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Msugupakulya BJ, Urio NH, Jumanne M, Ngowo HS, Selvaraj P, Okumu FO, Wilson AL. Changes in contributions of different Anopheles vector species to malaria transmission in east and southern Africa from 2000 to 2022. Parasit Vectors 2023; 16:408. [PMID: 37936155 PMCID: PMC10631025 DOI: 10.1186/s13071-023-06019-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Malaria transmission in Africa is facilitated by multiple species of Anopheles mosquitoes. These vectors have different behaviors and vectorial capacities and are affected differently by vector control interventions, such as insecticide-treated nets and indoor residual spraying. This review aimed to assess changes in the contribution of different vector species to malaria transmission in east and southern Africa over 20 years of widespread insecticide-based vector control. METHODS We searched PubMed, Global Health, and Web of Science online databases for articles published between January 2000 and April 2023 that provided species-specific sporozoite rates for different malaria vectors in east and southern Africa. We extracted data on study characteristics, biting rates, sporozoite infection proportions, and entomological inoculation rates (EIR). Using EIR data, the proportional contribution of each species to malaria transmission was estimated. RESULTS Studies conducted between 2000 and 2010 identified the Anopheles gambiae complex as the primary malaria vector, while studies conducted from 2011 to 2021 indicated the dominance of Anopheles funestus. From 2000 to 2010, in 57% of sites, An. gambiae demonstrated higher parasite infection prevalence than other Anopheles species. Anopheles gambiae also accounted for over 50% of EIR in 76% of the study sites. Conversely, from 2011 to 2021, An. funestus dominated with higher infection rates than other Anopheles in 58% of sites and a majority EIR contribution in 63% of sites. This trend coincided with a decline in overall EIR and the proportion of sporozoite-infected An. gambiae. The main vectors in the An. gambiae complex in the region were Anopheles arabiensis and An. gambiae sensu stricto (s.s.), while the important member of the An. funestus group was An. funestus s.s. CONCLUSION The contribution of different vector species in malaria transmission has changed over the past 20 years. As the role of An. gambiae has declined, An. funestus now appears to be dominant in most settings in east and southern Africa. Other secondary vector species may play minor roles in specific localities. To improve malaria control in the region, vector control should be optimized to match these entomological trends, considering the different ecologies and behaviors of the dominant vector species.
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Affiliation(s)
- Betwel J Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Naomi H Urio
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
| | - Mohammed Jumanne
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Prashanth Selvaraj
- Institute for Disease Modeling, Bill and Melinda Gates Foundation, Seattle, USA
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK.
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Park Town, Johannesburg, Republic of South Africa.
| | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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Feufack-Donfack LB, Sarah-Matio EM, Abate LM, Bouopda Tuedom AG, Ngano Bayibéki A, Maffo Ngou C, Toto JC, Sandeu MM, Eboumbou Moukoko CE, Ayong L, Awono-Ambene P, Morlais I, Nsango SE. Epidemiological and entomological studies of malaria transmission in Tibati, Adamawa region of Cameroon 6 years following the introduction of long-lasting insecticide nets. Parasit Vectors 2021; 14:247. [PMID: 33964974 PMCID: PMC8106832 DOI: 10.1186/s13071-021-04745-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/23/2021] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Malaria remains a serious public health problem in Cameroon. Implementation of control interventions requires prior knowledge of the local epidemiological situation. Here we report the results of epidemiological and entomological surveys carried out in Tibati, Adamawa Region, Cameroon, an area where malaria transmission is seasonal, 6 years after the introduction of long-lasting insecticidal bed nets. METHODS Cross-sectional studies were carried out in July 2015 and 2017 in Tibati. Thick blood smears and dried blood spots were collected from asymptomatic and symptomatic individuals in the community and at health centers, respectively, and used for the molecular diagnosis of Plasmodium species. Adult mosquitoes were collected by indoor residual spraying and identified morphologically and molecularly. The infection status of Plasmodium spp. was determined by quantitative PCR, and positivity of PCR-positive samples was confirmed by Sanger sequencing. RESULTS Overall malaria prevalence in our study population was 55.0% (752/1367) and Plasmodium falciparum was the most prevalent parasite species (94.3%), followed by P. malariae (17.7%) and P. ovale (0.8%); 92 (12.7%) infections were mixed infections. Infection parameters varied according to clinical status (symptomatic/asymptomatic) and age of the sampled population and the collection sites. Infection prevalence was higher in asymptomatic carriers (60.8%), but asexual and sexual parasite densities were lower. Prevalence and intensity of infection decreased with age in both the symptomatic and asymptomatic groups. Heterogeneity in infections was observed at the neighborhood level, revealing hotspots of transmission. Among the 592 Anopheles mosquitoes collected, 212 (35.8%) were An. gambiae, 172 (29.1%) were An. coluzzii and 208 (35.1%) were An. funestus (s.s.). A total of 26 (4.39%) mosquito specimens were infected by Plasmodium sp. and the three Anopheles mosquitoes transmitted Plasmodium at equal efficiency. Surprisingly, we found an An. coluzzii specimen infected by Plasmodium vivax, which confirms circulation of this species in Cameroon. The positivity of all 26 PCR-positive Plasmodium-infected mosquitoes was successively confirmed by sequencing analysis. CONCLUSION Our study presents the baseline malaria parasite burden in Tibati, Adamawa Region, Cameroon. Our results highlight the high malaria endemicity in the area, and hotspots of disease transmission are identified. Parasitological indices suggest low bednet usage and that implementation of control interventions in the area is needed to reduce malaria burden. We also report for the first time a mosquito vector with naturally acquired P. vivax infection in Cameroon.
