Evaluation des risques de réémergence de l'épidémie du virus Chikungunya dans la vallée du Monastère de Mont Ngafula, RD Congo

Contexte et objectif. L'épidémie à virus Chikungunya est émergente, invalidante et mortelle qui sévi partout. Le virus Chikungunya est transmis à l'homme par la piqûre des insectes infectés du genre Aedes. A Kinshasa, le récent épisode de l'épidémie remonte à 4 années. L'objectif de la présente étude a été d'évaluer les risques de réémergence de l'épidémie du virus Chikungunya à Kinshasa Mont Ngafula. Méthodes. Il s'agissait d'une étude transversale menée à Mont Ngafula, dans laquelle 4 sites ont été sélectionnés à l'aide d'un plan d'échantillonnage à plusieurs degrés du 1er juin au 30 août 2021. Les larves et les nymphes des insectes ont constitué le matériel biologique de l'étude. Des variables environnementales (Température, pH, turbidité, Conductivité et Saturation en oxygène) ont été recueillies dans les gîtes larvaires. Une analyse de régression logistique multivariée a été effectuée pour identifier les prédicteurs de la densité des gîtes larvaires. Résultats. 400 ménages et 738 gîtes larvaires ont été explorés. Les indices entomologiques, indice récipient (IR), indice maison (IM) et indice de Breteau (IB) évalués étaient supérieurs aux critères et normes de l'OMS. La saturation en oxygène, la turbidité et la conductivité se sont avérées significativement associées à la densité des gîtes larvaires. Conclusion. Les risques de réémergence de l'épidémie de Chikungunya à Kinshasa sont réels. Une surveillance entomologique est nécessaire pour mettre en place des mesures de prévention et de contrôle de santé publique.

Susceptibility of Culex Quinquefasciatus say (Diptera: Culicidae) in Khartoum Locality (Sudan) to Malathion; Temephos; Lambdacyhalothrin and Permethrin Insecticides

Abstract:background et objectives:Mosquito control is becoming increasingly difficult because of the developmentof resistance in vectors to conventional insecticides. The resistance in vectors warrants development of newer insecticides for mosquito control besides use of other counter-measures. This study aimed to determine the susceptibility of adult and larvae of Cx.quinquefasciatus mosquitoes (Diptera: Culicidae) to malathion; temephos; lambdacyhalothrin and permethrin insecticides in Khartoum locality.Material et methods:Susceptibility of Culex quinquefasciatus mosquitoes to malathion; lambdacyhalothrin and permethrin; and of the larvae to temephos in Khartoum locality was carried out; following WHO standard susceptibility tests. One to three days old female mosquitoes; which were reared from field collected immature stages; were exposed to discriminating dosages of the insecticides; for respective exposure periods. Then knockdown time and 24-hours mortality were recorded. For larvae which were exposed to a series of temephos concentrations; and LC 50 and LC 90 values were calculated.results:The study revealed that;Culex quinquefasciatus is predominant in Khartoum locality. Evidence of resistance was revealed to malathion and the two pyrethroids against Culex quinquefasciatus. The average KDT 50 values consider high and indicated resistance. But larvae stages were found to be susceptible to temephos.Interpretation et conclusion:Resistance of the field population of Cx. quinquefasciatus in Khartoum was revealed to malathion; lambdacyhalothrin and permethrin. On the other hand; the same population of Cx. quinquefasciatus is still sensitive to temephos. Therefore; the vector control unit should consider introducing rotation of insecticidesas a management strategy to increase the duration of the usage of the current insecticides. Furthermore; a rationalized use of insecticides coupled with regular monitoring of insecticide resistance is recommended to mitigate the rapid emergence of insecticide resistance

Millions of Nets : But are they being used?

