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Holla P, Bhardwaj J, Tran TM. Mature beyond their years: young children who escape detection of parasitemia despite living in settings of intense malaria transmission. Biochem Soc Trans 2024; 52:1025-1034. [PMID: 38752830 PMCID: PMC11209762 DOI: 10.1042/bst20230401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/01/2024] [Accepted: 05/02/2024] [Indexed: 05/18/2024]
Abstract
Despite having the highest risk of progressing to severe disease due to lack of acquired immunity, the youngest children living in areas of highly intense malaria transmission have long been observed to be infected at lower rates than older children. Whether this observation is due to reduced exposure to infectious mosquito bites from behavioral and biological factors, maternally transferred immunity, genetic factors, or enhanced innate immunity in the young child has intrigued malaria researchers for over half a century. Recent evidence suggests that maternally transferred immunity may be limited to early infancy and that the young child's own immune system may contribute to control of malarial symptoms early in life and prior to the development of more effective adaptive immunity. Prospective studies of active and passive detection of Plasmodium falciparum blood-stage infections have identified young children (<5 years old) who remain uninfected through a defined surveillance period despite living in settings of highly intense malaria transmission. Yet, little is known about the potential immunological basis for this 'aparasitemic' phenotype. In this review, we summarize the observational evidence for this phenotype in field studies and examine potential reasons why these children escape detection of parasitemia, covering factors that are either extrinsic or intrinsic to their developing immune system. We discuss the challenges of distinguishing malaria protection from lack of malaria exposure in field studies. We also identify gaps in our knowledge regarding cellular immunity in the youngest age group and propose directions that researchers may take to address these gaps.
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Affiliation(s)
- Prasida Holla
- Ryan White Center for Global Health and Pediatric Infectious Diseases, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Jyoti Bhardwaj
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Tuan M. Tran
- Ryan White Center for Global Health and Pediatric Infectious Diseases, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
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Marothia M, Behl A, Maurya P, Saini M, Shoaib R, Garg S, Kumari G, Biswas S, Munjal A, Anand S, Kahlon AK, Gupta P, Biswas S, Goswami B, Abdulhameed Almuqdadi HT, Bhowmick IP, Shevtsov M, Ramalingam S, Ranganathan A, Singh S. Targeting PfProhibitin 2-Hu-Hsp70A1A complex as a unique approach towards malaria vaccine development. iScience 2024; 27:109918. [PMID: 38812541 PMCID: PMC11134565 DOI: 10.1016/j.isci.2024.109918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/13/2024] [Accepted: 05/03/2024] [Indexed: 05/31/2024] Open
Abstract
Malaria parasite invasion to host erythrocytes is mediated by multiple interactions between merozoite ligands and erythrocyte receptors that contribute toward the development of disease pathology. Here, we report a novel antigen Plasmodium prohibitin "PfPHB2" and identify its cognate partner "Hsp70A1A" in host erythrocyte that plays a crucial role in mediating host-parasite interaction during merozoite invasion. Using small interfering RNA (siRNA)- and glucosamine-6-phosphate riboswitch (glmS) ribozyme-mediated approach, we show that loss of Hsp70A1A in red blood cells (RBCs) or PfPHB2 in infected red blood cells (iRBCs), respectively, inhibit PfPHB2-Hsp70A1A interaction leading to invasion inhibition. Antibodies targeting PfPHB2 and monoclonal antibody therapeutics against Hsp70A1A efficiently block parasite invasion. Recombinant PfPHB2 binds to RBCs which is inhibited by anti-PfPHB2 antibody and monoclonal antibody against Hsp70A1A. The validation of PfPHB2 to serve as antigen is further supported by detection of anti-PfPHB2 antibody in patient sera. Overall, this study proposes PfPHB2 as vaccine candidate and highlights the use of monoclonal antibody therapeutics for future malaria treatment.
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Affiliation(s)
- Manisha Marothia
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Ankita Behl
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Preeti Maurya
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Monika Saini
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Rumaisha Shoaib
- Department of Bioscience, Jamia Millia Islamia, New Delhi, India
| | - Swati Garg
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Geeta Kumari
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Shreeja Biswas
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Akshay Munjal
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Sakshi Anand
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Amandeep Kaur Kahlon
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Pragya Gupta
- CSIR-Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi 110025, India
| | - Saurav Biswas
- Regional Medical Research Center-Northeast Region (RMRC-NE)-ICMR, Dibrugarh 786001, India
| | - Bidhan Goswami
- Multidisciplinary Research Unit, Agartala Government Medical College, Agartala, Tripura (West), India
| | - Haider Thaer Abdulhameed Almuqdadi
- Department of Bioscience, Jamia Millia Islamia, New Delhi, India
- Department of Chemistry, College of Science, Al-Nahrain University, Baghdad, Iraq
| | - Ipsita Pal Bhowmick
- Regional Medical Research Center-Northeast Region (RMRC-NE)-ICMR, Dibrugarh 786001, India
| | - Maxim Shevtsov
- Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany
- Institute of Cytology of the Russian Academy of Sciences (RAS), 194064 St. Petersburg, Russia
- Personalized Medicine Centre, Almazov National Medical Research Centre, Akkuratova Str. 2, 197341 St. Petersburg, Russia
| | - Sivaprakash Ramalingam
- CSIR-Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi 110025, India
| | - Anand Ranganathan
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Shailja Singh
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
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3
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Trape JF, Diagne N, Diene-Sarr F, Faye J, Dieye-Ba F, Bassène H, Badiane A, Bouganali C, Tall A, Ndiaye R, Doucouré S, Wotodjo AN, Vigan-Womas I, Guillotte-Blisnick M, Talla C, Niang M, Touré-Baldé A, Perraut R, Roussilhon C, Druilhe P, Rogier C, Mercereau-Puijalon O, Loucoubar C, Sokhna C. One hundred malaria attacks since birth. A longitudinal study of African children and young adults exposed to high malaria transmission. EClinicalMedicine 2024; 67:102379. [PMID: 38188691 PMCID: PMC10770423 DOI: 10.1016/j.eclinm.2023.102379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 01/09/2024] Open
Abstract
Background Despite significant progress in malaria control over the past twenty years, malaria remains a leading cause of child morbidity and mortality in Tropical Africa. As most patients do not consult any health facility much uncertainty persists about the true burden of the disease and the range of individual differences in susceptibility to malaria. Methods Over a 25-years period, from 1990 to 2015, the inhabitants of Dielmo village, Senegal, an area of intense malaria transmission, have been monitored daily for their presence in the village and the occurrence of diseases. In case of fever thick blood films were systematically examined through microscopy for malaria parasites and patients received prompt diagnosis and treatment. Findings We analysed data collected in 111 children and young adults monitored for at least 10 years (mean 17.3 years, maximum 25 years) enrolled either at birth (95 persons) or during the two first years of life. A total of 11,599 episodes of fever were documented, including 5268 malaria attacks. The maximum number of malaria attacks in a single person was 112. Three other persons suffered one hundred or more malaria attacks during follow-up. The minimum number of malaria attacks in a single person was 11. The mean numbers of malaria attacks in children reaching their 4th, 7th, and 10th birthdays were 23.0, 37.7, and 43.6 attacks since birth, respectively. Sixteen children (14.4%) suffered ten or more malaria attacks each year at ages 1-3 years, and six children (5.4%) each year at age 4-6 years. Interpretation Long-term close monitoring shows that in highly endemic areas the malaria burden is higher than expected. Susceptibility to the disease may vary up to 10-fold, and for most children childhood is an endless history of malaria fever episodes. No other parasitic, bacterial or viral infection in human populations has such an impact on health. Funding The Pasteur Institutes of Dakar and Paris, the Institut de Recherche pour le Développement, and the French Ministry of Cooperation provided funding.
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Affiliation(s)
| | - Nafissatou Diagne
- Institut de Recherche pour le Développement, VITROME, Dakar, Senegal
| | | | - Joseph Faye
- Institut Pasteur de Dakar, Epidemiology Unit, Dakar, Senegal
| | - Fambaye Dieye-Ba
- Institut de Recherche pour le Développement, VITROME, Dakar, Senegal
| | - Hubert Bassène
- Institut de Recherche pour le Développement, VITROME, Dakar, Senegal
| | | | - Charles Bouganali
- Institut de Recherche pour le Développement, VITROME, Dakar, Senegal
| | - Adama Tall
- Institut Pasteur de Dakar, Epidemiology Unit, Dakar, Senegal
| | | | | | | | - Inès Vigan-Womas
- Institut Pasteur de Dakar, Immunology Unit, Dakar, Senegal
- Institut Pasteur, Department of Parasitology and Insect Vectors, Paris, France
| | | | - Cheikh Talla
- Institut Pasteur de Dakar, Epidemiology Unit, Dakar, Senegal
| | - Makhtar Niang
- Institut Pasteur de Dakar, Immunology Unit, Dakar, Senegal
| | | | - Ronald Perraut
- Institut Pasteur de Dakar, Immunology Unit, Dakar, Senegal
- Institut Pasteur, Department of Parasitology and Insect Vectors, Paris, France
| | - Christian Roussilhon
- Institut Pasteur de Dakar, Immunology Unit, Dakar, Senegal
- Institut Pasteur, Bio-medical Parasitology, Paris, France
| | - Pierre Druilhe
- Institut Pasteur, Bio-medical Parasitology, Paris, France
| | - Christophe Rogier
- Institut Pasteur de Dakar, Epidemiology Unit, Dakar, Senegal
- Primum Vitare, Paris, France
| | | | | | - Cheikh Sokhna
- Institut de Recherche pour le Développement, VITROME, Dakar, Senegal
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4
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Ranjha R, Singh K, Baharia RK, Mohan M, Anvikar AR, Bharti PK. Age-specific malaria vulnerability and transmission reservoir among children. GLOBAL PEDIATRICS 2023; 6:None. [PMID: 38440360 PMCID: PMC10911094 DOI: 10.1016/j.gpeds.2023.100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 10/03/2023] [Accepted: 10/16/2023] [Indexed: 03/06/2024]
Abstract
Purpose The pediatric population, especially under-five children, is highly susceptible to malaria and accounts for 76 % of global malaria deaths according to the World Malaria Report 2022. The purpose of this manuscript is to discuss the various factors involved in the susceptibility of the pediatric population to Malaria and the importance of this age group for malaria elimination. Methodology Data on pediatric malaria epidemiology that includes prevalence, risk factors, immune factors, socioeconomic factors, control methods, etc. were extracted from published literature using PubMed and Google Scholar. This data was further correlated with malaria incidence data from the World Health Organization (WHO) and the National Center for Vector Borne Diseases Control (NCVBDC). Results The younger age group is vulnerable to severe malaria due to an immature immune system. The risk of infection and clinical disease increases after the waning of maternal immunity. In the initial years of life, the developing brain is more susceptible to malaria infection and its after-effects. The pediatric population may act as a malaria transmission reservoir due to parasite density and asymptomatic infections. WHO recommended RTS,S/AS01 has limitations and may not be applicable in all settings to propel malaria elimination. Conclusion The diagnosis of malaria is based on clinical suspicion and confirmed with microscopy and/or rapid diagnostic testing. The school-age pediatric population serves as a transmission reservoir in the form of asymptomatic malaria since they have acquired some immunity due to exposure in early childhood. Targeting the hidden reservoir in the pediatric population and protecting this vulnerable group will be essential for malaria elimination from the countries targeting elimination.
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Affiliation(s)
- Ritesh Ranjha
- ICMR-National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Kuldeep Singh
- ICMR-National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | | | - Mradul Mohan
- ICMR-National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Anup R Anvikar
- ICMR-National Institute of Malaria Research, New Delhi, India
| | - Praveen K. Bharti
- ICMR-National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
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Natama HM, Moncunill G, Vidal M, Rouamba T, Aguilar R, Santano R, Rovira-Vallbona E, Jiménez A, Somé MA, Sorgho H, Valéa I, Coulibaly-Traoré M, Coppel RL, Cavanagh D, Chitnis CE, Beeson JG, Angov E, Dutta S, Gamain B, Izquierdo L, Mens PF, Schallig HDFH, Tinto H, Rosanas-Urgell A, Dobaño C. Associations between prenatal malaria exposure, maternal antibodies at birth, and malaria susceptibility during the first year of life in Burkina Faso. Infect Immun 2023; 91:e0026823. [PMID: 37754682 PMCID: PMC10580994 DOI: 10.1128/iai.00268-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 08/12/2023] [Indexed: 09/28/2023] Open
Abstract
In this study, we investigated how different categories of prenatal malaria exposure (PME) influence levels of maternal antibodies in cord blood samples and the subsequent risk of malaria in early childhood in a birth cohort study (N = 661) nested within the COSMIC clinical trial (NCT01941264) in Burkina Faso. Plasmodium falciparum infections during pregnancy and infants' clinical malaria episodes detected during the first year of life were recorded. The levels of maternal IgG and IgG1-4 to 15 P. falciparum antigens were measured in cord blood by quantitative suspension array technology. Results showed a significant variation in the magnitude of maternal antibody levels in cord blood, depending on the PME category, with past placental malaria (PM) more frequently associated with significant increases of IgG and/or subclass levels across three groups of antigens defined as pre-erythrocytic, erythrocytic, and markers of PM, as compared to those from the cord of non-exposed control infants. High levels of antibodies to certain erythrocytic antigens (i.e., IgG to EBA140 and EBA175, IgG1 to EBA175 and MSP142, and IgG3 to EBA140 and MSP5) were independent predictors of protection from clinical malaria during the first year of life. By contrast, high levels of IgG, IgG1, and IgG2 to the VAR2CSA DBL1-2 and IgG4 to DBL3-4 were significantly associated with an increased risk of clinical malaria. These findings indicate that PME categories have different effects on the levels of maternal-derived antibodies to malaria antigens in children at birth, and this might drive heterogeneity to clinical malaria susceptibility in early childhood.