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Affiliation(s)
- Lionel Brice Feufack-Donfack
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- CNRS UPR 9022, Inserm U 963, Université de Strasbourg, 2, allée Konrad Roentgen, 67084 Strasbourg Cedex, France
| | - Elangwe Milo Sarah-Matio
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- UMR MIVEGEC, IRD, CNRS, Université de Montpellier, Institut de Recherche pour le Développement, 911 avenue Agropolis, 34394 Montpellier, France
| | - Luc Marcel Abate
- UMR MIVEGEC, IRD, CNRS, Université de Montpellier, Institut de Recherche pour le Développement, 911 avenue Agropolis, 34394 Montpellier, France
| | - Aline Gaelle Bouopda Tuedom
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- Faculté de Médecine et des Sciences Pharmaceutiques de l’Université de Douala (FMSP–UD), BP 2701 Douala, Cameroon
| | - Albert Ngano Bayibéki
- Université Catholique d’Afrique Centrale, Yaoundé-Campus Messa, BP 1110, Yaounde, Cameroon
| | - Christelle Maffo Ngou
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- UMR MIVEGEC, IRD, CNRS, Université de Montpellier, Institut de Recherche pour le Développement, 911 avenue Agropolis, 34394 Montpellier, France
| | - Jean-Claude Toto
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, BP 288, Yaounde, Cameroon
| | - Maurice Marcel Sandeu
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaounde, 13591 Cameroon
- Department of Microbiology and Infectious Diseases, School of Veterinary Medicine and Sciences, University of Ngaoundere, PO Box 454, Ngaoundere, Cameroon
| | - Carole Else Eboumbou Moukoko
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- Faculté de Médecine et des Sciences Pharmaceutiques de l’Université de Douala (FMSP–UD), BP 2701 Douala, Cameroon
| | - Lawrence Ayong
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
| | - Parfait Awono-Ambene
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, BP 288, Yaounde, Cameroon
| | - Isabelle Morlais
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- UMR MIVEGEC, IRD, CNRS, Université de Montpellier, Institut de Recherche pour le Développement, 911 avenue Agropolis, 34394 Montpellier, France
| | - Sandrine Eveline Nsango
- Service de Paludisme du Centre Pasteur Cameroun, BP 1274, Yaounde, Cameroon
- Faculté de Médecine et des Sciences Pharmaceutiques de l’Université de Douala (FMSP–UD), BP 2701 Douala, Cameroon
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Population Dynamics and Insecticide Susceptibility of Anopheles culicifacies in Malaria Endemic Districts of Chhattisgarh, India. INSECTS 2021; 12:insects12040284. [PMID: 33806071 PMCID: PMC8064500 DOI: 10.3390/insects12040284] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/13/2021] [Accepted: 03/20/2021] [Indexed: 11/22/2022]
Abstract
Simple Summary Malaria is a complex disease in part due to multiple vectors having different biological characteristics. In India, there are six primary vectors of malaria viz., Anopheles culicifacies, An. fluviatitlis, An. stephensi, An. subpictus, An. Minimus, and An. epiroticus. All these vectors have different ecological and seasonal distributions, transmission potential, and insecticide susceptibility status. In addition, except An. stephensi, all the five vectors comprise species complexes having sibling species which again differ in characteristics. Therefore, it is imperative to know the characteristics of the local vector population when it comes to planning control strategies. We carried out a study in tribal areas of Chhattisgarh state to investigate the seasonal and ecotype-wise distribution, breeding habits, sibling species composition, insecticide susceptibility, and role in the transmission of the local vector population. A high diversity of species was observed with around 16 species of Anopheles. An. culicifacies was the most dominant species and also was found to play a role in malaria transmission. The species was found to be resistant to dichlorodiphenyltrichloroethane (DDT) and Malathion, while an increasing trend of pyrethroid resistance was observed at some sites. Overall, our findings provide a picture of the characteristics of the local vector population in malaria-endemic regions. Abstract A study was undertaken in the villages of Korea and Bastar district (Chhattisgarh) during the years 2012–2015 to investigate the bionomics of malaria vectors and the prevalence of their sibling species complexes. Entomological surveys carried out every month included indoor resting collections, pyrethrum spray catches, light trap catches, and insecticide susceptibility status of Anopheles culicifacies using World Health Organization (WHO) methods. Anopheles culicifacies and Anopheles fluviatilis species were assayed by polymerase chain reaction (PCR) for the detection of malaria parasite, and sibling species were identified using PCR and DNA sequencing. A total of 13,186 samples of Anopheles comprising 15 species from Bastar and 16 from Korea were collected. An. Culicifacies was recorded as the most dominant species and also the only active vector at both sites. This species was found to be resistant to dichlorodiphenyltrichloroethane (DDT) and Malathion, showing signs of emerging resistance against pyrethroids. Among the sibling species of An. culicifacies, the group BCE was found in maximum numbers, while sibling species T of the An. fluviatilis was recorded to be dominant among its complex. The study provides a comprehensive view of the vector bionomics in the highly malarious regions of India that may have importance in developing vector control strategies.
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Oboh MA, Oyebola KM, Idowu ET, Badiane AS, Otubanjo OA, Ndiaye D. Rising report of Plasmodium vivax in sub-Saharan Africa: Implications for malaria elimination agenda. SCIENTIFIC AFRICAN 2020. [DOI: 10.1016/j.sciaf.2020.e00596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Remote Sensing and Multi-Criteria Evaluation for Malaria Risk Mapping to Support Indoor Residual Spraying Prioritization in the Central Highlands of Madagascar. REMOTE SENSING 2020. [DOI: 10.3390/rs12101585] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The National Malaria Control Program (NMCP) in Madagascar classifies Malagasy districts into two malaria situations: districts in the pre-elimination phase and districts in the control phase. Indoor residual spraying (IRS) is identified as the main intervention means to control malaria in the Central Highlands. However, it involves an important logistical mobilization and thus necessitates prioritization of interventions according to the magnitude of malaria risks. Our objectives were to map the malaria transmission risk and to develop a tool to support the Malagasy Ministry of Public Health (MoH) for selective IRS implementation. For the 2014–2016 period, different sources of remotely sensed data were used to update land cover information and substitute in situ climatic data. Spatial modeling was performed based on multi-criteria evaluation (MCE) to assess malaria risk. Models were mainly based on environment and climate. Three annual malaria risk maps were obtained for 2014, 2015, and 2016. Annual parasite incidence data were used to validate the results. In 2016, the validation of the model using a receiver operating characteristic (ROC) curve showed an accuracy of 0.736; 95% CI [0.669–0.803]. A free plugin for QGIS software was made available for NMCP decision makers to prioritize areas for IRS. An annual update of the model provides the basic information for decision making before each IRS campaign. In Madagascar and beyond, the availability of the free plugin for open-source software facilitates the transfer to the MoH and allows further application to other problems and contexts.
