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Antonio-Nkondjio C, Ndo C, Njiokou F, Bigoga JD, Awono-Ambene P, Etang J, Ekobo AS, Wondji CS. Review of malaria situation in Cameroon: technical viewpoint on challenges and prospects for disease elimination. Parasit Vectors 2019; 12:501. [PMID: 31655608 PMCID: PMC6815446 DOI: 10.1186/s13071-019-3753-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 10/18/2019] [Indexed: 11/30/2022] Open
Abstract
Malaria still has a devastating impact on public health and welfare in Cameroon. Despite the increasing number of studies conducted on disease prevalence, transmission patterns or treatment, there are to date, not enough studies summarising findings from previous works in order to identify gaps in knowledge and areas of interest where further evidence is needed to drive malaria elimination efforts. The present study seeks to address these gaps by providing a review of studies conducted so far on malaria in Cameroon since the 1940s to date. Over 250 scientific publications were consulted for this purpose. Although there has been increased scale-up of vector control interventions which significantly reduced the morbidity and mortality to malaria across the country from a prevalence of 41% of the population reporting at least one malaria case episode in 2000 to a prevalence of 24% in 2017, the situation is not yet under control. There is a high variability in disease endemicity between epidemiological settings with prevalence of Plasmodium parasitaemia varying from 7 to 85% in children aged 6 months to 15 years after long-lasting insecticidal nets (LLINs) scale-up. Four species of Plasmodium have been recorded across the country: Plasmodium falciparum, P. malariae, P. ovale and P. vivax. Several primate-infecting Plasmodium spp. are also circulating in Cameroon. A decline of artemisinin-based combinations therapeutic efficacy from 97% in 2006 to 90% in 2016 have been reported. Several mutations in the P. falciparum chloroquine resistance (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr1) genes conferring resistance to either 4-amino-quinoleine, mefloquine, halofanthrine and quinine have been documented. Mutations in the Pfdhfr and Pfdhps genes involved in sulfadoxine-pyrimethamine are also on the rise. No mutation associated with artemisinin resistance has been recorded. Sixteen anopheline species contribute to malaria parasite transmission with six recognized as major vectors: An. gambiae, An. coluzzii, An. arabiensis, An. funestus, An. nili and An. moucheti. Studies conducted so far, indicated rapid expansion of DDT, pyrethroid and carbamate resistance in An. gambiae, An. coluzzii, An. arabiensis and An. funestus threatening the performance of LLINs. This review highlights the complex situation of malaria in Cameroon and the need to urgently implement and reinforce integrated control strategies in different epidemiological settings, as part of the substantial efforts to consolidate gains and advance towards malaria elimination in the country.
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Affiliation(s)
- Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B. P.288 Yaoundé, Cameroun
- Centre for Research in Infectious Disease (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Vector Biology Liverpool School of Tropical medicine Pembroke Place, Liverpool, UK
| | - Cyrille Ndo
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
- Centre for Research in Infectious Disease (CRID), P.O. Box 13591, Yaoundé, Cameroon
| | - Flobert Njiokou
- Centre for Research in Infectious Disease (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Jude D. Bigoga
- Laboratory for Vector Biology and control, National Reference Unit for Vector Control, The Biotechnology Center, Nkolbisson-University of Yaounde I, P.O. Box 3851, Messa, Yaounde, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde, Cameroon
| | - Parfait Awono-Ambene
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B. P.288 Yaoundé, Cameroun
| | - Josiane Etang
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B. P.288 Yaoundé, Cameroun
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
- Institute for Insect Biotechnology, Justus Liebig University Gießen, Winchester Str. 2, 35394 Gießen, Germany
| | - Albert Same Ekobo
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Charles S. Wondji
- Centre for Research in Infectious Disease (CRID), P.O. Box 13591, Yaoundé, Cameroon
- Vector Biology Liverpool School of Tropical medicine Pembroke Place, Liverpool, UK
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Ruzzante L, Reijnders MJ, Waterhouse RM. Of Genes and Genomes: Mosquito Evolution and Diversity. Trends Parasitol 2019; 35:32-51. [DOI: 10.1016/j.pt.2018.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/07/2018] [Accepted: 10/08/2018] [Indexed: 12/16/2022]
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Artemov GN, Velichevskaya AI, Bondarenko SM, Karagyan GH, Aghayan SA, Arakelyan MS, Stegniy VN, Sharakhov IV, Sharakhova MV. A standard photomap of the ovarian nurse cell chromosomes for the dominant malaria vector in Europe and Middle East Anopheles sacharovi. Malar J 2018; 17:276. [PMID: 30060747 PMCID: PMC6065146 DOI: 10.1186/s12936-018-2428-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/25/2018] [Indexed: 08/10/2023] Open
Abstract
Background Anopheles sacharovi is a dominant malaria vector species in South Europe and the Middle East which has a highly plastic behaviour at both adult and larval stages. Such plasticity has prevented this species from eradication by several anti-vector campaigns. The development of new genome-based strategies for vector control will benefit from genome sequencing and physical chromosome mapping of this mosquito. Although a cytogenetic photomap for chromosomes from salivary glands of An. sacharovi has been developed, no cytogenetic map suitable for physical genome mapping is available. Methods Mosquitoes for this study were collected at adult stage in animal shelters in Armenia. Polytene chromosome preparations were prepared from ovarian nurse cells. Fluorescent in situ hybridization (FISH) was performed using PCR amplified probes. Results This study constructed a high-quality standard photomap for polytene chromosomes from ovarian nurse cells of An. sacharovi. Following the previous nomenclature, chromosomes were sub-divided into 39 numbered and 119 lettered sub-divisions. Chromosomal landmarks for the chromosome recognition were described. Using FISH, 4 PCR-amplified genic probes were mapped to the chromosomes. The positions of the probes demonstrated gene order reshuffling between An. sacharovi and Anopheles atroparvus which has not been seen cytologically. In addition, this study described specific chromosomal landmarks that can be used for the cytotaxonomic diagnostics of An. sacharovi based on the banding pattern of its polytene chromosomes. Conclusions This study constructed a high-quality standard photomap for ovarian nurse cell chromosomes of An. sacharovi and validated its utility for physical genome mapping. Based on the map, cytotaxonomic features for identification of An. sacharovi have been described. The cytogenetic map constructed in this study will assist in creating a chromosome-based genome assembly for this mosquito and in developing cytotaxonomic tools for identification of other species from the Maculipennis group.
