understanding of the blood-stage biology of P. vivax.
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226
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Ashton RA, Kefyalew T, Rand A, Sime H, Assefa A, Mekasha A, Edosa W, Tesfaye G, Cano J, Teka H, Reithinger R, Pullan RL, Drakeley CJ, Brooker SJ. Geostatistical modeling of malaria endemicity using serological indicators of exposure collected through school surveys. Am J Trop Med Hyg 2015; 93:168-177. [PMID: 25962770 PMCID: PMC4497890 DOI: 10.4269/ajtmh.14-0620] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 02/25/2015] [Indexed: 11/23/2022] Open
Abstract
Ethiopia has a diverse ecology and geography resulting in spatial and temporal variation in malaria transmission. Evidence-based strategies are thus needed to monitor transmission intensity and target interventions. A purposive selection of dried blood spots collected during cross-sectional school-based surveys in Oromia Regional State, Ethiopia, were tested for presence of antibodies against Plasmodium falciparum and P. vivax antigens. Spatially explicit binomial models of seroprevalence were created for each species using a Bayesian framework, and used to predict seroprevalence at 5 km resolution across Oromia. School seroprevalence showed a wider prevalence range than microscopy for both P. falciparum (0–50% versus 0–12.7%) and P. vivax (0–53.7% versus 0–4.5%), respectively. The P. falciparum model incorporated environmental predictors and spatial random effects, while P. vivax seroprevalence first-order trends were not adequately explained by environmental variables, and a spatial smoothing model was developed. This is the first demonstration of serological indicators being used to detect large-scale heterogeneity in malaria transmission using samples from cross-sectional school-based surveys. The findings support the incorporation of serological indicators into periodic large-scale surveillance such as Malaria Indicator Surveys, and with particular utility for low transmission and elimination settings.
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Affiliation(s)
- Ruth A. Ashton
- *Address correspondence to Ruth A. Ashton, Malaria Consortium, Development House, 56-64 Leonard Street, London. E-mail:
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Subramaniam KS, Skinner J, Ivan E, Mutimura E, Kim RS, Feintuch CM, Portugal S, Anastos K, Crompton PD, Daily JP. HIV Malaria Co-Infection Is Associated with Atypical Memory B Cell Expansion and a Reduced Antibody Response to a Broad Array of Plasmodium falciparum Antigens in Rwandan Adults. PLoS One 2015; 10:e0124412. [PMID: 25928218 PMCID: PMC4415913 DOI: 10.1371/journal.pone.0124412] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/13/2015] [Indexed: 11/18/2022] Open
Abstract
HIV infected individuals in malaria endemic areas experience more frequent and severe malaria episodes compared to non HIV infected. This clinical observation has been linked to a deficiency in antibody responses to Plasmodium falciparum antigens; however, prior studies have only focused on the antibody response to <0.5% of P. falciparum proteins. To obtain a broader and less-biased view of the effect of HIV on antibody responses to malaria we compared antibody profiles of HIV positive (HIV+) and negative (HIV-) Rwandan adults with symptomatic malaria using a microarray containing 824 P. falciparum proteins. We also investigated the cellular basis of the antibody response in the two groups by analyzing B and T cell subsets by flow cytometry. Although HIV malaria co-infected individuals generated antibodies to a large number of P. falciparum antigens, including potential vaccine candidates, the breadth and magnitude of their response was reduced compared to HIV- individuals. HIV malaria co-infection was also associated with a higher percentage of atypical memory B cells (MBC) (CD19+CD10-CD21-CD27-) compared to malaria infection alone. Among HIV+ individuals the CD4+ T cell count and HIV viral load only partially explained variability in the breadth of P. falciparum-specific antibody responses. Taken together, these data indicate that HIV malaria co-infection is associated with an expansion of atypical MBCs and a diminished antibody response to a diverse array of P. falciparum antigens, thus offering mechanistic insight into the higher risk of malaria in HIV+ individuals.
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Affiliation(s)
- Krishanthi S. Subramaniam
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Jeff Skinner
- Malaria Infection Biology and Immunity Unit, Laboratory of Immunogenetics, NIAID/NIH, Bethesda, Maryland, United States of America
| | - Emil Ivan
- Department of Biomedical Laboratory Sciences, University of Rwanda, College of Medicine and Health Sciences, Kigali, Rwanda
| | - Eugene Mutimura
- Regional Alliance for Sustainable Development, Kigali, Rwanda
| | - Ryung S. Kim
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Catherine M. Feintuch
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Silvia Portugal
- Malaria Infection Biology and Immunity Unit, Laboratory of Immunogenetics, NIAID/NIH, Bethesda, Maryland, United States of America
| | - Kathryn Anastos
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Peter D. Crompton
- Malaria Infection Biology and Immunity Unit, Laboratory of Immunogenetics, NIAID/NIH, Bethesda, Maryland, United States of America
| | - Johanna P. Daily
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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228
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Hodgson SH, Juma E, Salim A, Magiri C, Njenga D, Molyneux S, Njuguna P, Awuondo K, Lowe B, Billingsley PF, Cole AO, Ogwang C, Osier F, Chilengi R, Hoffman SL, Draper SJ, Ogutu B, Marsh K. Lessons learnt from the first controlled human malaria infection study conducted in Nairobi, Kenya. Malar J 2015; 14:182. [PMID: 25927522 PMCID: PMC4416324 DOI: 10.1186/s12936-015-0671-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/15/2015] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Controlled human malaria infection (CHMI) studies, in which healthy volunteers are infected with Plasmodium falciparum to assess the efficacy of novel malaria vaccines and drugs, have become a vital tool to accelerate vaccine and drug development. CHMI studies provide a cost-effective and expeditious way to circumvent the use of large-scale field efficacy studies to deselect intervention candidates. However, to date few modern CHMI studies have been performed in malaria-endemic countries. METHODS An open-label, randomized pilot CHMI study was conducted using aseptic, purified, cryopreserved, infectious P. falciparum sporozoites (SPZ) (Sanaria® PfSPZ Challenge) administered intramuscularly (IM) to healthy Kenyan adults (n = 28) with varying degrees of prior exposure to P. falciparum. The purpose of the study was to establish the PfSPZ Challenge CHMI model in a Kenyan setting with the aim of increasing the international capacity for efficacy testing of malaria vaccines and drugs, and allowing earlier assessment of efficacy in a population for which interventions are being developed. This was part of the EDCTP-funded capacity development of the CHMI platform in Africa. DISCUSSION This paper discusses in detail lessons learnt from conducting the first CHMI study in Kenya. Issues pertinent to the African setting, including community sensitization, consent and recruitment are considered. Detailed reasoning regarding the study design (for example, dose and route of administration of PfSPZ Challenge, criteria for grouping volunteers according to prior exposure to malaria and duration of follow-up post CHMI) are given and changes other centres may want to consider for future studies are suggested. CONCLUSIONS Performing CHMI studies in an African setting presents unique but surmountable challenges and offers great opportunity for acceleration of malaria vaccine and drug development. The reflections in this paper aim to aid other centres and partners intending to use the CHMI model in Africa.
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Affiliation(s)
| | - Elizabeth Juma
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya.
- Centre for Research in Therapeutic Sciences, Strathmore University, Nairobi, Kenya.
| | - Amina Salim
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Charles Magiri
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Daniel Njenga
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Sassy Molyneux
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Patricia Njuguna
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Ken Awuondo
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Brett Lowe
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | | | - Andrew O Cole
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya.
- Centre for Research in Therapeutic Sciences, Strathmore University, Nairobi, Kenya.
| | - Caroline Ogwang
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Faith Osier
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
| | - Roma Chilengi
- Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.
| | | | | | - Bernhards Ogutu
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya.
