[Impact of egg laying delay on reproduction, gorging habit and mortality in gravid females Anopheles gambiae (Diptera Culicidae)]. / Impact du retard de ponte sur la reproduction, l'habitude de gorgement et la mortalité chez les femelles gravides d'Anopheles gambiae (Diptera Culicidae).

The main vector of malaria Anopheles gambiae maintains the transmission of malaria over long periods of time, because of the exceptional longevity and great ability to adapt to various environments. The aim of this study is to understand the impact of the predefined egg laying delay that characterizes long dry seasons on reproductive dynamics, feeding habit, and mortality rate of An. gambiae gravid females. For this purpose, gravid females of An. gambiae awaiting laying, previously fed with blood were kept under observation in cages for several weeks. Then, at the end of predefined periods of observation, these gravid females were individually made to lay eggs, and the development cycle of eggs was studied in comparison with eggs laid in the normal conditions (controls). In addition, the behaviour of feeding and mortality rate were studied in gravid females kept in cages, without laying, for several weeks. The results obtained show that the average egg-laying number of the control females varies little from that of the females obliged to retain their eggs in abdomen for several days. The hatching rate was 86.2% in no retention batches and 31% in a 50-day retention batches. The adults' emergence rate was 77.7% in no eggs retention batches and 18.3% for eggs laid after 50 days of retention. In the batches of eggs with 20 days of retention, the emergence rate decreased significantly 0.89 times compared to control batches. The feeding rate of gravid females increased from 96.7% at the 1st blood meal to 12.5% at the 10th. In addition, the mortality rate of gravid females awaiting for laying is 0.36 times lower than that of no gravid females.

[Detection of the IS2404 insertion sequence and ketoreductase produced by Mycobacterium ulcerans in the aquatic Heteroptera in the health districts of Dabou and Tiassalé in Côte d'Ivoire]. / Mise en évidence de la séquence d'insertion IS2404 et de la kétoréductase (Kr) produite par Mycobacterium ulcerans chez les Hétéroptères aquatiques dans les districts sanitaires de Dabou et Tiassalé en Côte d'Ivoire.

Buruli ulcer (BU) disease, caused by Mycobacterium ulcerans, is a major public health problem in Côte d'Ivoire. Until now, the mode of BU transmission was unknown, but recent studies implicate aquatic Heteroptera in the chain of transmission. This study was launched in Côte d'Ivoire to search for specific genetic markers for M. ulcerans in these bugs, including the insertion sequence IS2404 and ketoreductase (Kr), both involved in the synthesis of mycolactone, a toxin produced by these mycobacteria. Samples of aquatic Heteroptera were collected monthly with deep nets from ponds near villages in the health districts of Dabou and Tiassalé. After identification and enumeration of the bugs, batches of the same taxon underwent real-time PCR to search for the IS2404 target and Kr. Saliva of 69 specimens of Diplonychus sp randomly selected in the samples was also analyzed by PCR. In all, 283 single-taxon batches were created. Thus, PCR identified 26 batches belonging to the families of Belostomatidae, Naucoridae, Corixidae, Ranatridae, and Nepidae as positive for both targets. The IS2404 insertion sequence and Kr were present in 6 of the 69 samples analyzed in the saliva of Diplonychus sp. These aquatic Heteroptera suspected of infection by M. ulcerans might release it into the environment because of their ability to fly. They might thus be the source of human contamination.

[Entomological evaluation of the risk of urban outbreak of yellow fever in 2008 in Abidjan, Côte d'Ivoire]. / Évaluation entomologique du risque d'épidémie urbaine de fièvre jaune survenue en 2008 dans le district d'Abidjan, Côte d'Ivoire.