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Affiliation(s)
- Hamtandi Magloire Natama
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Gemma Moncunill
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Marta Vidal
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Toussaint Rouamba
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Ruth Aguilar
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Rebeca Santano
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Eduard Rovira-Vallbona
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Alfons Jiménez
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Epidemiologia y Salud Pública (CIBERESP), Barcelona, Spain
| | - M. Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Maminata Coulibaly-Traoré
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Ross L. Coppel
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - David Cavanagh
- Centre for Immunity, Infection & Evolution, Institute of Immunology & Infection Research, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Chetan E. Chitnis
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Université de Paris, Paris, France
| | | | - Evelina Angov
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Sheetij Dutta
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | | | - Luis Izquierdo
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Petra F. Mens
- Academic Medical Centre at the University of Amsterdam, Amsterdam, the Netherlands
| | | | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Carlota Dobaño
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
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Rent S, Bauserman M, Laktabai J, Tshefu AK, Taylor SM. Malaria in Pregnancy: Key Points for the Neonatologist. Neoreviews 2023; 24:e539-e552. [PMID: 37653081 DOI: 10.1542/neo.24-9-e539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
In malaria-endemic regions, infection with the malaria parasite Plasmodium during pregnancy has been identified as a key modifiable factor in preterm birth, the delivery of low-birthweight infants, and stillbirth. Compared with their nonpregnant peers, pregnant persons are at higher risk for malaria infection. Malaria infection can occur at any time during pregnancy, with negative effects for the pregnant person and the fetus, depending on the trimester in which the infection is contracted. Pregnant patients who are younger, in their first or second pregnancy, and those coinfected with human immunodeficiency virus are at increased risk for malaria. Common infection prevention measures during pregnancy include the use of insecticide-treated bed nets and the use of intermittent preventive treatment with monthly doses of antimalarials, beginning in the second trimester in pregnant patients in endemic areas. In all trimesters, artemisinin-combination therapies are the first-line treatment for uncomplicated falciparum malaria, similar to treatment in nonpregnant adults. The World Health Organization recently revised its recommendations, now listing the specific medication artemether-lumefantrine as first-line treatment for uncomplicated malaria in the first trimester. While strong prevention and detection methods exist, use of these techniques remains below global targets. Ongoing work on approaches to treatment and prevention of malaria during pregnancy remains at the forefront of global maternal child health research.
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Affiliation(s)
- Sharla Rent
- Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | | | | | - Antoinette K Tshefu
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of the Congo
| | - Steve M Taylor
- Department of Medicine, Duke University School of Medicine, Durham, NC
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Leonard CM, Uhomoibhi P, Abubakar A, Ogunniyi A, Mba N, Greby SM, Okoye MI, Iriemenam NC, Ihekweazu C, Steinhardt L, Rogier E. Dynamics of IgG antibody response against Plasmodium antigens among Nigerian infants and young children. Front Immunol 2023; 14:1208822. [PMID: 37691957 PMCID: PMC10484571 DOI: 10.3389/fimmu.2023.1208822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/24/2023] [Indexed: 09/12/2023] Open
Abstract
Background Plasmodium falciparum malaria is a leading cause of child mortality in Nigeria. Neonates are born with maternal antibodies from placental transfer which may protect against malaria infection in the first months of life. The IgG dynamics of the transition from passively transferred antimalarial antibodies to actively acquired IgG from natural exposure have not been well elucidated. Methods Blood samples collected during a 2018 Nigeria nationwide HIV/AIDS household survey were available for 9,443 children under 5 years of age, with a subset of infants under 2 months of age having maternal samples available (n=41). Samples were assayed for the P. falciparum HRP2 antigen and anti-malarial IgG antibodies. LOESS regression examined the dynamics in IgG response in the first 5 years of life. Correlation with maternal IgG levels was assessed for mother/child pairs. Results Consistent decreases were observed in median IgG levels against all Plasmodium spp. antigen targets for the first months of life. At a population level, P. falciparum apical membrane antigen-1 (AMA1) and merozoite surface protein-1 19kD (PfMSP1) IgG decreased during the first 12 months of life before reaching a nadir, whereas IgGs to other targets only declined for the first 4 months of life. Seropositivity showed a similar decline with the lowest seropositivity against AMA1 and PfMSP1 at 10-12 months, though remaining above 50% during the first 2 years of life in higher transmission areas. No protective association was observed between IgG positivity and P. falciparum infection in infants. Maternal antibody levels showed a strong positive correlation with infant antibody levels for all P. falciparum antigens from birth to 2 months of age, but this correlation was lost by 6 months of age. Discussion Maternally transferred anti-malarial IgG antibodies rapidly decline during the first 6 months of life, with variations among specific antigens and malaria transmission intensity. From 3-23 months of age, there was a wide range in IgG levels for the blood-stage antigens indicating high individual variation in antibody production as children are infected with malaria. Non-falciparum species-specific antigens showed similar patterns in waning immunity and correlation with paired mother's IgG levels compared to P. falciparum antigens.
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Affiliation(s)
- Colleen M. Leonard
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- Oak Ridge Institute for Science and Education, U.S. Department of Energy, Oak Ridge, TN, United States
| | - Perpetua Uhomoibhi
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | - Ado Abubakar
- Institute of Human Virology (IHVN), Abuja, Nigeria
| | | | - Nwando Mba
- Nigeria Centre for Disease Control (NCDC), Abuja, Nigeria
| | - Stacie M. Greby
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | - McPaul I. Okoye
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | - Nnaemeka C. Iriemenam
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | | | - Laura Steinhardt
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Eric Rogier
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - NMS4 Technical Working Group
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
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8
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Jelínková L, Roberts B, Ajayi DT, Peabody DS, Chackerian B. The Immunogenicity of a VLP-based Malaria Vaccine Targeting CSP in Pregnant and Neonatal Mice. Biomolecules 2023; 13:202. [PMID: 36830571 PMCID: PMC9953288 DOI: 10.3390/biom13020202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Maternal antibodies are passively transferred to the fetus via the placenta during gestation and can play an important role in protecting the newborn from infection. For example, in malaria-endemic regions, maternal antibodies likely provide substantial protection against Plasmodium falciparum malaria in the first 6 months of life. However, circulating maternal antibodies can also interfere with vaccine efficacy. Here, we used a mouse maternal transfer model to evaluate whether maternal antibodies interfere with the responsiveness to a virus-like particle (VLP)-based vaccine targeting the CIS43 epitope of the malaria circumsporozoite protein (CSP). We found immunized dams passively transfer to pups high levels of anti-CSP IgG antibodies that steadily decline as the animals age. We also found that the neonatal offspring of immunized mice do not respond to de novo immunization with the CIS43-targeted VLP vaccine until maternal antibody titers decline below an inhibitory threshold. These findings may have important implications for delineating the delicate balance between protection conferred by maternal antibodies and the offspring's ability to respond to immunization.
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Affiliation(s)
| | | | | | | | - Bryce Chackerian
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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9
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Starck T, Dambach P, Rouamba T, Tinto H, Osier F, Oldenburg CE, Adam M, Bärnighausen T, Jaenisch T, Bulstra CA. The effect of malaria on childhood anemia in a quasi-experimental study of 7,384 twins from 23 Sub-Saharan African countries. Front Public Health 2022; 10:1009865. [PMID: 36561861 PMCID: PMC9766366 DOI: 10.3389/fpubh.2022.1009865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/18/2022] [Indexed: 12/12/2022] Open
Abstract
Background Young children in Sub-Saharan Africa (SSA), particularly those from resource-limited settings, are heavily burdened by anemia and malaria. While malaria infected children frequently become anemic (hemoglobin < 110 g/L), anemia is a strongly multifactorial disease with many other risk factors than malaria. Due to the complex and often overlapping contributors to anemia, it remains challenging to isolate the true impact of malaria on population level hemoglobin concentrations. Methods We quantified the malaria-induced effect on hemoglobin levels in children under 5 years of age, leveraging data from 7,384 twins and other multiples, aged 6 to 59 months, from 57 nationally representative Demographic and Health Surveys (DHSs) from 23 SSA countries from 2006 to 2019. The quasi-experimental twin fixed-effect design let us minimize the impact of potential confounders that do not vary between twins. Results Our analyses of twins revealed a malaria-induced hemoglobin decrease in infected twins of 9 g/L (95% CI -10; -7, p<0.001). The relative risk of severe anemia was higher (RR = 3.01, 95% CI 1.79; 5.1, p<0.001) among malaria positive children, compared to malaria negative children. Conversely, malaria positive children are only half as likely to be non-anemic (RR = 0.51, 95% CI 0.43; 0.61, p<0.001). Conclusion Even after rigorous control for confounding through a twin fixed-effects study design, malaria substantially decreased hemoglobin levels among SSA twins, rendering them much more susceptible to severe anemia. This effect reflects the population-level effect of malaria on anemia.
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Affiliation(s)
- Tim Starck
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany,*Correspondence: Tim Starck
| | - Peter Dambach
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany
| | - Toussaint Rouamba
- Clinical Research Unit of Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Halidou Tinto
- Clinical Research Unit of Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Faith Osier
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany,KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Catherine E. Oldenburg
- Francis I Proctor Foundation, University of California, San Francisco, San Francisco, CA, United States,Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, United States,Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, United States
| | - Maya Adam
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany,Deptartment of Pediatrics, Stanford School of Medicine, Stanford, CA, United States
| | - Till Bärnighausen
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany,Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA, United States,Africa Health Research Institute (AHRI), KwaZulu-Natal, South Africa
| | - Thomas Jaenisch
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany,Center for Global Health, Colorado School of Public Health, Aurora, CO, United States,Department of Epidemiology, Colorado School of Public Health, Aurora, CO, United States
| | - Caroline A. Bulstra
- Heidelberg Institute of Global Health, Heidelberg University Hospital, Heidelberg, Germany,Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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10
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Tassi Yunga S, Siriwardhana C, Fouda GG, Bobbili N, Sama G, Chen JJ, Leke RFG, Taylor DW. Characterization of the primary antibody response to Plasmodium falciparum antigens in infants living in a malaria-endemic area. Malar J 2022; 21:346. [PMCID: PMC9675181 DOI: 10.1186/s12936-022-04360-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022] Open
Abstract
Background The primary antibody (Ab) response to Plasmodium falciparum is a critical step in developing immunity to malaria. Information on the initial Ab responses of babies in malaria-endemic areas is incomplete, in part, because babies receive maternal IgG via transplacental-transfer and usually become infected before maternal IgG wanes. The study aimed to identify the primary IgM and IgG Ab responses to malarial antigens in Cameroonian babies. Methods Infants (n = 70) living in a high malaria transmission area were followed from birth throughout the first year of life (mean 341 ± 42 days, an average of 8.5 time points per infant). Malaria infection was assessed by microscopy and PCR, and IgM and IgG antibodies (Abs) were measured using a multiplex immunoassay to AMA1, EBA-175, MSP1-42, MSP2, MSP3, RESA, LSA1, and CSP. Results The half-life of maternal IgG varied among the antigens, ranging from 0.7 to 2.5 months. The first infection of 41% of the babies was sub-microscopic and only 11 to 44% of the babies produced IgM to the above antigens; however, when the first infection was detected by microscopy, 59–82% of the infants made IgM Abs to the antigens. Infants were able to produce IgM even when maternal IgG was present, suggesting maternal Abs did not suppress the baby’s initial Ab response. Using longitudinal regression models that incorporated time-varying covariates, infants were found to produce IgG Ab to only AMA-1 when the first infection was sub-microscopic, but they produced IgG Abs to MSP1-42 (3D7, FVO), AMA1 (3D7, FVO) MSP2-FC27, MSP3, RESA, and LSA1, but not MSP 2-3D7, EBA-175, and CSP during their first slide-positive infection. Notably, the primary and secondary IgG responses were short-lived with little evidence of boosting. Conclusions The primary Ab response of babies who had maternal IgG was similar to that reported for primary infections in malaria-naïve adults. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04360-x.
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Affiliation(s)
- Samuel Tassi Yunga
- grid.410445.00000 0001 2188 0957Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, Bioscience Building Suite 320, Honolulu, HI 96813 USA ,grid.5288.70000 0000 9758 5690Cancer Early Detection Advanced Research Center (CEDAR), School of Medicine, Knight Cancer Institute, Oregon Health & Science University, 2720 S. Moody Avenue, Portland, OR USA
| | - Chathura Siriwardhana
- grid.410445.00000 0001 2188 0957Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, MEB411, Honolulu, HI 96813 USA
| | - Genevieve G. Fouda
- grid.5386.8000000041936877XDepartment of Pediatrics, Joan & Sanford I. Weill Medical College of Cornell University, New York, NY USA
| | - Naveen Bobbili
- grid.410445.00000 0001 2188 0957Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, Bioscience Building Suite 320, Honolulu, HI 96813 USA
| | - Grace Sama
- grid.412661.60000 0001 2173 8504The Biotechnology Center, University of Yaoundé 1, Messa, BP 3851 Yaoundé, Cameroon
| | - John J. Chen
- grid.410445.00000 0001 2188 0957Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, MEB411, Honolulu, HI 96813 USA
| | - Rose F. G. Leke
- grid.412661.60000 0001 2173 8504The Biotechnology Center, University of Yaoundé 1, Messa, BP 3851 Yaoundé, Cameroon
| | - Diane Wallace Taylor
- grid.410445.00000 0001 2188 0957Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, Bioscience Building Suite 320, Honolulu, HI 96813 USA
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11
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Prolonged Breastfeeding and the Risk of Plasmodium vivax Infection and Clinical Malaria in Early Childhood: A Birth Cohort Study. Pediatr Infect Dis J 2022; 41:793-799. [PMID: 35763695 DOI: 10.1097/inf.0000000000003618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Relatively few Amazonian infants have clinical malaria diagnosed, treated and notified before their first birthday, either because they are little exposed to an infection or remain asymptomatic once infected. Here we measure the proportion of children who have experienced Plasmodium vivax infection and malaria by 2 years of age in the main transmission hotspot of Amazonian Brazil. METHODS We measured IgG antibodies to 3 blood-stage P. vivax antigens at the 1- and 2-year follow-up assessment of 435 participants in a population-based birth cohort. Children's malaria case notifications were retrieved from the electronic database of the Ministry of Health. We used multiple Poisson regression models to identify predictors of serologically proven P. vivax infection and clinical vivax malaria during the first 2 years of life. RESULTS Overall, 23 [5.3%; 95% confidence interval (CI): 3.5-7.8%) children had antibodies to ≥2 antigens detected during at least one follow-up assessment, consistent with past P. vivax infection(s). Fifteen (3.4%; 95% CI: 2.1-5.6%) children had clinical vivax episodes notified during the first 2 years of life; 7 of them were seronegative. We estimate that half of the infections remained unnotified. Children born to women who experienced P. vivax infection during pregnancy were more likely to be infected and develop clinical vivax malaria, while those breast-fed for ≥12 months had their risk of being P. vivax -seropositive (which we take as evidence of blood-stage P. vivax infection during the first 2 years of life) decreased by 79.8% (95% CI: 69.3-86.7%). CONCLUSION P. vivax infections in early childhood are underreported in the Amazon, are associated with anemia at 2 years of age, and appear to be partially prevented by prolonged breastfeeding.