- Centre for Research in Therapeutic Sciences, Strathmore University, Nairobi, Kenya.
| | - Kevin Marsh
- Kenya Medical Research Institute - Wellcome Trust, Centre for Geographical Medical Research (Coast), Kilifi, Kenya.
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Badu K, Gyan B, Appawu M, Mensah D, Dodoo D, Yan G, Drakeley C, Zhou G, Owusu-Dabo E, Koram KA. Serological evidence of vector and parasite exposure in Southern Ghana: the dynamics of malaria transmission intensity. Parasit Vectors 2015; 8:251. [PMID: 25928847 PMCID: PMC4418069 DOI: 10.1186/s13071-015-0861-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/15/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Seroepidemiology provides robust estimates for tracking malaria transmission when intensity is low and useful when there is no baseline entomological data. Serological evidence of exposure to malaria vectors and parasite contribute to our understanding of the risk of pathogen transmission, and facilitates implementation of targeted interventions. Ab to Anopheles gambiae salivary peptide (gSG6-P1) and merozoite surface protein one (MSP-1(19)) reflect human exposure to malaria vectors and parasites. This study estimated malaria transmission dynamics using serological evidence of vector and parasite exposure in southern Ghana. METHODS Total IgG responses to both antigens in an age stratified cohort (<5, 5-14, >14) were measured from South-eastern Ghana. 295 randomly selected sera were analyzed from archived samples belonging to a cohort study that were followed at 3 consecutive survey months (n = 885); February, May and August 2009. Temporal variations in seroprevalence of both antigens as well as differences between the age-stratified cohorts were determined by χ (2) test with p < 0.05 statistically significant. Non-parametric repeated ANOVA - Friedman's test was used to test differences in antibody levels. Seroprevalence data were fitted to reversible catalytic model to estimate sero-conversion rates. RESULTS Whereas parasite prevalence was generally low 2.4%, 2.7% and 2.4% with no apparent trends with season, seroprevalence to both gSG6-P1 and MSP1(19) were high (59%, 50.9%, 52.2%) and 57.6%, 52.3% and 43.6% in respective order from Feb. to August. Repeated measures ANOVA showed differences in median antibody levels across surveys with specific significant differences between February and May but not August by post hoc Dunn's multiple comparison tests for gSG6-P1. For MSP1(19), no differences were observed in antibody levels between February and May but a significant decline was observed from May to August. Seroconversion rates for gSG6-P1 increased by 1.5 folds from February to August and 3 folds for MSP1(19). CONCLUSION Data suggests exposure to infectious bites may be declining whereas mosquito bites remains high. Sustained malaria control efforts and surveillance are needed to drive malaria further down and to prevent catastrophic rebound. Operational factors for scaling up have been discussed.
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Affiliation(s)
- Kingsley Badu
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
| | - Ben Gyan
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
| | - Maxwell Appawu
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
| | - Daniel Mensah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
| | - Daniel Dodoo
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
| | - Guiyun Yan
- Program in Public Health, Room 3038, Hewitt Hall, College of Health Science, University of California, Irvine, CA, 92697-4050, USA.
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, UK.
| | - Guofa Zhou
- Program in Public Health, Room 3038, Hewitt Hall, College of Health Science, University of California, Irvine, CA, 92697-4050, USA.
| | - Ellis Owusu-Dabo
- Kumasi Centre for Collaborative Research in Tropical Medicine, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Kwadwo Ansah Koram
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Science University of Ghana, LG581, , Legon, Accra, Ghana.
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Dent AE, Nakajima R, Liang L, Baum E, Moormann AM, Sumba PO, Vulule J, Babineau D, Randall A, Davies DH, Felgner PL, Kazura JW. Plasmodium falciparum Protein Microarray Antibody Profiles Correlate With Protection From Symptomatic Malaria in Kenya. J Infect Dis 2015; 212:1429-38. [PMID: 25883384 DOI: 10.1093/infdis/jiv224] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/25/2015] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Immunoglobulin G antibodies (Abs) to Plasmodium falciparum antigens have been associated with naturally acquired immunity to symptomatic malaria. METHODS We probed protein microarrays covering 824 unique P. falciparum protein features with plasma from residents of a community in Kenya monitored for 12 weeks for (re)infection and symptomatic malaria after administration of antimalarial drugs. P. falciparum proteins recognized by Abs from 88 children (aged 1-14 years) and 86 adults (aged ≥ 18 years), measured at the beginning of the observation period, were ranked by Ab signal intensity. RESULTS Abs from immune adults reacted with a total 163 of 824 P. falciparum proteins. Children gradually acquired Abs to the full repertoire of antigens recognized by adults. Abs to some antigens showed high seroconversion rates, reaching maximal levels early in childhood, whereas others did not reach adult levels until adolescence. No correlation between Ab signal intensity and time to (re)infection was observed. In contrast, Ab levels to 106 antigens were significantly higher in children who were protected from symptomatic malaria compared with those who were not. Abs to antigens predictive of protection included P. falciparum erythrocyte membrane protein 1, merozoite surface protein (MSP) 10, MSP2, liver-stage antigen 3, PF70, MSP7, and Plasmodium helical interspersed subtelomeric domain protein. CONCLUSIONS Protein microarrays may be useful in the search for malaria antigens associated with protective immunity.
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Affiliation(s)
- Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University Rainbow Babies and Children's Hospital, Cleveland, Ohio
| | | | - Li Liang
- University of California, Irvine
| | | | - Ann M Moormann
- Center for Global Health Research, University of Massachusetts Medical School, Worcester
| | | | | | | | | | | | | | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University
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Jones S, Grignard L, Nebie I, Chilongola J, Dodoo D, Sauerwein R, Theisen M, Roeffen W, Singh SK, Singh RK, Singh S, Kyei-Baafour E, Tetteh K, Drakeley C, Bousema T. Naturally acquired antibody responses to recombinant Pfs230 and Pfs48/45 transmission blocking vaccine candidates. J Infect 2015; 71:117-27. [PMID: 25869538 DOI: 10.1016/j.jinf.2015.03.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 03/13/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Pfs48/45 and Pfs230 are Plasmodium falciparum sexual stage proteins and promising malaria transmission-blocking vaccine candidates. Antibody responses against these proteins may be naturally acquired and target antigens may be under selective pressure. This has consequences for the future evaluation of vaccine immunogenicity and efficacy in populations naturally exposed to malaria. METHODS We determined naturally acquired antibody responses to the recombinant proteins Pfs48/45-10C and Pfs230-230CMB in children from three malaria endemic settings in Ghana, Tanzania and Burkina Faso. We also examined genetic polymorphisms in the P. falciparum gene pfs48/45. RESULTS Antibody prevalence was 1.1-18.2% for 10C and 6.7-18.9% for 230CMB. In Burkina Faso we observed evidence of an age-dependent acquisition pattern for both 10C (p < 0.001) and 230CMB (p = 0.031). Membrane feeding assays on a separate dataset demonstrated an association between functional transmission reducing activity and antibody prevalence for both 10C (p = 0.017) and 230CMB (p = 0.049). 17 single nucleotide polymorphisms were found in pfs48/45 (from 126 samples), with 5 non-synonymous SNPs in the Pfs48/45 10C region. CONCLUSIONS We conclude there are naturally acquired antibody responses to both vaccine candidates which have functional relevance by reducing the transmissibility of infected individuals. We identified genetic polymorphisms, in pfs48/45 which exhibited geographical specificity.
