[Efficacy against Malaria Vectors of Long-Lasting Insecticide-Treated Mosquito Nets after 17 Months of Use in the City of Bouaké, in the Center of Côte d'Ivoire]. / Efficacité contre les vecteurs du paludisme de moustiquaires imprégnées d'insecticide à longue durée d'action après 17 mois d'utilisation dans la ville de Bouaké, au centre de la Côte d'Ivoire.

Malaria remains a public health problem in Côte d'Ivoire despite a 95% coverage rate with long-lasting insecticide-treated mosquito nets (LLINs) since 2015. A study was conducted in Bouaké to determine the residual efficacy of LLINs used during 17 months (N = 30) and of stored and unpacked LLINs (N = 8). The physical integrity of LLINs and their biological efficacy on populations of Anopheles gambiae (sensitive and resistant to insecticides) were assessed. The study revealed that 57% (17/30) of LLINs recovered from households have a hole. The proportional hole indices indicated that 70% (21/30) of LLINs were in good condition, 20% (6/30) were repairable and 10% (3/30) were unusable.This study also showed that the LLINs used and stored were effective on the sensitive Kisumu strain but ineffective on resistant populations of An. gambiae of Bouaké. Average knock-down and mortality rates induced by LLINs used on the populations of An. gambiae from Bouaké were 23% and 9%, respectively. The resistance of mosquitoes to insecticides and the alteration of the physil integrity of mosquito nets are probably major factors to be taken into account in estimating the efficacy of LLINs in the field.

Le paludisme demeure un problème de santé publique en Côte d'Ivoire malgré un taux de couverture en moustiquaires imprégnées à longue durée d'action (MILDA) de 95 % depuis 2015. Une étude a été menée à Bouaké afin de déterminer l'efficacité résiduelle de MILDA utilisées pendant 17 mois (n = 30) et celle de MILDA stockées et non déballées (n = 8). Pour ce faire, l'intégrité physique des MILDA et leur efficacité biologique sur des populations d'Anopheles gambiae (sensibles et résistants aux insecticides) ont été évaluées. L'étude a révélé que 57 % (17/30) des MILDA récupérées dans les ménages sont trouées et que les indices proportionnels de trous les plaçaient dans la catégorie des moustiquaires en bon état pour 70 % (21/30) d'entre elles, réparables pour 20 % (6/30) d'entre elles, inutilisables pour les 10 % (3/30) restants. Cette étude a également montré que les MILDA utilisées et stockées étaient efficaces sur la souche sensible Kisumu, mais inefficaces sur les populations résistantes d'An. gambiae de terrain. Les taux moyens de knock-down et de mortalité induits par les MILDA utilisées sur les populations d'An. gambiae de Bouaké étaient respectivement de 23 et 9 %. La résistance des moustiques aux insecticides et l'altération de l'intégrité physique des moustiquaires sont probablement des facteurs majeurs à prendre en compte dans l'estimation de l'efficacité des MILDA sur le terrain.

Review of cattle ticks (Acari, Ixodida) in Ivory Coast and geographic distribution of Rhipicephalus (Boophilus) microplus, an emerging tick in West Africa.

The exotic tick Rhipicephalus (Boophilus) microplus was discovered in Ivory Coast in 2007 and then gradually in other countries in West Africa. It is known to induce significant losses in farming and to replace other species of the same genus. In order to contribute to improve health and productivity of cattle in Ivory Coast regarding the emergence of this dreaded tick, a study was conducted to determine the current geographic distribution of the tick R. (B.) microplus and review cattle ticks in general. To this end, 23,460 ticks were collected from 180 farms located throughout the country. Ten species of ticks belonging to the genus Rhipicephalus (including those of the subgenus Boophilus), Hyalomma and Ambyomma were identified. It was found that the exotic tick R. (B.) microplus has invaded the entire Ivorian territory and is now the main cattle tick (63.6% of ticks collected), followed by Amblyomma variegatum that remains still dominant in the North. The population of indigenous species of Rhipicephalus (Boophilus) is in drastic decline.

Prevalence of geohelminths in savana and forest areas of Côte d'Ivoire.

BACKGROUND: Côte d'Ivoire has large regional variation in intestinal helminth prevalence. STUDY DESIGN: In a large cross-sectional study conducted from 1997 to 1999, stool samples from 6952 children aged 4-15 years were examined for helminth eggs by the Kato/ Katz technique from 24 villages in the savanna (North) and from 21 villages in the forest (West) in Côte d'Ivoire. RESULTS AND CONCLUSION: Ascariasis lumbricoides (0.7%) was the only species present in the savana area. In the forest area, ascariasis occurred most frequently (18.9%), followed by trichuriasis (2%), Strongyloidiasis (0.1%) and oxyuriasis (0.03%). Ascariasis prevalence was not significantly associated with age within each ecological zone, but was significantly higher in boys in the forest zone. This study confirms that in the more arid savanna, the conditions are less suitable for helminth transmission than in the forest zone.

Rice irrigation and schistosomiasis in savannah and forest areas of Côte d'Ivoire.

Prevalence and intensity of infection of Schistosoma haematobium and Schistosoma mansoni were studied in relation to irrigated rice cultivation in Côte d'Ivoire. Urine and stool samples were collected from 4 to 15-year-old children in 24 villages in the savannah zone and 21 villages in the forest zone. Villages were classified according to surrounding inland valleys into three agro-ecosystems: (R2) full or partial water control allowing two rice cycles per year; (R1) no or partial water control allowing one harvest per year and (R0) absence of rice growing. In the savannah zone, S. haematobium prevalence was 4.8%, 2.3% and 0.7% and S. mansoni prevalence was 16.1%, 11.9% and 2.1% in R2, R1 and R0, respectively. In the forest zone, S. haematobium prevalence was 0.9%, 4.4% and 1.7% and S. mansoni prevalence was 61.3%, 46.6% and 17.5% in R2, in R1 and R0, respectively. Prevalences of S. mansoni adjusted for village effects were significantly different between agro-ecosystems in both zones. Significance of differences between agro-ecosystems of S. haematobium infection were strongly influenced by outlying villages. In savannah rice growing villages, negative binomial regression on infection intensity of each species showed significant positive relations to the surface of rice cultivated inland valleys, whereas uncultivated inland valleys showed no significant relation. However, in forest rice growing villages, S. mansoni infection intensity showed significant positive relations to the surface of uncultivated inland valleys, whereas surface water on rice cultivated land showed significant negative relations with infection intensity of each schistosomiasis species.