High malaria transmission sustained by Anopheles gambiae s.l. occurring both indoors and outdoors in the city of Yaoundé, Cameroon

Background: Malaria remains a major public health problem in Cameroon; however, despite reports on the adaptation of anopheline species to urban habitats, there is still not enough information on malaria transmission pattern in urban settings. In the frame of a larval control trial in the city of Yaoundé, we conducted baseline surveys to assess malaria transmission dynamics in this city. Methods: Adult mosquitoes were collected indoors and outdoors using CDC light traps and human landing catches from March 2017 to March 2018 in 30 districts of Yaoundé, Cameroon. Mosquitoes were sorted by genus and identified to the species level using PCR. The TaqMan method and ELISA were used to determine mosquito infection status to Plasmodium. Bioassays were conducted to assess female Anopheles gambiae susceptibility to insecticides. Results: A total of 218,991 mosquitoes were collected. The main malaria vectors were An. gambiae s.l. (n=6154) and An. funestus s.l. (n=229). Of the 1476 An. gambiae s.l. processed by PCR, 92.19% were An. coluzzii and 7.81% An. gambiae. An. funestus s.l. was composed of 93.01% (173/186) An. funestus and 4.84% (13/186) An. leesoni. The average biting rate of anopheline was significantly high outdoor than indoor (P=0.013). Seasonal variation in mosquito abundance and biting rate was recorded. The infection rate by Plasmodium falciparum was 2.13% (104/4893 mosquitoes processed). The annual entomological inoculation rate was found to vary from 0 to 92 infective bites/man/year (ib/m/y). Malaria transmission risk was high outdoor (66.65 ib/m/y) compared to indoor (31.14 ib/m/y). An. gambiae s.l. was found highly resistant to DDT, permethrin and deltamethrin. High prevalence of the West Africa kdr allele 1014F was recorded and this was not found to influence An. gambiae s.l. infection status. Conclusion: The study suggests high malaria transmission occurring in the city of Yaoundé and call for immediate actions to improve control strategies.

[1]  Antonio Nkondjio Christophe.  Raw data_Malaria transmission Yaoundé (Doumbé et al) , 2018 .

[2]  C. Antonio-Nkondjio,et al.  Review of the evolution of insecticide resistance in main malaria vectors in Cameroon from 1990 to 2017 , 2017, Parasites & Vectors.

[3]  L. Amekudzi,et al.  Diversity in breeding sites and distribution of Anopheles mosquitoes in selected urban areas of southern Ghana , 2017, Parasites & Vectors.

[4]  C. Costantini,et al.  Investigation of mechanisms of bendiocarb resistance in Anopheles gambiae populations from the city of Yaoundé, Cameroon , 2016, Malaria Journal.

[5]  E. Williams,et al.  Ecology of urban malaria vectors in Niamey, Republic of Niger , 2016, Malaria Journal.

[6]  M. Molyneux,et al.  Commentary ( The Lancet ) Bednets and malaria in Africa , 2016 .

[7]  C. Antonio-Nkondjio,et al.  Rapid evolution of pyrethroid resistance prevalence in Anopheles gambiae populations from the cities of Douala and Yaoundé (Cameroon) , 2015, Malaria Journal.

[8]  N. Besansky,et al.  Habitat segregation and ecological character displacement in cryptic African malaria mosquitoes , 2015, Evolutionary applications.

[9]  R. Christen,et al.  Composition of Anopheles coluzzii and Anopheles gambiae microbiota from larval to adult stages. , 2014, Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases.

[10]  R. Cibulskis,et al.  World Malaria Report 2013 , 2014 .

[11]  H. Ranson,et al.  Resistance to DDT in an Urban Setting: Common Mechanisms Implicated in Both M and S Forms of Anopheles gambiae in the City of Yaoundé Cameroon , 2013, PloS one.

[12]  P. Awono-ambene,et al.  Application of a qPCR Assay in the Investigation of Susceptibility to Malaria Infection of the M and S Molecular Forms of An. gambiae s.s. in Cameroon , 2013, PloS one.

[13]  C. Antonio-Nkondjio,et al.  High mosquito burden and malaria transmission in a district of the city of Douala, Cameroon , 2012, BMC Infectious Diseases.

[14]  N. Besansky,et al.  Anthropogenic Habitat Disturbance and Ecological Divergence between Incipient Species of the Malaria Mosquito Anopheles gambiae , 2012, PloS one.

[15]  C. Costantini,et al.  Water Quality and Anopheles gambiae Larval Tolerance to Pyrethroids in the Cities of Douala and Yaoundé (Cameroon) , 2012, Journal of tropical medicine.

[16]  H. Overgaard,et al.  Light traps fail to estimate reliable malaria mosquito biting rates on Bioko Island, Equatorial Guinea , 2012, Malaria Journal.

[17]  F. Pagés,et al.  Malaria transmission in Libreville: results of a one year survey , 2012, Malaria Journal.

[18]  Adalgisa Caccone,et al.  Outdoor host seeking behaviour of Anopheles gambiae mosquitoes following initiation of malaria vector control on Bioko Island, Equatorial Guinea , 2011, Malaria Journal.

