Preventive chemotherapy for elimination of lymphatic filariasis and onchocerciasis in Sierra Leone.
Lymphatic filariasis (LF) and onchocerciasis are highly endemic in Sierra Leone. Using World Health Organization (WHO) guidelines for monitoring national programmes where both infections are co-endemic, this study aimed to determine the impact of preventive chemotherapy on transmission intensity by measuring changes in human infection status using standard epidemiological indicators. Separate longitudinal studies designed to deliver WHO outcomes for programmes targeting the elimination of both diseases were conducted. Onchocerciasis mapping surveys from 1988-2005 revealed that twelve of fourteen health districts were endemic. The baseline average mf prevalence was 53.1%, and mf densities in positive-only or entire populations were 28.87 and 15.33 mf/snip, respectively. Mf prevalence and density increased with age and was higher in males than females. Baseline prevalence and intensity surveys showed that LF was endemic in all 14 districts. Mf prevalence was also relatively higher in the northeast. A qualitative study examining the impact of the Ebola virus disease (EVD) outbreak on the NTD programme found that despite a one-year absence of interventions, two rounds of MDA had been completed, including one during the ongoing outbreak in May/June 2015. Although it compromised the likelihood of achieving the 2020 targets of LF elimination and Onchocerciasis control, the EVD outbreak has enhanced awareness about the important role of community volunteers in ensuring its success. While it may be the ‘endgame’ for LF, the NTD community and collaborating research institutions must address additional challenges if Onchocerciasis is to be eliminated from Sierra Leone.