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Affiliation(s)
- Gleb N Artemov
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia
| | - Alena I Velichevskaya
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia
| | - Semen M Bondarenko
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia
| | - Gayane H Karagyan
- Scientific Center of Zoology and Hydroecology, The National Academy of Sciences of the Republic of Armenia, Yerevan, Armenia
| | - Sargis A Aghayan
- Scientific Center of Zoology and Hydroecology, The National Academy of Sciences of the Republic of Armenia, Yerevan, Armenia.,Chair of Zoology, Yerevan State University, Yerevan, Armenia
| | | | - Vladimir N Stegniy
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia
| | - Igor V Sharakhov
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia. .,Department of Entomology, Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
| | - Maria V Sharakhova
- Laboratory of Ecology, Genetics and Environment Protection, Tomsk State University, Tomsk, Russia. .,Department of Entomology, Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
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Fouet C, Kamdem C, Gamez S, White BJ. Genomic insights into adaptive divergence and speciation among malaria vectors of the Anopheles nili group. Evol Appl 2017; 10:897-906. [PMID: 29151881 PMCID: PMC5680430 DOI: 10.1111/eva.12492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/27/2017] [Indexed: 01/16/2023] Open
Abstract
Ongoing speciation in the most important African malaria vectors gives rise to cryptic populations, which differ remarkably in their behavior, ecology, and capacity to vector malaria parasites. Understanding the population structure and the drivers of genetic differentiation among mosquitoes is crucial for effective disease control because heterogeneity within vector species contributes to variability in malaria cases and allow fractions of populations to escape control efforts. To examine population structure and the potential impacts of recent large-scale control interventions, we have investigated the genomic patterns of differentiation in mosquitoes belonging to the Anopheles nili group-a large taxonomic group that diverged ~3 Myr ago. Using 4,343 single nucleotide polymorphisms (SNPs), we detected strong population structure characterized by high-FST values between multiple divergent populations adapted to different habitats within the Central African rainforest. Delineating the cryptic species within the Anopheles nili group is challenging due to incongruence between morphology, ribosomal DNA, and SNP markers consistent with incomplete lineage sorting and/or interspecific gene flow. A very high proportion of loci are fixed (FST = 1) within the genome of putative species, which suggests that ecological and/or reproductive barriers are maintained by strong selection on a substantial number of genes.
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Affiliation(s)
- Caroline Fouet
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Colince Kamdem
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Stephanie Gamez
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Bradley J. White
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
- Center for Disease Vector ResearchInstitute for Integrative Genome BiologyUniversity of CaliforniaRiversideCAUSA
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Kamali M, Marek PE, Peery A, Antonio-Nkondjio C, Ndo C, Tu Z, Simard F, Sharakhov IV. Multigene phylogenetics reveals temporal diversification of major African malaria vectors. PLoS One 2014; 9:e93580. [PMID: 24705448 PMCID: PMC3976319 DOI: 10.1371/journal.pone.0093580] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 03/05/2014] [Indexed: 12/21/2022] Open
Abstract
The major vectors of malaria in sub-Saharan Africa belong to subgenus Cellia. Yet, phylogenetic relationships and temporal diversification among African mosquito species have not been unambiguously determined. Knowledge about vector evolutionary history is crucial for correct interpretation of genetic changes identified through comparative genomics analyses. In this study, we estimated a molecular phylogeny using 49 gene sequences for the African malaria vectors An. gambiae, An. funestus, An. nili, the Asian malaria mosquito An. stephensi, and the outgroup species Culex quinquefasciatus and Aedes aegypti. To infer the phylogeny, we identified orthologous sequences uniformly distributed approximately every 5 Mb in the five chromosomal arms. The sequences were aligned and the phylogenetic trees were inferred using maximum likelihood and neighbor-joining methods. Bayesian molecular dating using a relaxed log normal model was used to infer divergence times. Trees from individual genes agreed with each other, placing An. nili as a basal clade that diversified from the studied malaria mosquito species 47.6 million years ago (mya). Other African malaria vectors originated more recently, and independently acquired traits related to vectorial capacity. The lineage leading to An. gambiae diverged 30.4 mya, while the African vector An. funestus and the Asian vector An. stephensi were the most closely related sister taxa that split 20.8 mya. These results were supported by consistently high bootstrap values in concatenated phylogenetic trees generated individually for each chromosomal arm. Genome-wide multigene phylogenetic analysis is a useful approach for discerning historic relationships among malaria vectors, providing a framework for the correct interpretation of genomic changes across species, and comprehending the evolutionary origins of this ubiquitous and deadly insect-borne disease.