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12
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Kalkman LC, Hanscheid T, Krishna S, Kremsner PG, Grobusch MP. Antimalarial treatment in infants. Expert Opin Pharmacother 2022; 23:1711-1726. [PMID: 36174125 DOI: 10.1080/14656566.2022.2130687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Malaria in infants is common in high-transmission settings, especially in infants >6 months. Infants undergo physiological changes impacting pharmacokinetics and pharmacodynamics of anti-malarial drugs and, consequently, the safety and efficacy of malaria treatment. Yet, treatment guidelines and evidence on pharmacological interventions for malaria often fail to address this vulnerable age-group. This review aims to summarise the available data on anti-malarial treatment in infants. AREAS COVERED The standard recommended treatments for severe and uncomplicated malaria are generally safe and effective in infants. However, infants have an increased risk of drug-related vomiting and have distinct pharmacokinetic parameters of antimalarials compared with older patients. These include larger volumes of distribution, higher clearance rates and immature enzyme systems. Consequently, infants with malaria may be at increased risk of treatment failure and drug toxicity. EXPERT OPINION Knowledge expansion to optimize treatment can be achieved by including more infants in antimalarial drug trials and by reporting separately on treatment outcomes in infants. Additional evidence on the efficacy, safety, tolerability, acceptability and effectiveness of ACTs in infants is needed, as well as population pharmacokinetics studies on antimalarials in the infant population.
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Affiliation(s)
- Laura C Kalkman
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam University Medical Centers, location Amsterdam, Amsterdam Infection & Immunity, Amsterdam Public Health, University of Amsterdam, Amsterdam, The Netherlands
| | - Thomas Hanscheid
- Instituto de Microbiologia, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sanjeev Krishna
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, and German Center for Infection Research (DZIF), Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon.,Clinical Academic Group, Institute for Infection and Immunity, and St. George's University Hospitals NHS Foundation Trust, St. George's University of London, London, UK
| | - Peter G Kremsner
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, and German Center for Infection Research (DZIF), Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
| | - Martin P Grobusch
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam University Medical Centers, location Amsterdam, Amsterdam Infection & Immunity, Amsterdam Public Health, University of Amsterdam, Amsterdam, The Netherlands.,Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, and German Center for Infection Research (DZIF), Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon.,Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa.,Masanga Medical Research Unit (MMRU), Masanga, Sierra Leone
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13
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Antibody Responses Against Plasmodium falciparum MSP3 Protein During Natural Malaria Infection in Individuals Living in Malaria-Endemic Regions of India. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, INDIA SECTION B: BIOLOGICAL SCIENCES 2022; 92:613-619. [PMID: 35411125 PMCID: PMC8985746 DOI: 10.1007/s40011-021-01330-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/04/2021] [Accepted: 11/16/2021] [Indexed: 12/03/2022]
Abstract
The humoral immune responses to blood-stage malaria proteins are requisite for the inhibition of parasite invasion. Plasmodium falciparum merozoite surface protein 3 (MSP3) is a secretory, expressed abundantly, merozoite surface protein that is important for the parasite invasion process. It has been shown to induce antibody responses during natural infections and is, therefore, considered to be the potential vaccine candidates against Plasmodium. Elucidating the immunogenicity and prevalence of anti-parasite antibodies is important in identifying potential targets as candidates for malarial diagnosis and anti‐malarial vaccine. The present study concerns the presence of antibodies against the MSP3 proteins of human malaria parasite- P. falciparum in infected individuals from endemic regions of India. Seventy-one anonymized P. falciparum infected serum samples were procured from the malaria fever clinic of ICMR-National Institute of Malaria Research (NIMR), New Delhi to detect the presence of antibodies against MSP3 protein by ELISA. The IgM antibody response against recombinant MSP3 was detected at significantly higher levels during acute malaria. The protein was found to be immunogenic and did not demonstrate any cross-reactivity with the serum of uninfected individuals or individuals infected with other Plasmodium species. The protein has hydrophilic regions in its N- and C-terminus which may contain immunogenic linear and conformational B-cell epitopes. The results from this study suggest that the MSP3 is immunogenic and likely a potential candidate for antibody-based diagnosis or vaccine development against the blood-stage of P. falciparum.
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14
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Rogier E, Nace D, Dimbu PR, Wakeman B, Beeson JG, Drakeley C, Tetteh K, Plucinski M. Antibody dynamics in children with first or repeat Plasmodium falciparum infections. Front Med (Lausanne) 2022; 9:869028. [PMID: 35928289 PMCID: PMC9343764 DOI: 10.3389/fmed.2022.869028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
Immunoglobulin (Ig) production during and after infection with Plasmodium parasites is one of the greatest adaptive immune defenses the human host has against this parasite. Infection with P. falciparum has been shown to induce different B cell maturation responses dependent upon the age of the patient, number of previous exposures, and severity of the disease. Described here are dynamics of Ig responses to a panel of 32 P. falciparum antigens by patients followed for 42 days and classified individuals as showing characteristics of an apparent first P. falciparum infection (naïve) or a repeat exposure (non-naïve). Six parameters were modeled to characterize the dynamics of IgM, IgG1, IgG3, and IgA for these two exposure groups with differences assessed among Ig isotypes/subclasses and unique antigens. Naïve patients had significantly longer periods of time to reach peak Ig titer (range 4–7 days longer) and lower maximum Ig titers when compared with non-naïve patients. Modeled time to seronegativity was significantly higher in non-naïve patients for IgM and IgA, but not for the two IgG subclasses. IgG1 responses to Rh2030, HSP40, and PfAMA1 were at the highest levels for non-naïve participants and may be used to predict previous or nascent exposure by themselves. The analyses presented here demonstrate the differences in the development of the Ig response to P. falciparum if the infection represents a boosting response or a primary exposure. Consistency in Ig isotype/subclasses estimates and specific data for P. falciparum antigens can better guide interpretation of seroepidemiological data among symptomatic persons.
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Affiliation(s)
- Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- *Correspondence: Eric Rogier,
| | - Doug Nace
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | | | - Brian Wakeman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - James G. Beeson
- Burnet Institute, Melbourne, VIC, Australia
- Central Clinical School, Monash University, Melbourne, VIC, Australia
- Department of Medicine, University of Melbourne, Melbourne, VIC, Australia
| | - Chris Drakeley
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kevin Tetteh
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Mateusz Plucinski
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- U.S. President’s Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, GA, United States
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15
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Sabourin KR, Nalwoga A, Whitby D, Newton R, Rochford R. Environmental determinants of Kaposi’s sarcoma-associated herpesvirus (KSHV) transmission in rural Uganda (ENDKU study): Contributions to research on KSHV infection and reactivation in African children; A longitudinal cohort study. Cancer Epidemiol 2022; 78:102154. [DOI: 10.1016/j.canep.2022.102154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/21/2022] [Accepted: 03/27/2022] [Indexed: 11/17/2022]
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16
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Mfisimana LD, Nibayisabe E, Badu K, Niyukuri D. Exploring predictive frameworks for malaria in Burundi. Infect Dis Model 2022; 7:33-44. [PMID: 35388371 PMCID: PMC8941165 DOI: 10.1016/j.idm.2022.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 02/22/2022] [Accepted: 03/05/2022] [Indexed: 11/10/2022] Open
Abstract
In Burundi, malaria infection has been increasing in the last decade despite efforts to increase access to health services, and several intervention programs. The use of heterogeneous data can help to build predictive models of malaria cases. We built predictive frameworks: the generalized linear model (GLM), and artificial neural network (ANN), to predict malaria cases in four sub-groups and the overall general population. Descriptive results showed that more than half of malaria infections are observed in pregnant women and children under 5 years, with high burden to children between 12 and 59 months. Modelling results showed that, ANN model performed better in predicting total cases compared to GLM. Both model frameworks showed that education rates and Insecticide Treated Bed Nets (ITNs) had decreasing effects on malaria cases, some other variables had an increasing effect. Thus, malaria control and prevention interventions program are encouraged to understand those variables, and take appropriate measures such as providing ITNs, sensitization in schools and the communities, starting within high dense communities, among others. Early prediction of cases can provide timely information needed to be proactive for intervention strategies, and it can help to mitigate the epidemics and reduce its impact on populations and the economy.
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Affiliation(s)
| | - Emile Nibayisabe
- Faculté des Sciences Fondamentales, Institut Supérieur des Cadres Militaires, Burundi
| | - Kingsley Badu
- Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Ghana
| | - David Niyukuri
- Faculté des Sciences Fondamentales, Institut Supérieur des Cadres Militaires, Burundi
- Division of Epidemiology & Biostatistics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- The South African Department of Science and Technology–National Research Foundation (DST-NRF) Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, Cape Town, South Africa
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17
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Orish VN, Boakye-Yiadom E, Ansah EK, Alhassan RK, Duedu K, Awuku YA, Owusu-Agyei S, Gyapong JO. Is malaria immunity a possible protection against severe symptoms and outcomes of COVID-19? Ghana Med J 2022; 55:56-63. [PMID: 35233116 PMCID: PMC8853697 DOI: 10.4314/gmj.v55i2s.9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Malaria-endemic areas of the world are noted for high morbidity and mortality from malaria. Also noted in these areas is the majority of persons in the population having acquired malaria immunity. Though this acquired malaria immunity does not prevent infection, it resists the multiplication of Plasmodium parasites, restricting disease to merely uncomplicated cases or asymptomatic infections. Does this acquired malaria immunity in endemic areas protect against other diseases, especially outbreak diseases like COVID-19? Does malaria activation of innate immunity resulting in trained or tolerance immunity contribute to protection against COVID-19? In an attempt to answer these questions, this review highlights the components of malaria and viral immunity and explores possible links with immunity against COVID-19. With malaria-endemic areas of the world having a fair share of cases of COVID-19, it is important to direct research in this area to evaluate and harness any benefits of acquired malaria immunity to help mitigate the effects of COVID-19 and any possible future outbreaks. Funding None declared.
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Affiliation(s)
- Verner N Orish
- Department of Microbiology and Immunology, School of Medicine, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Emily Boakye-Yiadom
- Department of Microbiology and Immunology, School of Medicine, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Evelyn K Ansah
- Centre for Malaria Research, Institute for Health Research, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Robert K Alhassan
- Institute of Health Research, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Kwabena Duedu
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Yaw A Awuku
- Department of Internal Medicine, School of Medicine, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Seth Owusu-Agyei
- Institute of Health Research, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - John O Gyapong
- Institute of Health Research, University of Health and Allied Sciences, Ho, Volta Region, Ghana
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18
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Sánchez KE, Spencer LM. Pregnancy-associated malaria: Effects of cytokine and chemokine expression. Travel Med Infect Dis 2022; 47:102282. [DOI: 10.1016/j.tmaid.2022.102282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/19/2021] [Accepted: 02/23/2022] [Indexed: 11/15/2022]
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19
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Acquired clinical immunity to malaria in non-human primates co-infected with Schistosoma and Plasmodium parasites. Infect Immun 2021; 90:e0046421. [PMID: 34871040 DOI: 10.1128/iai.00464-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background. Naturally acquired immunity to malaria develops over several years and can be compromised by concomitant infections. This study explored the influence of chronic schistosomiasis on clinical outcome and immunity to repeated malaria infection. Methods. Two groups of baboons (n=8 each), were infected with Schistosoma mansoni cercariae to establish chronic infections. One of the two groups was treated with Praziquantel to eliminate schistosome infection. The two groups plus a new malaria control group (n=8), were inoculated three times with Plasmodium knowlesi parasites at one-month intervals. Clinical data, IgG, IgG1, memory T-cells and monocyte levels were recorded. Results. We observed after three P. knowlesi infections; i) reduced clinical symptoms in all groups with each subsequent infection, ii) increase IgG and IgG1in the malaria control (Pk-only) group iii) increased IgG and IgG1, CD14+ and CD14-CD16+ in the Schistosoma treated (Schisto/PZQ+Pk) group and iv) significantly lower IgG and IgG1 levels compared to Pk-only, reduced CD4+CD45RO+ and increased CD14-CD16+ cells in the co-infected (Schisto+Pk) group. Conclusion. Chronic S. mansoni does not compromise establishment of clinical immunity after multiple malaria infections with non-classical monocytes seeming to play a role. Failure to develop robust antibody and memory T-cells may have a long-term impact on acquired immunity to malaria infection.