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Niass O, Saint-Pierre P, Niang M, Diop F, Diouf B, Faye MM, Sarr FD, Faye J, Diagne N, Sokhna C, Trape JF, Perraut R, Tall A, Diongue AK, Toure Balde A. Modelling dynamic change of malaria transmission in holoendemic setting (Dielmo, Senegal) using longitudinal measures of antibody prevalence to Plasmodium falciparum crude schizonts extract. Malar J 2017; 16:409. [PMID: 29020949 PMCID: PMC5637097 DOI: 10.1186/s12936-017-2052-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/04/2017] [Indexed: 11/25/2022] Open
Abstract
Background Evaluation of local Plasmodium falciparum malaria transmission has been investigated previously using the reversible catalytic model based on prevalence of antibody responses to single antigen to estimate seroconversion rates. High correlations were observed between seroconversion rates and entomological inoculation rates (EIR). However, in this model, the effects of malaria control interventions and clinical episodes on serological measurements were not assessed. This study monitors the use of antibody responses to P. falciparum crude extracts for assessing malaria transmission, compares seroconversion rates estimated from longitudinal data to those derived from cross-sectional surveys and investigates the effects of malaria control interventions on these measures in an area of declining malaria transmission. In addition, the validity of this model was evaluated by comparison with the alternative model. Methods Five cross-sectional surveys were carried out at the end of the wet season in Dielmo, a malaria-endemic Senegalese rural area in 2000, 2002, 2008, 2010 and 2012. Antibodies against schizonts crude extract of a local P. falciparum strain adapted to culture (Pf 07/03) were measured by ELISA. Age-specific seroprevalence model was used both for cross-sectional surveys and longitudinal data (combined data of all surveys). Results A total of 1504 plasma samples obtained through several years follow-up of 350 subjects was used in this study. Seroconversion rates based on P. falciparum schizonts crude extract were estimated for each cross-sectional survey and were found strongly correlated with EIR. High variability between SCRs from cross-sectional and longitudinal surveys was observed. In longitudinal studies, the alternative catalytic reversible model adjusted better with serological data than the catalytic model. Clinical malaria attacks and malaria control interventions were found to have significant effect on seroconversion. Discussion The results of the study suggested that crude extract was a good serological tool that could be used to assess the level of malaria exposure in areas where malaria transmission is declining. However, additional parameters such as clinical malaria and malaria control interventions must be taken into account for determining serological measurements for more accuracy in transmission assessment. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2052-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Oumy Niass
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.,Laboratoire d'étude et de Recherche en Statistique et Développement, Université Gaston Berger, BP 237, Saint-Louis, Senegal
| | | | - Makhtar Niang
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Fode Diop
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Babacar Diouf
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Michel Matar Faye
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Fatoumata Diène Sarr
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Joseph Faye
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Nafissatou Diagne
- Institut de Recherche pour le Développement, BP 1386, Dakar, Senegal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement, BP 1386, Dakar, Senegal
| | | | - Ronald Perraut
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Adama Tall
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Abdou Kâ Diongue
- Laboratoire d'étude et de Recherche en Statistique et Développement, Université Gaston Berger, BP 237, Saint-Louis, Senegal
| | - Aïssatou Toure Balde
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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Rakotoson JD, Fornadel CM, Belemvire A, Norris LC, George K, Caranci A, Lucas B, Dengela D. Insecticide resistance status of three malaria vectors, Anopheles gambiae (s.l.), An. funestus and An. mascarensis, from the south, central and east coasts of Madagascar. Parasit Vectors 2017; 10:396. [PMID: 28835269 PMCID: PMC5569519 DOI: 10.1186/s13071-017-2336-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 08/16/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-based vector control, which comprises use of insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS), is the key method to malaria control in Madagascar. However, its effectiveness is threatened as vectors become resistant to insecticides. This study investigated the resistance status of malaria vectors in Madagascar to various insecticides recommended for use in ITNs and/or IRS. METHODS WHO tube and CDC bottle bioassays were performed on populations of Anopheles gambiae (s.l.), An. funestus and An. mascarensis. Adult female An. gambiae (s.l.) mosquitoes reared from field-collected larvae and pupae were tested for their resistance to DDT, permethrin, deltamethrin, alpha-cypermethrin, lambda-cyhalothrin, bendiocarb and pirimiphos-methyl. Resting An. funestus and An. mascarensis female mosquitoes collected from unsprayed surfaces were tested against permethrin, deltamethrin and pirimiphos-methyl. The effect on insecticide resistance of pre-exposure to the synergists piperonyl-butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) also was assessed. Molecular analyses were done to identify species and determine the presence of knock-down resistance (kdr) and acetylcholinesterase resistance (ace-1 R ) gene mutations. RESULTS Anopheles funestus and An. mascarensis were fully susceptible to permethrin, deltamethrin and pirimiphos-methyl. Anopheles gambiae (s.l.) was fully susceptible to bendiocarb and pirimiphos-methyl. Among the 17 An. gambiae (s.l.) populations tested for deltamethrin, no confirmed resistance was recorded, but suspected resistance was observed in two sites. Anopheles gambiae (s.l.) was resistant to permethrin in four out of 18 sites (mortality 68-89%) and to alpha-cypermethrin (89% mortality) and lambda-cyhalothrin (80% and 85%) in one of 17 sites, using one or both assay methods. Pre-exposure to PBO restored full susceptibility to all pyrethroids tested except in one site where only partial restoration to permethrin was observed. DEF fully suppressed resistance to deltamethrin and alpha-cypermethrin, while it partially restored susceptibility to permethrin in two of the three sites. Molecular analysis data suggest absence of kdr and ace-1 R gene mutations. CONCLUSION This study suggests involvement of detoxifying enzymes in the phenotypic resistance of An. gambiae (s.l.) to pyrethroids. The absence of resistance in An. funestus and An. mascarensis to pirimiphos-methyl and pyrethroids and in An. gambiae (s.l.) to carbamates and organophosphates presents greater opportunity for managing resistance in Madagascar.
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Affiliation(s)
- Jean-Desire Rakotoson
- President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, Antananarivo, Madagascar
| | - Christen M Fornadel
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Allison Belemvire
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Laura C Norris
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Kristen George
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Angela Caranci
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Bradford Lucas
- President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, 4550 Montgomery Ave, Suite 800 North, Bethesda, MD, 20814, USA
| | - Dereje Dengela
- President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, 4550 Montgomery Ave, Suite 800 North, Bethesda, MD, 20814, USA.