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Affiliation(s)
- Maryam Kamali
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Paul E Marek
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Ashley Peery
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | | | - Cyrille Ndo
- Malaria Research Laboratory, OCEAC, Yaounde, Cameroon; MIVEGEC (UMR IRD224-CNRS5290-UM1-UM2), Institut de Recherche pour le Développement (IRD), Montpellier, France; Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
| | - Zhijian Tu
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Frederic Simard
- MIVEGEC (UMR IRD224-CNRS5290-UM1-UM2), Institut de Recherche pour le Développement (IRD), Montpellier, France
| | - Igor V Sharakhov
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
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Sharakhova MV, Peery A, Antonio-Nkondjio C, Xia A, Ndo C, Awono-Ambene P, Simard F, Sharakhov IV. Cytogenetic analysis of Anopheles ovengensis revealed high structural divergence of chromosomes in the Anopheles nili group. INFECTION GENETICS AND EVOLUTION 2013; 16:341-8. [PMID: 23523820 DOI: 10.1016/j.meegid.2013.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/25/2013] [Accepted: 03/05/2013] [Indexed: 01/15/2023]
Abstract
Cytogenetic analysis is an informative classical approach to understanding the relationships among members in a group of closely related species of mosquitoes. Anopheles ovengensis is a recently discovered species of the Anopheles nili group and is one of the important malaria vectors in the African equatorial forest. This study characterized polytene chromosomes of An. ovengensis and compared them with polytene chromosomes of An. nili. Using fluorescent in situ hybridization and chromosome banding pattern comparison we have established correspondence between chromosomal arms of An. ovengensis and An. nili. Analysis of chromosome morphology in the two species revealed a limited similarity in the banding patterns. The most extensive reorganization occurs in pericentromeric and intercalary heterochromatin. Chromosomes of An. ovengensis are joined together by a diffuse chromocenter and they have two large regions of intercalary heterochromatin in arms 2L and 3R. In contrast, the chromocenter and intercalary heterochromatin are not seen in An. nili chromosomes. Comparative analysis of the arm association suggests the occurrence of a whole-arm translocation between the two members of the group. The observed, substantial reorganizations of chromosome structure implies either a rapid rate of chromosome evolution in the An. nili group, or that the two species belong to different taxonomic groups within subgenus Cellia.
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Ndo C, Simard F, Kengne P, Awono-Ambene P, Morlais I, Sharakhov I, Fontenille D, Antonio-Nkondjio C. Cryptic genetic diversity within the Anopheles nili group of malaria vectors in the equatorial forest area of Cameroon (Central Africa). PLoS One 2013; 8:e58862. [PMID: 23516565 PMCID: PMC3597579 DOI: 10.1371/journal.pone.0058862] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 02/07/2013] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND The Anopheles nili group of mosquitoes includes important vectors of human malaria in equatorial forest and humid savannah regions of sub-Saharan Africa. However, it remains largely understudied, and data on its populations' bionomics and genetic structure are crucially lacking. Here, we used a combination of nuclear (i.e. microsatellite and ribosomal DNA) and mitochondrial DNA markers to explore and compare the level of genetic polymorphism and divergence among populations and species of the group in the savannah and forested areas of Cameroon, Central Africa. PRINCIPAL FINDINGS All the markers provided support for the current classification within the An. nili group. However, they revealed high genetic heterogeneity within An. nili s.s. in deep equatorial forest environment. Nuclear markers showed the species to be composed of five highly divergent genetic lineages that differed by 1.8 to 12.9% of their Internal Transcribed Spacer 2 (ITS2) sequences, implying approximate divergence time of 0.82 to 5.86 million years. However, mitochondrial data only detected three major subdivisions, suggesting different evolutionary histories of the markers. CONCLUSIONS/SIGNIFICANCE This study enlightened additional cryptic genetic diversity within An. nili s.s. in the deep equatorial forest environment of South Cameroon, reflecting a complex demographic history for this major vector of malaria in this environment. These preliminary results should be complemented by further studies which will shed light on the distribution, epidemiological importance and evolutionary history of this species group in the African rainforest, providing opportunities for in-depth comparative studies of local adaptation and speciation in major African malaria vectors.
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Affiliation(s)
- Cyrille Ndo
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.
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