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Mwaiswelo RO, Mmbando BP, Chacky F, Molteni F, Mohamed A, Lazaro S, Mkalla SF, Samuel B, Ngasala B. Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented. PLoS One 2021; 16:e0260785. [PMID: 34855878 PMCID: PMC8638878 DOI: 10.1371/journal.pone.0260785] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/16/2021] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Malaria and anemia remain major public health challenges in Tanzania. Household socioeconomic factors are known to influence these conditions. However, it is not clear how these factors influence malaria transmission and anemia in Masasi and Nanyumbu Districts. This study presents findings on malaria and anemia situation in under-five children and its influencing socioeconomic factors in Masasi and Nanyumbu Districts, surveyed as part of an ongoing seasonal malaria chemoprevention operational study. METHODS A community-based cross-sectional survey was conducted between August and September 2020. Finger-prick blood samples collected from children aged 3-59 months were used to test for malaria infection using malaria rapid diagnostic test (mRDT), thick smears for determination of asexual and sexual parasitemia, and thin smear for parasite speciation. Hemoglobin concentration was measured using a HemoCue spectrophotometer. A structured questionnaire was used to collect household socioeconomic information from parents/caregivers of screened children. The prevalence of malaria was the primary outcome. Chi-square tests, t-tests, and logistic regression models were used appropriately. RESULTS Overall mRDT-based malaria prevalence was 15.9% (373/2340), and was significantly higher in Nanyumbu (23.7% (167/705) than Masasi District (12.6% (206/1635), p<0.001. Location (Nanyumbu), no formal education, household number of people, household number of under-fives, not having a bed net, thatched roof, open/partially open eave, sand/soil floor, and low socioeconomic status were major risks for malaria infection. Some 53.9% (1196/2218) children had anemia, and the majority were in Nanyumbu (63.5% (458/705), p<0.001. Location (Nanyumbu), mRDT positive, not owning a bed net, not sleeping under bed net, open/partially open eave, thatched window, sex of the child, and age of the child were major risk factors for anemia. CONCLUSION Prevalence of malaria and anemia was high and was strongly associated with household socioeconomic factors. Improving household socioeconomic status is expected to reduce the prevalence of the conditions in the area.
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Affiliation(s)
- Richard O. Mwaiswelo
- Department of Microbiology, Immunology and Parasitology, Hubert Kairuki Memorial University, Dar es Salaam, Tanzania
| | - Bruno P. Mmbando
- Tanga Research Centre, National Institute for Medical Research, Tanga, Tanzania
| | - Frank Chacky
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Fabrizio Molteni
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Samwel Lazaro
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Sylvia F. Mkalla
- Directorate of Research, Coordination, and Promotion, Tanzania Commission for Science and Technology, Dar es Salaam, Tanzania
| | - Bushukatale Samuel
- Department of Medical Parasitology and Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Billy Ngasala
- Department of Medical Parasitology and Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
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21
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The Impact of Maternal Depression and Parent-Child Interactions on Risk of Parasitic Infections in Early Childhood: A Prospective Cohort in Benin. Matern Child Health J 2021; 26:1049-1058. [PMID: 34850311 PMCID: PMC9023386 DOI: 10.1007/s10995-021-03317-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 11/16/2022]
Abstract
Objectives Maternal depression occurs in 13–20% of women from low-income countries, which is associated with negative child health outcomes, including diarrheal disease. However, few studies have investigated its impact on child risk of infectious disease. We studied the impacts of maternal depressive symptoms and parent–child interactions, independently, on the risk of Plasmodium falciparum malaria and soil-transmitted helminth infection in Beninese children. Methods Our population included mothers and children enrolled in a clinical trial during pregnancy (MiPPAD) in Benin. The Edinburgh Postnatal Depression Scale (EPDS) assessed maternal depressive symptoms and the home observation measurement of the environment (HOME) assessed parent–child interactions. Blood and stool sample analyses diagnosed child malaria and helminth infection at 12, 18, and 24 months. Negative binomial and Poisson regression models with robust variance tested associations. Results Of the 302 mother–child pairs, 39 (12.9%) mothers had depressive symptoms. Median number of malaria episodes per child was 3 (0–14) and 29.1% children had at least one helminth infection. Higher EPDS scores were associated with lower HOME scores; relative risk (RR) 0.97 (95% confidence interval (CI) 0.95, 0.99), particularly with lower acceptance, involvement, and variety subscales; RR 0.92 (95% CI 0.85, 0.99), RR 0.82 (95% CI 0.77, 0.88), RR 0.93 (95% CI 0.88, 0.99), respectively. However, neither exposure was associated with risk of parasitic infection in children. Conclusions for Practice Maternal depressive symptoms are associated with poor parent–child interactions, particularly acceptance of behavior, involvement with children, and variety of interactions, but these exposures do not independently impact risk of parasitic infection in children.
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22
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Rojas-Pirela M, Medina L, Rojas MV, Liempi AI, Castillo C, Pérez-Pérez E, Guerrero-Muñoz J, Araneda S, Kemmerling U. Congenital Transmission of Apicomplexan Parasites: A Review. Front Microbiol 2021; 12:751648. [PMID: 34659187 PMCID: PMC8519608 DOI: 10.3389/fmicb.2021.751648] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 09/01/2021] [Indexed: 12/17/2022] Open
Abstract
Apicomplexans are a group of pathogenic protists that cause various diseases in humans and animals that cause economic losses worldwide. These unicellular eukaryotes are characterized by having a complex life cycle and the ability to evade the immune system of their host organism. Infections caused by some of these parasites affect millions of pregnant women worldwide, leading to various adverse maternal and fetal/placental effects. Unfortunately, the exact pathogenesis of congenital apicomplexan diseases is far from being understood, including the mechanisms of how they cross the placental barrier. In this review, we highlight important aspects of the diseases caused by species of Plasmodium, Babesia, Toxoplasma, and Neospora, their infection during pregnancy, emphasizing the possible role played by the placenta in the host-pathogen interaction.
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Affiliation(s)
- Maura Rojas-Pirela
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.,Facultad de Farmacia y Bioanálisis, Universidad de Los Andes, Mérida, Venezuela
| | - Lisvaneth Medina
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Maria Verónica Rojas
- Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Ana Isabel Liempi
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Christian Castillo
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Núcleo de Investigación Aplicada en Ciencias Veterinarias y Agronómicas, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
| | | | - Jesús Guerrero-Muñoz
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sebastian Araneda
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Facultad de Salud y Odontología, Universidad Diego Portales, Santiago, Chile
| | - Ulrike Kemmerling
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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23
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Ndeketa L, Mategula D, Terlouw DJ, Bar-Zeev N, Sauboin CJ, Biernaux S. Cost-effectiveness and public health impact of RTS,S/AS01 E malaria vaccine in Malawi, using a Markov static model. Wellcome Open Res 2021; 5:260. [PMID: 34632084 PMCID: PMC8491149 DOI: 10.12688/wellcomeopenres.16224.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2021] [Indexed: 12/02/2022] Open
Abstract
Background: The RTS,S/AS01
E malaria vaccine is being assessed in Malawi, Ghana and Kenya as part of a large-scale pilot implementation programme. Even if impactful, its incorporation into immunisation programmes will depend on demonstrating cost-effectiveness. We analysed the cost-effectiveness and public health impact of the RTS,S/AS01
E malaria vaccine use in Malawi. Methods: We calculated the Incremental Cost Effectiveness Ratio (ICER) per disability-adjusted life year (DALY) averted by vaccination and compared it to Malawi’s mean per capita Gross Domestic Product. We used a previously validated Markov model, which simulated malaria progression in a 2017 Malawian birth cohort for 15 years. We used a 46% vaccine efficacy, 75% vaccine coverage, USD5 estimated cost per vaccine dose, published local treatment costs for clinical malaria and Malawi specific malaria indicators for interventions such as bed net and antimalarial use. We took a healthcare provider, household and societal perspective. Costs were discounted at 3% per year, no discounting was applied to DALYs. For public health impact, we calculated the DALYs, and malaria events averted. Results: The ICER/DALY averted was USD115 and USD109 for the health system perspective and societal perspective respectively, lower than GDP per capita of USD398.6 for Malawi. Sensitivity analyses exploring the impact of variation in vaccine costs, vaccine coverage rate and coverage of four doses showed vaccine implementation would be cost-effective across a wide range of different outcomes. RTS,S/AS01 was predicted to avert a median of 93,940 (range 20,490–126,540) clinical cases and 394 (127–708) deaths for the three-dose schedule, or 116,480 (31,450–160,410) clinical cases and 484 (189–859) deaths for the four-dose schedule, per 100 000 fully vaccinated children. Conclusions: We predict the introduction of the RTS,S/AS01 vaccine in the Malawian expanded programme of immunisation (EPI) likely to be highly cost effective.
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Affiliation(s)
- Latif Ndeketa
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Donnie Mategula
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Dianne J Terlouw
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, College of Medicine, University of Malawi, Blantyre, Malawi.,Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Naor Bar-Zeev
- International Vaccine Access Center, Department of International Health, 3. Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | | | - Sophie Biernaux
- Coalition for Epidemic Preparedness Innovations, London, NW1 2BE, UK
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24
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Bonam SR, Rénia L, Tadepalli G, Bayry J, Kumar HMS. Plasmodium falciparum Malaria Vaccines and Vaccine Adjuvants. Vaccines (Basel) 2021; 9:1072. [PMID: 34696180 PMCID: PMC8541031 DOI: 10.3390/vaccines9101072] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/10/2021] [Accepted: 09/22/2021] [Indexed: 12/02/2022] Open
Abstract
Malaria-a parasite vector-borne disease-is a global health problem, and Plasmodium falciparum has proven to be the deadliest among Plasmodium spp., which causes malaria in humans. Symptoms of the disease range from mild fever and shivering to hemolytic anemia and neurological dysfunctions. The spread of drug resistance and the absence of effective vaccines has made malaria disease an ever-emerging problem. Although progress has been made in understanding the host response to the parasite, various aspects of its biology in its mammalian host are still unclear. In this context, there is a pressing demand for the development of effective preventive and therapeutic strategies, including new drugs and novel adjuvanted vaccines that elicit protective immunity. The present article provides an overview of the current knowledge of anti-malarial immunity against P. falciparum and different options of vaccine candidates in development. A special emphasis has been made on the mechanism of action of clinically used vaccine adjuvants.
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Affiliation(s)
- Srinivasa Reddy Bonam
- Institut National de la Santé et de la Recherche Médicale, Centre de Recherche des Cordeliers, Equipe-Immunopathologie et Immunointervention Thérapeutique, Sorbonne Université, Université de Paris, F-75006 Paris, France;
| | - Laurent Rénia
- A*STAR Infectious Diseases Labs, 8A Biomedical Grove, Singapore 138648, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore 308232, Singapore
| | - Ganesh Tadepalli
- Vaccine Immunology Laboratory, Organic Synthesis and Process Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India;
| | - Jagadeesh Bayry
- Institut National de la Santé et de la Recherche Médicale, Centre de Recherche des Cordeliers, Equipe-Immunopathologie et Immunointervention Thérapeutique, Sorbonne Université, Université de Paris, F-75006 Paris, France;
- Biological Sciences & Engineering, Indian Institute of Technology Palakkad, Palakkad 678623, India
| | - Halmuthur Mahabalarao Sampath Kumar
- Vaccine Immunology Laboratory, Organic Synthesis and Process Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India;
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25
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Awosolu OB, Yahaya ZS, Farah Haziqah MT. Prevalence, Parasite Density and Determinants of Falciparum Malaria Among Febrile Children in Some Peri-Urban Communities in Southwestern Nigeria: A Cross-Sectional Study. Infect Drug Resist 2021; 14:3219-3232. [PMID: 34434052 PMCID: PMC8380643 DOI: 10.2147/idr.s312519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/27/2021] [Indexed: 11/23/2022] Open
Abstract
Background Malaria remains a serious public health problem worldwide, particularly in tropical and subtropical regions, including Nigeria. This study investigates the prevalence, parasite density and determinants of malaria among symptomatic children in some peri-urban communities in southwestern Nigeria. Methods This was a randomized cross-sectional and hospital-based study. The standard method of microscopy was employed. Thick and thin films were prepared and viewed under a light microscope to identify and quantify malaria parasites. A well-structured and pre-tested questionnaire was used to obtain the subject’s information on the demographic, socio-economic and environmental variables. Results A total of 380 (71.7%) participants were infected with Plasmodium falciparum with a mean parasite density of 1857.11 parasite/µL of blood. Malaria prevalence and mean parasite density were significantly higher among male compared to their female counterparts [80.3% vs 61.4% and 2026.46 vs 1619.63 parasite/µL of blood]. Similarly, age group ≤5 years had the highest malaria prevalence (92.2%) and mean parasite density (2031.66 parasite/µL of blood) than other age groups (AOR 2.281, 95% CI: 1.187–4.384, P < 0.05). The multivariate logistic analysis showed that malaria disease is significantly associated with having mother with no formal education (AOR 12.235, 95% CI: 3.253–46.021, P < 0.05), having well and river as a major source of household water supply (AOR 13.810, 95% CI: 3.012–63.314, P < 0.05 vs AOR 5.639, 95% CI: 1.455–21.853, P < 0.05) and presence of stagnant water around home (AOR 5.22, 95% CI: 2.921–9.332, P < 0.05). Furthermore, protective factors observed include ownership of mosquito bed net (AOR 0.474, 95% CI: 0.223–1.008, P < 0.05) and distance of home to hospital (AOR 0.279, 95% CI: 0.158–0.493, P < 0.05). Conclusion Malaria remains a serious public health problem in the study area. Adopting integrated malaria control measures including educating parents on malaria prevention and control strategies, distributing mosquito bed nets, and establishing larvae source management program is highly imperative.
