Entomological survey of Aedes spp. in an outbreak response of yellow fever in Benue State, Nigeria, 2018

Background: Worldwide, there are estimated 200,000 cases of yellow fever (YF) causing 30,000 deaths annually with 90% occurring in Africa. In Nigeria it has become a public health problem with a total of 3510 suspected cases including 74 deaths (CFR: 2.1%) in 2018. Following a report of suspected YF outbreak in Vandeikiya local government area (LGA) of Benue State, we conducted an entomological investigation to establish the presence of the principal vectors of YF virus and institute appropriate preventive measures. Methods and materials: We collected various developmental stages of Aedes mosquitoes from Vandiekya, Kwande, Konshisha and Ushongo using ovitrap setting, larval sampling, modified human landing catch (HLC), adult collection traps. We assessed the general living environment of suspected cases of YF and mosquito breeding sites within the community and nearby rivers using a check list. We screened captured mosquitoes using a light microscope to view the morphology. Results: A total of 71 mosquitoes were captured using traps (Aedes albopictus 7, Aedes aegypti 60, Aedes leutocephalus 4). Eighty-two larval containers were inspected from 22 houses. Forty-one eggs and 37 larvae were collected. Larval indices especially the house index was high unlike the Breteau index that was equal to 20 in Tongo. Culex mosquito species especially the Culex quinquefasciatus were seen in almost all the communities. Conclusion: We established the presence of YF vector (Aedes aegypti) in the four LGAs where entomology surveys were carried out and residents not immunized against YF are at risk. We conducted community sensitization and social mobilization of the people on yellow fever transmission. Environmental spraying should be encouraged.

Abstract licence: CC BY-NC-ND

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