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Affiliation(s)
- Sophie Jones
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Lynn Grignard
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Issa Nebie
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Daniel Dodoo
- Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michael Theisen
- Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institut, Copenhagen, Denmark; Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Will Roeffen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Sanjay Singh
- Gennova Bio Pharmaceuticals Limited, Pune, India
| | - Eric Kyei-Baafour
- Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Kevin Tetteh
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom; Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
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Sepúlveda N, Drakeley C. Sample size determination for estimating antibody seroconversion rate under stable malaria transmission intensity. Malar J 2015; 14:141. [PMID: 25889960 PMCID: PMC4419413 DOI: 10.1186/s12936-015-0661-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 03/16/2015] [Indexed: 11/10/2022] Open
Abstract
Background In the last decade, several epidemiological studies have demonstrated the potential of using seroprevalence (SP) and seroconversion rate (SCR) as informative indicators of malaria burden in low transmission settings or in populations on the cusp of elimination. However, most of studies are designed to control ensuing statistical inference over parasite rates and not on these alternative malaria burden measures. SP is in essence a proportion and, thus, many methods exist for the respective sample size determination. In contrast, designing a study where SCR is the primary endpoint, is not an easy task because precision and statistical power are affected by the age distribution of a given population. Methods Two sample size calculators for SCR estimation are proposed. The first one consists of transforming the confidence interval for SP into the corresponding one for SCR given a known seroreversion rate (SRR). The second calculator extends the previous one to the most common situation where SRR is unknown. In this situation, data simulation was used together with linear regression in order to study the expected relationship between sample size and precision. Results The performance of the first sample size calculator was studied in terms of the coverage of the confidence intervals for SCR. The results pointed out to eventual problems of under or over coverage for sample sizes ≤250 in very low and high malaria transmission settings (SCR ≤ 0.0036 and SCR ≥ 0.29, respectively). The correct coverage was obtained for the remaining transmission intensities with sample sizes ≥ 50. Sample size determination was then carried out for cross-sectional surveys using realistic SCRs from past sero-epidemiological studies and typical age distributions from African and non-African populations. For SCR < 0.058, African studies require a larger sample size than their non-African counterparts in order to obtain the same precision. The opposite happens for the remaining transmission intensities. With respect to the second sample size calculator, simulation unravelled the likelihood of not having enough information to estimate SRR in low transmission settings (SCR ≤ 0.0108). In that case, the respective estimates tend to underestimate the true SCR. This problem is minimized by sample sizes of no less than 500 individuals. The sample sizes determined by this second method highlighted the prior expectation that, when SRR is not known, sample sizes are increased in relation to the situation of a known SRR. In contrast to the first sample size calculation, African studies would now require lesser individuals than their counterparts conducted elsewhere, irrespective of the transmission intensity. Conclusions Although the proposed sample size calculators can be instrumental to design future cross-sectional surveys, the choice of a particular sample size must be seen as a much broader exercise that involves weighting statistical precision with ethical issues, available human and economic resources, and possible time constraints. Moreover, if the sample size determination is carried out on varying transmission intensities, as done here, the respective sample sizes can also be used in studies comparing sites with different malaria transmission intensities. In conclusion, the proposed sample size calculators are a step towards the design of better sero-epidemiological studies. Their basic ideas show promise to be applied to the planning of alternative sampling schemes that may target or oversample specific age groups. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0661-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nuno Sepúlveda
- London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK. .,Center of Statistics and Applications of University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Bloco C6 - Piso 4, 1749-1016, Lisboa, Portugal.
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK.
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Daou M, Kituma E, Kavishe R, Chilongola J, Mosha F, van der Ven A, Kouriba B, Bousema T, Sauerwein R, Doumbo O. α-Thalassaemia trait is associated with antibody prevalence against malaria antigens AMA-1 and MSP-1. J Trop Pediatr 2015; 61:139-42. [PMID: 25604491 DOI: 10.1093/tropej/fmu077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
A longitudinal study was conducted in a low endemic area in northern Tanzania to examine the influence of the α-thalassaemia trait on malaria incidence and antibody responses to malaria apical membrane antigen-1 (AMA-1) and merozoite surface protein1-19 (MSP-119). Out of 394 children genotyped for α-thalassaemia trait, 4.1% (16 of 394) and 30.7% (121 of 394) were homozygous and heterozygous, respectively. During the 1 year follow-up, four incidents of malaria cases were detected without an evident association with α-thalassaemia. Being heterozygous or homozygous for α-thalassaemia was associated with an increased prevalence of antibodies to AMA-1 [odds ratio (OR): 1.83, 95% confidence interval (CI): 1.07-3.12, p = 0.027] and MSP-1 (OR: 2.04, 95% CI: 1.16-3.60, p = 0.013) after adjustment for age and reported bednet use. The observed association between α-thalassaemia and malaria antibody responses may reflect longer-term differences in antigen exposure or differences in antibody acquisition upon exposure in this low endemic setting.
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Affiliation(s)
- Modibo Daou
- Faculty of Pharmacy, Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Mali Kilimanjaro Christians Medical, Center: Department of Kilimanjaro Clinical Research Institute Moshi Tanzania Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elimsaada Kituma
- Kilimanjaro Christians Medical, Center: Department of Kilimanjaro Clinical Research Institute Moshi Tanzania
| | - Reginald Kavishe
- Kilimanjaro Christians Medical, Center: Department of Kilimanjaro Clinical Research Institute Moshi Tanzania
| | - Jaffu Chilongola
- Kilimanjaro Christians Medical, Center: Department of Kilimanjaro Clinical Research Institute Moshi Tanzania
| | - Frank Mosha
- Kilimanjaro Christians Medical, Center: Department of Kilimanjaro Clinical Research Institute Moshi Tanzania
| | - André van der Ven
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bourema Kouriba
- Faculty of Pharmacy, Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Mali
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands Department of Immunology & Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ogobaro Doumbo
- Faculty of Pharmacy, Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Mali
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234
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Longwe H, Jambo KC, Phiri KS, Mbeye N, Gondwe T, Hall T, Tetteh KKA, Drakeley C, Mandala WL. The effect of daily co-trimoxazole prophylaxis on natural development of antibody-mediated immunity against P. falciparum malaria infection in HIV-exposed uninfected Malawian children. PLoS One 2015; 10:e0121643. [PMID: 25807475 PMCID: PMC4373908 DOI: 10.1371/journal.pone.0121643] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/02/2015] [Indexed: 11/24/2022] Open
Abstract
Background and Objectives Co-trimoxazole prophylaxis, currently recommended in HIV-exposed, uninfected (HEU) children as protection against opportunistic infections, also has some anti-malarial efficacy. We determined whether daily co-trimoxazole prophylaxis affects the natural development of antibody-mediated immunity to blood-stage Plasmodium falciparum malaria infection. Methods Using an enzyme-linked immunosorbent assay, we measured antibodies to 8Plasmodium falciparum antigens (AMA-1, MSP-119, MSP-3, PfSE, EBA-175RII, GLURP R0, GLURP R2 and CSP) in serum samples from 33 HEU children and 31 HIV-unexposed, uninfected (HUU) children, collected at 6, 12 and 18 months of age. Results Compared to HIV-uninfected children, HEU children had significantly lower levels of specific IgG against AMA-1 at 6 months (p = 0.001), MSP-119 at 12 months (p = 0.041) and PfSE at 6 months (p = 0.038), 12 months (p = 0.0012) and 18 months (p = 0.0097). No differences in the IgG antibody responses against the rest of the antigens were observed between the two groups at all time points. The breadth of specificity of IgG response was reduced in HEU children compared to HUU children during the follow up period. Conclusions Co-trimoxazole prophylaxis seems to reduce IgG antibody responses to P. falciparum blood stage antigens, which could be as a result of a reduction in exposure of those children under this regime. Although antibody responses were regarded as markers of exposure in this study, further studies are required to establish whether these responses are correlated in any way to clinical immunity to malaria.