In April 2008, seven years after the outbreak of 2001, Abidjan faced another epidemic of yellow fever. Three weeks after the case detected in the commune of Treichville at 28(th) of April 2008, two other cases were notified, the first one in Port-Bouet and the second one in Cocody located respectively in the south and north of the city of Abidjan. In order to determine a large-scale risk of urban yellow fever epidemic, epidemiological and entomological investigations were conducted by the Ministry of Health and Public Hygiene of Cote d'Ivoire with the support of the Global Outbreak Alert and Response Network. Entomological investigations revealed the predominance of Aedes ægypti, urban vector of yellow fever in neighborhood visited with larval density indices between 2 and 5, indicating the existence of a sufficient density of the vector for cause an explosion of the epidemic. In fact, the massive influx of people from inside cities towards Abidjan caused by the socio-political crisis occurred in the country in 2002, the deterioration of environment with the creation of more breeding sites of Ae. ægypti as corollary and the circulation of the virus at mosquito level were many factors favorable to the yellow fever outbreak in Abidjan city.

[Culex quinquefasciatus sensitivity to insecticides in relation to the urbanization level and sewage water in Yopougon, a township of Abidjan (Côte-d'Ivoire)]. / Sensibilité de Culex quinquefasciatus aux pyréthrinoïdes en relation avec le niveau d'urbanisation et l'évacuation des eaux usées dans la commune de Yopougon à Abidjan (Côte-d'Ivoire).

This survey, conducted from July 2003 to June 2004, was to assess the variation of the level of sensitivity of Cx. quinquefasciatus to the pyrethroids recommended for the impregnation of the mosquito nets, in the township of Yopougon situated in the Northwest of Abidjan city in relation with the bed of a drainage channel of sewage water that passes through the township from the north to the south. Five districts have been chosen along this channel according to the level of urbanization, for the withdrawal of the pre-imaginal populations of Cx. quinquefasciatus in collections of stagnant sewage water of this township. The female Cx. quinquefasciatus aged three to five days from the exits of the insectarium have been exposed to papers impregnated with deltamethrin 0.05%, permethrin 1% and DDT 4% in view of the diagnosis of a possible resistance of these populations to these insecticides. The populations of Cx. quinquefasciatus proved to be resistant to the three insecticides used, in four districts. On the other hand, the population of Cx. quinquefasciatus from the district "Zone industrielle," situated upstream of the channel, proved to be sensitive to permethrin 1%, and a drastic decrease of sensitivity of the same mosquito has been observed with deltamethrin 0.05% and DDT 4%.

[Resistance of Anopheles gambiae s.l. to pyrethroids and DDT at Tiassalékro, an irrigated rice-growing village in the southern forest of Ivory Coast]. / Résistance d'Anopheles gambiae s.l. aux pyréthrinoïdes et au DDT à Tiassalékro, village de riziculture irriguée en zone sud forestière de Côte-d'Ivoire.

An assessment of the sensitivity of Anopheles gambiae s.l.to three pyrethroids (alphacypermethrin, permethrin, deltamethrin) and DDT has been carried out with a laboratory strain (Kisumu reference sensitive strain) and a wild strain (Tiassalékro strain) using larvae from an irrigated rice-growing area of Tiassalékro, located in the southern forest of Ivory Coast. The sensitivity tests were performed according to the standard WHO cylinder tests with adult female A. gambiae s.l. aged 2 to 4 days. The results showed that the strain of Tiassalékro is resistant to the three tested pyrethroids and DDT. The molecular forms M and S were identified, with a predominance of M form. The resistance mechanism involved is the Kdr mutation. In this region, control measures against malaria vectors by using bed nets impregnated with these insecticides or household sprays could be compromised.

[Detection of Mycobacterium ulcerans DNA in water bugs collected outside the aquatic environment in Benin]. / Détection des signatures moléculaires de Mycobacterium ulcerans chez des punaises aquatiques capturées au Bénin en dehors de leur environnement aquatique.

Hosting of Mycobacterium ulcerans by water bugs is now well established and their vectoring role has been demonstrated experimentally. These findings were recently corroborated by detection of viable bacilli in the saliva of wild water bugs. However, the extent of water bug involvement in M. ulcerans ecology remains unclear and difficult to evaluate due to lack of understanding about water bug biology. The purpose of this study is to describe the first detection of M. ulcerans DNA in the tissue of water bugs captured outside the aquatic environment. This finding supports the hypothesis that water bug migratory behavior contributes not only to the spread of M. ulcerans but also to transmission outside the aquatic environment.