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Affiliation(s)
- Oluwaseun Bunmi Awosolu
- School of Biological Sciences, Universiti Sains Malaysia, Penang, 11800 USM, Malaysia.,Department of Biology, Federal University of Technology, Akure, Nigeria
| | - Zary Shariman Yahaya
- School of Biological Sciences, Universiti Sains Malaysia, Penang, 11800 USM, Malaysia
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26
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Pincelli A, Cardoso MA, Malta MB, Johansen IC, Corder RM, Nicolete VC, Soares IS, Castro MC, Ferreira MU. Low-level Plasmodium vivax exposure, maternal antibodies, and anemia in early childhood: Population-based birth cohort study in Amazonian Brazil. PLoS Negl Trop Dis 2021; 15:e0009568. [PMID: 34264946 PMCID: PMC8282015 DOI: 10.1371/journal.pntd.0009568] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 06/16/2021] [Indexed: 11/26/2022] Open
Abstract
Background Malaria causes significant morbidity and mortality in children under 5 years of age in sub-Saharan Africa and the Asia-Pacific region. Neonates and young infants remain relatively protected from clinical disease and the transplacental transfer of maternal antibodies is hypothesized as one of the protective factors. The adverse health effects of Plasmodium vivax malaria in early childhood–traditionally viewed as a benign infection–remain largely neglected in relatively low-endemicity settings across the Amazon. Methodology/Principal findings Overall, 1,539 children participating in a birth cohort study in the main transmission hotspot of Amazonian Brazil had a questionnaire administered, and blood sampled at the two-year follow-up visit. Only 7.1% of them experienced malaria confirmed by microscopy during their first 2 years of life– 89.1% of the infections were caused by P. vivax. Young infants appear to be little exposed to, or largely protected from infection, but children >12 months of age become as vulnerable to vivax malaria as their mothers. Few (1.4%) children experienced ≥4 infections during the 2-year follow-up, accounting for 43.4% of the overall malaria burden among study participants. Antenatal malaria diagnosed by microscopy during pregnancy or by PCR at delivery emerged as a significant correlate of subsequent risk of P. vivax infection in the offspring (incidence rate ratio, 2.58; P = 0.002), after adjusting for local transmission intensity. Anti-P. vivax antibodies measured at delivery do not protect mothers from subsequent malaria; whether maternal antibodies transferred to the fetus reduce early malaria risk in children remains undetermined. Finally, recent and repeated vivax malaria episodes in early childhood are associated with increased risk of anemia at the age of 2 years in this relatively low-endemicity setting. Conclusions/Significance Antenatal infection increases the risk of vivax malaria in the offspring and repeated childhood P. vivax infections are associated with anemia at the age of 2 years. Plasmodium vivax malaria causes frequent hospital admissions of infants and toddlers in areas of intense transmission in the Asia-Pacific region, often due to severe anemia, but its epidemiology and burden have been understudied in children from other endemic settings. Here we characterize the cumulative impact of P. vivax infections in infants and toddlers exposed to relatively low levels of malaria transmission in the Brazilian Amazon. We have previously shown that vivax malaria in pregnancy is associated with increased risk of maternal anemia and impaired fetal growth in this population. Now we show that the adverse effects of malaria extend to early childhood. Children born to mothers who had one or more infections during pregnancy are at an elevated risk of P. vivax malaria in their early life, although the transfer of maternal antibodies to the fetus may provide some short-term protection. Children who are repeatedly infected with P. vivax since birth are more likely to be anemic at the age of 2 years. These findings further challenge the traditional view of vivax malaria as a relatively benign infection in pregnancy and early childhood in the Amazon.
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Affiliation(s)
- Anaclara Pincelli
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marly A. Cardoso
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, Brazil
| | - Maíra B. Malta
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, Brazil
- Graduate Program in Collective Health, Catholic University of Santos, Santos, Brazil
| | - Igor C. Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vanessa C. Nicolete
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Irene S. Soares
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marcia C. Castro
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail:
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27
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Gómez A, Pernía B, Zamora L, Spencer LM. Effect of Plasmodium berghei infection on fetuses in pregnant BALB/c mice at two periods of pregnancy. BIONATURA 2021. [DOI: 10.21931/rb/2021.06.02.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Malaria is a disease caused by a protozoan of the genus Plasmodium in humans and vertebrates. It has a high morbidity and mortality rate, especially in pregnant women living in countries with high transmission rates. Murine models have been an excellent tool to evaluate the effects of malarial infection in the mother-fetus relationship. For this reason, we evaluated the effect of malarial infection on fetal development at the beginning and middle of the gestational period in BALB/c mice infected with Plasmodium berghei ANKA. Our results show that malarial infection at the beginning of pregnancy markedly affects the development of the fetus in size, weight, and development of its limbs so that the control of the pregnant mother is relevant at the beginning of gestation
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Affiliation(s)
- Andreina Gómez
- Cell Biology Department, Simón Bolívar University, Valle de Sartenejas, Caracas
| | - Beatriz Pernía
- University of Guayaquil, Faculty of Natural Sciences, Av. Raúl Gómez Lince s/n y Av. Juan Tanca Marengo, Guayaquil, Ecuador
| | - Lizbeth Zamora
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Ecuador
| | - Lilian M. Spencer
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Ecuador Cell Biology Department, Simón Bolívar University, Valle de Sartenejas, Caracas
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28
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Steinhardt LC, Richie TL, Yego R, Akach D, Hamel MJ, Gutman JR, Wiegand RE, Nzuu EL, Dungani A, Kc N, Murshedkar T, Church LWP, Sim BKL, Billingsley PF, James ER, Abebe Y, Kariuki S, Samuels AM, Otieno K, Sang T, Kachur SP, Styers D, Schlessman K, Abarbanell G, Hoffman SL, Seder RA, Oneko M. Safety, Tolerability, and Immunogenicity of Plasmodium falciparum Sporozoite Vaccine Administered by Direct Venous Inoculation to Infants and Young Children: Findings From an Age De-escalation, Dose-Escalation, Double-blind, Randomized Controlled Study in Western Kenya. Clin Infect Dis 2021; 71:1063-1071. [PMID: 31555824 DOI: 10.1093/cid/ciz925] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/16/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The whole Plasmodium falciparum sporozoite (PfSPZ) vaccine is being evaluated for malaria prevention. The vaccine is administered intravenously for maximal efficacy. Direct venous inoculation (DVI) with PfSPZ vaccine has been safe, tolerable, and feasible in adults, but safety data for children and infants are limited. METHODS We conducted an age de-escalation, dose-escalation randomized controlled trial in Siaya County, western Kenya. Children and infants (aged 5-9 years, 13-59 months, and 5-12 months) were enrolled into 13 age-dose cohorts of 12 participants and randomized 2:1 to vaccine or normal saline placebo in escalating doses: 1.35 × 105, 2.7 × 105, 4.5 × 105, 9.0 × 105, and 1.8 × 106 PfSPZ, with the 2 highest doses given twice, 8 weeks apart. Solicited adverse events (AEs) were monitored for 8 days after vaccination, unsolicited AEs for 29 days, and serious AEs throughout the study. Blood taken prevaccination and 1 week postvaccination was tested for immunoglobulin G antibodies to P. falciparum circumsporozoite protein (PfCSP) using enzyme-linked immunosorbent assay. RESULTS Rates of AEs were similar in vaccinees and controls for solicited (35.7% vs 41.5%) and unsolicited (83.9% vs 92.5%) AEs, respectively. No related grade 3 AEs, serious AEs, or grade 3 laboratory abnormalities occurred. Most (79.0%) vaccinations were administered by a single DVI. Among those in the 9.0 × 105 and 1.8 × 106 PfSPZ groups, 36 of 45 (80.0%) vaccinees and 4 of 21 (19.0%) placebo controls developed antibodies to PfCSP (P < .001). CONCLUSIONS PfSPZ vaccine in doses as high as 1.8 × 106 can be administered to infants and children by DVI, and was safe, well tolerated, and immunogenic. CLINICAL TRIALS REGISTRATION NCT02687373.
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Affiliation(s)
- Laura C Steinhardt
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Reuben Yego
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Dorcas Akach
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Mary J Hamel
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Julie R Gutman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Ryan E Wiegand
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Elizabeth L Nzuu
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Allan Dungani
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | | | | | | | | | | | | | | | - Simon Kariuki
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Aaron M Samuels
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Kephas Otieno
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Tony Sang
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - S Patrick Kachur
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.,Mailman School of Public Health, Columbia University, New York, New York, USA
| | | | | | - Ginnie Abarbanell
- Washington University School of Medicine and St Louis Children's Hospital, St Louis, Missouri, USA
| | | | | | - Martina Oneko
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
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Abstract
Serology data are an increasingly important tool in malaria surveillance, especially in low transmission settings where the estimation of parasite-based indicators is often problematic. Existing methods rely on the use of thresholds to identify seropositive individuals and estimate transmission intensity, while making assumptions about the temporal dynamics of malaria transmission that are rarely questioned. Here, we present a novel threshold-free approach for the analysis of malaria serology data which avoids dichotomization of continuous antibody measurements and allows us to model changes in the antibody distribution across age in a more flexible way. The proposed unified mechanistic model combines the properties of reversible catalytic and antibody acquisition models, and allows for temporally varying boosting and seroconversion rates. Additionally, as an alternative to the unified mechanistic model, we also propose an empirical approach to analysis where modelling of the age-dependency is informed by the data rather than biological assumptions. Using serology data from Western Kenya, we demonstrate both the usefulness and limitations of the novel modelling framework.
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30
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Zehner N, Adrama H, Kakuru A, Andra T, Kajubi R, Conrad M, Nankya F, Clark TD, Kamya M, Rodriguez-Barraquer I, Dorsey G, Jagannathan P. Age-related Changes in Malaria Clinical Phenotypes During Infancy are Modified by Sickle Cell Trait. Clin Infect Dis 2021; 73:1887-1895. [PMID: 33738485 PMCID: PMC8599196 DOI: 10.1093/cid/ciab245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 12/02/2022] Open
Abstract
Background Infants are protected against Plasmodium falciparum malaria. Mechanisms that drive this protection remain unclear due to a poor understanding of malaria clinical phenotypes during infancy. Methods We enrolled a birth cohort of 678 infants in Busia, Uganda, an area of high malaria transmission. We followed infants through 12 months of age and quantified protection against parasitemia and clinical disease. Results Symptomatic malaria incidence increased from 1.2 to 2.6 episodes per person-year between 0 and <6 months and between 6 and 12 months of age, while the monthly probability of asymptomatic parasitemia given infection decreased from 32% to 21%. Sickle cell trait (HbAS) was protective against symptomatic malaria (incidence rate ratio = 0.57 comparing HbAS vs hemoglobin AA (HbAA); 95% confidence interval, 0.44–0.74; P < .001), but age modified this relationship (Pint = <0.001), with nonlinear protection that waned between 0 and 9 months of age before increasing. Increasing age was associated with higher parasite densities at the time of infection and, in infants with HbAS, a reduced ability to tolerate high parasite densities without fever. Conclusions Age-dependent changes in HbAS protective efficacy in infancy were accompanied by differential loss of antiparasite and antidisease protection among HbAS and HbAA infants. This provides a framework for investigating the mechanisms that underlie infant protection against malaria. Clinical Trials Registration NCT02793622.
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Affiliation(s)
| | - Harriet Adrama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Abel Kakuru
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Teddy Andra
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Richard Kajubi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa Conrad
- Department of Medicine, University of California, San Francisco, USA
| | | | - Tamara D Clark
- Department of Medicine, University of California, San Francisco, USA
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, USA
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31
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Callaway PC, Farrington LA, Feeney ME. Malaria and Early Life Immunity: Competence in Context. Front Immunol 2021; 12:634749. [PMID: 33679787 PMCID: PMC7933008 DOI: 10.3389/fimmu.2021.634749] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 02/02/2021] [Indexed: 12/31/2022] Open
Abstract
Childhood vaccines have been the cornerstone tool of public health over the past century. A major barrier to neonatal vaccination is the “immaturity” of the infant immune system and the inefficiency of conventional vaccine approaches at inducing immunity at birth. While much of the literature on fetal and neonatal immunity has focused on the early life propensity toward immune tolerance, recent studies indicate that the fetus is more immunologically capable than previously thought, and can, in some circumstances, mount adaptive B and T cell responses to perinatal pathogens in utero. Although significant hurdles remain before these findings can be translated into vaccines and other protective strategies, they should lend optimism to the prospect that neonatal and even fetal vaccination is achievable. Next steps toward this goal should include efforts to define the conditions for optimal stimulation of infant immune responses, including antigen timing, dose, and route of delivery, as well as antigen presentation pathways and co-stimulatory requirements. A better understanding of these factors will enable optimal deployment of vaccines against malaria and other pathogens to protect infants during their period of greatest vulnerability.
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Affiliation(s)
- Perri C Callaway
- Infectious Diseases and Immunity Graduate Group, University of California, Berkeley, Berkeley, CA, United States.,Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Lila A Farrington
- Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Margaret E Feeney
- Department of Medicine, University of California, San Francisco, San Francisco, CA, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, CA, United States
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Parra M, Yang J, Weitner M, Akkoyunlu M. Neonatal mice resist Plasmodium yoelii infection until exposed to para-aminobenzoic acid containing diet after weaning. Sci Rep 2021; 11:90. [PMID: 33420157 PMCID: PMC7794322 DOI: 10.1038/s41598-020-79703-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/04/2020] [Indexed: 12/03/2022] Open
Abstract
We developed a newborn (NB) mouse Plasmodium yoelii NL infection model to study malaria in early age. Surprisingly, the onset of parasitemia in P. yoelii challenged NB mice was delayed compared to adults and coincided with the weaning date when weanlings switched from maternal milk to normal chow diet. Also, compared to adult mice, parasitemia resolved much later (48 days vs 20 days post challenge) and the peak parasitemia was twice as high in weanlings. Concurrently, weanlings’ germinal center reaction was delayed and diminished compared to adult mice. Maternal milk is deficient in para-aminobenzoic acid (PABA), which is required for de novo folate synthesis by Plasmodium. Suggesting a possible role for the protection afforded by PABA-deficient maternal milk, mice fed with a PABA-deficient diet after the weaning continued to control parasitemia. Despite the reduced parasitemia, these mice developed robust T follicular helper (Tfh) responses and were protected from a second P. yoelii challenge. The NB malaria model provides mechanistic insight into the human infant malaria manifestations where a diet solely based on breast-feeding reduces the incidence of severe malaria in infants. NB mice experiments also support further studies to investigate dietary PABA restriction in the management of severe malaria in infants.
