Assessing the Risk of Exposure to Vectors of Malaria using Entomological Inoculation Rate among Houses at Auyo Irrigation Rice Farming Community in Jigawa State

Abstract

A longitudinal entomological survey of malaria vectors was carried out aiming to assess the transmission risk factors with regard to housing types at the rice irrigation community of Auyo LGA. The study was carried out in 32 households from March 2017 to February 2018. Adult mosquitoes were collected from the selected residential houses using the Pyrethrum spray collection method. The Human biting rate, sporozoite and entomological inoculation rates (EIR) were calculated based on common housing type and three seasons of the collection period. A total of 3,998 female Anopheline mosquitoes were collected. The most abundant species was Anopheles gambiae sl, (94.5%) followed by An. Funestus (4.5%) and other minor spp (1%) including An. pharoensis and An. coustani. Members of An. gambaie complex was analysed by PCR and An. coluzzi accounts for about 92.3%, An. gambiae ss 3.9% and An. arabiensis 3.7%. The human biting rate was highest in the thatch houses (22.64), compared to Mud and concrete houses with 10.6 and 2.4 respectively. Enzyme-linked immunosorbent Assay (ELISA) yielded 64 positive results which account for a sporozoite rate of 0.11(11%). The rates of infection by Plasmodium species in mosquitoes and Entomological Inoculation Rate (EIR) were higher in thatch and mud houses compared to concrete houses. The estimated cumulative infective bites per person per year was (138) in thatch, (74) in mud and (0) in concrete house (p- 0.001). Based on these findings, it is recommended that malaria control may be achieved by introducing mosquito-proofed housing and good environmental management.