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Affiliation(s)
- Herbert Longwe
- Department of Basic Medical Sciences, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Kondwani C. Jambo
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Kamija S. Phiri
- Tropical Haematology Research Unit, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Nyanyiwe Mbeye
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Thandile Gondwe
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tom Hall
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Wilson L. Mandala
- Department of Basic Medical Sciences, College of Medicine, University of Malawi, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- * E-mail:
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235
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Yeka A, Nankabirwa J, Mpimbaza A, Kigozi R, Arinaitwe E, Drakeley C, Greenhouse B, Kamya MR, Dorsey G, Staedke SG. Factors associated with malaria parasitemia, anemia and serological responses in a spectrum of epidemiological settings in Uganda. PLoS One 2015; 10:e0118901. [PMID: 25768015 PMCID: PMC4358889 DOI: 10.1371/journal.pone.0118901] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 01/21/2015] [Indexed: 11/19/2022] Open
Abstract
Background Understanding the current epidemiology of malaria and the relationship between intervention coverage, transmission intensity, and burden of disease is important to guide control activities. We aimed to determine the prevalence of anemia, parasitemia, and serological responses to P. falciparum antigens, and factors associated with these indicators, in three different epidemiological settings in Uganda. Methods and Findings In 2012, cross-sectional surveys were conducted in 200 randomly selected households from each of three sites: Walukuba, Jinja district (peri-urban); Kihihi, Kanungu district (rural); and Nagongera, Tororo district (rural) with corresponding estimates of annual entomologic inoculation rates (aEIR) of 3.8, 26.6, and 125.0, respectively. Of 2737 participants, laboratory testing was done in 2227 (81.4%), including measurement of hemoglobin, parasitemia using microscopy, and serological responses to P. falciparum apical membrane antigen 1 (AMA-1) and merozoite surface protein 1, 19 kilodalton fragment (MSP-119). Analysis of laboratory results was restricted to 1949 (87.5%) participants aged ≤ 40 years. Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites. Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites. Seropositivity to AMA-1 was 53.3% in Walukuba, 63.0% in Kihihi, and 83.7% in Nagongera and was associated with increasing age at all sites. AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not. Conclusion Anemia was predominant in young children and parasitemia peaked by 11 years across 3 sites with varied transmission intensity. Serological responses to AMA-1 appeared to best reflect transmission intensity, and may be a more accurate indicator for malaria surveillance than anemia or parasitemia.
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Affiliation(s)
- Adoke Yeka
- Makerere University School of Public Health, College of Health Sciences, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
- * E-mail:
| | - Joaniter Nankabirwa
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Arthur Mpimbaza
- Child Health and Development Centre, Makerere University College of Health Sciences, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Ruth Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Bryan Greenhouse
- Department of Medicine, University of California San Francisco, San Francisco, United States of America
| | - Moses R. Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, United States of America
| | - Sarah G. Staedke
- Infectious Diseases Research Collaboration, Kampala, Uganda
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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236
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Martin DL, Bid R, Sandi F, Goodhew EB, Massae PA, Lasway A, Philippin H, Makupa W, Molina S, Holland MJ, Mabey DCW, Drakeley C, Lammie PJ, Solomon AW. Serology for trachoma surveillance after cessation of mass drug administration. PLoS Negl Trop Dis 2015; 9:e0003555. [PMID: 25714363 PMCID: PMC4340913 DOI: 10.1371/journal.pntd.0003555] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/21/2015] [Indexed: 11/26/2022] Open
Abstract
Background Trachoma, caused by Chlamydia trachomatis (Ct), is the leading infectious cause of blindness worldwide. Yearly azithromycin mass drug administration (MDA) plays a central role in efforts to eliminate blinding trachoma as a public health problem. Programmatic decision-making is currently based on the prevalence of the clinical sign “trachomatous inflammation-follicular” (TF) in children. We sought to test alternative tools for trachoma surveillance based on serology in the 12-year cohort of Kahe Mpya, Rombo District, Tanzania, where ocular chlamydial infection was eliminated with azithromycin MDA by 2005. Methodology and Principal Findings The present study was a community-based cross-sectional survey in Kahe Mpya. Of 989 residents, 571 people aged 6 months to 87 years were enrolled: 58% of the total population and 73% of 1–9 year olds, the key WHO indicator age group. Participants were examined for TF, had conjunctival swabs collected for nucleic acid amplification test (NAAT)-based detection of Ct, and blood collected for analysis of antibodies to the Ct antigens pgp3 and CT694 by multiplex bead-based immunoassay. Seroconversion rate was used to estimate changes in the force of infection in a reversible catalytic model. No conjunctival swabs tested positive for Ct infection by NAAT. Among 1–9 year olds, TF prevalence was 6.5%, whereas only 3.5% were seropositive. Force of infection modelling indicated a 10-fold decrease in seroconversion rate at a time corresponding to MDA commencement. Without baseline serological data, the inferences we can make about antibody status before MDA and the longevity of the antibody response are limited, though our use of catalytic modelling overcomes some of these limitations. Conclusions/Significance Serologic tests support NAAT findings of very low to zero prevalence of ocular Ct in this community and have potential to provide objective measures of transmission and useful surveillance tools for trachoma elimination programs. Trachoma is the leading infectious cause of blindness. The infectious agent, Chlamydia trachomatis, can be treated with a single oral dose of azithromycin. Donated drug is a cornerstone of programs dedicated to the elimination of trachoma as a public health problem. Azithromycin is given to the entire district for 3–5 years when 10% or more of 1–9 year-olds in the district have signs of a defined follicular conjunctivitis in one or both eyes. However, follicles can be difficult to reliably diagnose and can be caused by other pathogens, especially in settings with low trachoma prevalence. More sensitive and specific ways to assess communities for trachoma transmission at program endpoints are needed. Herein we examined antibody responses in children living in a community in Tanzania born after stopping drug treatment 10 years previously. Low antibody levels (3.5% in 1–9 year-olds) reflected the lack of ocular chlamydial infection in these children. We also modelled the data to show that changes in age-specific antibody prevalence occurred when the mass drug treatment stopped. These data suggest that the age-specific prevalence of antibody responses may be of use to programs seeking to demonstrate the impact of interventions against trachoma.
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Affiliation(s)
- Diana L Martin
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Rhiannon Bid
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Frank Sandi
- Kilimanjaro Christian Medical University College, Moshi, Tanzania; The University of Dodoma, Dodoma, Tanzania
| | - E Brook Goodhew
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Patrick A Massae
- Department of Ophthalmology, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | | | - Heiko Philippin
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Department of Ophthalmology, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - William Makupa
- Department of Ophthalmology, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - Sandra Molina
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Martin J Holland
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - David C W Mabey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Patrick J Lammie
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Anthony W Solomon
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Rouhani M, Zakeri S, Mehrizi AA, Djadid ND. Comparative analysis of the profiles of IgG subclass-specific responses to Plasmodium falciparum apical membrane antigen-1 and merozoite surface protein-1 in naturally exposed individuals living in malaria hypoendemic settings, Iran. Malar J 2015; 14:58. [PMID: 25652589 PMCID: PMC4365771 DOI: 10.1186/s12936-015-0547-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/06/2015] [Indexed: 01/27/2023] Open
Abstract
Background Plasmodium falciparum apical membrane antigen-1 (PfAMA-1) and the 19-kDa C-terminal region of merozoite surface protein-1 (PfMSP-119) are candidate malaria vaccine antigens expressed on merozoites and sporozoites. This investigation was performed to evaluate simultaneously the naturally-acquired antibodies to PfAMA-1 and PfMSP-119 and to compare IgG subclass profiles to both antigens in naturally exposed individuals living in malaria hypoendemic areas in Iran to determine which antigen has better ability to detect sero-positive individuals infected with P. falciparum. Methods In this investigation, 101 individuals from the malaria-endemic areas in Iran were examined. PfAMA-1 and PfMSP-119 were expressed in Escherichia coli, and IgG isotype composition of naturally acquired antibodies to the antigens (as single or in combination) was measured by ELISA assay. Results The result showed that 87.1% and 84.2% of the studied individuals had positive anti-PfAMA-1 and -PfMSP-119 IgG antibody responses, respectively, and the prevalence of responders did not differ significantly (P > 0.05). Moreover, IgG1 and IgG3 were predominant over IgG2 and IgG4 antibodies and the prevalence of IgG and its subclasses to two tested antigens had no significant correlation with age and exposure (P > 0.05). The present data confirmed that when recombinant PfAMA-1 and recombinant PfMSP-119 antigens were combined in ELISA at equal ratios of 200 ng (100 ng each antigen/well) and 400 ng (200 ng each antigen/well), 86.1% and 87.1% of positives sera were detected among the examined samples, respectively. Conclusions The two tested recombinant antigens are immunogenic molecules, and individuals in low transmission areas in Iran could develop and maintain equal immune responses to PfAMA-1 and PfMSP-119. Therefore, these results could support the design of a universal PfAMA-1- and PfMSP-119-based vaccine. Also, both recombinant antigens could be used in combination as reliable serology markers to perform immuno-epidemiological studies in malaria-endemic areas of Iran during elimination strategy. The present information could be of use in control and elimination programmes in Iran and other similar malaria settings.
