Molecular characterization of wuchereria bancrofti in mosquitoes of Pangani district, North Eastern Tanzania

Abstract

Wuchereria bancrofti is the most widely distributed of the three nematodes known to cause lymphatic filariasis, the other two being Brugia malayi and B. timori. The present study was carried out to investigate strains of W. bancrofti in mosquito vectors responsible for lymphatic filariasis transmission in Pangani district, north-eastern Tanzania. In addition, the vector abundance and vector infection rates were investigated. The presence of W. bancrofti in mosquitoes was determined by polymerase chain reaction (PCR) using primers NV1 and NV2 while Poolscreen2 software was used to determine W. bancrofti infection rate in mosquitoes. A total of 951 mosquitoes were collected in five randomly selected villages of Pangani district including Bweni, Madanga, Meka, Msaraza and Pangani West. Out of 951 collected mosquitoes, the majority were Culex quinquefasciatus (99.36%) followed by Anopheles gambiae (0.32%) and other Culex species (0.32%). The W. bancrofti vector infection rate in the present study was found to be 35.1%, indicating that there may be positive individuals in Pangani district. Phylogenetic analysis of Ssp 1repeat region sequence of W. bancrofti obtained in the study clustered the parasite into a distinct group compared with other W. bancrofti. In addition, the W. bancrofti sequences in Pangani district were not, 100% identical but genetically related. Further studies, using alternate typing methods, are however required for an in-depth understanding of strains that respond more slowly to drugs or strains that demonstrate greater fecundity. The information would enhance strategy development regarding the impact of mass drug administration (MDA), such as how long to run an MDA program and the optimal size of the human population treatment unit.