Etienne Fondjo Jean-Claude Toto Magellan Tchouakui Wolfgang Ekoko Eyisap Salomon Patchoke Benjamin Menze Boris Njeambosay Francis Zeukeug Raymond Tabue Ngomdjum Elysée Mandeng Emmanuel Elanga-Ndille Edmond Kopya Jerome Achille Binyang Cyrille Ndo Billy Tene-Fossog Armel Tedjou Elysée Nchoutpouen Frederic Tchouine Dorothy Achu Kelley Ambrose Judith Hedje Celestin Kouambeng Jenny Carlson Sarah Zohdy Joseph Chabi

Malaria Journal

Abstract Background Malaria remains one of the main causes of morbidity and mortality in Cameroon. To inform vector control intervention decision making, malaria vector surveillance was conducted monthly from October 2018 to September 2020 in five selected sentinel sites (Gounougou and Simatou in the North, and Bonabéri, Mangoum and Nyabessang in the South). Methods Human landing catches (HLCs), U.S. Centers for Disease Control and Prevention (CDC) light traps, and pyrethrum spray catches (PSCs) were used to assess vector density, species composition, human biting rate (HBR), endophagic index, indoor resting density (IRD), parity, sporozoite infection rates, entomological inoculation rate (EIR), and Anopheles vectorial capacity. Results A total of 139,322 Anopheles mosquitoes from 18 species (or 21 including identified sub-species) were collected across all sites. Out of the 18 species, 12 were malaria vectors including Anopheles gambiae sensu lato (s.l.), Anopheles funestus s.l.., Anopheles nili, Anopheles moucheti, Anopheles paludis, Anopheles demeilloni, Anopheles. pharoensis, Anopheles ziemanni, Anopheles multicinctus, Anopheles tenebrosus, Anopheles rufipes, and Anopheles marshallii. Anopheles gambiae s.l. remains the major malaria vector (71% of the total Anopheles) collected, though An. moucheti and An. paludis had the highest sporozoite rates in Nyabessang. The mean indoor HBR of Anopheles ranged from 11.0 bites/human/night (b/h/n) in Bonabéri to 104.0 b/h/n in Simatou, while outdoors, it varied from 24.2 b/h/n in Mangoum to 98.7 b/h/n in Simatou. Anopheles gambiae s.l. and An. moucheti were actively biting until at least 8:00 a.m. The mean Anopheles IRD was 17.1 females/room, and the parity rate was 68.9%. The mean EIRs for each site were 55.4 infective bites/human/month (ib/h/m) in Gounougou, 99.0 ib/h/m in Simatou, 51.2 ib/h/m in Mangoum, 24.4 ib/h/m in Nyabessang, and 18.1 ib/h/m in Bonabéri. Anopheles gambiae s.l. was confirmed as the main malaria vector with the highest vectorial capacity in all sites based on sporozoite rate, except in Nyabessang. Conclusion These findings highlight the high malaria transmission occurring in Cameroon and will support the National Malaria Control Program to design evidence-based malaria vector control strategies, and deployment of effective and integrated vector control interventions to reduce malaria transmission and burden in Cameroon, where several Anopheles species could potentially maintain year-round transmission.

2023-04-13

Moussa Keïta Nafomon Sogoba Fousseyni Kané Boissé Traoré Francis Zeukeng Boubacar Coulibaly Ambiélè Bernard Sodio Sekou Fantamady Traoré Rousseau Djouaka Seydou Doumbia

The Journal of Infectious Diseases

Abstract Background Insecticide-based vector control is responsible for reducing malaria mortality and morbidity. Its success depends on a better knowledge of the vector, its distribution, and resistance status to the insecticides used. In this paper, we assessed Anopheles gambiae sensu lato (A gambiae s.l.) population resistance to pyrethroids in different ecological settings. Methods The World Health Organization standard bioassay test was used to assess F0A gambiae s.l. susceptibility to pyrethroids. Biochemical Synergist assays were conducted with piperonyl butoxide (PBO), S,S,S-tributyl phosphotritioate, and diethyl maleate. L1014F, L1014S, and N1575Y knockdown resistance (kdr) mutations were investigated using TaqMan genotyping. Results Anopheles gambiae sensu lato was composed of Anopheles arabienisis, Anopheles coluzzii, and A gambiae in all study sites. Anopheles gambiae sensu lato showed a strong phenotypic resistance to deltamethrin and permethrin in all sites (13% to 41% mortality). In many sites, pre-exposure to synergists partially improved the mortality rate suggesting the presence of detoxifying enzymes. The 3 kdr (L1014F, L1014S, and N1575Y) mutations were found, with a predominance of L1014F, in all species. Conclusions Multiple resistance mechanisms to pyrethroids were observed in A gambiae s.l. in Mali. The PBO provided a better partial restoration of susceptibility to pyrethroids, suggesting that the efficacy of long-lasting insecticidal nets may be improved with PBO.