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Affiliation(s)
- Marcela Parra
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Jiyeon Yang
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Megan Weitner
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA.,Viral & Rickettsial Diseases Department (NMRC VRDD), Naval Medical Research Center, Silver Spring, MD, USA
| | - Mustafa Akkoyunlu
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA. .,DBPAP, US FDA, CBER, 10903 New Hampshire Ave., Building 52/72, Room, 5214, Silver Spring, MD, 209903, USA.
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Zohar T, Loos C, Fischinger S, Atyeo C, Wang C, Slein MD, Burke J, Yu J, Feldman J, Hauser BM, Caradonna T, Schmidt AG, Cai Y, Streeck H, Ryan ET, Barouch DH, Charles RC, Lauffenburger DA, Alter G. Compromised Humoral Functional Evolution Tracks with SARS-CoV-2 Mortality. Cell 2020; 183:1508-1519.e12. [PMID: 33207184 PMCID: PMC7608014 DOI: 10.1016/j.cell.2020.10.052] [Citation(s) in RCA: 224] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/15/2020] [Accepted: 10/29/2020] [Indexed: 12/19/2022]
Abstract
The urgent need for an effective SARS-CoV-2 vaccine has forced development to progress in the absence of well-defined correlates of immunity. While neutralization has been linked to protection against other pathogens, whether neutralization alone will be sufficient to drive protection against SARS-CoV-2 in the broader population remains unclear. Therefore, to fully define protective humoral immunity, we dissected the early evolution of the humoral response in 193 hospitalized individuals ranging from moderate to severe. Although robust IgM and IgA responses evolved in both survivors and non-survivors with severe disease, non-survivors showed attenuated IgG responses, accompanied by compromised Fcɣ receptor binding and Fc effector activity, pointing to deficient humoral development rather than disease-enhancing humoral immunity. In contrast, individuals with moderate disease exhibited delayed responses that ultimately matured. These data highlight distinct humoral trajectories associated with resolution of SARS-CoV-2 infection and the need for early functional humoral immunity.
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Affiliation(s)
- Tomer Zohar
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Carolin Loos
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Stephanie Fischinger
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA,PhD Program in Immunology and Virology, University of Duisburg-Essen, Essen, Germany
| | - Caroline Atyeo
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA,PhD Program in Virology, Division of Medical Sciences, Harvard University, Boston, MA, USA
| | - Chuangqi Wang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - John Burke
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA
| | - Jingyou Yu
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard, Medical School, Boston, MA 02215, USA
| | - Jared Feldman
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA
| | | | - Tim Caradonna
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA
| | | | - Yongfei Cai
- Division of Molecular Medicine, Boston Children’s Hospital and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Hendrik Streeck
- Institute of Virology, University Hospital, University of Bonn and German Center for Infection Research (DZIF), Bonn-Cologne, Bonn, Germany
| | - Edward T. Ryan
- Infectious Disease Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Dan H. Barouch
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard, Medical School, Boston, MA 02215, USA
| | - Richelle C. Charles
- Infectious Disease Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA,Corresponding author
| | - Douglas A. Lauffenburger
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA,Corresponding author
| | - Galit Alter
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA.
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Ndeketa L, Mategula D, Terlouw DJ, Bar-Zeev N, Sauboin CJ, Biernaux S. Cost-effectiveness and public health impact of RTS,S/AS01E malaria vaccine in Malawi, using a Markov static model. Wellcome Open Res 2020; 5:260. [DOI: 10.12688/wellcomeopenres.16224.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2020] [Indexed: 11/20/2022] Open
Abstract
Background: The RTS,S/AS01E malaria vaccine is being assessed in Malawi, Ghana and Kenya as part of a large-scale pilot implementation programme. Even if impactful, its incorporation into immunisation programmes will depend on demonstrating cost-effectiveness. We analysed the cost-effectiveness and public health impact of the RTS,S/AS01E malaria vaccine use in Malawi. Methods: We calculated the Incremental Cost Effectiveness Ratio (ICER) per disability-adjusted life year (DALY) averted by vaccination and compared it to Malawi’s mean per capita Gross Domestic Product. We used a previously validated Markov model, which simulated malaria progression in a 2017 Malawian birth cohort for 15 years. We used a 46% vaccine efficacy, 75% vaccine coverage, USD5 estimated cost per vaccine dose, published local treatment costs for clinical malaria and Malawi specific malaria indicators for interventions such as bed net and antimalarial use. We took a healthcare provider, household and societal perspective. Costs were discounted at 3% per year, no discounting was applied to DALYs. For public health impact, we calculated the DALYs, and malaria events averted. Results: The ICER/DALY averted was USD115 and USD109 for the health system perspective and societal perspective respectively, lower than GDP per capita of USD398.6 for Malawi. Sensitivity analyses exploring the impact of variation in vaccine costs, vaccine coverage rate and coverage of four doses showed vaccine implementation would be cost-effective across a wide range of different outcomes. RTS,S/AS01 was predicted to avert a median of 93,940 (range 20,490–126,540) clinical cases and 394 (127–708) deaths for the three-dose schedule, or 116,480 (31,450–160,410) clinical cases and 484 (189–859) deaths for the four-dose schedule, per 100 000 fully vaccinated children. Conclusions: We predict the introduction of the RTS,S/AS01 vaccine in the Malawian expanded programme of immunisation (EPI) likely to be highly cost effective.
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Profiles of Plasmodium falciparum infections detected by microscopy through the first year of life in Kintampo a high transmission area of Ghana. PLoS One 2020; 15:e0240814. [PMID: 33075074 PMCID: PMC7571695 DOI: 10.1371/journal.pone.0240814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 10/02/2020] [Indexed: 11/24/2022] Open
Abstract
Although malaria mortality among children under five years of age is high, the characteristics of their infection patterns are not well described. The aim of this study was to examine the longitudinal sequence pattern of Plasmodium falciparum infections in the first year of life within a birth cohort in Kintampo, Ghana (N = 1855). Infants were monitored at home with monthly sampling and also at the clinic for any febrile illness between 2008 and 2011. Light microscopy was performed on monthly scheduled visits and febrile ill visits over twelve months of follow-ups (n = 19231). Microscopy-positive visits accompanied with or without symptoms were rare during the first five months of life but were common from six to twelve months of age. Among 1264 infants with microscopy data over a minimum of eight monthly visits and also throughout in sick visits, some were microscopy negative (36%), and others positive: only-symptomatic (35%), alternating (22%) and only-asymptomatic (7%). The median age of microscopic infection was seven months for the alternating group and eight months for both the only-symptomatic and only-asymptomatic groups. The alternating group had the highest cumulative incidence of microscopic infections, the lowest age at first infection and 87 different infection patterns. Parasite densities detected by microscopy were significantly higher for symptomatic versus asymptomatic infection. We conclude that infants in malaria endemic areas experience diverse infection profiles throughout their first year of life. Further investigations should include submicroscopic reservoir and may shed more light on the factors that determine susceptibility to malaria during infancy.
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Saito M, Briand V, Min AM, McGready R. Deleterious effects of malaria in pregnancy on the developing fetus: a review on prevention and treatment with antimalarial drugs. THE LANCET CHILD & ADOLESCENT HEALTH 2020; 4:761-774. [PMID: 32946830 DOI: 10.1016/s2352-4642(20)30099-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 03/09/2020] [Accepted: 03/25/2020] [Indexed: 12/29/2022]
Abstract
All malaria infections are harmful to both the pregnant mother and the developing fetus. One in ten maternal deaths in malaria endemic countries are estimated to result from Plasmodium falciparum infection. Malaria is associated with a 3-4 times increased risk of miscarriage and a substantially increased risk of stillbirth. Current treatment and prevention strategies reduce, but do not eliminate, malaria's damaging effects on pregnancy outcomes. Reviewing evidence generated from meta-analyses, systematic reviews, and observational data, the first paper in this Series aims to summarise the adverse effects of malaria in pregnancy on the fetus and how the current drug treatment and prevention strategies can alleviate these effects. Although evidence supports the safety and treatment efficacy of artemisinin-based combination therapies in the first trimester, these therapies have not been recommended by WHO for the treatment of malaria at this stage of pregnancy. Intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine is contraindicated in the first trimester and provides imperfect chemoprevention because of inadequate dosing, poor (few and late) antenatal clinic attendance, increasing antimalarial drug resistance, and decreasing naturally acquired maternal immunity due to the decreased incidence of malaria. Alternative strategies to prevent malaria in pregnancy are needed. The prevention of all malaria infections by providing sustained exposure to effective concentrations of antimalarial drugs is key to reducing the adverse effects of malaria in pregnancy.
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Affiliation(s)
- Makoto Saito
- Division of Infectious Diseases, Advanced Clinical Research Center, The Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Valérie Briand
- Infectious Diseases in Lower Income Countries, Research Institute for Sustainable Development, French National Institute of Health and Medical Research, University of Bordeaux, Bordeaux, France
| | - Aung Myat Min
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Rose McGready
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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37
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Hartley MA, Hofmann N, Keitel K, Kagoro F, Antunes Moniz C, Mlaganile T, Samaka J, Masimba J, Said Z, Temba H, Gonzalez I, Felger I, Genton B, D’Acremont V. Clinical relevance of low-density Plasmodium falciparum parasitemia in untreated febrile children: A cohort study. PLoS Med 2020; 17:e1003318. [PMID: 32956354 PMCID: PMC7505590 DOI: 10.1371/journal.pmed.1003318] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 08/13/2020] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Low-density (LD) Plasmodium infections are missed by standard malaria rapid diagnostic tests (standard mRDT) when the blood antigen concentration is below the detection threshold. The clinical impact of these LD infections is unknown. This study investigates the clinical presentation and outcome of untreated febrile children with LD infections attending primary care facilities in a moderately endemic area of Tanzania. METHODS/FINDINGS This cohort study includes 2,801 febrile pediatric outpatients (median age 13.5 months [range 2-59], female:male ratio 0.8:1.0) recruited in Dar es Salaam, Tanzania between 01 December 2014 and 28 February 2016. Treatment decisions were guided by a clinical decision support algorithm run on a mobile app, which also collected clinical data. Only standard mRDT+ cases received antimalarials. Outcomes (clinical failure, secondary hospitalization, and death) were collected in follow-up visits or interviews on days 3, 7, and 28. After patient recruitment had ended, frozen blood from all 2,801 patients was tested for Plasmodium falciparum (Pf) by ultrasensitive-quantitative polymerase chain reaction (qPCR), standard mRDT, and "ultrasensitive" mRDT. As the latter did not improve sensitivity beyond standard mRDT, it is hereafter excluded. Clinical features and outcomes in LD patients (standard mRDT-/ultrasensitive-qPCR+, not given antimalarials) were compared with those with no detectable (ND) parasitemia (standard mRDT-/ultrasensitive-qPCR-) or high-density (HD) infections (standard mRDT+/ultrasensitive-qPCR+, antimalarial-treated). Pf positivity rate was 7.1% (n = 199/2,801) and 9.8% (n = 274/2,801) by standard mRDT and ultrasensitive qPCR, respectively. Thus, 28.0% (n = 76/274) of ultrasensitive qPCR+ cases were not detected by standard mRDT and labeled "LD". LD patients were, on average, 10.6 months younger than those with HD infections (95% CI 7.0-14.3 months, p < 0.001). Compared with ND, LD patients more frequently had the diagnosis of undifferentiated fever of presumed viral origin (risk ratio [RR] = 2.0, 95% CI 1.3-3.1, p = 0.003) and were more often suffering from severe malnutrition (RR = 3.2, 95% CI 1.1-7.5, p = 0.03). Despite not receiving antimalarials, outcomes for the LD group did not differ from ND regarding clinical failures (2.6% [n = 2/76] versus 4.0% [n = 101/2,527], RR = 0.7, 95% CI 0.2-3.5, p = 0.7) or secondary hospitalizations (2.6% [n = 2/76] versus 2.8% [n = 72/2,527], RR = 0.7,95% CI 0.2-3.2, p = 0.9), and no deaths were reported in any Pf-positive groups. HD patients experienced more secondary hospitalizations (10.1% [n = 20/198], RR = 0.3, 95% CI 0.1-1.0, p = 0.005) than LD patients. All the patients in this cohort were febrile children; thus, the association between parasitemia and fever cannot be investigated, nor can the conclusions be extrapolated to neonates and adults. CONCLUSIONS During a 28-day follow-up period, we did not find evidence of a difference in negative outcomes between febrile children with untreated LD Pf parasitemia and those without Pf parasitemia. These findings suggest LD parasitemia may either be a self-resolving fever or an incidental finding in children with other infections, including those of viral origin. These findings do not support a clinical benefit nor additional risk (e.g. because of missed bacterial infections) to using ultrasensitive malaria diagnostics at a primary care level.