[Micronecta sp (Corixidae) and Diplonychus sp (Belostomatidae), two aquatic Hemiptera hosts and/or potential vectors of Mycobacterium ulcerans (pathogenic agent of Buruli ulcer) in Cote d'Ivoire]. / Micronecta sp (Corixidae) et Diplonychus sp (Belostomatidae), deux hémiptères aquatiques hôtes et/ou vecteurs potentiels de Mycobacterium ulcerans agent pathogène de l'ulcère de Buruli en Côte d'Lvoire.

Buruli ulcer is currently a major public health problem in Côte d'Ivoire. It is a neglected tropical disease closely associated with aquatic environments. Aquatic insects of the Hemiptera order have been implicated in human transmission of Mycobacterium ulcerans, the pathogenic agent of Buruli ulcer. The purpose of this preliminary study using the polymerase chain reaction (PCR) method was to evaluate aquatic insects in Sokrogbo, a village in the Tiassalé sanitary district where Buruli ulcer is endemic. Findings identified two water bugs hosting Mycobacterium ulcerans, i.e., one of the Micronecta genus in the Corixidae family and another of the Diplonychus genus in the Belostomatidae family. The PCR technique used revealed the molecular signatures of M. ulcerans in tissue from these two insects. Based on these findings, these two water bugs can be considered as potential hosts and/or vectors of M. ulcerans in the study zone. Unlike Diplonychus sp., this is the first report to describe Micronecta sp as a host of M. ulcerans. Further investigation will be needed to assess the role of these two water bugs in human transmission of M. ulcerans in Côte d'Ivoire.

[Entomological investigations conducted around ten cases of yellow fever in 2009 in the Denguélé sanitary region, Côte-d'Ivoire]. / Investigations entomologiques menées autour de dix cas de fièvre jaune survenus en 2009 dans la région sanitaire du Denguélé, Côte-d'Ivoire.

In November 2009, ten suspicious cases of yellow fever, including six deaths, were notified in the region of Denguélé, in the northwest of Côte-d'Ivoire. In order to evaluate the extent of yellow fever virus circulation and the risk for local people, a mission of entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte-d'Ivoire. Entomological investigations were conducted in the villages of confirmed cases (Banakoro and Tron-Touba) and the centers of consultation and hospitalization of cases during illness. Breteau index and recipient index were quasi nil. Aedes aegypti was absent among the captured mosquitoes. On the other hand, Aedes luteocephalus and Aedes opok were present at Banakoro and Tron-Touba with respective average biting rates of 0.8 and 0.6 bite/man/twilight. This situation of epidemic in the northwest of Côte-d'Ivoire could be explained by the deterioration of Denguélé region's health system which is a consequence of the war started in the country in 2002 and which has lowered the immunity of the population.

[Specific diversity and culicidian nuisance in the villages of N'gatty and Allaba in laguna area of Ivory Coast]. / Diversité spécifique et nuisance culicidienne dans les villages de N'gatty et d'Allaba en milieu côtier lagunaire de Côte-d'Ivoire.

Entomological surveys were undertaken between June and December 2006 in N'gatty and Allaba. These villages are located in southern Ivory Coast in a laguna area in Dabou department. In these villages, there are large swampy areas, which have caused the multiplication of anthropophilic Culicidae. Mosquitoes have been collected at preimaginal stage at the time of the larval prospecting and at adult stage through human landing catch. Larval collections have been made using the classic method of "dipping". Larvae have been identified to the genus level. Then, they have been bred in the laboratory to identify adults. Adults collection has been made once a month during three consecutive nights by human landing catch inside houses. Adults have been identified to the specific level. Eight genera of mosquitoes have been collected in these two villages: Aedes, Anopheles, Coquillettidia, Culex, Eretmapodites, Mansonia, Toxorhynchites and Uranotaenia. Twenty-four species have been listed during this stu y. The genus Mansonia is the most predominant with 86% (N = 15,811) and 80% (N = 1,385), respectively, in N'gatty and Allaba. The average biting rate per day varies between N'gatty and Allaba. It is estimated to 308 bites per human per night (b/h/n) in N'gatty and 72 b/h/n in Allaba. In these villages, mosquito nuisance is mainly due to Mansonia with 264 b/h/n and 58 b/h/n, respectively, in N'gatty and Allaba. However, Anopheles gambiae s.l. average rate was 12 b/h/n in N'gatty and 2 b/h/n in Allaba.