[19]  Parfait Awono-Ambene,et al.  Anopheles gambiae distribution and insecticide resistance in the cities of Douala and Yaoundé (Cameroon): influence of urban agriculture and pollution , 2011, Malaria Journal.

[20]  F. Pagés,et al.  Malaria transmission and insecticide resistance of Anopheles gambiae in Libreville and Port-Gentil, Gabon , 2010, Malaria Journal.

[21]  R. Dabiré,et al.  Diversity in anopheline larval habitats and adult composition during the dry and wet seasons in Ouagadougou (Burkina Faso) , 2010, Malaria Journal.

[22]  John Vontas,et al.  PCR-based detection of Plasmodium in Anopheles mosquitoes: a comparison of a new high-throughput assay with existing methods , 2008, Malaria Journal.

[23]  Y. Qi,et al.  Insertion polymorphisms of SINE200 retrotransposons within speciation islands of Anopheles gambiae molecular forms , 2008, Malaria Journal.

[24]  M. Donnelly,et al.  Impact of urban agriculture on malaria vectors in Accra, Ghana , 2008, Malaria Journal.

[25]  John Vontas,et al.  Detection of knockdown resistance (kdr) mutations in Anopheles gambiae: a comparison of two new high-throughput assays with existing methods , 2007, Malaria Journal.

[26]  F. Simard,et al.  Complexity of the Malaria Vectorial System in Cameroon: Contribution of Secondary Vectors to Malaria Transmission , 2006, Journal of medical entomology.

[27]  A. Githeko,et al.  Effects of microclimatic changes caused by deforestation on the survivorship and reproductive fitness of Anopheles gambiae in western Kenya highlands. , 2006, The American journal of tropical medicine and hygiene.

[28]  Thomas A. Smith,et al.  Rapid Urban Malaria Appraisal (RUMA) III: epidemiology of urban malaria in the municipality of Yopougon (Abidjan) , 2006, Malaria Journal.

[29]  C. Lengeler,et al.  Malaria and urbanization in sub-Saharan Africa , 2005, Malaria Journal.

[30]  P. Atkinson,et al.  Opinion — tropical infectious diseases: Urbanization, malaria transmission and disease burden in Africa , 2005, Nature Reviews Microbiology.

[31]  Thomas A. Smith,et al.  Urbanization in sub-saharan Africa and implication for malaria control. , 2004, The American journal of tropical medicine and hygiene.

[32]  Andrew J Tatem,et al.  The global distribution and population at risk of malaria: past, present, and future. , 2004, The Lancet. Infectious diseases.

[33]  R. Sauerwein,et al.  Transmission of Plasmodium falciparum in urban Yaoundé, Cameroon, is seasonal and age-dependent. , 2003, Transactions of the Royal Society of Tropical Medicine and Hygiene.

[34]  J. Beier,et al.  Malaria transmission in urban sub-Saharan Africa. , 2003, The American journal of tropical medicine and hygiene.

[35]  R. Hunt,et al.  A cocktail polymerase chain reaction assay to identify members of the Anopheles funestus (Diptera: Culicidae) group. , 2002, The American journal of tropical medicine and hygiene.

[36]  C. Antonio-Nkondjio,et al.  High Malaria Transmission Intensity in a Village Close to Yaounde, the Capital City of Cameroon , 2002, Journal of medical entomology.

[37]  P. Carnevale,et al.  [Malaria vector control in Cameroon: past, present, future. Reflections]. , 2001, Bulletin de la Societe de pathologie exotique.

[38]  D. Mathanga,et al.  Bednets and malaria in Africa , 2001, The Lancet.

[39]  D. Fontenille,et al.  Le paludisme urbain à Yaoundé (Cameroun) en 2000 : étude entomologique dans le quartier central "Dakar" , 2001 .

[40]  V. Titanji,et al.  The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa. , 2000, The American journal of tropical medicine and hygiene.

[41]  P. Carnevale,et al.  Le paludisme urbain à Yaoundé, Cameroun 1. Etude entomoIogique dans deux quartiers qentraux* , 1992 .

[42]  P. Carnevale,et al.  [Urban malaria in Yaounde (Cameroon). 2. Entomologic study in 2 suburban districts]. , 1992, Bulletin de la Societe de pathologie exotique.

[43]  T. Burkot,et al.  Field evaluation of enzyme-linked immunosorbent assays for Plasmodium falciparum and Plasmodium vivax sporozoites in mosquitoes (Diptera: Culicidae) from Papua New Guinea. , 1987, Journal of medical entomology.

[44]  W. S. Abbott,et al.  A method of computing the effectiveness of an insecticide. 1925. , 1925, Journal of the American Mosquito Control Association.

[45]  K. Livak.  Organization and mapping of a sequence on the Drosophila melanogaster X and Y chromosomes that is transcribed during spermatogenesis. , 1984, Genetics.

[46]  M. Gillies.,et al.  The Anophelinae of Africa South of the Sahara , 1968 .

[47]  F. W. Edwards.  Mosquitoes of the Ethiopian Region. HI. - Culicine Adults and Pupae. , 1941 .