2021-04-27

Rousseau Djouaka Joseph M. Vinetz Francis Zeukeng Jude Daiga Bigoga Solange E. Kakou-Ngazoa Romaric Akoton Genevieve Tchigossou David N’golo Coulibaly Sodjinin Jean-Eudes Tchebe Sylla Aboubacar Clavella Nantcho Nguepdjo Eric Tossou Razack Adeoti Thèrèse Marie Ngo Nsonga Yao Akpo Innocent Djegbe Manuele Tamo Wilfred Fon Mbacham Anthony Ablordey

PLOS Neglected Tropical Diseases

2018-07-02

Romaric Akoton Genevieve M. Tchigossou Innocent Djègbè Akadiri Yessoufou Michael Seun Atoyebi Eric Tossou Francis Zeukeng Pelagie Boko Helen Irving Razack Adéoti Jacob Riveron Charles S. Wondji Kabirou Moutairou Rousseau Djouaka

Wellcome Open Research

2018-06-13

Achille Jerome Binyang Emmanuel ELANGA-NDILLE Billy Tene-Fossog Cyrille Ndo Lynda Nouage Tatiane Assatse Yvan Fotso-Toguem Raymond Tabue Francis Zeukeng Daniel Nguete Nguiffo Josiane Etang Flobert Njiokou Charles S. Wondji

Parasites & Vectors

Abstract Background Cameroon is considering the implementation of indoor residual spraying (IRS) as a complementary measure to control malaria in the context of high pyrethroid resistance in major malaria vectors. Non-pyrethroid insecticide classes such as organophosphates and carbamates may be utilized in IRS due to widespread pyrethroid resistance. However, the success of this strategy depends on good knowledge of the resistance status of malaria vectors to carbamates and organophosphates. Here, we assessed the susceptibility profile of Anopheles gambiae sensu lato with respect to carbamates and organophosphate and the distribution of the molecular mechanism underlying resistance to these insecticides. Methods Anopheles gambiae s.l. mosquitoes were collected from nine settings across the country and bio-assayed with bendiocarb, propoxur and pirimiphos-methyl. The Ace-1 target-site G119S mutation was genotyped using a TaqMan assay. To investigate the polymorphism in the Ace-1 gene, a region of 924 base pairs in a sequence of the gene was amplified from both live and dead females of An. gambiae exposed to bendiocarb. Results Pirimiphos-methyl induced full mortality in An. gambiae s.l. from all study sites, whereas for carbamates, resistance was observed in four localities, with the lowest mortality rate recorded in Mangoum (17.78 ± 5.02% for bendiocarb and 18.61 ± 3.86% for propoxur) in the southern part of Cameroon. Anopheles coluzzii was found to be the predominant species in the northern tropical part of the country where it is sympatric with Anopheles arabiensis. In the localities situated in southern equatorial regions, this species was predominant in urban settings, while An. gambiae was the most abundant species in rural areas. The G119S Ace-1 target-site mutation was detected only in An. gambiae and only in the sites located in southern Cameroon. Phylogenetic analyses showed a clustering according to the phenotype. Conclusion The occurrence of the Ace-1 target-site substitution G119S in An. gambiae s.l. populations highlights the challenge associated with the impending deployment of IRS in Cameroon using carbamates or organophosphates. It is therefore important to think about a resistance management plan including the use of other insecticide classes such as neonicotinoids or pyrrole to guarantee the implementation of IRS in Cameroon. Graphical Abstract

2022-02-14

Eric Tossou Ghislain Tepa-Yotto Ouorou K. Douro Kpindou Ruth Sandeu Benjamin Datinon Francis Zeukeng Romaric Akoton Généviève M. Tchigossou Innocent Djègbè John Vontas Thibaud Martin Charles Wondji Manuele Tamò Aimé H. Bokonon-Ganta Rousseau Djouaka

International Journal of Environmental Research and Public Health

2019-05-28

Zeukeng, F. Tchinda, V.H.M. Bigoga, J.D. Seumen, C.H.T. Ndzi, E.S. Abonweh, G. Makoge, V. Motsebo, A. Moyou, R.S.