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Rice BL, Golden CD, Anjaranirina EJG, Botelho CM, Volkman SK, Hartl DL. Genetic evidence that the Makira region in northeastern Madagascar is a hotspot of malaria transmission. Malar J 2016; 15:596. [PMID: 27998292 PMCID: PMC5175380 DOI: 10.1186/s12936-016-1644-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/01/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Encouraging advances in the control of Plasmodium falciparum malaria have been observed across much of Africa in the past decade. However, regions of high relative prevalence and transmission that remain unaddressed or unrecognized provide a threat to this progress. Difficulties in identifying such localized hotspots include inadequate surveillance, especially in remote regions, and the cost and labor needed to produce direct estimates of transmission. Genetic data can provide a much-needed alternative to such empirical estimates, as the pattern of genetic variation within malaria parasite populations is indicative of the level of local transmission. Here, genetic data were used to provide the first empirical estimates of P. falciparum malaria prevalence and transmission dynamics for the rural, remote Makira region of northeastern Madagascar. METHODS Longitudinal surveys of a cohort of 698 total individuals (both sexes, 0-74 years of age) were performed in two communities bordering the Makira Natural Park protected area. Rapid diagnostic tests, with confirmation by molecular methods, were used to estimate P. falciparum prevalence at three seasonal time points separated by 4-month intervals. Genomic loci in a panel of polymorphic, putatively neutral markers were genotyped for 94 P. falciparum infections and used to characterize genetic parameters known to correlate with transmission levels. RESULTS Overall, 27.8% of individuals tested positive for P. falciparum over the 10-month course of the study, a rate approximately sevenfold higher than the countrywide average for Madagascar. Among those P. falciparum infections, a high level of genotypic diversity and a high frequency of polygenomic infections (68.1%) were observed, providing a pattern consistent with high and stable transmission. CONCLUSIONS Prevalence and genetic diversity data indicate that the Makira region is a hotspot of P. falciparum transmission in Madagascar. This suggests that the area should be highlighted for future interventions and that additional areas of high transmission may be present in ecologically similar regions nearby.
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Affiliation(s)
- Benjamin L. Rice
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA USA
| | - Christopher D. Golden
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA USA
- Harvard University Center for the Environment, Cambridge, MA USA
- Madagascar Health and Environmental Research (MAHERY), Maroantsetra, Madagascar
| | | | | | - Sarah K. Volkman
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA USA
| | - Daniel L. Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA USA
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Ratovonjato J, Randrianarivelojosia M, Rakotondrainibe ME, Raharimanga V, Andrianaivolambo L, Le Goff G, Rogier C, Ariey F, Boyer S, Robert V. Entomological and parasitological impacts of indoor residual spraying with DDT, alphacypermethrin and deltamethrin in the western foothill area of Madagascar. Malar J 2014; 13:21. [PMID: 24423246 PMCID: PMC3906765 DOI: 10.1186/1475-2875-13-21] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 12/31/2013] [Indexed: 11/29/2022] Open
Abstract
Background In Madagascar, indoor residual spraying (IRS) with insecticide was part of the national malaria control programme since the middle of the twentieth century. It was mainly employed in the highlands and the foothill areas, which are prone to malaria epidemics. Prior to a policy change foreseeing a shift from DDT to pyrethroids, a study was carried out to assess the entomological and parasitological impacts of IRS in areas with DDT or pyrethroids and in areas without IRS. Methods The study was carried out from October 2002 to February 2005 in three communes of the western foothill area of Madagascar. Two communes received IRS with DDT in February 2003, then IRS with pyrethroids (alphacypermethrin or deltamethrin) in February 2004. The third commune remained untreated. Mosquitoes were collected at night using human landing catches and early in the morning in resting places. Blood smears were obtained from schoolchildren and microscopically examined for Plasmodium presence. Results In total, 18,168 human landing mosquitoes and 12,932 resting anophelines were collected. The Anopheles species caught comprised 10 species. The main and most abundant malaria vector was Anopheles funestus (72.3% of human-seeking malaria vectors caught indoors). After IRS had taken place, this species exhibited a lower human biting rate and a lower sporozoite index. Overall, 5,174 blood smears were examined with a mean plasmodic index of 19.9%. A total of four Plasmodium species were detected. Amongst tested school children the highest plasmodial index was 54.6% in the untreated commune, compared to 19.9% in the commune sprayed with DDT and 11.9% in the commune sprayed with pyrethroid. The highest prevalence of clinical malaria attacks in children present at school the day of the survey was 33% in the untreated commune compared to 8% in the areas which received IRS. Conclusion In terms of public health, the present study shows (1) a high efficacy of IRS with insecticide, (2) a similar efficacy of DDT and pyrethroid and (3) a similar efficacy of alphacypermethrin and deltamethrin. The use of IRS with DDT and pyrethroid greatly decreased the vector-human contact, with an associated decrease of the plasmodial index. However malaria transmission did not reach zero, probably due to the exophilic host-seeking and resting behaviours of the malaria vectors, thus avoiding contact with insecticide-treated surfaces indoors. The study highlights the strengths and weaknesses of the IRS implementation and the need for complementary tools for an optimal vector control in Madagascar.
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Affiliation(s)
- Jocelyn Ratovonjato
- Institut Pasteur de Madagascar, Ambatofotsikely, Antananarivo 101, BP 1274, Madagascar.
