Malaria Transmission Pattern in an Area Selected for Clinical Trials in the Sudanian Area of Senegal (West Africa)

Abstract

Malaria transmission pattern was studied in 3 villages (Toubanding, Daga Ndoup, and Keur Samba Guèye) situated within an area selected for clinical trials. The study was conducted in the rainy season from July to December 2011. The main objective of this work was to gather baseline data on malaria transmission intensity and other entomological parameters before the advent of clinical trials. Mosquitoes were collected by Human-Landing Collections (HLCs) and by pyrethrum spray catches (PSCs). Five anopheline species were collected, namely, An. arabiensis, An. gambiae, An. funestus, An. pharoensis, and An. rufipes, giving a heterogeneous distribution within the study area. The populations dynamics of the vectors varied temporarily in each village depending on the pattern of the rainy season. Transmission intensity estimated by the entomological inoculation rate (EIR) was measured in each of the three villages with the variations linked to the microecological differences between the villages. Measurements were calculated for August, September, and October and were found to vary between 4 and 30 infected bites per person over the study period with a peak intensity observed in September. These results indicate that epidemiological field trials on malaria could be conducted in this area on the basis of the differences observed with transmission intensity, micro-ecological variations, and the objectives of the trials.

Malaria incidence and assessment of entomological indices among resettled communities in Ethiopia: a longitudinal study

“…The higher EIRs observed in the resettlement villages indicate that malaria transmission intensity was higher in those villages. Heterogeneity in anopheline mosquito infectivity rate among villages was also reported in studies conducted in Ghana [ 32 ], Burkina Faso [ 25 ] and Sudanian area of Senegal [ 33 ]. Small-area variation in Plasmodium infectivity rates can be explained by the spatial heterogeneity of exposures to infection that is, human vector contacts.…”

Spatio-Temporal Variations in Malaria Incidence in Children Less than 10 Years Old, Health District of Sokone, Senegal, 2010–2013

“…Thus varying malaria attack rates were observed in the villages of our study area, which were at most 5 km distant from each other. These results was confirmed by those obtained from an entomologic survey [ 10 ] and a bednets use survey implemented in March 2013 [data not shown] .Thus in villages with the higher malaria incidence, a high level of transmission was recorded based on a higher entomological inoculation rate (EIR) and a lower use of bednets. An 8-fold variation of EIR was observed between the village with the higher incidence of malaria and the village with the lower incidence, in terms of transmission potential [ 10 ].…”

“…These results was confirmed by those obtained from an entomologic survey [ 10 ] and a bednets use survey implemented in March 2013 [data not shown] .Thus in villages with the higher malaria incidence, a high level of transmission was recorded based on a higher entomological inoculation rate (EIR) and a lower use of bednets. An 8-fold variation of EIR was observed between the village with the higher incidence of malaria and the village with the lower incidence, in terms of transmission potential [ 10 ]. In any case, the clusters of higher malaria incidence could not be explained by closer vicinity to health care facilities—that is, a higher likelihood that children whose households were located near the health care centre would report at the health centre with suspected malaria.…”

“…Malaria transmission in the study area is markedly seasonal and intense during the rainy season (from June to October). The entomological inoculation rate varied from 4 to 30 infective bites/person/month during the rainy season of 2011 [ 10 ]. In the studied region, in 2008–2009, ITN coverage, measured by ownership of at least one mosquito net per household, reached 89% and approximately 52% of the population in general, and 65% of children <5 years, had slept under an Insecticide Treated Net the previous night [ 11 ].…”

Shift in species composition in the Anopheles gambiae complex after implementation of long‐lasting insecticidal nets in Dielmo, Senegal

“…The less anthropophilic, more zoophilic species An. arabiensis was also reported to be the dominant species in a village located 1.5 km from Dielmo (Niang et al ., ), probably as a result of the widespread use of mosquito nets and easier access to alternatives to human hosts.…”