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Affiliation(s)
- Maryam Rouhani
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Pasteur Avenue, P.O. BOX 1316943551, Tehran, Iran.
| | - Sedigheh Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Pasteur Avenue, P.O. BOX 1316943551, Tehran, Iran.
| | - Akram A Mehrizi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Pasteur Avenue, P.O. BOX 1316943551, Tehran, Iran.
| | - Navid D Djadid
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Pasteur Avenue, P.O. BOX 1316943551, Tehran, Iran.
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Hodgson SH, Juma E, Salim A, Magiri C, Kimani D, Njenga D, Muia A, Cole AO, Ogwang C, Awuondo K, Lowe B, Munene M, Billingsley PF, James ER, Gunasekera A, Sim BKL, Njuguna P, Rampling TW, Richman A, Abebe Y, Kamuyu G, Muthui M, Elias SC, Molyneux S, Gerry S, Macharia A, Williams TN, Bull PC, Hill AVS, Osier FH, Draper SJ, Bejon P, Hoffman SL, Ogutu B, Marsh K. Evaluating controlled human malaria infection in Kenyan adults with varying degrees of prior exposure to Plasmodium falciparum using sporozoites administered by intramuscular injection. Front Microbiol 2014; 5:686. [PMID: 25566206 PMCID: PMC4264479 DOI: 10.3389/fmicb.2014.00686] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 11/14/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Controlled human malaria infection (CHMI) studies are a vital tool to accelerate vaccine and drug development. As CHMI trials are performed in a controlled environment, they allow unprecedented, detailed evaluation of parasite growth dynamics (PGD) and immunological responses. However, CHMI studies have not been routinely performed in malaria-endemic countries or used to investigate mechanisms of naturally-acquired immunity (NAI) to Plasmodium falciparum. METHODS We conducted an open-label, randomized CHMI pilot-study using aseptic, cryopreserved P. falciparum sporozoites (PfSPZ Challenge) to evaluate safety, infectivity and PGD in Kenyan adults with low to moderate prior exposure to P. falciparum (Pan African Clinical Trial Registry: PACTR20121100033272). RESULTS All participants developed blood-stage infection confirmed by quantitative polymerase chain reaction (qPCR). However one volunteer (110) remained asymptomatic and blood-film negative until day 21 post-injection of PfSPZ Challenge. This volunteer had a reduced parasite multiplication rate (PMR) (1.3) in comparison to the other 27 volunteers (median 11.1). A significant correlation was seen between PMR and screening anti-schizont Enzyme Linked Immunosorbent Assays (ELISA) OD (p = 0.044, R = -0.384) but not when volunteer 110 was excluded from the analysis (p = 0.112, R = -0.313). CONCLUSIONS PfSPZ Challenge is safe and infectious in malaria-endemic populations and could be used to assess the efficacy of malaria vaccines and drugs in African populations. Whilst our findings are limited by sample size, our pilot study has demonstrated for the first time that NAI may impact on PMR post-CHMI in a detectable fashion, an important finding that should be evaluated in further CHMI studies.
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Affiliation(s)
| | - Elizabeth Juma
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya ; Centre for Research in Therapeutic Sciences, Strathmore University Nairobi, Kenya
| | - Amina Salim
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Charles Magiri
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya
| | - Domtila Kimani
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Daniel Njenga
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya
| | - Alfred Muia
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya
| | - Andrew O Cole
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya ; Centre for Research in Therapeutic Sciences, Strathmore University Nairobi, Kenya
| | - Caroline Ogwang
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Ken Awuondo
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Brett Lowe
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Marianne Munene
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | | | | | | | | | - Patricia Njuguna
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | | | | | | | - Gathoni Kamuyu
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Michelle Muthui
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Sean C Elias
- The Jenner Institute, University of Oxford Oxford, UK
| | - Sassy Molyneux
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Stephen Gerry
- Centre for Statistics in Medicine, University of Oxford Oxford, UK
| | - Alex Macharia
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | - Thomas N Williams
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya ; Department of Medicine, Imperial College London London, UK
| | - Peter C Bull
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | | | - Faith H Osier
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | | | - Philip Bejon
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
| | | | - Bernhards Ogutu
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya ; Centre for Research in Therapeutic Sciences, Strathmore University Nairobi, Kenya
| | - Kevin Marsh
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute - Wellcome Trust Kilifi, Kenya
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Acquisition of antibodies against Plasmodium falciparum merozoites and malaria immunity in young children and the influence of age, force of infection, and magnitude of response. Infect Immun 2014; 83:646-60. [PMID: 25422270 DOI: 10.1128/iai.02398-14] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Individuals in areas of Plasmodium falciparum endemicity develop immunity to malaria after repeated exposure. Knowledge of the acquisition and nature of protective immune responses to P. falciparum is presently limited, particularly for young children. We examined antibodies (IgM, IgG, and IgG subclasses) to merozoite antigens and their relationship to the prospective risk of malaria in children 1 to 4 years of age in a region of malaria endemicity in Papua New Guinea. IgG, IgG1, and IgG3 responses generally increased with age, were higher in children with active infection, and reflected geographic heterogeneity in malaria transmission. Antigenic properties, rather than host factors, appeared to be the main determinant of the type of IgG subclass produced. High antibody levels were not associated with protection from malaria; in contrast, they were typically associated with an increased risk of malaria. Adjustment for malaria exposure, using a novel molecular measure of the force of infection by P. falciparum, accounted for much of the increased risk, suggesting that the antibodies were markers of higher exposure to P. falciparum. Comparisons between antibodies in this cohort of young children and in a longitudinal cohort of older children suggested that the lack of protective association was explained by lower antibody levels among young children and that there is a threshold level of antibodies required for protection from malaria. Our results suggest that in populations with low immunity, such as young children, antibodies to merozoite antigens may act as biomarkers of malaria exposure and that, with increasing exposure and responses of higher magnitude, antibodies may act as biomarkers of protective immunity.