[Entomological investigation following the re-emergence of yellow fever in 2008 in Abidjan area (Côte d'Ivoire)]. / Investigation entomologique à la suite de la réémergence de la fièvre jaune en 2008 à Abidjan (Côte d'Ivoire).

In April 2008, Abidjan was again faced with another case of yellow fever after the epidemic of 2001 causing mass immunization campaign. In order to evaluate the extent of amaril virus circulation and the risk for local people, an entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte d'Ivoire. At "Entent" area of Treichville, Breteau index was estimated at 34, recipient index at 20% and house index at 25%. Those indexes were respectively 53, 21 and 31% at "Vridi canal" of Port Bouet. In the both neighborhood, Aedes aegypti accounted for more than 80% of mosquitoes caught and more than 90% of mosquitoes adults obtained from larval breeding. This new situation of epidemic risk could be explained by several factors including the reception of 70% of forced migration people caused by the crisis in the country occurred in 2002, the probable drop of preventive immunization, the environment deterioration creating of more breeding sites of Ae. aegypti.

[Malaria transmission in Tiassalékro, a irrigated rice growing village situated in the South forest area of Côte d'Ivoire]. / Transmission du paludisme a Tiassalèkro, village de riziculture irriguèe situé en zone sud forestière de Côte d'Ivoire.

A longitudinal entomological study was carried out from January to June 2007 in the rice-growing area of Tiassaékro, a village located in the forest, South of Côte d'Ivoire. The study was based on samples of mosquitoes caught on human volunteers indoors and outdoors. During the 6 months of the study 29481 female mosquitoes were caught. The average biting rate was 272.9 bites per man per night (b/m/n). An. gambiae was the most predominant with 79.1% of mosquitoes caught. The average biting rate of An. gambiae was of 216 b/m/n. The biting activity of this species was noticed between 8 p.m. and 6 a.m. The estimated average sporozoite index was 0.32% (n = 3423 dissected). The inoculation rate was 0.69 ib/m/n with the highest rate (1.99 ib//n) recorded in April. The entomological parameters of the transmission are influenced by the different stages of rice growing.

[Comparison of specific composition and mosquitoes population dynamics in two villages of the centre of Côte-d'Ivoire, with and without irrigated rice growing area]. / Comparaison de la composition spécifique et de la dynamique des populations de moustiques dans deux villages du centre de la Côte-d'Ivoire, avec et sans périmètre de riziculture irriguée.

Entomological surveys were undertaken between October 1994 and August 1995 and from April to August 1995 in the villages of Kafiné and Pékaha, respectively These villages are located in the centre of Côte-d'Ivoire in a humid savannah area in the prefecture of Niakaramandougou. Rice plots are located to about 500 meters from the first habitations of Kafiné. They also form an enclosure around the village causing a great culicidian nuisance. On the other hand in the village of Pékaha, situated at 8 km from the enclosure, one can find a non-developed low ground area with swamps according to the season which has caused the multiplication of anthropophilic Culicidae. Five genera of mosquito were caught in the two villages: Anopheles, Aedes, Culex, Mansonia and Uranotaenia. The genus Anopheles is by far the most predominant in Kafiné with 84.3% (n=17556). Mansonia, Culex and Aedes respectively constitute 12%, 3% and 0.01% of the total anthropophilic mosquitoes. In the contrary the genus Mansonia was the most predominant in Pékaha with 78.2% (n=6642). Anopheles, Aedes and Culex respectively represent 13.2%, 8.3% and 0.1% of the total number of mosquitoes caught during the surveys. If in the village of Kafiné, the culicidian nuisance is mainly due to anopheles mosquitoes (84.3%) and particularly to An. gambiae s.s. (70.6%), in the village of Pékaha, dwellers suffer more from Mansonia (78.2%) bites than those of Anopheles (13.2%).

[Influence of social perceptions and practices on the use of bednets in the malaria control programme in Ivory Coast (West Africa)]. / Representations sociales et pratiques liées à l'utilisation des moustiquaires dans la lutte contre le paludisme en Côte d'Ivoire (Afrique de l'Ouest).

