Catching the mosquitoes that spread lymphatic filariasis

We recorded the number and type of mosquitoes in each trap, collected daily. This meant we were able to calculate the cost of each mosquito collected to determine the most cost-effective way to trap them.

Our study shows that, in urban contexts, using a combination of gravid and exit traps is the optimum method for catching Culex and Anopheles mosquitoes in the most cost-effective way.

The findings from this phase are already being used to improve a similar exercise in Monrovia, Liberia, and will help the country as it moves towards eliminating LF. I will also be presenting these results at the 11th European Congress on Tropical Medicine and International Health (ECTMIH 2019) on 17 September 2019.

The importance of community researchers

Recruiting local people to work as community researchers is crucial for research like this to succeed. For the study to be successful, we needed people to give us regular access to their homes during unsociable hours. Our team of community researchers proved invaluable: recruiting people who were well known and trusted helped households to understand what we were doing and why, meaning people were more likely to agree to take part.

Our community recruits were also invaluable field researchers, which we had discovered during a similar research project in Ghana. After basic training, the researchers were able to help with all aspects of mosquito collection, laying traps then safely emptying them and transferring the caught mosquitoes to our field entomologists for lab processing. Using a mix of local women and men was also important: in some instances it was more acceptable for female researchers to enter people’s homes.

Their days involved early starts, often beginning around 6am to empty the gravid traps, before conducting an early morning visit to people’s homes, emptying exit traps and spraying the insecticides for the PSCs. Around sunset they would go around setting gravid traps, then do it all again the next day.

Unexpected benefits

During their rounds the community researchers chatted to people from the households taking part, answering questions or listening to their concerns. I lost track of the number of times they resolved issues or smoothed over misunderstandings about why some houses were taking part and others weren’t. Without them, our research would have faced many more, potentially insurmountable, obstacles.

As well as being paid for their time, the researchers were also involved in the study in other ways. Umar, a young community researcher I met in Kaduna who also worked as a florist, had taught his friends, family and colleagues how best to protect themselves from mosquito bites so they could avoid mosquito borne-diseases.

Results in action

Our findings on whether the mosquitoes show if LF is being transmitted in these urban areas will be released early next year. What we do know from the data we already have is the optimum methods for catching the mosquitoes that spread the disease.

I hope these findings will help others working to determine whether LF is present in urban communities. This will ensure treatment is more effective and can be redirected to where it is needed most, meaning more people can be freed from the risk of this debilitating disease.

Author

Dr Rogers Nditanchou

Dr Rogers is a regional research advisor for NTDs, based in Sightsavers’ Cameroon country office. He will present this research at the ECTMIH on 17 September 2019.
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