Project Lead(s): Yahya Derua
Lymphatic filariasis is a chronic filarial infection transmitted by mosquitoes. The disease is caused by a nematode parasite known as Wuchereria bancrofti. In Tanzania, Culex quinquefasciatus is an important vector and also considered as the most important nuisance mosquito. Due to its insecticide tolerance, insecticide-treated mosquito nets have proven to be ineffective in controlling the mosquito.
The project, carried out in Tanzania, involved introducing a natural oviposition attractant from grass infusion to lure gravid Culex quinquefasciatus to breed in biolarvicide-treated sites to disrupt development of its immature stages, including eggs and larvae.
In the study areas, experiments were undertaken to determine mosquito abundance and transmission indices of Wuchereria bancrofti.
The lure and kill experiments were conducted using grass infusion as an oviposition attractant and neem seed cake extract as a biolarvicide.
The findings showed that Culex quinquefasciatus was the most abundant mosquito caught, accounting for 90.3% (n=38,655) of the collected mosquitoes.
One out of 1,400 Culex quinquefasciatus dissected for filarial infection was carrying an infective parasite-causing lymphatic filariaisis. While using the polymerase chain reaction (PCR) technique, of 324 pools (each with 25 mosquitoes) tested, 113 pools were infected with at least a larvae stage of the parasite. Using a Poolscreen program, filarial infection rates in the vector were estimated at 1.7%.
These findings indicate that transmission of lymphatic filariasis is ongoing, despite nine rounds of mass drug administration to control the disease in the area. Interestingly, neem (used as biolarvicide) was also observed to be a potential attractant for gravid Culex quinquefasciatus. The two formulations remained effective for two weeks.
Research showed that the combination of neem seed cake extract as a biolarvicide and grass infusion as an attractant had the potential to lure gravid Culex quinquefasciatus to lay eggs in treated sites and prevented egg hatching.
The research project contributed to the strengthening of capacity of local researchers and health practitioners.
The findings have been shared with the National Neglected Tropical Disease Control Program.
The project team plans to collaborate with U.S.-based ISCA Technologies, the Ministries of Health, Agriculture, Environment and Finance, the World Health Organization, the respective District Council and communities to further validate the products. This will require approximately $25,000 for implementation.