The National Malaria Programme in Ivory Coast has encountered difficulty in winning public acceptance of insecticide-treated bednets. We speculate that resistance to the use of bednets could be rooted in social perceptions, beliefs and practices in the communities. The purpose of this study was to identify sociocultural and environmental factors that could be used to support promotion strategies and acceptance of impregnated bednets in Ivory Coast. Survey findings confirmed that bednets were not in widespread use among the population (25%). The most widely used methods were burning mosquito coils (50%) and indoor spraying (31%). Use of impregnated bednets was low (6%). Most survey respondents (73%) indicated initial appreciation for the effectiveness of bednets in protecting against mosquitoes as a nuisance. However only 9% of respondents thought that impregnated bednets provided protection against malaria although they did not necessarily use them. Design was a determinant factor for the use, and even acceptance, of bednets. The population want rectangular, permanently impregnated bednets large enough to accommodate at least 2 persons. Cost was a major obstacle to wider use by the population. According to our data the best price for the population would be between 2000 and 2500 FCFA as compared to the current price of 3500 FCFA in Ivory Coast.

Representations sociales et pratiques liees a l'utilisation des moustiquaires dans la lutte contre le paludisme en Cote d'Ivoire (Afrique de l'Ouest)

Devant les difficultes que rencontre le Programme National de Lutte contre le Paludisme (PNLP) de Cote d'Ivoire; dans sa volonte d'amener les populations a adopter les moustiquaires impregnees d'insecticide; nous nous sommes demandes si les representations sociales; les attitudes et les pratiques des communautes liees a l'utilisation des moustiquaires n'expliquent pas cette contre-performance. Notre etude a eu pour but de documenter les facteurs socioculturels et environnementaux pour renforcer les strategies de promotion et de vulgarisation de la moustiquaire impregnee en Cote d'Ivoire. Les resultats obtenus montrent qu'au niveau des enquetes quantitatives; la moustiquaire en general est faiblement utilisee par les populations (25). Les moyens les plus utilises sont les serpentins fumigenes (50) et les bombes aerosols (31). La moustiquaire impregnee est tres faiblement utilisee (6). La moustiquaire est; de maniere generale; appreciee dans un premier temps pour son efficacite dans la protection contre les nuisances dues aux moustiques par 73des enquetes. Seulement 9de ces enquetes pensent que la moustiquaire impregnee sert a se proteger contre le paludisme; mais ne l'utilisent pas necessairement. L'organisation des unites de couchage; voire leur inadaptation; sont determinantes dans l'utilisation de la moustiquaire. La moustiquaire souhaitee par les populations est celle d'au moins 2 places; de forme rectangulaire; de couleur blanche; faite en tulle a mailles fines; transparente; impregnee d'insecticide et a impregnation definitive. Toutefois; son cout semble etre le handicap majeur a son adoption par les populations; pour qui le cout ideal de la moustiquaire a l'achat; se situe entre 2000 et 2500 FCFA contre les 3 500 Frs actuellement pratiques en Cote d'Ivoire

[Knowledge, attitudes and practices of populations towards mosquitoes in urban and rural area (Côte d'Ivoire--West Africa)]. / Connaissances, attitudes et pratiques des populations vis-à-vis des moustiques dans la zone urbaine et périurbaine de Bouaké et dans les villages de Kafiné et de Kabolo (Côte d'Ivoire--Afrique de l'Ouest).