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Sagna AB, Gaayeb L, Sarr JB, Senghor S, Poinsignon A, Boutouaba-Combe S, Schacht AM, Hermann E, Faye N, Remoue F, Riveau G. Plasmodium falciparum infection during dry season: IgG responses to Anopheles gambiae salivary gSG6-P1 peptide as sensitive biomarker for malaria risk in Northern Senegal. Malar J 2013; 12:301. [PMID: 23988032 PMCID: PMC3766161 DOI: 10.1186/1475-2875-12-301] [Citation(s) in RCA: 28] [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: 06/26/2013] [Accepted: 08/27/2013] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The Northern part of Senegal is characterized by a low and seasonal transmission of malaria. However, some Plasmodium falciparum infections and malaria clinical cases are reported during the dry season. This study aims to assess the relationship between IgG antibody (Ab) responses to gSG6-P1 mosquito salivary peptide and the prevalence of P. falciparum infection in children during the dry season in the Senegal River Valley. The positive association of the Ab response to gSG6-P1, as biomarker of human exposure to Anopheles vector bite, and P. falciparum infectious status (uninfected, infected-asymptomatic or infected-symptomatic) will allow considering this biomarker as a potential indicator of P. falciparum infection risk during the dry season. METHODS Microscopic examination of thick blood smears was performed in 371 and 310 children at the start (January) and at the end (June) of the dry season, respectively, in order to assess the prevalence of P. falciparum infection. Collected sera were used to evaluate IgG response to gSG6-P1 by ELISA. Association between parasitological and clinical data (infected-asymptomatic or infected-symptomatic) and the anti-gSG6-P1 IgG levels were evaluated during this period. RESULTS The prevalence of P. falciparum infection was very low to moderate according to the studied period and was higher in January (23.5%) compared to June (3.5%). Specific IgG response was also different between uninfected children and asymptomatic carriers of the parasite. Children with P. falciparum infection in the dry season showed higher IgG Ab levels to gSG6-P1 than uninfected children. CONCLUSIONS The results strengthen the hypothesis that malaria transmission is maintained during the dry season in an area of low and seasonal transmission. The measurement of IgG responses to gSG6-P1 salivary peptide could be a pertinent indicator of human malaria reservoir or infection risk in this particular epidemiological context. This promising immunological marker could be useful for the evaluation of the risk of P. falciparum exposure observed during dry season and, by consequences, could be used for the survey of potential pre-elimination situation.
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Affiliation(s)
- André B Sagna
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
- Département de Biologie Animale, Laboratoire de parasitologie générale, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Lobna Gaayeb
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
- CIIL, Inserm U1019, CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019 Lille cedex, France
| | - Jean B Sarr
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
- Institut de Recherche pour le Développement, UMR 224 MIVEGEC, 911 avenue Agropolis, BP: 64501F-34394 Montpellier, France
| | - Simon Senghor
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
| | - Anne Poinsignon
- Institut de Recherche pour le Développement, UMR 224 MIVEGEC, 911 avenue Agropolis, BP: 64501F-34394 Montpellier, France
| | - Samy Boutouaba-Combe
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
| | - Anne-Marie Schacht
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
- CIIL, Inserm U1019, CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019 Lille cedex, France
| | - Emmanuel Hermann
- CIIL, Inserm U1019, CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019 Lille cedex, France
| | - Ngor Faye
- Département de Biologie Animale, Laboratoire de parasitologie générale, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Franck Remoue
- Institut de Recherche pour le Développement, UMR 224 MIVEGEC, 911 avenue Agropolis, BP: 64501F-34394 Montpellier, France
- Centre de Recherche Entomologique de Cotonou, BP: 4414, Cotonou RP 01, Bénin
| | - Gilles Riveau
- Centre de Recherche Biomédicale Espoir Pour La Santé, 269 Route de la corniche, Sor, BP: 226, Saint-Louis, Sénégal
- CIIL, Inserm U1019, CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, 1 rue du Pr. Calmette, 59019 Lille cedex, France
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Sinka ME, Bangs MJ, Manguin S, Coetzee M, Mbogo CM, Hemingway J, Patil AP, Temperley WH, Gething PW, Kabaria CW, Okara RM, Van Boeckel T, Godfray HCJ, Harbach RE, Hay SI. The dominant Anopheles vectors of human malaria in Africa, Europe and the Middle East: occurrence data, distribution maps and bionomic précis. Parasit Vectors 2010; 3:117. [PMID: 21129198 PMCID: PMC3016360 DOI: 10.1186/1756-3305-3-117] [Citation(s) in RCA: 411] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 12/03/2010] [Indexed: 11/10/2022] Open
Abstract
Background This is the second in a series of three articles documenting the geographical distribution of 41 dominant vector species (DVS) of human malaria. The first paper addressed the DVS of the Americas and the third will consider those of the Asian Pacific Region. Here, the DVS of Africa, Europe and the Middle East are discussed. The continent of Africa experiences the bulk of the global malaria burden due in part to the presence of the An. gambiae complex. Anopheles gambiae is one of four DVS within the An. gambiae complex, the others being An. arabiensis and the coastal An. merus and An. melas. There are a further three, highly anthropophilic DVS in Africa, An. funestus, An. moucheti and An. nili. Conversely, across Europe and the Middle East, malaria transmission is low and frequently absent, despite the presence of six DVS. To help control malaria in Africa and the Middle East, or to identify the risk of its re-emergence in Europe, the contemporary distribution and bionomics of the relevant DVS are needed. Results A contemporary database of occurrence data, compiled from the formal literature and other relevant resources, resulted in the collation of information for seven DVS from 44 countries in Africa containing 4234 geo-referenced, independent sites. In Europe and the Middle East, six DVS were identified from 2784 geo-referenced sites across 49 countries. These occurrence data were combined with expert opinion ranges and a suite of environmental and climatic variables of relevance to anopheline ecology to produce predictive distribution maps using the Boosted Regression Tree (BRT) method. Conclusions The predicted geographic extent for the following DVS (or species/suspected species complex*) is provided for Africa: Anopheles (Cellia) arabiensis, An. (Cel.) funestus*, An. (Cel.) gambiae, An. (Cel.) melas, An. (Cel.) merus, An. (Cel.) moucheti and An. (Cel.) nili*, and in the European and Middle Eastern Region: An. (Anopheles) atroparvus, An. (Ano.) labranchiae, An. (Ano.) messeae, An. (Ano.) sacharovi, An. (Cel.) sergentii and An. (Cel.) superpictus*. These maps are presented alongside a bionomics summary for each species relevant to its control.