PLoS Neglected Tropical Diseases

2014-01-01

Genevieve Tchigossou Romaric Akoton Akadiri Yessoufou Innocent Djegbe Francis Zeukeng Seun M Atoyebi Eric Tossou Kabirou Moutairou Rousseau Djouaka

2018-01-29

Rousseau Djouaka Francis Zeukeng Jude Daiga Bigoga David N’golo Coulibaly Genevieve Tchigossou Romaric Akoton Sylla Aboubacar Sodjinin Jean-Eudes Tchebe Clavella Nantcho Nguepdjo Razack Adeoti Innocent Djegbe Manuele Tamo Wilfred Fon Mbacham Solange E. Kakou-Ngazoa Anthony Ablordey

Canadian Journal of Infectious Diseases and Medical Microbiology

2017-01-01

Pilate N. Kwi Elvis E. Ewane Marcel N. Moyeh Livinus N. Tangi Vincent N. Ntui Francis Zeukeng Denis D. Sofeu-Feugaing Eric A. Achidi Fidelis Cho-Ngwa Alfred Amambua-Ngwa Jude D. Bigoga Tobias O. Apinjoh

Parasites & Vectors

Abstract Background Malaria remains endemic in Cameroon, with heterogeneous transmission related to eco-climatic variations, vector diversity and spatial distribution. The intensification of malaria prevention and control through the free distribution of insecticide-treated nets in recent years may have altered the composition, geographic distribution and natural infection rate of Anopheles species, with implications for malaria transmission dynamics. The present study seeks to assess the vectorial diversity, dynamics and infectivity across different seasons and altitudes in relationship to parasite prevalence around the slopes of Mount Cameroon, southwestern region. Method Mosquitoes were sampled (indoors and outdoors) in 11 eco-epidemiological settings at low (18–197 m), intermediate (371–584 m) and high (740–1067 m) altitude by nightly human landing catches. The mosquitoes were identified morphologically and Anopheles gambiae sibling species identified by PCR. Parity status was ascertained by examining the ovaries and the entomological inoculation rates (EIR) determined by Plasmodium falciparum circumsporozoite antigen ELISA of the head-thorax. The prevalence of Plasmodium infection across target communities was assessed using rapid diagnostic tests. Results A total of 7327 (18.0 mosquitoes/trap/night) mosquitoes were trapped, mainly during the rainy season (5678, 77.5%) and at low altitude (3669, 50.1%). Anopheles spp. (5079, 69.3%) was the most abundant genera and An. gambiae complex (2691, 36.7%) the major vector, varying with altitude (χ2 = 183.87, df = 8, P < 0.001) and season (χ2 = 28.14, df = 4, P < 0.001). Only An. gambiae (s.s.) was identified following molecular analysis of An. gambiae complex siblings. The overall biting peak for An. gambiae complex was 2—3 a.m. Anopheles cinctus was the most abundant secondary vector in the area. The average EIR in the area was 2.08 infective bites per person per night (ib/p/n), higher at low (2.45 ib/p/n) than at intermediate altitude (1.39 ib/p/n) and during the rainy (1.76 ib/p/n) compared to the dry season (0.34 ib/p/n). Anopheles funestus was most infectious overall (28.1%, 16/57) while An. gambiae had the highest inoculation rates averaging 1.33 ib/p/n. Most Anopheles species across all altitudes and seasons were parous, highest in communities with the highest proportion of malaria parasite infections. Conclusion Anopheles gambiae (s.s.) remains the major malaria vector in the area and An. cinctus possibly a secondary vector of the disease in the slopes of Mt. Cameroon. The seasonal and altitudinal effects on the distribution of these mosquitoes may have implications for the transmission of malaria and its control strategies in the area. Regular monitoring of the bionomics of local Anopheles vector species and targeted control interventions in the ‘hotspots’ is necessary to curb the prevalence of the infection and incidence of disease.

2022-09-28

Genevieve Tchigossou Romaric Akoton Akadiri Yessoufou Innocent Djegbe Francis Zeukeng Seun M Atoyebi Eric Tossou Kabirou Moutairou Rousseau Djouaka

2017-11-10

F. Zeukeng R. Djouaka J.D. Bigoga S.E. Kakou-Ngazoa D. N’golo Coulibaly T.M. Ngo Nsonga M. Tamo W.F. Mbacham A. Ablordey

International Journal of Infectious Diseases

2020-01-01

Tchinda, V.H.M. Socpa, A. Keundo, A.A. Zeukeng, F. Seumen, C.T. Leke, R.G.F. Moyou, R.S.

