Arthur Mbida Mbida’s research while affiliated with University of Douala and other places

Background. The effectiveness of Long-Lasting Insecticidal Nets (LLINs) and indoor residual spraying (IRS) in controlling malaria vectors is hampered by the resistance of anopheles to insecticides. A good knowledge of the breeding sites and of the resistance profile of the vectors could facilitate the development of an appropriate control strategy. This study looks at the larval ecology and the susceptibility profile of An. gambiae s.l. to insecticides in urban and rural areas in Kribi, South Region of Cameroon. Methods. Mosquito breeding sites were categorized and geo-referenced. For each site, larvae were collected and reared and physicochemical parameters were measured in situ. T he susceptibility of anopheles to dichlorodiphenyltrichloroethane (DDT), deltamethrin and permethrin, after pre-exposure to piperonyl butoxide (PBO) or not, was evaluated on the reared larvae. The Kdr mutation was detected using the Hot Oligonucleotide Ligation Assay (HOLA). Results. Natural breeding sites of An. gambiae s.l. were tyre tracks (12%, n=10), unbuilt wells (5%, n=4), pools of residual water (57%, n=48), foot and hoof prints, gullies, streams and the banks of the Kienké River (15%, n=13). Artificial breeding sites were abandoned dugouts (11%, n=9). Breeding sites in urban areas were characterized by higher mean values of temperature, conductivity, salinity and turbidity compared to the breeding sites in the rural area. The breeding sites of An. gambiae s.l. in urban Kribi were found to be sunnier than those in rural Kribi. A total of 4320 adults were used for testing, 1 440 mosquitoes from rural Kribi, 1 440 from urban Kribi and 1 440 specimens from the laboratory Kisumu strain. For DDT and deltamethrin, susceptibility tests showed that mortality was lower in a situation of no pre-exposure to PBO than in a situation of pre-exposure to PBO in the two study areas. The frequency of the resistant allele (R) was high for the Kdr West mutation in both urban (0.94) and rural areas in Kribi (0.93). Conclusion. An. gambiae s.l. colonizes a wide range of breeding sites and develops metabolic and mutation resistance to recommended insecticides. The search of alternative molecules for vector control is a necessity. Keywords: Anopheles gambiae s.l., Ecology, Breeding sites, Resistance to insecticides, Kdr mutation, Metabolic resistance, Kribi, Cameroon, Sub-Saharan Africa

Objective: The implementation of an efficient and successful control strategy requires a recurrent evaluation of the relationship between local populations and the disease. The objective of this study was to assess knowledge, attitudes and practices (KAP) on the treatment and prevention of malaria. Methodology and results: The study was carried out from 7 to 14 February 2019 among 509 heads of household in the localities of Bafang and Bakassa in the western region of Cameroon using a standard survey. The respondents associated the transmission of malaria with mosquito bites in 76.5% of cases in Bafang (n = 305) against 67% in Bakassa (n = 59). In case of a malaria crisis, 36.3% of the respondents in the city of Bafang (n = 151) and 48.4% of the respondents in the locality of Bakassa (n = 45) went to the hospital. The remaining part of the population practiced either traditional medicine or self-medication, purchasing drugs from pharmacy or street. For treatment and prevention against malaria, each household spent an average of 8640 FCFA (13.17 €) in Bafang and 7300 FCFA (11.13 €) in Bakassa. The rates of use of insecticide-treated nets (ITNs) by respondents in Bafang and Bakassa were 68.7% and 65.6% respectively. However, other means of prevention were practiced in the two localities: environmental sanitation, the use of sprays and blankets/curtains. Conclusion and Application of Results: Populations in study areas have an acceptable level of knowledge of malaria, control practices, and case management. However, the ITN utilization rate remains below that recommended by WHO. Outreach programs should improve this situation.