The year 2010 was targetted at the 2000 Abuja Malaria Summit as the time when 80of vulnerable groups (pregnant women; children below 5 years of age) would be sleeping under insecticide-treated nets (ITNs).1 Subsequently the US President's Malaria Initiative (PMI) raised the bar to 85in its 15 focus countries.2 Most recently; the United Nations3 broadened the scope of ITN use and stressed that 2010 would be the year of Universal Coverage (UC). UC is variously interpreted in each endemic country and can mean one net distributed for each two people in the population to two nets per household. Ultimately it has been recognised that in order to reduce the burden of malariadisease; everyone should sleep under an ITN; or as now being used; a long-lasting insecticide-treated net (LLIN)

La presence des bovins comme hotes alternatifs peut-elle modifier le comportement trophique des vecteurs du paludisme en zone de foret?

Des enquetes entomologiques longitudinales ont ete effectuees de novembre 1998 a novembre 2000 en vue de determiner le comportement trophique des anopheles en presence de bovins comme hotes alternatifs a l`homme dans deux localites de la zone de foret du sud Cameroun; Obala et Nkolbisson. Les collectes des moustiques ont eu lieu a l`interieur des habitations par pulverisation intra domiciliaire et a l`exterieur a l`aide de captures sous moustiquaire piege avec comme appats l`homme et le veau. L`origine du repas de sang et l`infectivite des moustiques ont ete identifiees par la technique ELISA (Enzyme Linked Immunosorbent Asay). Au total; 992 anopheles appartenant a 8 especes ont ete collectees au cours de cette etude. An. funestus etait l`espece la plus abondante a Obala tandis qu`An. nili predominait a Nkolbisson. Le taux d`anthropophilie etait plus eleve chez les moustiques collectes a l`interieur des habitations que chez ceux collectes a l`exterieur sous moustiquaire piege. An. gambiae et An. funestus ont montre une nette preference pour l`homme tandis qu`An. nili a pique indifferemment l`homme et le boeuf. An. gambiae etait de loin le vecteur principal dans les deux sites d`etude avec 24 cas d`infections sur les 42 trouves. Ces resultats montrent que les vecteurs en zone de foret peuvent diversifier la source de leur repas de sang en presence d`hotes alternatifs tels que les bovins. Toutefois; il serait important de comprendre si l`introduction de l`elevage de bovins dans cette region pourrait influencer le cycle de transmission du paludisme

Epidemiological Importance of the Anopheles Nili Group of Malaria Vectors in Equatorial Villages of Cameroon; Central Africa

From March 1999 to March 2007; entomological surveys were conducted in eight riverside locations of the equatorial domain in Cameroon; to assess the contribution of Anopheles nili group to malaria transmission. Results showed that the anthropophilic Anopheles nili; Anopheles carnevalei and Anopheles ovengensis were involved in 5-68of the Plasmodium falciparum entomological inoculation rates (EIRs) in all the study sites. Alongside; vectors such as Anopheles Gambiae; Anopheles moucheti; Anopheles funestus; Anopheles marshallii and Anopheles hancocki also took a substantial part to these transmission rates in sympatric conditions. Anopheles nili s.s. was the major vector in villages situated near the Sanaga river; with more than 100 infective bites/person/year. Its true Plasmodium falciparum infections rates ranged from 1.4to 6.1. Anopheles carnevalei and Anopheles ovengensis were mainly distributed in the equatorial cross-bordering areas; where they contributed for less than 30of the Plasmodium falciparum EIRs in villages located along the Nten river and Congo river networks. These findings confirm Anopheles nili s.s. as a major malaria vector mosquito; and also provided more data regarding the epidemiological role of Anopheles carnevalei and Anopheles ovengensis througout the central African region

Insecticide-Treated Nets Usage and Malaria Episodes among Boarding Students in Zaria; Northern Nigeria