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Serologically defined variations in malaria endemicity in Pará state, Brazil. PLoS One 2014; 9:e113357. [PMID: 25419900 PMCID: PMC4242530 DOI: 10.1371/journal.pone.0113357] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 10/25/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Measurement of malaria endemicity is typically based on vector or parasite measures. A complementary approach is the detection of parasite specific IgG antibodies. We determined the antibody levels and seroconversion rates to both P. vivax and P. falciparum merozoite antigens in individuals living in areas of varying P. vivax endemicity in Pará state, Brazilian Amazon region. METHODOLOGY/PRINCIPAL FINDINGS The prevalence of antibodies to recombinant antigens from P. vivax and P. falciparum was determined in 1,330 individuals. Cross sectional surveys were conducted in the north of Brazil in Anajás, Belém, Goianésia do Pará, Jacareacanga, Itaituba, Trairão, all in the Pará state, and Sucuriju, a free-malaria site in the neighboring state Amapá. Seroprevalence to any P. vivax antigens (MSP1 or AMA-1) was 52.5%, whereas 24.7% of the individuals were seropositive to any P. falciparum antigens (MSP1 or AMA-1). For P. vivax antigens, the seroconversion rates (SCR) ranged from 0.005 (Sucuriju) to 0.201 (Goianésia do Pará), and are strongly correlated to the corresponding Annual Parasite Index (API). We detected two sites with distinct characteristics: Goianésia do Pará where seroprevalence curve does not change with age, and Sucuriju where seroprevalence curve is better described by a model with two SCRs compatible with a decrease in force of infection occurred 14 years ago (from 0.069 to 0.005). For P. falciparum antigens, current SCR estimates varied from 0.002 (Belém) to 0.018 (Goianésia do Pará). We also detected a putative decrease in disease transmission occurred ∼29 years ago in Anajás, Goianésia do Pará, Itaituba, Jacareacanga, and Trairão. CONCLUSIONS We observed heterogeneity of serological indices across study sites with different endemicity levels and temporal changes in the force of infection in some of the sites. Our study provides further evidence that serology can be used to measure and monitor transmission of both major species of malaria parasite.
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Wong J, Hamel MJ, Drakeley CJ, Kariuki S, Shi YP, Lal AA, Nahlen BL, Bloland PB, Lindblade KA, Were V, Otieno K, Otieno P, Odero C, Slutsker L, Vulule JM, Gimnig JE. Serological markers for monitoring historical changes in malaria transmission intensity in a highly endemic region of Western Kenya, 1994-2009. Malar J 2014; 13:451. [PMID: 25416454 PMCID: PMC4258276 DOI: 10.1186/1475-2875-13-451] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 11/11/2014] [Indexed: 11/25/2022] Open
Abstract
Background Monitoring local malaria transmission intensity is essential for planning evidence-based control strategies and evaluating their impact over time. Anti-malarial antibodies provide information on cumulative exposure and have proven useful, in areas where transmission has dropped to low sustained levels, for retrospectively reconstructing the timing and magnitude of transmission reduction. It is unclear whether serological markers are also informative in high transmission settings, where interventions may reduce transmission, but to a level where considerable exposure continues. Methods This study was conducted through ongoing KEMRI and CDC collaboration. Asembo, in Western Kenya, is an area where intense malaria transmission was drastically reduced during a 1997–1999 community-randomized, controlled insecticide-treated net (ITN) trial. Two approaches were taken to reconstruct malaria transmission history during the period from 1994 to 2009. First, point measurements were calculated for seroprevalence, mean antibody titre, and seroconversion rate (SCR) against three Plasmodium falciparum antigens (AMA-1, MSP-119, and CSP) at five time points for comparison against traditional malaria indices (parasite prevalence and entomological inoculation rate). Second, within individual post-ITN years, age-stratified seroprevalence data were analysed retrospectively for an abrupt drop in SCR by fitting alternative reversible catalytic conversion models that allowed for change in SCR. Results Generally, point measurements of seroprevalence, antibody titres and SCR produced consistent patterns indicating that a gradual but substantial drop in malaria transmission (46-70%) occurred from 1994 to 2007, followed by a marginal increase beginning in 2008 or 2009. In particular, proportionate changes in seroprevalence and SCR point estimates (relative to 1994 baseline values) for AMA-1 and CSP, but not MSP-119, correlated closely with trends in parasite prevalence throughout the entire 15-year study period. However, retrospective analyses using datasets from 2007, 2008 and 2009 failed to detect any abrupt drop in transmission coinciding with the timing of the 1997–1999 ITN trial. Conclusions In this highly endemic area, serological markers were useful for generating accurate point estimates of malaria transmission intensity, but not for retrospective analysis of historical changes. Further investigation, including exploration of different malaria antigens and/or alternative models of population seroconversion, may yield serological tools that are more informative in high transmission settings. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-451) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jacklyn Wong
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Ahmed Ismail H, Tijani MK, Langer C, Reiling L, White MT, Beeson JG, Wahlgren M, Nwuba R, Persson KEM. Subclass responses and their half-lives for antibodies against EBA175 and PfRh2 in naturally acquired immunity against Plasmodium falciparum malaria. Malar J 2014; 13:425. [PMID: 25373511 PMCID: PMC4232678 DOI: 10.1186/1475-2875-13-425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/25/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Plasmodium falciparum EBA175 and PfRh2 belong to two main families involved in parasite invasion, and both are potential vaccine candidates. Current knowledge is limited regarding which target antigens and subclasses of antibodies are actually important for protection, and how naturally acquired immunity is achieved. METHODS Repeated blood samples were collected from individuals in Nigeria over a period of almost one year. ELISA was used to analyse subclasses of IgG responses. RESULTS For both EBA175 (region III-V) and (a fragment of) PfRh2, the dominant antibody responses consisted of IgG1 and IgG3 followed by IgG2, while for PfRh2 there was also a relatively prominent response for IgG4. High levels of IgG1, IgG2 and IgG3 for EBA175 and total IgG for PfRh2 correlated significantly with a lower parasitaemia during the study period. Children with HbAS had higher levels of some subclasses compared to children with HbAA, while in adults the pattern was the opposite. The half-lives of IgG2 and IgG4 against EBA175 were clearly shorter than those for IgG1 and IgG3. CONCLUSION EBA175 and PfRh2 are potential targets for protective antibodies since both correlated with lower parasitaemia. The shorter half-lives for IgG2 and IgG4 might explain why these subclasses are often considered less important in protection against malaria. Triggering the right subclass responses could be of critical importance in a successful vaccine. Further studies are needed to evaluate the role of haemoglobin polymorphisms and their malaria protective effects in this process.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Nobels väg 16, 17177 Stockholm, Sweden.
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Elliott SR, Fowkes FJ, Richards JS, Reiling L, Drew DR, Beeson JG. Research priorities for the development and implementation of serological tools for malaria surveillance. F1000PRIME REPORTS 2014; 6:100. [PMID: 25580254 PMCID: PMC4229730 DOI: 10.12703/p6-100] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Surveillance is a key component of control and elimination programs. Malaria surveillance has been typically reliant on case reporting by health services, entomological estimates and parasitemia (Plasmodium species) point prevalence. However, these techniques become less sensitive and relatively costly as transmission declines. There is great potential for the development and application of serological biomarkers of malaria exposure as sero-surveillance tools to strengthen malaria control and elimination. Antibodies to malaria antigens are sensitive biomarkers of population-level malaria exposure and can be used to identify hotspots of malaria transmission, estimate transmission levels, monitor changes over time or the impact of interventions on transmission, confirm malaria elimination, and monitor re-emergence of malaria. Sero-surveillance tools could be used in reference laboratories or developed as simple point-of-care tests for community-based surveillance, and different applications and target populations dictate the technical performance required from assays that are determined by properties of antigens and antibody responses. To advance the development of sero-surveillance tools for malaria elimination, major gaps in our knowledge need to be addressed through further research. These include greater knowledge of potential antigens, the sensitivity and specificity of antibody responses, and the longevity of these responses and defining antigens and antibodies that differentiate between exposure to Plasmodium falciparum and P. vivax. Additionally, a better understanding of the influence of host factors, such as age, genetics, and comorbidities on antibody responses in different populations is needed.