La lutte anti moustique au Cameroun repose en grande partie sur une bonne utilisation des mois après la distribution des moustiquaires.L’intégrité physique des MILDA a été d’Anopheles gambiaes.l. non gorgées âgées de deux à cinq jours, élevées en insectarium et MILDA ont été effectués suivant le protocole des tests en cône en utilisant des femelles® l’efficacité des MILDA (marque Interceptor d’utilisation des MILDA a été évalué par une enquête menée auprès des populations) sur les populations d’Anopheles gambiaes.l. dans deux zones, urbaine et rurale, du district de santé d’Ayos. Le niveau de couverture et évaluée en mesurant les trous suivant la méthode de l’OMS. Les tests de bioefficacité des pour améliorer la stratégie. Le présent travail a pour but de mesurer l’intégrité physique et nécessaire de suivre l’efficacité de ces dernières afin de proposer des mesures correctives moustiquaires imprégnées d’insecticide à longue durée d’action(MILDA).Il est issues de deux souches: la souche locale et une souche sensible de référence.

Mosquito control in Cameroon relies largely on the proper use of Long-Lasting Insecticidal Nets (LLINs). It is necessary to monitor their effectiveness in order to propose corrective measures to improve the strategy. The aim of this work was to determine the physical integrity and effectiveness of LLINs (Interceptor brand) on Anopheles gambiae s.l. populations in two urban and rural areas of the Ayos health district. The level of LLIN coverage and use was assessed through a population survey. The physical integrity of LLINs was assessed by measuring the holes according to the WHO method. Bio-efficacy testing of ITNs was carried out according to the cone test protocol using 2-5-day-old, non-blood fed Anopheles gambiae s.l. females from the natural field strain and the reference susceptible strain. Household LLIN coverage rates in urban and rural areas were 55.50% and 66.94%, respectively. On the other hand, the rates of use were 78.01% and 75.22% in urban and rural areas respectively. The proportion of nets that had lost their physical integrity after 36 months of use was 47.00% and 59.63% in urban and rural areas respectively. The size of holes ranged from 0.5 to 25 cm. Alphacypermethrin was found to be ineffective against both strains of Anopheles gambiae s.l. tested. Knockdown rates ranged from 8.5% to 73% for the reference susceptible strain and less than 2.5% for the natural field strain. Mortality rates for the natural strain of Anopheles gambiae s.l. ranged from 0% to 2.5% while they were between 29% and 70% for the susceptible strain. The results show a decrease in the effectiveness of LLINs against the mosquitoes tested. This may be due to the lower than expected WHO possession and use rates of LLINs, their relatively high degree of wear and tear, and the resistance of the vectors to alphacypermethrin.