Background : Despite malaria being the largest public health problem in Africa South of Sahara with over one million associated deaths each year, there has been little progress in its prevention/control during the past decades. Therefore, this study was conducted to determine the knowledge, attitude, use of insecticide-treated nets (ITNs), and the prevalence of malaria episodes among boarding secondary school pupils in Zaria, Nigeria. Methods : A multi-stage sampling technique was used to sample five (5) secondary schools within Zaria, from which six classes (JSS 1 - 3 and SS 1- 3) of respondents were then randomly selected. Structured, closed-ended self-administered questionnaires were used to collect information on demographic characteristics, knowledge, attitude, and use of ITNs, reasons for non-use and malaria episodes in last 12 months. Results : A total of 150 students from the five (5) boarding secondary schools were interviewed, majority were in the age group 15-17 (53.3%) with a mean (x) +- SD of 16.8 +- 0.8 years. Males were 60% and females 40% of respondents. Majority of the respondents (87.3%) knew about and had actually seen an ITN; only 43.3% were current users. Most of the current users of ITN noticed a significant reduction in malaria episodes in the last 12 months. This was statistically significant (P=0.004). Cost and availability were reasons sited by non-ITN users. Conclusion : There is urgent need on the part of all the three tiers of Government for public health awareness campaigns through information, education and communication (IEC) to create positive ITN culture and usage. It is also suggested that ITN usage among boarding school pupils should be incorporated into school health service

Vector Species Composition and Malaria Infectivity Rates in Mkuzi; Muheza District; North-Eastern Tanzania

Entomological surveys were conducted in Mkuzi village in Muheza District; north-east Tanzania from April to September 2003. The objectives were to determine the species composition and infectivity rates of mosquitoes in Mkuzi village. Mosquito collection was done using CDC light trap and pyrethrum spray catch (PSC) techniques. The light trap: spray catch ratio was 2.2:1. A total of 2157 mosquitoes were collected (light trap= 1483; PSC= 674). Anopheles gambiae s.s. accounted for 56.7(N=1224) of all mosquitoes collected. Other species were An. funestus complex (19.2) and Culex quinquefasciatus (24.1).The mosquito density per room was 74.15 and 33.7 for light trap and PSC techniques; respectively. A total of 1637 Anopheles mosquitoes were tested for circumsporozoite protein by Enzyme linked Immunosobent Assay (ELISA). The overall infectivity rate for circumsporozoite protein for P. falciparum in Anopheles mosquitoes was 21.14(346/1637). Species-specific infectivity rates were 22.7(278/1224) in An. gambiae s.s. and 24.0(68/283) in An. funestus funestus; 0(0/80) for An. rivulorum and 0(0/50) for An.parensis. Blood meal analysis indicated that 92.3of An. gambiae s.s; 88.9of An. funestus s.s.; 64.5of An. rivulorum and 67.7of An. parensis had taken blood meal from human hosts. In conclusion; malaria transmission in Mkuzi area of Muheza district is mainly by the highly anthropophagic An. gambiae s.s. and An. funestus s.s. More studies are needed to identify the seasonal variation of species composition and transmission dynamics in this village

Repellency Property of Long Chain Aliphatic Methyl Ketones against Anopheles gambiae s.s

Long chain aliphatic methyl ketone series of C7-C15 were tested for repellency activity against the malaria transmitting mosquito Anopheles gambiae s.s. All methyl ketones produced a dose dependent (P0.001) repellency response with 2-tridecanone giving comparable protection efficacy to DEET at 10 and 1concentrations. Aliphatic methyl ketones of C7-C10 had lower activity than those of C11-C15. However; within this range compounds with odd carbon atoms (2-undecanone; 2-tridecanone and 2-pentadecanone) were more effective than compounds with even carbon atoms (2-decanone and 2- dodecanone). Comparable repellency activity of 2-tridecanone to DEET show that; it may save as Anopheles gambiae s.s. mosquito repellent

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria

Abstract: The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the fi ve habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-signifi-cant difference in species occurrence in the fi ve habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic fi lariasis and malaria suggest that the residents of Abeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites

Sampling mosquitoes with CDC light trap in rice field and plantation communities in Ogun State, Nigeria