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Affiliation(s)
| | - Freya J.I. Fowkes
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Epidemiology and Preventive Medicine, Monash University99 Commercial Road, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
| | - Jack S. Richards
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
- Department of Microbiology, Monash UniversityVictoria 3800Australia
| | - Linda Reiling
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
| | - Damien R. Drew
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
| | - James G. Beeson
- Burnet Institute85 Commercial Road, Melbourne, Victoria 3004Australia
- School of Population Health and Department of Medicine (RMH), University of MelbourneVictoria 3010Australia
- Department of Microbiology, Monash UniversityVictoria 3800Australia
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244
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Okebe J, Affara M, Correa S, Muhammad AK, Nwakanma D, Drakeley C, D’Alessandro U. School-based countrywide seroprevalence survey reveals spatial heterogeneity in malaria transmission in the Gambia. PLoS One 2014; 9:e110926. [PMID: 25338083 PMCID: PMC4206471 DOI: 10.1371/journal.pone.0110926] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/25/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND As the geographical distribution of malaria transmission becomes progressively clustered, identifying residual pockets of transmission is important for research and for targeting interventions. Malarial antibody-based surveillance is increasingly recognised as a valuable complement to classic methods for the detection of infection foci especially at low transmission levels. The study presents serological evidence for transmission heterogeneity among school children in The Gambia measured during the dry, non-transmission season. METHODS Healthy primary school children were randomly selected from 30 schools across the country and screened for malaria infection (microscopy) and antimalarial antibodies (MSP119). Antibody distribution was modelled using 2-component finite mixture model with cut-off for positivity from pooled sera set at 2-standard deviation from the mean of the first component. Factors associated with a positive serological status were identified in a univariate model and then combined in a multilevel mixed-effects logistic regression model, simultaneously adjusting for variations between individuals and school. RESULTS A total of 4140 children, 1897 (46%) boys, were enrolled with mean age of 10.2 years (SD 2.6, range 4-20 years). Microscopy results available for 3640 (87.9%) children showed that 1.9% (69) were positive for Plasmodium falciparum infections, most of them (97.1%, 67/69) asymptomatic. The overall seroprevalence was 12.7% (527/4140) with values for the schools ranging from 0.6% to 43.8%. Age (OR 1.12, 95% CI 1.07-1.16,) and parasite carriage (OR 3.36, 95% CI 1.95-5.79) were strongly associated with seropositivity. CONCLUSION Serological responses to malaria parasites could identify individuals who were or had been infected, and clusters of residual transmission. Field-adapted antibody tests able to guide mass screening and treatment campaigns would be extremely useful.
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Affiliation(s)
- Joseph Okebe
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
- * E-mail:
| | - Muna Affara
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - Simon Correa
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - Abdul Khalie Muhammad
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - Davis Nwakanma
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - Chris Drakeley
- Department of Immunology and Infection, London school of Hygiene and Tropical Medicine, London, United Kingdom
| | - Umberto D’Alessandro
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
- Department of Disease Control, Faculty of infectious and Tropical Diseases, London school of Hygiene and Tropical Medicine, London, United Kingdom
- Department of Public health, Institute of Tropical Medicine, Antwerp, Belgium
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von Fricken ME, Weppelmann TA, Lam B, Eaton WT, Schick L, Masse R, Beau De Rochars MV, Existe A, Larkin J, Okech BA. Age-specific malaria seroprevalence rates: a cross-sectional analysis of malaria transmission in the Ouest and Sud-Est departments of Haiti. Malar J 2014; 13:361. [PMID: 25218803 PMCID: PMC4172790 DOI: 10.1186/1475-2875-13-361] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/26/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria transmission continues to occur in Haiti, with 25,423 confirmed cases of Plasmodium falciparum and 161,236 suspected infections reported in 2012. At low prevalence levels, passive surveillance measures, which rely primarily on reports from health systems, becomes less appropriate for capturing annual malaria incidence. To improve understanding of malaria transmission in Haiti, participants from the Ouest and Sud-Est departments were screened using a highly sensitive enzyme-linked immunosorbent assay (ELISA). METHODS Between February and May 2013, samples were collected from four different sites including a rural community, two schools, and a clinic located in the Ouest and Sud-Est departments of Haiti. A total of 815 serum samples were screened for malaria antibodies using an indirect ELISA coated with vaccine candidates apical membrane antigen (AMA-1) and merozoite surface protein-1 (MSP-119). The classification of previous exposure was established by using a threshold value that fell three standard deviations above the mean absorbance for suspected seronegative population members (OD of 0.32 and 0.26 for AMA-1 and MSP-1, respectively). The observed seroprevalence values were used to fit a modified reverse catalytic model to yield estimates of seroconversion rates. RESULTS Of the samples screened, 172 of 815 (21.1%) were AMA-1 positive, 179 of 759 (23.6%) were MSP-119 positive, and 247 of 815 (30.3%) were positive for either AMA-1 or MSP-1; indicating rates of previous infections between 21.1% and 30.3%. Not surprisingly, age was highly associated with the likelihood of previous infection (p-value <0.001). After stratification by age, the estimated seroconversion rate indicated that the annual malaria transmission in the Ouest and Sud-Est department is approximately 2.5% (95% CI SCR: 2.2%, 2.8%). CONCLUSIONS These findings suggest that despite the absence of sustained malaria control efforts in Haiti, transmission has remained relatively low over multiple decades. Elimination in Haiti appears to be feasible; however, surveillance must continue to be strengthened in order to respond to areas with high transmission and measure the impact of future interventions.
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Affiliation(s)
- Michael E von Fricken
- Emerging Pathogens Institute, University of Florida, 2055 Mowry Road, Gainesville, FL 32611, USA.
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Stuckey EM, Smith T, Chitnis N. Seasonally dependent relationships between indicators of malaria transmission and disease provided by mathematical model simulations. PLoS Comput Biol 2014; 10:e1003812. [PMID: 25187979 PMCID: PMC4154642 DOI: 10.1371/journal.pcbi.1003812] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 07/17/2014] [Indexed: 11/24/2022] Open
Abstract
Evaluating the effectiveness of malaria control interventions on the basis of their impact on transmission as well as impact on morbidity and mortality is becoming increasingly important as countries consider pre-elimination and elimination as well as disease control. Data on prevalence and transmission are traditionally obtained through resource-intensive epidemiological and entomological surveys that become difficult as transmission decreases. This work employs mathematical modeling to examine the relationships between malaria indicators allowing more easily measured data, such as routine health systems data on case incidence, to be translated into measures of transmission and other malaria indicators. Simulations of scenarios with different levels of malaria transmission, patterns of seasonality and access to treatment were run with an ensemble of models of malaria epidemiology and within-host dynamics, as part of the OpenMalaria modeling platform. For a given seasonality profile, regression analysis mapped simulation results of malaria indicators, such as annual average entomological inoculation rate, prevalence, incidence of uncomplicated and severe episodes, and mortality, to an expected range of values of any of the other indicators. Results were validated by comparing simulated relationships between indicators with previously published data on these same indicators as observed in malaria endemic areas. These results allow for direct comparisons of malaria transmission intensity estimates made using data collected with different methods on different indicators. They also address key concerns with traditional methods of quantifying transmission in areas of differing transmission intensity and sparse data. Although seasonality of transmission is often ignored in data compilations, the models suggest it can be critically important in determining the relationship between transmission and disease. Application of these models could help public health officials detect changes of disease dynamics in a population and plan and assess the impact of malaria control interventions. While malaria is still a major public health problem in many parts of the world, control programs have greatly reduced the burden of disease in recent years and many countries are now considering the goal of elimination. Unfortunately, malaria transmission becomes more difficult to measure when it is low because traditional methods involve capturing mosquitoes; an expensive and time-consuming technique. To measure transmission in areas without adequate field data, we run simulations of a mathematical model of malaria over a range of transmission intensities and seasonal patterns to examine how different measurements of malaria (prevalence, clinical disease, and death) relate to each other, how they relate to transmission, and if the relationships are likely to vary by seasonal pattern of transmission. These simulated relationships allow us to translate easily measured data, such as clinical case incidence seen at health facilities, into estimates of transmission. This technique can help public health officials plan and assess the impact of malaria control interventions, even in areas without intensive research activities.