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Affiliation(s)
- Mary-Anne Hartley
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- EPFL, Machine Learning and Optimization Laboratory, Lausanne, Switzerland
| | - Natalie Hofmann
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Kristina Keitel
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Frank Kagoro
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Clara Antunes Moniz
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Tarsis Mlaganile
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Josephine Samaka
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
- Amana hospital, Dar es Salaam, United Republic of Tanzania
| | - John Masimba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Zamzam Said
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Hosiana Temba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Iveth Gonzalez
- Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Blaise Genton
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Valérie D’Acremont
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
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38
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Macedo-da-Silva J, Marinho CRF, Palmisano G, Rosa-Fernandes L. Lights and Shadows of TORCH Infection Proteomics. Genes (Basel) 2020; 11:E894. [PMID: 32764347 PMCID: PMC7464470 DOI: 10.3390/genes11080894] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 12/25/2022] Open
Abstract
Congenital abnormalities cause serious fetal consequences. The term TORCH is used to designate the most common perinatal infections, where: (T) refers to toxoplasmosis, (O) means "others" and includes syphilis, varicella-zoster, parvovirus B19, zika virus (ZIKV), and malaria among others, (R) refers to rubella, (C) relates to cytomegalovirus infection, and (H) to herpes simplex virus infections. Among the main abnormalities identified in neonates exposed to congenital infections are central nervous system (CNS) damage, microcephaly, hearing loss, and ophthalmological impairment, all requiring regular follow-up to monitor its progression. Protein changes such as mutations, post-translational modifications, abundance, structure, and function may indicate a pathological condition before the onset of the first symptoms, allowing early diagnosis and understanding of a particular disease or infection. The term "proteomics" is defined as the science that studies the proteome, which consists of the total protein content of a cell, tissue or organism in a given space and time, including post-translational modifications (PTMs) and interactions between proteins. Currently, quantitative bottom-up proteomic strategies allow rapid and high throughput characterization of complex biological mixtures. Investigating proteome modulation during host-pathogen interaction helps in elucidating the mechanisms of infection and in predicting disease progression. This "molecular battle" between host and pathogen is a key to identify drug targets and diagnostic markers. Here, we conducted a survey on proteomic techniques applied to congenital diseases classified in the terminology "TORCH", including toxoplasmosis, ZIKV, malaria, syphilis, human immunodeficiency virus (HIV), herpes simplex virus (HSV) and human cytomegalovirus (HCVM). We have highlighted proteins and/or protein complexes actively involved in the infection. Most of the proteomic studies reported have been performed in cell line models, and the evaluation of tissues (brain, muscle, and placenta) and biofluids (plasma, serum and urine) in animal models is still underexplored. Moreover, there are a plethora of studies focusing on the pathogen or the host without considering the triad mother-fetus-pathogen as a dynamic and interconnected system.
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Affiliation(s)
- Janaina Macedo-da-Silva
- Glycoproteomics Laboratory, Department of Parasitology, University of Sao Paulo, Sao Paulo 05508-000, Brazil;
| | - Claudio Romero Farias Marinho
- Laboratory of Experimental Immunoparasitology, Department of Parasitology, University of Sao Paulo, Sao Paulo 05508-000, Brazil;
| | - Giuseppe Palmisano
- Glycoproteomics Laboratory, Department of Parasitology, University of Sao Paulo, Sao Paulo 05508-000, Brazil;
| | - Livia Rosa-Fernandes
- Glycoproteomics Laboratory, Department of Parasitology, University of Sao Paulo, Sao Paulo 05508-000, Brazil;
- Laboratory of Experimental Immunoparasitology, Department of Parasitology, University of Sao Paulo, Sao Paulo 05508-000, Brazil;
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Kurtis JD, Raj DK, Michelow IC, Park S, Nixon CE, McDonald EA, Nixon CP, Pond-Tor S, Jha A, Taliano RJ, Kabyemela ER, Friedman JF, Duffy PE, Fried M. Maternally-derived Antibodies to Schizont Egress Antigen-1 and Protection of Infants From Severe Malaria. Clin Infect Dis 2020; 68:1718-1724. [PMID: 30165569 DOI: 10.1093/cid/ciy728] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/21/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In holoendemic areas, children suffer the most from Plasmodium falciparum malaria, yet newborns and young infants express a relative resistance to both infection and severe malarial disease (SM). This relative resistance has been ascribed to maternally-derived anti-parasite immunoglobulin G; however, the targets of these protective antibodies remain elusive. METHODS We enrolled 647 newborns at birth from a malaria-holoendemic region of Tanzania. We collected cord blood, measured antibodies to Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1), and related these antibodies to the risk of severe malaria in the first year of life. In addition, we vaccinated female mice with PbSEA-1, mated them, and challenged their pups with P. berghei ANKA parasites to assess the impact of maternal PbSEA-1 vaccination on newborns' resistance to malaria. RESULTS Children with high cord-blood anti-PfSEA-1 antibody levels had 51.4% fewer cases of SM compared to individuals with lower anti-PfSEA-1 levels over 12 months of follow-up (P = .03). In 3 trials, pups born to PbSEA-1-vaccinated dams had significantly lower parasitemia and longer survival following a P. berghei challenge compared to pups born to control dams. CONCLUSIONS We demonstrate that maternally-derived, cord-blood anti-PfSEA-1 antibodies predict decreased risk of SM in infants and vaccination of mice with PbSEA-1 prior to pregnancy protects their offspring from lethal P. berghei challenge. These results identify, for the first time, a parasite-specific target of maternal antibodies that protect infants from SM and suggest that vaccination of pregnant women with PfSEA-1 may afford a survival advantage to their offspring.
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Affiliation(s)
- Jonathan D Kurtis
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Dipak K Raj
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Ian C Michelow
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Sangshin Park
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Christina E Nixon
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Emily A McDonald
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Christian P Nixon
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Sunthorn Pond-Tor
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Ambrish Jha
- Center for International Health Research, Brown University Medical School, Providence
| | - Ross J Taliano
- Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Edward R Kabyemela
- Mother Offspring Malaria Studies (MOMS) Project, Seattle Biomedical Research Institute, Washington.,Muheza Designated District Hospital.,Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Jennifer F Friedman
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
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40
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Addressing the Challenges to Diagnose Neonatal Hemolytic Anemia's Aetiologies in Low Ressources Countries: A Case Report. Case Rep Hematol 2020; 2020:3247127. [PMID: 32158566 PMCID: PMC7061141 DOI: 10.1155/2020/3247127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 01/04/2020] [Accepted: 02/05/2020] [Indexed: 11/17/2022] Open
Abstract
Background. The diagnosis of neonatal hemolysis is an easy exercise. However, the diagnosis of its etiology can be very challenging especially in low ressources countries where laboratory capacities are limited. We report the case of hemolytic anemia episodes that started in the neonatal period, for which the trigger factor, infectious of paracetamol, is debatable.
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Cheaveau J, Mogollon DC, Mohon MAN, Golassa L, Yewhalaw D, Pillai DR. Asymptomatic malaria in the clinical and public health context. Expert Rev Anti Infect Ther 2019; 17:997-1010. [PMID: 31718324 DOI: 10.1080/14787210.2019.1693259] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Introduction: Historically, the global community has focused on the control of symptomatic malaria. However, interest in asymptomatic malaria has been growing, particularly in the context of malaria elimination.Areas covered: We undertook a comprehensive PubMed literature review on asymptomatic malaria as it relates to detection and elimination with emphasis between 2014 and 2019. Diagnostic tools with a low limit of detection (LOD) have allowed us to develop a more detailed understanding of asymptomatic malaria and its impact. These highly sensitive diagnostics have demonstrated that the prevalence of asymptomatic malaria is greater than previously thought. In addition, it is now possible to detect the malaria reservoir in the community, something that was previously not feasible. Asymptomatic malaria has previously not been treated, but research has begun to examine whether treating individuals with asymptomatic malaria may lead to health benefits. Finally, we have begun to understand the importance of asymptomatic malaria in ongoing transmission.Expert opinion: Therefore, with malaria elimination back on the agenda, asymptomatic malaria can no longer be ignored, especially in light of new ultra-sensitive diagnostic tools.
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Affiliation(s)
- James Cheaveau
- Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Canada, AB, Canada
| | - Daniel Castaneda Mogollon
- Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Canada, AB, Canada
| | - Md Abu Naser Mohon
- Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Canada, AB, Canada
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Delenasaw Yewhalaw
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Dylan R Pillai
- Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Canada, AB, Canada.,Department of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada
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Stopping Plasmodium Parasite Invasion by Boosting Humoral Immunity. Hemasphere 2019; 3:e206. [PMID: 31723834 PMCID: PMC6746016 DOI: 10.1097/hs9.0000000000000206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Collins-Andrews B, McQuilkin P, Udhayashankar K, Adu E, Moormann A. Presentation and Treatment Outcomes of Liberian Children Age 5 Years and Under Diagnosed With Severe Malaria. Glob Pediatr Health 2019; 6:2333794X19884818. [PMID: 31700947 PMCID: PMC6826913 DOI: 10.1177/2333794x19884818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/25/2019] [Accepted: 09/13/2019] [Indexed: 11/15/2022] Open
Abstract
Malaria is endemic in Liberia with a prevalence rate of up to 60% in some regions, and it has been a major cause of death in children under 5 years of age. Prior to the recent Ebola epidemic, we undertook a prospective, hospital-based pilot study at the National Referral Hospital in Monrovia, to characterize the presentation, accuracy of diagnosis, and treatment outcomes of children presenting for treatment of malaria. From June 2013 to May 2014, we recruited children 5 years and under who presented to the JFK Medical Center with suspected malaria. We collected both clinical and laboratory data on admission and on discharge. We enrolled 477 patients with an average age of 1.6 years. Demographic factors associated with testing negative for malaria included regular bed net use and prior treatment for malaria. The most common presenting symptoms of severe malaria in this population were headache and seizures. Of 246 patients admitted and treated for severe malaria, 33% tested negative by rapid diagnostic test and blood smear for malaria. The case fatality rate was higher for the patients who tested negative for malaria (4.9%) versus those who tested positive (0.6%). Three children who tested negative for malaria showed evidence of undiagnosed Salmonella typhi infection. These results suggest that malaria may be overdiagnosed and that the diagnoses of other infectious diseases, which present in a similar fashion, may be neglected. These findings underscore the need to develop rapid diagnostic tests to screen for alternative causes of febrile illness.
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Affiliation(s)
| | | | | | - Eric Adu
- JFK Medical Center, Monrovia, Liberia
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Kivisi CA, Muthui M, Hunt M, Fegan G, Otto TD, Githinji G, Warimwe GM, Rance R, Marsh K, Bull PC, Abdi AI. Exploring Plasmodium falciparum Var Gene Expression to Assess Host Selection Pressure on Parasites During Infancy. Front Immunol 2019; 10:2328. [PMID: 31681266 PMCID: PMC6798654 DOI: 10.3389/fimmu.2019.02328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/16/2019] [Indexed: 11/13/2022] Open
Abstract
In sub-Saharan Africa, children below 5 years bear the greatest burden of severe malaria because they lack naturally acquired immunity that develops following repeated exposure to infections by Plasmodium falciparum. Antibodies to the surface of P. falciparum infected erythrocytes (IE) play an important role in this immunity. In children under the age of 6 months, relative protection from severe malaria is observed and this is thought to be partly due to trans-placental acquired protective maternal antibodies. However, the protective effect of maternal antibodies has not been fully established, especially the role of antibodies to variant surface antigens (VSA) expressed on IE. Here, we assessed the immune pressure on parasites infecting infants using markers associated with the acquisition of naturally acquired immunity to surface antigens. We hypothesized that, if maternal antibodies to VSA imposed a selection pressure on parasites, then the expression of a relatively conserved subset of var genes called group A var genes in infants should change with waning maternal antibodies. To test this, we compared their expression in parasites from children between 0 and 12 months and above 12 months of age. The transcript quantity and the proportional expression of group A var subgroup, including those containing domain cassette 13, were positively associated with age during the first year of life, which contrasts with above 12 months. This was accompanied by a decline in infected erythrocyte surface antibodies and an increase in parasitemia during this period. The observed increase in group A var gene expression with age in the first year of life, when the maternal antibodies are waning and before acquisition of naturally acquired antibodies with repeated exposure, is consistent with the idea that maternally acquired antibodies impose a selection pressure on parasites that infect infants and may play a role in protecting these infants against severe malaria.
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Affiliation(s)
- Cheryl A Kivisi
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya.,Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | | | - Martin Hunt
- Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Greg Fegan
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - George M Warimwe
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Richard Rance
- Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| | - Kevin Marsh
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Peter C Bull
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Abdirahman I Abdi
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
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45
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Feeney ME. The immune response to malaria in utero. Immunol Rev 2019; 293:216-229. [PMID: 31553066 DOI: 10.1111/imr.12806] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/13/2022]
Abstract
Malaria causes tremendous early childhood morbidity and mortality, providing an urgent impetus for the development of a vaccine that is effective in neonates. However, the infant immune response to malaria may be influenced by events that occur well before birth. Placental malaria infection complicates one quarter of all pregnancies in Africa and frequently results in exposure of the fetus to malaria antigens in utero, while the immune system is still developing. Some data suggest that in utero exposure to malaria may induce immunologic tolerance that interferes with the development of protective immunity during childhood. More recently, however, a growing body of evidence suggests that fetal malaria exposure can prime highly functional malaria-specific T- and B-cells, which may contribute to postnatal protection from malaria. In utero exposure to malaria also impacts the activation and maturation of fetal antigen presenting cells and innate lymphocytes, which could have implications for global immunity in the infant. Here, we review recent advances in our understanding of how various components of the fetal immune system are altered by in utero exposure to malaria, discuss factors that may tilt the critical balance between tolerance and adaptive immunity, and consider the implications of these findings for malaria prevention strategies.