Three surveys related to the knowledge, attitude and practices of populations towards mosquitoes were conducted in Côte d'Ivoire. The first survey was undertaken in June 1994 in the city of Bouaké and the other two respectively in January 1996 and in June 1999 in the village of Kafiné. The surveys have revealed that whatever the environment, nuisance due to mosquitoes constitutes a great concern for the population of the villages. The majority of people interviewed in urban (94%), peri-urban (68%) zones and in Kafiné (94%) associates mosquito with malaria against 18% only in Kabolo. Furthermore, these surveys have allowed the inventory of methods of controlling mosquito currently used by the communities in both urban and rural areas. Generally mosquito coils as well as insect sprays are currently used because of their cheapness and their availability on the local market. in Bouaké, insect sprays (97% to 99%) are used as much as mosquito coils (87% to 98%). However, in Kafiné and Kabolo, insect sprays are only used by respectively 76% and 69% and the mosquito coils by respectively 68% and 71%. In urban zones, the insect sprays are more common than mosquito coils. On the contrary mosquito coils are currently used in villages due to their low price (40 to 50 FCFA) and their constant availability on the local market. Furthermore, local plants characterized by a repulsive essence are known by 48% and 75% of people interviewed respectively in the urban and peri-urban area of the city of Bouak6, by 74 % of the population of Kafiné and 73% of people living in Kabolo. In the last village 57% of people who were interviewed do not use any means of orotection due to financial reason; only 14% use mosquito coils and 20% use local plants with a repulsive essence. Mosquito net is known by the majority of people interviewed (82 - 98%) as an excellent means of orotection against mosquito bites. However only 27%, 13%, 26% and 5% of people respectively living in the urban and peri-urban areas of Bouaké and in the villages of Kafiné and Kabolo own their mosquito net. Its cost is the main reason for not using it as mentionned by 25% of people interviewed in the urban neighborhood, by 48% in the peri-urban areas, respectively 46% and 89% in the villages of Kafiné and Kabolo. Although its effectiveness has been proved by the communities, mosquito net still remains less common. Its price is relatively high (3500 - 5000 FCFA). It is not constantly available on the local market. Other socio-cultural factors such as local beliefs and taboos hinder the use of mosquito nets by the communities.

[Evaluation of the efficacity of coconut (Cocos nucifera), palm nut (Eleais guineensis) and gobi (Carapa procera) lotions and creams in indivirual protection against Simulium damnosum s.l. bites in Côte d'Ivoire]. / Evaluation de l'efficacité de lotions et de crémes à base d'huiles de coco (Cocos nucifera), de palmiste (Eleais guineensis) et de gobi (Carapa procera) dans la protection individuelle contre les piqûres de Simulium damnosum s.l. en Côte d'Ivoire.

With the interruption of larva treatments done by OCP as part of onchocerciasis control in West Africa, Simulium came back in abundance in forest regions and savannah fertile valleys. In addition to the severe discomfort, nuisance by Simulium is in certain cases incompatible with land use. Since ground treatment of larval breading sites using insecticides is not always possible or efficient, it is therefore a necessity to develop other methods among which individual protection against Simulium bites. The general objective of our study was to evaluate different vegetable oil compound repellent formulas against Simulium bites. Activities were carried out in savannah zone (Niakaramandougou) and in forest zone (Soubré) in Côte d'Ivoire. The methodology consisted in catching blackflies on volunteers whose legs were rubbed with a repellent. Gobi raw oil and coconut, palm nut and gobi formulas (lotions and creams) were tested. During each session, which lasted from 07:00 am to 12:00 and from 03:00 pm to 06:00 pm, one person did not apply any repellent and was used as the control person. The results of our experimentations show that for a given zone (savannah, forest), a repellent (coconut, palm nut, gobi) and a compound (shea butter, vaseline), there is no significant difference between protection rates obtained with lotions (maximum: 21 bites/person/day) and those obtained with creams (maximum: 30 bites/person/day). In other respects, the lotion of a given repellent seems to be efficient in savannah as in the forest, in protecting against Simulium bites. It is the same situation with creams. So, repellents can be an efficient solution against Simulium nuisance. However, experimentations should continue to confirm the high repellency of tested formulas, proceed to the identification of principles and evaluate the toxicity and irritant effect of repellents to be applied on the skin.

[Resistance of Culex quinquefasciatus (Say, 1823) to deltamethrin and the use of impregnated mosquito nets in an urban area of Bouaké, Côte d'Ivoire]. / Résistance de Culex quinquefasciatus (Say, 1823) à la deltaméthrine et l'utilisation de la moustiquaire imprégnée en milieu urbain de Bouaké, Côte d'Ivoire.