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Affiliation(s)
- Marianne E Sinka
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Andrianaivolambo L, Domarle O, Randrianarivelojosia M, Ratovonjato J, Le Goff G, Talman A, Ariey F, Robert V. Anthropophilic mosquitoes and malaria transmission in the eastern foothills of the central highlands of Madagascar. Acta Trop 2010; 116:240-5. [PMID: 20804715 DOI: 10.1016/j.actatropica.2010.08.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 08/20/2010] [Accepted: 08/23/2010] [Indexed: 11/24/2022]
Abstract
Malaria remains a major public health problem in Madagascar, as it is the first cause of morbidity in health care facilities. Its transmission remains poorly documented. An entomological study was carried out over 1 year (October 2003-September 2004) in Saharevo, a village located at an altitude of 900m on the eastern edge of the Malagasy central highlands. Mosquitoes were sampled weekly upon landing on human volunteers and in various resting-places. Out of 5515 mosquitoes collected on humans, 3219 (58.4%) were anophelines. Eleven anopheline species were represented, among which Anopheles funestus, Anopheles gambiae, Anopheles arabiensis and Anopheles mascarensis. Out of 677 mosquitoes collected in bedrooms by pyrethrum spray catches and in Muirhead-Thomson pits, 656 (96.9%) were anopheline belonging to these four latter species. The proportion of mosquitoes that fed on human varied according to the resting-places and the mosquito species: 86% of An. funestus resting in bedrooms fed on humans, whereas only 16% of An. funestus and 0% of An. mascarensis resting in pits fed on humans. The proportion of anopheline mosquitoes infected with human Plasmodium was measured by circumsporozoite protein-ELISA: 10/633 An. funestus (1.58%), 1/211 An. gambiae s.l. (0.48%) and 2/268 An. mascarensis (0.75%). The annual entomological inoculation rate (number of bites of infected anophelines per adult) was estimated at 2.78. The transmission was mainly due to An. funestus and only observed in the second half of the rainy season, from February to May. These results are discussed in the context of the current malaria vector control policy in Madagascar.
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Cook J, Reid H, Iavro J, Kuwahata M, Taleo G, Clements A, McCarthy J, Vallely A, Drakeley C. Using serological measures to monitor changes in malaria transmission in Vanuatu. Malar J 2010; 9:169. [PMID: 20553604 PMCID: PMC2904786 DOI: 10.1186/1475-2875-9-169] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 06/16/2010] [Indexed: 12/01/2022] Open
Abstract
Background With renewed interest in malaria elimination, island environments present unique opportunities to achieve this goal. However, as transmission decreases, monitoring and evaluation programmes need increasingly sensitive tools to assess Plasmodium falciparum and Plasmodium vivax exposure. In 2009, to assess the role of serological markers in evaluating malaria transmission, a cross-sectional seroprevalence study was carried out in Tanna and Aneityum, two of the southernmost islands of the Vanuatu archipelago, areas where malaria transmission has been variably reduced over the past few decades. Methods Malaria transmission was assessed using serological markers for exposure to P. falciparum and P. vivax. Filter blood spot papers were collected from 1,249 people from Tanna, and 517 people from Aneityum to assess the prevalence of antibodies to two P. falciparum antigens (MSP-119 and AMA-1) and two P. vivax antigens (MSP-119 and AMA-1). Age-specific prevalence was modelled using a simple catalytic conversion model based on maximum likelihood to generate a community seroconversion rate (SCR). Results Overall seropositivity in Tanna was 9.4%, 12.4% and 16.6% to P. falciparum MSP-119, AMA-1 and Schizont Extract respectively and 12.6% and 15.0% to P. vivax MSP-119 and AMA-1 respectively. Serological results distinguished between areas of differential dominance of either P. vivax or P. falciparum and analysis of age-stratified results showed a step in seroprevalence occurring approximately 30 years ago on both islands, indicative of a change in transmission intensity at this time. Results from Aneityum suggest that several children may have been exposed to malaria since the 2002 P. vivax epidemic. Conclusion Seroepidemiology can provide key information on malaria transmission for control programmes, when parasite rates are low. As Vanuatu moves closer to malaria elimination, monitoring changes in transmission intensity and identification of residual malaria foci is paramount in order to concentrate intervention efforts.
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Affiliation(s)
- Jackie Cook
- London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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Andriantsoanirina V, Ménard D, Tuseo L, Durand R. History and current status of Plasmodium falciparum antimalarial drug resistance in Madagascar. ACTA ACUST UNITED AC 2010; 42:22-32. [PMID: 19883158 DOI: 10.3109/00365540903289670] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Malaria remains a major health problem in Madagascar. Over past decades, the burden of malarial disease has fluctuated over time, partly in line with the successes and failures of antimalarial policy. In the 1950s and 1960s, a sharp decline in malaria transmission was observed in the central highlands due to indoor spraying with DDT and to the massive use of chloroquine by the population. Following this, the discontinuation of the 'nivaquinization' policy was followed by devastating outbreaks in the central highlands in the 1980s. Currently, the rate of in vitro chloroquine-resistant Plasmodium falciparum isolates does not exceed 5%. This figure appears disconnected from the high level of clinical treatment failure (near 40%). pfcrt mutant isolates are found in less than 1% of isolates on the Island. Conversely, pfmdr1 mutant isolates are found in more than 60% of isolates and may be responsible for the bulk of resistance to chloroquine in Madagascar. Other antimalarials remain generally effective in Madagascar. Recent clinical and in vitro data support the complete efficacy of the combination artesunate-amodiaquine in Madagascar. As such, this artemisinin combination therapy should play a central role in the control and possible elimination of P. falciparum malaria in Madagascar
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Rabarijaona LP, Randrianarivelojosia M, Raharimalala LA, Ratsimbasoa A, Randriamanantena A, Randrianasolo L, Ranarivelo LA, Rakotomanana F, Randremanana R, Ratovonjato J, Rason MA, Duchemin JB, Tall A, Robert V, Jambou R, Ariey F, Domarle O. Longitudinal survey of malaria morbidity over 10 years in Saharevo (Madagascar): further lessons for strengthening malaria control. Malar J 2009; 8:190. [PMID: 19660116 PMCID: PMC3224923 DOI: 10.1186/1475-2875-8-190] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 08/06/2009] [Indexed: 12/02/2022] Open
Abstract
Background Madagascar has been known for having bio-geo-ecological diversity which is reflected by a complex malaria epidemiology ranging from hyperendemic to malaria-free areas. Malaria-related attacks and infection are frequently recorded both in children and adults living in areas of low malaria transmission. To integrate this variability in the national malaria control policy, extensive epidemiological studies are required to up-date previous records and adjust strategies. Methods A longitudinal malaria survey was conducted from July 1996 to June 2005 among an average cohort of 214 villagers in Saharevo, located at 900 m above the sea. Saharevo is a typical eastern foothill site at the junction between a costal wet tropical area (equatorial malaria pattern) and a drier high-altitude area (low malaria transmission). Results Passive and active malaria detection revealed that malaria transmission in Saharevo follows an abrupt seasonal variation. Interestingly, malaria was confirmed in 45% (1,271/2,794) of malaria-presumed fevers seen at the health centre. All four Plasmodia that infect humans were also found: Plasmodium falciparum; Plasmodium vivax, Plasmodium malariae and Plasmodium ovale. Half of the malaria-presumed fevers could be confirmed over the season with the highest malaria transmission level, although less than a quarter in lower transmission time, highlighting the importance of diagnosis prior to treatment intake. P. falciparum malaria has been predominant (98%). The high prevalence of P. falciparum malaria affects more particularly under 10 years old children in both symptomatic and asymptomatic contexts. Children between two and four years of age experienced an average of 2.6 malaria attacks with P. falciparum per annum. Moreover, estimated incidence of P. falciparum malaria tends to show that half of the attacks (15 attacks) risk to occur during the first 10 years of life for a 60-year-old adult who would have experienced 32 malaria attacks. Conclusion The incidence of malaria decreased slightly with age but remained important among children and adults in Saharevo. These results support that a premunition against malaria is slowly acquired until adolescence. However, this claims for a weak premunition among villagers in Saharevo and by extension in the whole eastern foothill area of Madagascar. While the Malagasy government turns towards malaria elimination plans nowadays, choices and expectations to up-date and adapt malaria control strategies in the foothill areas are discussed in this paper.
