Prevalence of Wuchereria bancrofti Infection in Mosquitoes from Pangani District, Northeastern Tanzania

Background: Wuchereria bancrofti is the most widely distributed of the 3 nematodes known to cause lymphatic filariasis, the other 2 being Brugia malayi and Brugia timori. Anopheles gambiae and Anopheles funestus are the main vectors. However, the relative contributions of mosquito vectors to disease burden and infectivity are becoming increasingly important in coastal East Africa, and this is particularly true in the urban and semiurban areas of Pangani District, Tanzania. Methods: Mosquitoes were sampled from 5 randomly selected villages of Pangani District, namely, Bweni, Madanga, Meka, Msaraza, and Pangani West. Sampling of mosquitoes was done using standard Centers for Disease Control light traps with incandescent light bulbs. The presence of W. bancrofti in mosquitoes was determined via polymerase chain reaction (PCR) assays using NV1 and NV2 primers, and PoolScreen 2 software was used to determine the estimated rate of W. bancrofti infection in mosquitoes. Results: A total of 951 mosquitoes were collected, of which 99.36% were Culex quinquefasciatus, 0.32% were Anopheles gambiae, and 0.32% other Culex species. The estimated rate of W. bancrofti infection among these mosquitoes was 3.3%. Conclusion: This was the first study employing the use of PoolScreen PCR to detect W. bancrofti circulating in mosquito vectors in Pangani District, northeastern Tanzania. The presence of W. bancrofti infection suggests the possibility of infected humans in the area. The high abundance of Cx. quinquefasciatus calls for integrated mosquito control interventions to minimise the risk of W. bancrofti transmission to humans. Further research is required to gain an in-depth understanding of the W. bancrofti larval stages in mosquitoes, their drug sensitivity and susceptibility profiles, and their fecundity.