The efficacy of pieces of nets treated with two formulations of deltamethrin (concentrated suspension at 1% and tablets at 25%) against two strains of Culex quinquefasciatus ("S-Lab", sensitive strain and "Bouaké", local strain) has been evaluated at the laboratory by experimental tunnels tests. The observed mortality of the sensitive strain has been 2-3 time more important than that of local strain. This observation seems to be linked to Culex quinquefasciatus of Bouaké pyrethrinoids-resistance. The excito-repellency effect of the two formulations has been lower for the local strain than for the sensitive strain. It has also been more important with the tablet at 25% than with concentrated suspension at 1%. The blood feeding rate has been more important for the local strain than for sensitive strain and it has been lower with the tablet at 25% than with the concentrated suspension at 1%.

Comparison of the effect of two excipients (karite nut butter and vaseline) on the efficacy of Cocos nucifera, Elaeis guineensis and Carapa procera oil-based repellents formulations against mosquitoes biting in Ivory Coast.

Repellents in the form of dermal pomades are recommended as a protection against awakening and bedtime mosquito bites. If synthesis repellents are available, they are nevertheless not common and the prices remain out of reach for the communities concerned. The people therefore have to resort more and more to traditional concoctions, some of which have been shown to be effective. After demonstrating that oil-based formulations (lotions, creams, pomades) of Cocos nucifera (coconut), Elaeis guineensis (oil palm) and Carapa procera (gobi) were effective against mosquitoes, it became necessary to study the impact of the two excipients used in their manufacture, on the effectiveness of the repellents. Experiments were carried with Anopheles gambiae and Aedes aegypti under lobaratory conditions and any other mosquitoes collected under field conditions in Ivory Coast. The laboratory results indicate that the average protection times obtained with formulations with karite nut butter as excipient (54.8 +/- 37.0 mn and 74.6 +/- 26.4 mn respectively on An. gambiae and Ae. aegypti) are higher than those recorded with vaseline as excipient (respectively 42.7 +/- 30.0 mn and 60.8 +/- 33.9 mn). On the other hand, under field conditions, the biting rate percentage reduction obtained with the products with karite nut butter and vaseline excipient were similar (respectively 29.8% and 35.9% for all mosquitoes collected and 45.7% and 47.4% against An. gambiae). Nevertheless, the use of karite nut butter on repellent products should be encouraged because its sale price is very lower (10 time less) than the vaseline's.

[The epidemiology of malaria in the southwestern forests of the Ivory Coast (Tai region)]. / Epidémiologie du paludisme dans le sud-ouest forestier de la Côte d'Ivoire (région de Taï).

An epidemiological study on malaria was undertaken between July 1995 and July 1996 in two villages (Zaïpobly and Gahably) and their encampments (Kouassikro, Hamanikro and Konankro), in the south-western forest area of Côte d'Ivoire (region of Taï). The parasitological scheme comprised a total of 2023 tests performed on children aged from 0 to 14 years. The species found were Plasmodium falciparum, P. malariae and P. ovale with a proportion of 84%, 14% and 2% respectively. The global parasite prevalence of all Plasmodium species was 85% and malaria was holoendemic. The average parasitic density decreased progressively as the age increased, in contrast to the plasmodic index which did not vary. All the malarial indexes were similar in the villages and their encampments. Only overall fever prevalence was permanent and in all age groups it was higher in the encampments than in the villages. The entomological findings showed that transmission was permanent and intense throughout the year, with a recrudescence during the rainy season. Transmission was attributed to Anopheles gambiae s.l. in 85% of the cases whereas An. funestus played a secondary role. The average sporozoïtic index was 7.6% and varied between 1.1% and 16.7%. The entomological inoculation rate was of 400 infected bites per person-year for An. gambiae s.l. In such conditions of intense transmission, acquisition of premunition starts at a very early age. This assertion is verified by the average parasite density and the frequency of high parasitic densities which were at their maximum between 1 and 4 years of age and decreased thereafter as the age increased. The paludometric and entomologic indexes obtained are the most elevated ever to have been observed in Côte d'Ivoire, as a result of considerable ecological changes linked to the deterioration of the forest environment over the past 30 years. This deterioration has probably been caused by demographic pressure resulting from internal and foreign immigration to the Taï region and more especially by the influx of Liberian refugees.