Objectif : La mise en œuvre d’une stratégie de lutte efficiente et réussie requiert une évaluation récurrente des rapports qu’entretiennent les populations locales avec la maladie. L’objectif de cette étude était d’évaluer les connaissances, les attitudes et les pratiques (CAP) sur le traitement et la prévention du paludisme. Méthodologie et résultats : L’étude a été réalisée du 7 au 14 février 2019 auprès de 509 chefs de ménage des localités de Bafang et Bakassa dans la région de l’ouest-Cameroun à l’aide d’un questionnaire standard administré aux enquêtés. Les enquêtés associaient la transmission du paludisme à des piqûres de moustiques dans 76,5% de cas à Bafang (n= 305) contre 67% à Bakassa (n=59). En cas de crise du paludisme, 36,3% des enquêtés de la ville de Bafang (n = 151) et 48,4% des enquêtés de la localité de Bakassa (n = 45) se rendaient à l’hôpital. La tranche de la population restante pratiquait soit la médecine traditionnelle, soit l’automédication, s’approvisionnant en médicaments de pharmacie ou de rue. Pour le traitement et la prévention contre le paludisme, chaque foyer dépensait mensuellement en moyenne 8640 FCFA (13,17 €) à Bafang et 7300 FCFA (11,13€) à Bakassa. Les taux d’utilisation des moustiquaires imprégnées d’insecticides (MII) par les enquêtés de Bafang et Bakassa étaient de 68,7% et 65,6% respectivement. Toutefois, d’autres moyens de prévention étaient pratiqués dans les 2 localités : l’assainissement de l’environnement, l’usage des sprays et les couvertures/rideaux. Conclusion et application des résultats : Les populations des localités d’étude ont un niveau acceptable de la connaissance du paludisme, des pratiques de lutte et de prise en charge des cas. Cependant le taux d’utilisation des MII reste en deçà de celui préconisé par l’OMS. Les programmes de sensibilisation des populations devraient améliorer cette situation. Mots clés : Paludisme, Connaissance, Attitude, Pratique, Bafang, Bakassa, Ouest-Cameroun Enama et al., J. Appl. Biosci. 2020 Le paludisme : connaissances, attitudes et pratiques des chefs de ménage de la region de l’ouest-Cameroun 15118 Malaria: Knowledge, Attitudes and Practices of Household Heads in the Western-Cameroon Region. ABSTRACT Objective: The implementation of an efficient and successful control strategy requires a recurrent evaluation of the relationship between local populations and the disease. The objective of this study was to assess knowledge, attitudes and practices (KAP) on the treatment and prevention of malaria. Methodology and results: The study was carried out from 7 to 14 February 2019 among 509 heads of household in the localities of Bafang and Bakassa in the western region of Cameroon using a standard survey. The respondents associated the transmission of malaria with mosquito bites in 76.5% of cases in Bafang (n = 305) against 67% in Bakassa (n = 59). In case of a malaria crisis, 36.3% of the respondents in the city of Bafang (n = 151) and 48.4% of the respondents in the locality of Bakassa (n = 45) went to the hospital. The remaining part of the population practiced either traditional medicine or self-medication, purchasing drugs from pharmacy or street. For treatment and prevention against malaria, each household spent an average of 8640 FCFA (13.17 €) in Bafang and 7300 FCFA (11.13 €) in Bakassa. The rates of use of insecticide-treated nets (ITNs) by respondents in Bafang and Bakassa were 68.7% and 65.6% respectively. However, other means of prevention were practiced in the two localities: environmental sanitation, the use of sprays and blankets/curtains. Conclusion and Application of Results: Populations in study areas have an acceptable level of knowledge of malaria, control practices, and case management. However, the ITN utilization rate remains below that recommended by WHO. Outreach programs should improve this situation. Keywords: Malaria, Knowledge, Attitude, Practice, Bafang, Bakassa, West Cameroon

Background: Effective malaria control relies on evidence-based interventions. Anopheline behaviour and Plasmodium infections were investigated in North Cameroon, following long-lasting insecticidal net (LLIN) distribution in 2010. Methods: During four consecutive years from 2011 to 2014, adult mosquitoes were collected indoors, outdoors and in exit traps across 38 locations in the Garoua, Pitoa and Mayo-Oulo health districts. Anophelines were morphologically and molecularly identified, then analysed for blood meal origins and Plasmodium falciparum circumsporozoite protein (Pf-CSP). Blood from children under 5 years-old using LLINs was examined for Plasmodium infections. Results: Overall, 9376 anophelines belonging to 14 species/sibling species were recorded. Anopheles gambiae (s.l.) [An. arabiensis (73.3%), An. coluzzii (17.6%) and An. gambiae (s.s.) (9.1%)] was predominant (72%), followed by An. funestus (s.l.) (20.5%) and An. rufipes (6.5%). The recorded blood meals were mainly from humans (28%), cattle (15.6%) and sheep (11.6%) or mixed (45%). Pf-CSP rates were higher indoors (3.2-5.4%) versus outdoors (0.8-2.0%), and increased yearly (χ2 < 18, df = 10, P < 0.03). Malaria prevalence in children under 5 years-old, in households using LLINs was 30% (924/3088). Conclusions: The present study revealed the variability of malaria vector resting and feeding behaviour, and the persistence of Plasmodium infections regardless the use of LLINs. Supplementary interventions to LLINs are therefore needed to sustain malaria prevention in North Cameroon.

