A better understanding of malaria transmission at a local scale is essential for developing and implementing effective control strategies. In the framework of a randomized controlled trial (RCT), we aimed to provide an updated description of malaria transmission in the Korhogo area, northern Côte d’Ivoire, and to obtain baseline data for the trial. We performed human landing collections (HLCs) in 26 villages in the Korhogo area during the rainy season (September–October 2016, April–May 2017) and the dry season (November–December 2016, February–March 2017). We used PCR techniques to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection, and insecticide resistance mechanisms in a subset of Anopheles vectors. Anopheles gambiae s.l. was the predominant malaria vector in the Korhogo area. Overall, more vectors were collected outdoors than indoors (p < 0.001). Of the 774 An. gambiae s.l. tested in the laboratory, 89.65% were An. gambiae s.s. and 10.35% were An. coluzzii. The frequencies of the kdr allele were very high in An. gambiae s.s. but the ace-1 allele was found at moderate frequencies. An unprotected individual living in the Korhogo area received an average of 9.04, 0.63, 0.06 and 0.12 infected bites per night in September–October, November–December, February–March, and April–May, respectively. These results demonstrate that the intensity of malaria transmission is extremely high in the Korhogo area, especially during the rainy season. Malaria control in highly endemic areas such as Korhogo needs to be strengthened with complementary tools in order to reduce the burden of the disease.
After the introduction of the invasive cattle tick Rhipicephalus microplus in West Africa in the last decade, farmers encounter ticks resistance to the use of acaricides in different region in Benin. In order to evaluate the level of resistance, an in vitro study was performed on five samples of R. (Boophilus) microplus collected from five farms in four of the eight agro-ecological zone of Benin. The districts concerned with the study in the agro-ecological zone were Houeyogbe (Kpinnou), Zangnanado (Samiondji), Tchaourou (Okpara), Gogounou (Fana) and Bassila (Manigri). A toxicological test, the Larval Packet Test (LPT) was performed in the laboratory of Biotechnology Research Unit of the Animal Production and Health (URBPSA) at the Polytechnic School of University of Abomey-Calavi in Benin with the susceptible, Rhipicephalus geigyi strain from Hounde in Burkina Faso. Three (3) acaricides commonly used by farmers in Benin to control ticks were evaluated: alpha-cypermethrin, deltamethrin and amitraz. The results showed that the resistance ratio at 50% (RR 50 95% CI) for the whole experiment varies from 1.96 to 338.5. Based on RR 50 and RR 90 values, only the population of Samiondji's state farm was susceptible to the alpha-cypermethrin with a resistance ratio RR 50 = 1.64 (95% CI: 0.2 to 12.6), all the other resistance tests conducted on moderate or high resistance Bassila and Kpinnou appear to host the most resistant samples. Moreover, a certain high variability of dose response relationship has been noticed with amitraz on the base of the higher slope of the related curves.
Cattle tick Rhipicephalus microplus has become a common problem for cattle herders in Côte d’Ivoire after its discovery there in the early 2000s, despite the availability of a large range of acaricide products. The objective of this study was to assess the resistance of the cattle tick R. microplus to alphacypermethrin, deltamethrin and amitraz, and to provide information to advice farmers of acaricide products choice in Côte d’Ivoire. A cross-sectional survey was conducted in September 2016 on nine farms where resistance to acaricides was suspected. Engorged R. microplus females were sampled and transported to the International Centre for Research and Development on Subhumid Livestock Production (CIRDES) in Burkina Faso. The FAO larval packet test method (adapted by CIRDES) was applied to assess the resistance-susceptibility level of the R. microplus tick populations to three common acaricidal molecules (alphacypermethrin, deltamethrin and amitraz) in Côte d’Ivoire. The results showed resistance ratios (RR) at 50% (RR50 95% CI) ranging from 0.26 (0.20-0.33) to 1910.3 (0.0-9063.3). High resistance to amitraz and deltamethrin was found on all farms, whereas resistance of tick populations to alphacypermethrin varied by farm from very susceptible to highly resistant. These results indicate that alphacypermetrin should remain a recommended acaricide on some farms in the country and underline the importance of raising awareness on the appropriate use of acaricides and monitoring acaricide resistance in tick populations in Côte d’Ivoire. Such actions will support farmers in the control and prevention of R. microplus infestation in cattle herds in Côte d’Ivoire.
Anaplasma phagocytophilum, a bacterium transmitted by ticks, is responsible for granulocytic anaplasmosis, an emerging zoonosis that has never been reported nor identified previously in Benin and in the West African sub-region. This study is designed not only to investigate the prevalence of the disease and evaluate mortalities recorded at Kpinnou farm after importing Girolando cattle from Brazil in 2014 but also to assess the prevalence of the emerging disease in Benin in the year 2014 period. A total number of 1427 ticks were collected, including 5 ml of blood from each one hundred cattle. Microscopic diagnosis reveals the presence of Rhipicephalus (Boophilus) spp., Rhipicephalus microplus, Amblyomma variegatum, Rhipicephalus spp and Hyalomma spp. Blood analysis results reveal the occurrence of 55% positive cases for A. phagocytophilum. Considering the effeiciency of the methods, 100% of A. phagocytophilum reported as positive by microscopy appear to be also positive with molecular analysis. PCR has greater sensitivity and specificity even with microscopy showing appreciable specificity. This study concludes that Anaplasma phagocytophilum is the primary suspect responsible for the massive deaths observed in cattle in the study area.
Background: A better understanding of malaria transmission at a local scale is essential for developing and implementing effective control strategies. In the frame of a randomized control trial, we aimed to provide an updated description of malaria transmission in the Korhogo area, northern Côte d'Ivoire, and to get baseline data for the trial. Methods:We performed Human Landing Collections in 26 villages in the Korhogo area during the rainy season
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