Dynamics of malaria vector indices in two vegetation zones within North Eastern Adamawa State, Nigeria
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Date
2020
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Abstract
Abstract. Studies profiling community and zonal malaria entomological risk indices are
required to identify high risk areas where targeted control resources are most needed or
likely to have the greatest impact on reducing risk of malaria infection. This study presents
a first report on malaria vector risk indices in two vegetation zones within Adamawa state,
Nigeria. Endophilic mosquitoes were collected for one year in selected communities in the
Guinea and Sudan savanna zones within the State. Plasmodium falciparum Sporozoite and
human blood meal ELISA assays were carried out on the female Anopheles mosquitoes
collected. Sibling species composition of the An. gambiae complex were determined using
PCR assays. Mean numbers of mosquitoes in the Guinea savanna communities were
significantly (t = 7.73, DF = 11, p < 0.001) higher than the Sudan. Man-biting rates (F = 2.76,
p = 0.13) of Anopheles mosquitoes were higher in the Guinea but not significantly different
from Sudan savanna. Sporozoite rates of mosquitoes within the Guinea savanna were 2.7
times higher than the Sudan. The predominant Anopheles coluzzii species encountered in the
state had higher overall human blood indices (0.63) and sporozoite rates (6.9%) compared to
An. gambiae (0.39, 1.9%) and An. arabiensis (0.58, 2.3%) respectively. Overall annual human
blood indices (0.59) of mosquitoes in Adamawa were lower compared to reports from other
States. Prevalence and higher transmission risks indices of endophilic An. coluzzii mosquitoes
reveal the need for LLIN and management of relatively permanent An. coluzzii breeding
sites in the State. Widespread cattle rearing lifestyle and lower human blood indices of
mosquitoes in the study area suggest the need to investigate cattle blood indices of the
mosquitoes in the state. Higher entomological risk indices in the Guinea Savanna zone provide
baseline information for prioritization of malaria vector control supplies within the State.