Anopheles hancocki est l’un des vecteurs secondaires du paludisme dont l’écologie larvaire est encore méconnue dans le bloc forestier sud-camerounais. Cette information est pourtant fondamentale pour la mise en place d’une stratégie de contrôle efficace là où ce moustique se fait le vecteur des plasmodiums responsables des paludismes. La présente étude détermine l’écologie larvaire d’An. hancocki et de son degré d’implication dans la transmission du paludisme dans un village fluvial du district de santé d’Ayos. L’échantillonnage des moustiques a eu lieu dans le courant de l’année 2018 au rythme d’une enquête par trimestre en combinant la méthode du « dipping » de collectes des larves à celle des captures des moustiques adultes sur les volontaires. Pour chaque gîte, les larves ont été prélevées puis élevées en insectarium et les paramètres physico-chimiques mesurés in situ. Les moustiques adultes ont été identifiés suivant les critères morphologiques et moléculaires. L’infectivité des vecteurs a été déterminée selon le test ELISA CSP et la détermination de leur âge physiologique basée sur l’aspect des trachéoles ovariennes. Un total de 3618 adultes de moustiques appartenant à 7 espèces a été obtenu dans la localité d’étude, comprenant An. hancocki, An. gambiae, An. moucheti, Mansonia africana, Culex pipiens quinquefasciatus, Aedes albopictus et Aedes aegypti. Les gîtes d’An. hancocki se sont montrés comparables à ceux d’An. gambiae. Toutefois les valeurs de ‘Total dissolved solid’ (TDS) et de conductivité des gîtes d’An. gambiae ont été significativement supérieures à celles des gîtes d’An. hancocki. Ce dernier s’est d’ailleurs montré comme étant l’espèce la plus agressive en représentant 45,6 % de la faune culicidienne capturée dans la zone d’étude. Son cycle nocturne d’agressivité a montré une activité maximale située dans la tranche horaire 20h-22h. Les femelles de cette espèce étaient significativement plus âgées que celles d’An. gambiae et contribuaient à 40 % de la transmission du paludisme dans la localité avec un taux d’inoculation entomologique (TIE) moyen annuel de 2,92 pi/H/an, pas loin derrière An. gambiae 3,65 pi/H/an. Les larves d’An. hancocki ont, à quelques différences près, les mêmes exigences écologiques que celles d’An. gambiae. An. hancocki entraîne une transmission pérenne du paludisme dans la région d’étude et impose de ce fait, la mise sur pied d’une stratégie durable de contrôle des paludismes.

Choosing an appropriate strategy for mosquito control in an eco-climatic facies requires knowledge of vector ecology, including the spatial distribution and productivity of larval habitats and their level of susceptibility to insecticides. This study maps, characterizes the mosquito breeding sites and evaluates the susceptibility to insecticides of malaria vectors to Banya II and Bodiman, two semi-urban and rural areas of the coastal region of Cameroon. The field surveys were conducted in May 2015. The mosquito breeding sites were geo-referenced. For each breeding site, larvae were collected then reared and physico-chemical parameters measured in situ. The susceptibility of vectors to dichlorodiphenyltrichloroethane (DDT), deltamethrin and permethrin was evaluated on the anopheline obtained from larva rearing. A variety of breeding sites has been identified in the study sites (ponds, rivers, ditches, tires, plastic wrap, water storage containers, abandoned containers, papaya holes, bamboo holes). However, Anopheles gambiae s.l, the most abundant species in Banya II was more common in the pools, while Culex poicilipes, the most abundant species in Bodiman was mainly collected in abandoned containers. The two categories of breeding sites had respectively electrical conductivity of 167.5 [16.9-305] and 170.43 [11.6-461] µs/cm, salinity of 90.5 [23.5-157] and 94.63[15-240] g/l and total dissolved solids of 119.6 [20.6-215] and 123.3 [7.8-354] ppm. Insecticides tests revealed mortality rates below 85 % for the Banya II Strain of A. gambiae s.l. and over 98 % for the Bodiman strain of A. nili. These informations should be taken into account for a better orientation of control strategies in order to control effectively the vectors in the study localities. © 2018 Societe Nationale de Protection de la Nature. All rights reserved.