Mosquito species were sampled to determine the mosquito composition and abundance in rice field and plantation communities in Ogun State Nigeria. Mosquitoes were caught once weekly from four selected houses in each of the two communities by means of CDC light traps. A total of 47,501 mosquitoes representing fifteen species were caught in the two communities of which the rice field community accounted for 63.8% of the total catch. Mansonia africana constituted the most important biting mosquito in the two communities representing 62.1% and 39.1% in rice field and plantation communities, respectively. Other species in decreasing order of abundance were M. uniformis, Anopheles gambiae, Coquilletidia fuscopennata, An. moucheti, An. funestus, An. nili, Culex quinquefasciatus, Eretmapodites chrysogaster, Coq.metallica, Cx annulioris, An. rhodesiensis, Aedes aegypti, An. squamosus and An. maculipennis. Seven mosquito species were caught throughout the year but mostly in the months of May to October. Abundance varied significantly between the study sites and between the months (F,1.11 =241.9 P<0.05) Most of the mosquitoes collected were unfed and nulliparous (87.1%). In spite of the high proportion of M. africana, its parous rate was low 0.53 and 0.59 in rice fileld and plantation, respectively. The highest parity was seen in Ae. aegypti (0.81-0.86) and An. gambiae, (0.69-0.68)

Les moustiques et la transmission du paludisme dans un village traditionnel du bloc forestier camerounais

Les auteurs presentent les resultats de trois enquetes transversales; concernant la faune culicidienne et la transmission du paludisme; effectuees dans un village de foret equatoriale. Trois genres culicidiens ont ete collectes a chaque enquete: Anopheles; Mansonia et Culex. Les anopheles vecteurs de paludisme sont; par ordre d'importance numerique: An.moucheti; An.gambiiae et An.funestus. Les densites anopheliennes ont ete faibles. Ces densites ont ete constantes pour An.funestus mais pas pour les deux autres especes. La transmission du paludisme; quoique seulement observee en avril et en juillet; doit etre permanente. Elle apparait relativement homogene dans tout le village

Croissance des larves de Culicidae a Kinshasa (Zaire) : influence physico-chimique des principaux gites de reproduction

Cette etude experimentale a porte sur les principaux gites permanents de reproduction des moustiques representes par les neuf plus importants cours d'eau drainant la ville de Kinshasa. La culture in vitro des larves d'Anopheles gambiae s.l. et de Culex quinquefasciatus a permis d'etudier leur croissance dans differents echantillons d'eau preleves dans ces gites. Les resultats ont montre que la croissance des larves de moustiques depend des conditions physico-chimiques du milieu de culture; reflet des conditions physico-chimiques qui regnent dans l'environnement draine par les collections d'eau etudiees. L'analyse multivariee a permis de caracteriser cinq profils physico-chimiques. Il existe des gites de reproduction plus favorable que d'autres; c'est les cas notamment des mares a vegetation aux eaux propres et ensoleillees qui offrent les meilleures conditions de survie et de croissance aussi bien pour les Anopheles que pour les Culex par rapport aux autres gites etudies. Quel que soit le profil physico-chimique du gite considere; le taux d'emergence des images pour le Culex s'est avere significativement plus eleve que celui des Anopheles; une larve de Culex a presente une chance sur deux de se transformer en image contre une chance sur trois pour une larve d'Anopheles. Cette difference est due au taux de mortalite relativement eleve des larves d'Anopheles par rapport aux larves de Culex durant la premiere semaine d'observation

Les moustiques communs du Zaire : description systematique et bio-ecologique; et quelques considerations sur la lutte

Ce livre est concu pour les personnes non expertes dans l'identification des moustiques les plus connus au Zaire. C'est un guide a l'intention des chercheurs travaillant dans le domaine medical et celui de la sante ainsi que ceux engages dans la recherche en biomedicale soit en laboratoire soit sur le terrain. Ce guide pourrait aussi interesser les enseignants des instituts superieurs et des universites

Etude de la sensibilite aux principaux insecticides d'aedes aegypti linne; 1762; Souche; Yaounde

Le present memoire montre qu'aedes aegypti est sensible au temephos; au fenitrothion; au chlorpyriphos; au malathion; a la deltamethrine et a la permethrine; mais est resistant au DDT et a la dieldrine. L'auteur recommande le chlorpyriphos et le temephos pour une campagne de lutte larvaire dans les mesures de prophylaxie contre la fievre jaune ou pour un assainissement urbain