Seasonal Transmitting Potential of Malaria Vectors in Six Communities in Ekiti State, Nigeria

Abstract

Malaria vectors are found virtually in all communities of Nigeria. Understanding the transmitting potential of these vectors in  relationship with the malaria parasite (MP) infection is essential to design a sustainable community base control programme. This study aimed at determining this relationship in six communities in Ekiti State, Nigeria. The communities were randomly selected through a multistage sampling. Blood samples were screened for MPinfection among human volunteers during dry and rainy seasons in each community. Adult mosquitoes were collected indoors for twelve months in the communities using light traps. Female  Anopheles mosquitoes collected were characterized by Polymerase Chain Reactions and circumsporozoite proteins of the infected mosquitoes were detected by Enzyme-Linked Immunosorbent Assay. Prevalence of MP infection, human biting rates (HBR), sporozoite rates and entomological inoculation rates (EIRs) were determined using appropriate formulae. Overall prevalence of MPinfection was 26% in dry season and 38% in rainy season (P=0.001). Female Anopheles mosquitoes collected were 428. Strong relationship existed between HBR and MP infection in rainy  season (R² = 0.671) but the relationship was weak (R² = 0.209) in dry season. Sporozoites were detected in 2.3% of the female Anopheles mosquitoes collected. EIRs were between 0.100 - 0.252 infective bites/person/night.  Transmission of malaria parasites occurred throughout the year particularly during rainy season when there were recorded EIRs. Malaria control interventions will be more appropriate during raining season in this region.

Keywords: Anophelesmosquitoes, Nigeria, transmission, malaria, season