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Affiliation(s)
- Margaret E Feeney
- Departments of Pediatrics and Medicine, University of California, San Francisco, San Francisco, CA, USA
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Watson OJ, Sumner KM, Janko M, Goel V, Winskill P, Slater HC, Ghani A, Meshnick SR, Parr JB. False-negative malaria rapid diagnostic test results and their impact on community-based malaria surveys in sub-Saharan Africa. BMJ Glob Health 2019; 4:e001582. [PMID: 31406591 PMCID: PMC6666813 DOI: 10.1136/bmjgh-2019-001582] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/30/2019] [Accepted: 07/02/2019] [Indexed: 12/24/2022] Open
Abstract
Surveillance and diagnosis of Plasmodium falciparum malaria relies predominantly on rapid diagnostic tests (RDT). However, false-negative (FN) RDT results are known to occur for a variety of reasons, including operator error, poor storage conditions, pfhrp2/3 gene deletions, poor performance of specific RDT brands and lots, and low-parasite density infections. We used RDT and microscopy results from 85 000 children enrolled in Demographic Health Surveys and Malaria Indicator Surveys from 2009 to 2015 across 19 countries to explore the distribution of and risk factors for FN-RDTs in sub-Saharan Africa, where malaria’s impact is greatest. We sought to (1) identify spatial and demographic patterns of FN-RDT results, defined as a negative RDT but positive gold standard microscopy test, and (2) estimate the percentage of infections missed within community-based malaria surveys due to FN-RDT results. Across all studies, 19.9% (95% CI 19.0% to 20.9%) of microscopy-positive subjects were negative by RDT. The distribution of FN-RDT results was spatially heterogeneous. The variance in FN-RDT results was best explained by the prevalence of malaria, with an increase in FN-RDT results observed at lower transmission intensities, among younger subjects, and in urban areas. The observed proportion of FN-RDT results was not predicted by differences in RDT brand or lot performance alone. These findings characterise how the probability of detection by RDTs varies in different transmission settings and emphasise the need for careful interpretation of prevalence estimates based on surveys employing RDTs alone. Further studies are needed to characterise the cost-effectiveness of improved malaria diagnostics (eg, PCR or highly sensitive RDTs) in community-based surveys, especially in regions of low transmission intensity or high urbanicity.
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Affiliation(s)
- Oliver J Watson
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Kelsey Marie Sumner
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Mark Janko
- Global Health Institute, Duke University, Durham, North Carolina, USA
| | - Varun Goel
- Department of Geography, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Peter Winskill
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Azra Ghani
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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47
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Park S, Nixon CE, Pond-Tor S, Kabyemela ER, Fried M, Duffy PE, Kurtis JD, Friedman JF. Impact of maternally derived antibodies to Plasmodium falciparum Schizont Egress Antigen-1 on the endogenous production of anti-PfSEA-1 in offspring. Vaccine 2019; 37:5044-5050. [PMID: 31288996 PMCID: PMC6677924 DOI: 10.1016/j.vaccine.2019.06.084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/07/2019] [Accepted: 06/27/2019] [Indexed: 02/03/2023]
Abstract
Background We evaluated whether maternally-derived antibodies to a malarial vaccine candidate, Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1), in cord blood interfered with the development of infant anti-PfSEA-1 antibodies in response to natural exposure. Methods We followed 630 Tanzanian infants who were measured their antibodies against PfSEA-1 (aa 810-1023; PfSEA-1A) at birth and 6, 12, 18, and 24 months of age, and examined the changes in anti-PfSEA-1A antibody levels in response to parasitemia, and evaluated whether maternally-derived anti-PfSEA-1A antibodies in cord blood modified infant anti-PfSEA-1A immune responses. Results Infants who experienced parasitemia during the first 6 months of life had significantly higher anti-PfSEA-1A antibodies at 6 and 12 months of age compared to uninfected infants. Maternally-derived anti-PfSEA-1A antibodies in cord blood significantly modified this effect during the first 6 months. During this period, infant anti-PfSEA-1A antibody levels were significantly associated with their P. falciparum exposure when they were born with low, but not higher, maternally-derived anti-PfSEA-1A antibody levels in cord blood. Nevertheless, during the first 6 months of life, maternally-derived anti-PfSEA-1A antibodies in cord blood did not abrogate the parasitemia driven development of infant anti-PfSEA-1A: parasitemia were significantly correlated with anti-PfSEA-1A antibody levels at 6 months of age in the infants born with low maternally-derived anti-PfSEA-1A antibody levels in cord blood and borderline significantly correlated in those infants born with middle and high levels. Conclusions Maternal vaccination with PfSEA-1A is unlikely to interfere with the development of naturally acquired anti-PfSEA-1A immune responses following exposure during infancy.
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Affiliation(s)
- Sangshin Park
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Department of Pediatrics, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Graduate School of Urban Public Health, University of Seoul, Seoul 02504, Republic of Korea.
| | - Christina E Nixon
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Department of Pathology and Laboratory Medicine, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States
| | - Sunthorn Pond-Tor
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Department of Pathology and Laboratory Medicine, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States
| | - Edward R Kabyemela
- Mother Offspring Malaria Studies (MOMS) Project, Seattle Biomedical Research Institute, Seattle, WA 98109, United States; Muheza Designated District Hospital, Muheza, Tanzania; Tumaini University, Moshi, Tanzania
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20892, United States
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20892, United States
| | - Jonathan D Kurtis
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Department of Pathology and Laboratory Medicine, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States
| | - Jennifer F Friedman
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States; Department of Pediatrics, The Warren Alpert Medical School of Brown University, Providence, RI 02903, United States
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48
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High-Sensitivity C-Reactive Protein: A Potential Ancillary Biomarker for Malaria Diagnosis and Morbidity. DISEASE MARKERS 2019; 2019:1408031. [PMID: 31089391 PMCID: PMC6476067 DOI: 10.1155/2019/1408031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 02/21/2019] [Accepted: 03/12/2019] [Indexed: 12/24/2022]
Abstract
Background Malaria remains an important cause of morbidity and mortality in Africa. Previous studies that assessed C-reactive protein (CRP) have centered on the conventional method. This study evaluated the usefulness of high-sensitivity CRP (hs-CRP) in malaria diagnosis and morbidity in a pediatric population in Ghana. Methodology A total of 267 subjects (100 microscopically proven nonmalarial parasitaemics as controls and 167 plasmodium parasitaemic subjects as cases), between the ages of 7 months and 18 years, were recruited for this case-control study. Blood samples were collected for malaria parasite density by microscopic examination; full blood count, electrolytes, and liver function tests using an automated analyzer; and hs-CRP levels by sandwich ELISA method. Results The median hs-CRP concentration was lowest in the control group and increased significantly from low to high parasitaemia. The median hs-CRP level was significantly higher in high malaria parasitaemia compared to moderate and low malaria parasitaemia. Increasing hs-CRP cutoff (3.12-4.64 mg/L) presented with increasing specificity (79.3-93.1%) and sensitivity (96.4%-97.4%), except for moderate parasitaemia where a decline in sensitivity (80.9%) was observed. However, hs-CRP had relatively lower PPV but high NPV at low parasitaemia while both the PPV and NPV were moderate in moderate parasitaemia. Conclusion hs-CRP yielded a high sensitivity, specificity, and accuracy for low, moderate, and high-grade malaria, respectively, and thus may serve as an effective supplementary diagnostic and prognostic biomarker for Plasmodium parasite infection. However, hs-CRP might not be readily useful yet for diagnostic purposes in hospitals due to the relatively low PPV and NPV for low and moderate parasitaemia and thus necessitates further studies in larger cohorts.
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Nawa M, Hangoma P, Morse AP, Michelo C. Investigating the upsurge of malaria prevalence in Zambia between 2010 and 2015: a decomposition of determinants. Malar J 2019; 18:61. [PMID: 30845998 PMCID: PMC6407176 DOI: 10.1186/s12936-019-2698-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 03/01/2019] [Indexed: 11/22/2022] Open
Abstract
Background Malaria is among the top causes of mortality and morbidity in Zambia. Efforts to control, prevent, and eliminate it have been intensified in the past two decades which has contributed to reductions in malaria prevalence and under-five mortality. However, there was a 21% upsurge in malaria prevalence between 2010 and 2015. Zambia is one of the only 13 countries to record an increase in malaria among 91 countries monitored by the World Health Organization in 2015. This study investigated the upsurge by decomposition of drivers of malaria. Methods The study used secondary data from three waves of nationally representative cross-sectional surveys on key malaria indicators conducted in 2010, 2012 and 2015. Using multivariable logistic regression, determinants of malaria prevalence were identified and then marginal effects of each determinant were derived. The marginal effects were then combined with changes in coverage rates of determinants between 2010 and 2015 to obtain the magnitude of how much each variable contributed to the change in the malaria prevalence. Results The odds ratio of malaria for those who slept under an insecticide-treated net (ITN) was 0.90 (95% CI 0.77–0.97), indoor residual spraying (IRS) was 0.66 (95% CI 0.49–0.89), urban residence was 0.23 (95% CI 0.15–0.37), standard house was 0.40 (95% CI 0.35–0.71) and age group 12–59 Months against those below 12 months was 4.04 (95% CI 2.80–5.81). Decomposition of prevalence changes by determinants showed that IRS reduced malaria prevalence by − 0.3% and ITNs by − 0.2% however, these reductions were overridden by increases in prevalence due to increases in the proportion of more at-risk children aged 12–59 months by + 2.3% and rural residents by + 2.2%. Conclusion The increases in interventions, such as ITNs and IRS, were shown to have contributed to malaria reduction in 2015; however, changes in demographics such as increases in the proportion of more at risk groups among under-five children and rural residents may have overridden the impact of these interventions and resulted in an overall increase. The upsurge in malaria in 2015 compared to 2010 may not have been due to weaknesses in programme interventions but due to increases in more at-risk children and rural residents compared to 2010. The apparent increase in rural residents in the sample population may not have been a true reflection of the population structure but due to oversampling in rural areas which was not fully adjusted for. The increase in malaria prevalence may therefore have been overestimated.
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Affiliation(s)
- Mukumbuta Nawa
- School of Public Health, University of Zambia, Ridgeway Campus, Lusaka, Zambia.
| | - Peter Hangoma
- School of Public Health, University of Zambia, Ridgeway Campus, Lusaka, Zambia
| | - Andrew P Morse
- Department of Geography and Planning, University of Liverpool, Liverpool, UK
| | - Charles Michelo
- School of Public Health, University of Zambia, Ridgeway Campus, Lusaka, Zambia
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50
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Akter J, Khoury DS, Aogo R, Lansink LIM, SheelaNair A, Thomas BS, Laohamonthonkul P, Pernold CPS, Dixon MWA, Soon MSF, Fogg LG, Engel JA, Elliott T, Sebina I, James KR, Cromer D, Davenport MP, Haque A. Plasmodium-specific antibodies block in vivo parasite growth without clearing infected red blood cells. PLoS Pathog 2019; 15:e1007599. [PMID: 30811498 PMCID: PMC6411214 DOI: 10.1371/journal.ppat.1007599] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/11/2019] [Accepted: 01/28/2019] [Indexed: 01/01/2023] Open
Abstract
Plasmodium parasites invade and multiply inside red blood cells (RBC). Through a cycle of maturation, asexual replication, rupture and release of multiple infective merozoites, parasitised RBC (pRBC) can reach very high numbers in vivo, a process that correlates with disease severity in humans and experimental animals. Thus, controlling pRBC numbers can prevent or ameliorate malaria. In endemic regions, circulating parasite-specific antibodies associate with immunity to high parasitemia. Although in vitro assays reveal that protective antibodies could control pRBC via multiple mechanisms, in vivo assessment of antibody function remains challenging. Here, we employed two mouse models of antibody-mediated immunity to malaria, P. yoelii 17XNL and P. chabaudi chabaudi AS infection, to study infection-induced, parasite-specific antibody function in vivo. By tracking a single generation of pRBC, we tested the hypothesis that parasite-specific antibodies accelerate pRBC clearance. Though strongly protective against homologous re-challenge, parasite-specific IgG did not alter the rate of pRBC clearance, even in the presence of ongoing, systemic inflammation. Instead, antibodies prevented parasites progressing from one generation of RBC to the next. In vivo depletion studies using clodronate liposomes or cobra venom factor, suggested that optimal antibody function required splenic macrophages and dendritic cells, but not complement C3/C5-mediated killing. Finally, parasite-specific IgG bound poorly to the surface of pRBC, yet strongly to structures likely exposed by the rupture of mature schizonts. Thus, in our models of humoral immunity to malaria, infection-induced antibodies did not accelerate pRBC clearance, and instead co-operated with splenic phagocytes to block subsequent generations of pRBC. Malaria occurs when Plasmodium parasites replicate inside red blood cells, with the number of parasitised cells (pRBC) correlating with disease severity. Antibodies are highly effective at controlling pRBC numbers in the bloodstream, and yet we know very little about how they function in vivo. Human in vitro studies predict that antibodies may function in a number of ways, including via phagocytes or different complement mechanisms. However, to date it has been challenging to explore how antibodies might control parasite numbers in vivo. Here, we have used a unique method in mice, where clearance and replication of a single cohort of pRBC was closely tracked in the presence of protective antibodies. Surprisingly, antibodies played no role whatsoever in accelerating the removal of pRBC. Instead, antibodies were highly effective at preventing parasites from progressing from one generation of pRBC to the next. This process partly depended on host phagocytes. However, we found no role for complement-mediated direct killing. Together, our in vivo data suggest in mouse models that naturally-acquired antibodies do not clear pRBC, and instead prevent transition from one red blood cell to the next.
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Affiliation(s)
- Jasmin Akter
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - David S. Khoury
- Infection Analytics Program, Kirby Institute, UNSW Australia, Kensington NSW, Australia
| | - Rosemary Aogo
- Infection Analytics Program, Kirby Institute, UNSW Australia, Kensington NSW, Australia
| | | | - Arya SheelaNair
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Bryce S. Thomas
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | | | | | - Matthew W. A. Dixon
- University of Melbourne, Department of Biochemistry and Molecular Biology, Melbourne, Victoria, Australia
| | - Megan S. F. Soon
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Lily G. Fogg
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Jessica A. Engel
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Trish Elliott
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Ismail Sebina
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Kylie R. James
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
| | - Deborah Cromer
- Infection Analytics Program, Kirby Institute, UNSW Australia, Kensington NSW, Australia
| | - Miles P. Davenport
- Infection Analytics Program, Kirby Institute, UNSW Australia, Kensington NSW, Australia
- * E-mail: (MPD); (AH)
| | - Ashraful Haque
- QIMR Berghofer Medical Research Institute, Herston, Brisbane QLD, Australia
- * E-mail: (MPD); (AH)
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