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Razakandrainibe R, Thonier V, Ratsimbasoa A, Rakotomalala E, Ravaoarisoa E, Raherinjafy R, Andrianantenaina H, Voahanginirina O, Rahasana TE, Carod JF, Domarle O, Menard D. Epidemiological situation of malaria in Madagascar: baseline data for monitoring the impact of malaria control programmes using serological markers. Acta Trop 2009; 111:160-7. [PMID: 19376076 DOI: 10.1016/j.actatropica.2009.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 02/18/2009] [Accepted: 04/08/2009] [Indexed: 11/18/2022]
Abstract
The aim of this study was to provide baseline information of the epidemiological situation of malaria in Madagascar using serological markers. We carried out cross-sectional studies in schoolchildren from eight sites in the four different malarious epidemiological strata of Madagascar. We studied the prevalence of anti-MSP1 antibodies to assess the burden, and anti-CSP antibodies to estimate the transmission intensity, of malaria. The overall prevalence of each antibody tested was 46.1% for anti-PfMSP-1, 15.2% for anti-PvMSP-1, 14.9% for anti-PfCSP, 4.9% for anti-PvCSP and 2.4% for anti-PmCSP. The prevalence of the five antibodies varied significantly between the sites (P<10(-6)). We also found significant effects of ethnic origin on the prevalence of anti-PfMSP1 antibodies. With regular testing in the same target populations, this data will be particularly useful for managing the elimination strategy supported by the Malagasy Government.
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Smith A. Infection prevalence and vector-borne transmission: are vectors always to blame? Trends Parasitol 2008; 24:492-6. [DOI: 10.1016/j.pt.2008.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/29/2008] [Accepted: 07/31/2008] [Indexed: 10/21/2022]
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Barnadas C, Tichit M, Bouchier C, Ratsimbasoa A, Randrianasolo L, Raherinjafy R, Jahevitra M, Picot S, Ménard D. Plasmodium vivax dhfr and dhps mutations in isolates from Madagascar and therapeutic response to sulphadoxine-pyrimethamine. Malar J 2008; 7:35. [PMID: 18302746 PMCID: PMC2268703 DOI: 10.1186/1475-2875-7-35] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 02/26/2008] [Indexed: 11/10/2022] Open
Abstract
Background Four of five Plasmodium species infecting humans are present in Madagascar. Plasmodium vivax remains the second most prevalent species, but is understudied. No data is available on its susceptibility to sulphadoxine-pyrimethamine, the drug recommended for intermittent preventive treatment during pregnancy. In this study, the prevalence of P. vivax infection and the polymorphisms in the pvdhfr and pvdhps genes were investigated. The correlation between these polymorphisms and clinical and parasitological responses was also investigated in P. vivax-infected patients. Methods Plasmodium vivax clinical isolates were collected in eight sentinel sites from the four major epidemiological areas for malaria across Madagascar in 2006/2007. Pvdhfr and pvdhps genes were sequenced for polymorphism analysis. The therapeutic efficacy of SP in P. vivax infections was assessed in Tsiroanomandidy, in the foothill of the central highlands. An intention-to-treat analysis of treatment outcome was carried out. Results A total of 159 P. vivax samples were sequenced in the pvdhfr/pvdhps genes. Mutant-types in pvdhfr gene were found in 71% of samples, and in pvdhps gene in 16% of samples. Six non-synonymous mutations were identified in pvdhfr, including two novel mutations at codons 21 and 130. For pvdhps, beside the known mutation at codon 383, a new one was found at codon 422. For the two genes, different combinations were ranged from wild-type to quadruple mutant-type. Among the 16 patients enrolled in the sulphadoxine-pyrimethamine clinical trial (28 days of follow-up) and after adjustment by genotyping, 3 (19%, 95% CI: 5%–43%) of them were classified as treatment failure and were pvdhfr 58R/117N double mutant carriers with or without the pvdhps 383G mutation. Conclusion This study highlights (i) that genotyping in the pvdhfr and pvdhps genes remains a useful tool to monitor the emergence and the spread of P. vivax sulphadoxine-pyrimethamine resistant in order to improve the national antimalarial drug policy, (ii) the issue of using sulphadoxine-pyrimethamine as a monotherapy for intermittent preventive treatment of pregnant women or children.
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Affiliation(s)
- Céline Barnadas
- EA4170, Parasitology and Tropical Medicine, University Lyon 1, Lyon, France.