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Affiliation(s)
- Erin M. Stuckey
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
| | - Thomas Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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247
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de Barra M, Islam MS, Curtis V. Disgust sensitivity is not associated with health in a rural Bangladeshi sample. PLoS One 2014; 9:e100444. [PMID: 24977418 PMCID: PMC4076222 DOI: 10.1371/journal.pone.0100444] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 05/28/2014] [Indexed: 12/31/2022] Open
Abstract
Disgust can be considered a psychological arm of the immune system that acts to prevent exposure to infectious agents. High disgust sensitivity is associated with greater behavioral avoidance of disease vectors and thus may reduce infection risk. A cross-sectional survey in rural Bangladesh provided no strong support for this hypothesis. In many species, the expression of pathogen- and predator-avoidance mechanisms is contingent on early life exposure to predators and pathogens. Using childhood health data collected in the 1990s, we examined if adults with more infectious diseases in childhood showed greater adult disgust sensitivity: no support for this association was found. Explanations for these null finding and possible directions for future research are discussed.
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Affiliation(s)
- Mícheál de Barra
- Environmental Health Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail:
| | | | - Val Curtis
- Environmental Health Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
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248
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Doderer-Lang C, Atchade PS, Meckert L, Haar E, Perrotey S, Filisetti D, Aboubacar A, Pfaff AW, Brunet J, Chabi NW, Akpovi CD, Anani L, Bigot A, Sanni A, Candolfi E. The ears of the African elephant: unexpected high seroprevalence of Plasmodium ovale and Plasmodium malariae in healthy populations in Western Africa. Malar J 2014; 13:240. [PMID: 24946685 PMCID: PMC4071337 DOI: 10.1186/1475-2875-13-240] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 05/29/2014] [Indexed: 11/25/2022] Open
Abstract
Background Malaria Is A Life-Threatening Pathology In Africa. Plasmodium Falciparum And Plasmodium Vivax Attract The Most Focus Because Of Their High Prevalence And Mortality. Knowledge About The Prevalence Of The Cryptic Pathogens Plasmodium Ovale And Plasmodium Malariae Is Limited. Thanks To Recombinant Tools, Their Seroprevalence Was Measured For The First Time, As Well As The Prevalence Of Mixed Infections In A Malaria-Asymptomatic Population In Benin, A Malaria-Endemic Country. Methods A Panel Of 1,235 Blood Donations Collected Over Ten Months In Benin Was Used For Validation Of The Recombinant Tools. Recombinant P. Falciparum, P. Malariae, P. Ovale MSP1, And P. Falciparum AMA1 Were Engineered And Validated On A Biobank With Malaria-Infected Patients (N = 144) Using A Species-Speific ELISA Test (Recelisa). Results Were Compared To An ELISA Using A Native P. Falciparum Antigen (NatELISA). Results Among Microscopically Negative African Blood Donors, 85% (1,050/1,235) Present Antibodies Directed To Native P. Falciparum, 94.4% (1,166/1,235) To rPfMSP1 And rPfAMA1, 56.8% (702/1,235) To rPoMSP1, 67.5% (834/1235) To rPmMSP1 And 45.3% Of The Malaria Seropositive Population Had Antibodies Recognizing The Three Species. Conclusion A High Rate Of Antibodies Against P. Ovale And P. Malariae Was Found In Asymptomatic Blood Donors. The Proportion Of Mixed Infections Involving Three Species Was Also Unexpected. These Data Suggest That Determining Seroprevalence For These Cryptic Species Is An Appropriate Tool To Estimate Their Incidence, At The Eve Of Upcoming Anti-P. Falciparum Vaccination Campaigns.
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Affiliation(s)
- Cécile Doderer-Lang
- Institut de Parasitologie et de Pathologie Tropicale Université de Strasbourg, 3, Rue Koeberlé, F67000 Strasbourg, France.
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Lewnard JA, Berrang-Ford L, Lwasa S, Namanya DB, Patterson KA, Donnelly B, Kulkarni MA, Harper SL, Ogden NH, Carcamo CP. Relative undernourishment and food insecurity associations with Plasmodium falciparum among Batwa pygmies in Uganda: evidence from a cross-sectional survey. Am J Trop Med Hyg 2014; 91:39-49. [PMID: 24821844 PMCID: PMC4080566 DOI: 10.4269/ajtmh.13-0422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Although malnutrition and malaria co-occur among individuals and populations globally, effects of nutritional status on risk for parasitemia and clinical illness remain poorly understood. We investigated associations between Plasmodium falciparum infection, nutrition, and food security in a cross-sectional survey of 365 Batwa pygmies in Kanungu District, Uganda in January of 2013. We identified 4.1% parasite prevalence among individuals over 5 years old. Severe food insecurity was associated with increased risk for positive rapid immunochromatographic test outcome (adjusted relative risk [ARR] = 13.09; 95% confidence interval [95% CI] = 2.23–76.79). High age/sex-adjusted mid-upper arm circumference was associated with decreased risk for positive test among individuals who were not severely food-insecure (ARR = 0.37; 95% CI = 0.19–0.69). Within Batwa pygmy communities, where malnutrition and food insecurity are common, individuals who are particularly undernourished or severely food-insecure may have elevated risk for P. falciparum parasitemia. This finding may motivate integrated control of malaria and malnutrition in low-transmission settings.
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Affiliation(s)
- Joseph A. Lewnard
- *Address correspondence to Joseph A. Lewnard, Department of Geography, McGill University, 805 Sherbrooke W, Burnside 705, Montreal, Quebec, Canada H3A 0B9. E-mail:
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Proietti C, Verra F, Bretscher MT, Stone W, Kanoi BN, Balikagala B, Egwang TG, Corran P, Ronca R, Arcà B, Riley EM, Crisanti A, Drakeley C, Bousema T. Influence of infection on malaria-specific antibody dynamics in a cohort exposed to intense malaria transmission in northern Uganda. Parasite Immunol 2014; 35:164-73. [PMID: 23473542 DOI: 10.1111/pim.12031] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 02/11/2013] [Indexed: 02/01/2023]
Abstract
The role of submicroscopic infections in modulating malaria antibody responses is poorly understood and requires longitudinal studies. A cohort of 249 children ≤5 years of age, 126 children between 6 and 10 years and 134 adults ≥20 years was recruited in an area of intense malaria transmission in Apac, Uganda and treated with artemether/lumefantrine at enrolment. Parasite carriage was determined at enrolment and after 6 and 16 weeks using microscopy and PCR. Antibody prevalence and titres to circumsporozoite protein, apical membrane antigen-1 (AMA-1), merozoite surface protein-1 (MSP-119 ), merozoite surface protein-2 (MSP-2) and Anopheles gambiae salivary gland protein 6 (gSG6) were determined by ELISA. Plasmodium falciparum infections were detected in 38·1% (194/509) of the individuals by microscopy and in 57·1% (284/493) of the individuals by PCR at enrolment. Antibody prevalence and titre against AMA-1, MSP-119 , MSP-2 and gSG6 were related to concurrent (sub-)microscopic parasitaemia. Responses were stable in children who were continuously infected with malaria parasites but declined in children who were never parasitaemic during the study or were not re-infected after treatment. These findings indicate that continued malaria infections are required to maintain antibody titres in an area of intense malaria transmission.
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Affiliation(s)
- C Proietti
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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