Prevalence and factors associated with transmission of lymphatic filariasis in South Sudan: a cross-sectional quantitative study.

Introduction: South Sudan is affected by a high burden of Neglected Tropical Diseases (NTDs). The country is very vulnerable to NTDs due to its favourable tropical climate and multiple risk factors. However, the distribution of the diseases and the populations at risk for the various NTDs is unknown. This paper describes the distribution of lymphatic filariasis (LF) in 58 counties of South Sudan.

Methods: a descriptive quantitative cross-sectional study of LF in 58 counties in 8 states of South Sudan recruited adult volunteers aged ≥ 15 years tested for circulating filarial antigens (CFA). A quantitative descriptive statistical was performed to determine the prevalence rates and the endemicity (CFA positivity rate ≥1%) of lymphatic filariasis in 9213 adult individuals from 101 villages.

Results: the overall prevalence of positive CFA was 1.6%, and the highest state prevalence was reported in the Upper Nile state at 3.4%. Based on the prevalence of positive CFA 64% of the surveyed counties are endemic to lymphatic filariasis. The endemicity ranged from 1-11.1% positive CFA. The highest prevalence of positive CAF was observed in the >50 years old age group (2.7%), followed by the 46-50 age group (2.3%). Males tested more positive than females (52.4% Vs 47.6%). Participants were three times more likely to test positive for CFA on filarial test strips (FTS) compared to immunochromatographic test (ICT). There was a statistically significant difference in the prevalence of positive CFA among the two tests (P=.002).

Conclusion: the distribution of LF is widespread, with varying transmission risks. The produced prevalence maps of infection provided evidence on the areas for targeted interventions in the national NTD program in South Sudan. An increased number of positive CFA were identified using FTS than ICT; hence, it is advisable to use FTS in the future transmission survey.