Pan African Medical Journal

2012-01-01

Moussa Keïta Fousseyni Kané Oumar Thiero Boissé Traoré Francis Zeukeng Ambiélè Bernard Sodio Sekou Fantamady Traoré Rousseau Djouaka Seydou Doumbia Nafomon Sogoba

Parasites &amp; Vectors

Abstract Background The long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are major malaria vector control strategies in Mali. The success of control strategies depends on a better understanding of the status of malaria vectors with respect to the insecticides used. In this study we evaluate the level of resistance of Anopheles gambiae (sensu lato) to bendiocarb and the molecular mechanism that underlies it. Methods Larvae of An. gambiae (s.l.) were collected from breeding habitats encountered in the three study sites and bioassayed with bendiocarb. The ace-1 target site substitution G119S was genotyped using a TaqMan assay. Results The three species of the An. gambiae complex in Mali, i.e. An. arabiensis, An. coluzzii and An. gambiae (s.s.) were found in sympatry in the three surveyed localities with different frequencies. We observed a resistance and suspicious resistance of the three species to bendiocarb with a mortality rate ranging from 37% to 86%. The allelic frequency of the G119S mutation was higher in An. gambiae (s.s.) compared to the other two species; 42.86%, 25.61% and 16.67% respectively in Dangassa, Koula, and Karadié. The allelic frequency of G119S in An. coluzzii ranged from 4.5% to 8.33% and from 1.43% to 21.15% for An. arabiensis. After exposure to bendiocarb, the G119S mutation was found only in survivors. The survival of Anopheles gambiae (s.l) populations from the three surveyed localities was associated with the presence of the mutation. Conclusions The study highlights the implication of G119S mutation in bendiocarb resistance in An. gambiae (s.s.), An. arabiensis and An. coluzzii populations from the three surveyed localities.

2020-12-01

Tabue N. Raymond Madgan E. Roland Kenfack M. M. Françoise Zeukeng Francis Esemu F. Livo Seumen T. H. Clovis

Infection Ecology &amp; Epidemiology

2015-01-01

Romaric Bidossessi Akoton Genevieve M. Tchigossou Innocent Djègbè Akadiri Yessoufou Seun Atoyebi Eric Tossou Francis Zeukeng Pelagie Boko Helen Irving Razack Adéoti Jacob Riveron Charles S. Wondji Kabirou Moutairou Rousseau Djouaka

Wellcome Open Research

Background:Insecticides resistance inAnophelesmosquitoes limits Long-Lasting Insecticidal Nets (LLIN) used for malaria control in Africa, especially Benin. This study aimed to evaluate the bio-efficacy of current LLINs in an area whereAn. funestuss.l.andAn. gambiaehave developed multi-resistance to insecticides, and to assess in experimental huts the performance of a mixed combination of pyrethroids and piperonyl butoxide (PBO) treated nets on these resistant mosquitoes.Methods:The study was conducted at Kpomè, Southern Benin. The bio-efficacy of LLINs againstAn. funestus and An. gambiaewas assessed using the World Health Organization (WHO) cone and tunnel tests. A released/recapture experiment following WHO procedures was conducted to compare the efficacy of conventional LLINs treated with pyrethroids only and LLINs with combinations of pyrethroids and PBO. Prior to huts trials, we confirmed the level of insecticide and PBO residues in tested nets using high performance liquid chromatography (HPLC).Results:Conventional LLINs (Type 2 and Type 4) have the lowest effect against local multi-resistantAn. funestus s.s. and An. coluzziipopulations from Kpomè. Conversely, when LLINs containing mixtures of pyrethroids and PBO (Type 1 and Type 3) were introduced in trial huts, we recorded a greater effect against the two mosquito populations (P < 0.0001). Tunnel test withAn. funestus s.s.revealed mortalities of over 80% with this new generation of LLINs (Type 1 and Type 3),while conventional LLINs produced 65.53 ± 8.33% mortalities for Type 2 and 71.25 ±7.92% mortalities for Type 4. Similarly, mortalities ranging from 77 to 87% were recorded with the local populations ofAn. coluzzii.Conclusion:This study suggests the reduced efficacy of conventional LLINs (Pyrethroids alone) currently distributed in Benin communities whereAnophelespopulations have developed multi-insecticide resistance. The new generation nets (pyrethroids+PBO) proved to be more effective on multi-resistant populations of mosquitoes.