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Bionomics of malaria vectors and relationship with malaria transmission and epidemiology in three physiographic zones in the Senegal River Basin. Acta Trop 2008; 105:145-53. [PMID: 18068685 DOI: 10.1016/j.actatropica.2007.10.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 09/20/2007] [Accepted: 10/25/2007] [Indexed: 11/24/2022]
Abstract
Following the implementation of two dams in the Senegal River, entomological and parasitological studies were conducted in three different ecological zones in the Senegal River Basin (the low valley of Senegal River, the Guiers Lake area and the low valley of Ferlo) every 3 month in June 2004, September 2004, December 2004 and March 2005. The objective of this work was to study the influence of environmental heterogeneities on vector bionomics and malaria epidemiology. Mosquitoes were collected when landing on human volunteers and by pyrethrum spray catches. In the parasitological survey, blood samples were taken from a cohort of schoolchildren under 9 years during each entomology survey. Seven anopheline species were collected: Anopheles arabiensis, Anopheles gambiae M form, Anopheles funestus, Anopheles pharoensis, Anopheles coustani, Anopheles wellcomei and Anopheles rufipes. A. arabiensis, A. funestus and A. pharoensis were predominant in the low valley of the Senegal River, A. funestus in the Guiers Lake area and A. arabiensis in the low valley of Ferlo. Mosquito populations' dynamics varied temporally depending on the rainy season for each zone. The anthropophilic rates varied between 6 and 76% for A. gambiae s.l. and 23 and 80% for A. funestus. Only 4/396 A. pharoensis and 1/3076 A. funestus tested carried Plasmodium falciparum CS antigen. These results suggest the implication of A. pharoensis in malaria transmission. The related entomological inoculation rates were estimated to 10.44 in Mbilor and 3 infected bites in Gankette Balla and were due, respectively, to A. pharoensis and A. funestus. Overall, 1636 thick blood smears were tested from blood samples taken from schoolchildren with, respectively, a parasite and gametocyte average prevalence of 9 and 0.9%. The parasite prevalence was uniformly low in Mbilor and Gankette Balla whereas; it increased in September (16%) and then remained stable in December and March (22%) in Mboula where malaria transmission was not perceptible. However, significant differences were observed over time for parasite prevalence in Mbilor and Mboula villages whereas; it was only in Gankette Balla village where gametocyte prevalence was significantly different over time. Our study demonstrates the influence of ecological changes resulted from dams implementation in the Senegal River on the composition of vectorial system, malaria transmission and epidemiology. Such changes should be thoroughly surveyed in order to prevent any possible malaria outbreak in the Senegal River Basin.
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Ménard D, Randrianarivo-Solofoniaina AE, Ahmed BS, Jahevitra M, Andriantsoanirina V, Rasolofomanana JR, Rabarijaona LP. Drug-resistant malaria parasites introduced into Madagascar from Comoros Islands. Emerg Infect Dis 2007; 13:1759-62. [PMID: 18217565 PMCID: PMC3375783 DOI: 10.3201/eid1311.070235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To determine risk for drug-resistant malaria parasites entering Madagascar from Comoros Islands, we screened travelers. For the 141 Plasmodium falciparum isolates detected by real-time PCR, frequency of mutant alleles of genes associated with resistance to chloroquine and pyrimethamine was high. International-level antimalarial policy and a regional antimalarial forum are needed.
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Affiliation(s)
- Didier Ménard
- Institut Pasteur de Madagascar, Antananarivo, Madagascar.
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Smith A, Telfer S, Burthe S, Bennett M, Begon M. A role for vector-independent transmission in rodent trypanosome infection? Int J Parasitol 2006; 36:1359-66. [PMID: 16876803 DOI: 10.1016/j.ijpara.2006.06.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 06/17/2006] [Accepted: 06/23/2006] [Indexed: 11/22/2022]
Abstract
Within host-pathogen systems where vector-borne transmission is the primary route of infection, little or no attention has been paid to the relative importance of secondary or alternative routes of transmission. Here, by contrast, we report the results from a controlled longitudinal field-scale experiment in which the prevalence of fleas (Siphonaptera) was manipulated and the occurrence and distribution of a flea-borne protozoan (Trypanosoma (Herpetosoma) microti) in a natural field vole (Microtus agrestis) population was monitored over a 2-year period. A non-systemic insecticide was applied to individual voles within two treatment grids and the prevalences of fleas and of T. microti were monitored on these and on two control grids. Blood samples were taken from all voles and PCR-based methods used to determine infection status. Insecticidal treatment was highly effective at reducing overall flea prevalence and recaptured animals (treated ca. 4 weeks previously) were very rarely infested (ca. 3%, compared with 50-70+% normally). On the other hand, the probability of trypanosome infection was reduced in treated animals on experimental grids to only around one-third of that normally observed. This suggests that direct, as opposed to flea-borne, transmission may not only occur, it may also be of epidemiological importance. The possibility that the importance of such transmission routes may have been underestimated in 'vector-borne' infections more generally is discussed.
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Affiliation(s)
- A Smith
- Population Biology Research Group, School of Biological Sciences, Bioscience Building, University of Liverpool, Merseyside L69 7ZB, UK.
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Duerr HP, Leary CC, Eichner M. High infection rates at low transmission potentials in West African onchocerciasis. Int J Parasitol 2006; 36:1367-72. [PMID: 16979644 DOI: 10.1016/j.ijpara.2006.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 07/31/2006] [Accepted: 08/01/2006] [Indexed: 11/24/2022]
Abstract
Onchocerciasis has been successfully controlled for many years in endemic countries but more than 120 million people are still at risk. Factors which stabilise the persistence of the parasite in the population must be studied to minimise the future risk of re-infection. Among these factors, the relationship between the annual transmission potential and the parasite establishment rate is a main determinant which has to date not been quantified. Using entomological information and palpation data collected by the Onchocerciasis Control Programme in West Africa prior to the initiation of control activities, we derive annual transmission potential-dependent estimates of the parasite establishment rate from statistical analyses and computer simulations. Even at very low transmission intensities, the filarial parasite Onchocerca volvulus can efficiently establish in the human population, originating from an infection process which is strongly limited with respect to the annual transmission potential. Implementing the estimates into a simplified transmission model predicts that the critical annual biting rate, below which transmission is not possible, is much lower than previously assumed. We conclude that under the current strategy of mass distribution of microfilaricides without additional measures of vector control, the risk of re-infection is higher than previously assumed.
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Affiliation(s)
- H P Duerr
- Department of Medical Biometry, University of Tübingen, Westbahnhofstr. 55, 72070 Tübingen, Germany.
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