2018-06-13

Raymond N. Tabue Boris A. Njeambosay Francis Zeukeng Livo F. Esemu Barrière A. Y. Fodjo Philomina Nyonglema Parfait Awono-Ambene Josiane Etang Etienne Fondjo Dorothy Achu Rose G. F. Leke Célestin Kouambeng Tessa B. Knox Abraham P. Mnzava Jude D. Bigoga

BioMed Research International

2019-04-16

Zeukeng F Anthony A Kakou-Ngazoa ES Ghogomu MS Coulibaly ND Ngo-Nsonga MT Mbacham FW Bigoga DJ Djouaka R

2021-01-01

Innocent Djègbè Romaric Akoton Genevieve M. Tchigossou Koffi Mensah Ahadji-Dabla Seun Michael Atoyebi Razack Adéoti Francis Zeukeng Guillaume Koffivi Ketoh Rousseau Djouaka

Wellcome Open Research

2018-03-19

Francis Zeukeng Anthony Ablordey Solange E. Kakou-Ngazoa Stephen Mbigha Ghogomu David N’golo Coulibaly Marie Thérèse Ngo Nsoga Wilfred Fon Mbacham Jude Daiga Bigoga Rousseau Djouaka

Tropical Medicine and Health

2021-12-01

Tchinda, V.H. Socpa, A. Keundo, A.A. Zeukeng, F. Seumen, C.T. Leke, R.G. Moyou, R.S.

The Pan African medical journal

2012-01-01

9. Kwi PN, Ewane E, Moyeh NM, Tangi NL, Ntui NV, Zeukeng F, Sofeu Feugaing DD, Achidi AE, Cho-Ngwa F, Amambua Ngwa A, Bigoga DJ, Apinjoh OT

Parasites & Vectors

Background: Malaria remains endemic in Cameroon, with heterogeneous transmission related to eco-climatic variations,
vector
diversity
and spatial distribution.
The
intensification
of malaria
prevention
and control
through
the free

distribution
of insecticide-treated
nets in recent
years
may
have
altered
the composition, geographic
distribution
and natural
infection
rate
of Anopheles
species,
with implications for
malaria
transmission dynamics.
The
present
study seeks
to
assess the vectorial
diversity,
dynamics and infectivity
across
different
seasons and altitudes in relationship
to

parasite
prevalence
around
the slopes of Mount
Cameroon,
southwestern
region.
Method: Mosquitoes were sampled (indoors and outdoors) in 11 eco-epidemiological settings at low (18–197 m), intermediate (371–584 m) and high (740–1067 m) altitude by nightly human landing catches. The mosquitoes were identified morphologically and Anopheles gambiae sibling species identified by PCR. Parity status was ascertained by examining the ovaries and the entomological inoculation rates (EIR) determined by Plasmodium falciparum circumsporozoite
antigen ELISA of the head-thorax.
The
prevalence
of Plasmodium
infection
across
target
communities was assessed
using rapid diagnostic
tests.
Results: A total of 7327 (18.0 mosquitoes/trap/night) mosquitoes were trapped, mainly during the rainy season (5678, 77.5%) and at low altitude (3669, 50.1%). Anopheles spp. (5079, 69.3%) was the most abundant genera and An. gambiae complex (2691, 36.7%) the major vector, varying with altitude (χ
2
 = 183.87, df = 8, P < 0.001) and season (χ
2
Parasites & Vectors
 = 28.14, df = 4, P < 0.001). Only An. gambiae (s.s.) was identified following molecular analysis of An. gambiae complex
siblings.
The
overall
biting peak for
An.
gambiae
complex was 2—3 a.m. Anopheles
cinctus
was the most abundant
secondary
vector
in the area.
The
average
EIR in the area
was 2.08 infective
bites
per person per night (ib/p/n), higher
at low
(2.45 ib/p/n) than at intermediate
altitude (1.39 ib/p/n) and during
the rainy
(1.76 ib/p/n) compared
to

the
dry
season (0.34 ib/p/n). Anopheles
funestus
was most infectious
overall
(28.1%, 16/57) while An.
gambiae
had the highest
inoculation rates
averaging
1.33 ib/p/n. Most
Anopheles
species across
all altitudes and seasons were
parous,

highest
in communities with the highest proportion
of malaria
parasite
infections.
Conclusion: Anopheles gambiae (s.s.) remains the major malaria vector in the area and An. cinctus possibly a secondary
vector
of the disease in the slopes of Mt. Cameroon.
The
seasonal and altitudinal effects
on the distribution
of these mosquitoes may have implications for the transmission of malaria and its control strategies in the area. Regular monitoring of the bionomics of local Anopheles vector species and targeted control interventions in the ‘hotspots’ is necessary to curb the prevalence of the infection and incidence of disease.

2022-09-28

Bekindaka Ngemani Obase Zeukeng Francis Esemu Livo Forgu Awanakam Honore Jude Daiga Bigoga Dickson S Nsagha

JMIR Research Protocols

2023-01-24