Lymphatic filariasis infection five years after discontinuing Mass Drug Administration in Lango Sub region of Northern Uganda

Abstract

Background: Lymphatic filariasis (LF) continues to cause preventable disability in tropical and subtropical countries, including Uganda. It is a disease targeted for elimination by the World Health Organisation using an Elimination strategy having Mass Drug Administration (MDA) as the main component. In Uganda, MDA has been stopped in all 66 endemic districts. However, LF transmission is focal in nature, and some districts have exhibited positive cases during Transmission Assessment surveys when interruption of transmission is determined. Therefore, the study investigated LF infection prevalence and associated factors in such areas in Lango sub region (Lira, Alebtong and Otuke districts) five years after the stoppage of MDA. Objective: To estimate the prevalence of Lymphatic filariasis infection and assess associated factors in the rural Lango subregion in individuals aged five years and above after five years of MDA discontinuation. Method: A cross-sectional study was conducted among 1442 participants aged five years and above. Four hundred and thirty one households in 30 villages from the eight sub-counties of Lira, Alebtong and Otuke districts participated in the study which took place in February 2021. A semistructured questionnaire was administered in each household to a proportion of consenting occupants aged ≥18 years and later provided a blood sample. The other proportion below 18 years, finger-prick blood samples were collected to test for the presence of infection using LF Test Strips (LFTSs) which detects circulating Wuchereria bancrofti antigen. The snowballing method was used to select participants for six focus group discussions. Quantitative data was analyzed using proportions and frequencies. Chi-square tests and odd ratio was used to determine variables associated with infection. For multivariate analysis, Cox Poisson Regression was used. Deductive analysis with the help of code trees was used to develop themes for focus group discussions (FGDs). The FGDs findings were later cross-validated with those from the questionnaire. Some of the instructive statements were pulled out as illustrative quotes. Results: Of the 1,442 study participants, 56% were female. Lymphatic filariasis infection was detected in 7/1442 people, giving a prevalence of 490 per 100,000 (95% CI 0.0023 – 0.0102). Lira district had six positive cases, Otuke had one and no case was found in Alebtong. Out of the 30 villages sampled, three of them had positive cases. More males (5) were found to be positive compared to females (2). All the positive cases were over 14 years of age. Bednets use showed to be protective for lymphatic filariasis (aOR 0.10 (0.02-0.47)). Likewise, among those who has positive results, none had adequate knowledge about LF. Focus group discussion revealed that LF chronic signs are less common. This was partly attributed to preventive measures like MDA, vector control and community sensitization. Participants during the discussion could not fail to mention witchcraft among others when asked about cause and transmission of LF. Instances of stigmatization and lack of mobility were common among those affected and their families. Conclusion: The prevalence of LF in the Lango subregion is low and below the threshold for mass drug administration. However, the positive cases among adults call for intensive control measures, which may include the use of a test and treat strategy. The villages sampled lie in the same ecological zone. This outcome needs to be investigated further by using appropriate surveillance tools such as molecular xenomonitoring. The need to assess transmission dynamics in the areas where positive cases are found is paramount. Meanwhile, ongoing investigation and surveillance where positive cases have been found should be undertaken by the Program. The population should have adequate knowledge about LF in order to avoid infection. Use of treated bednets could be a suitable vector control strategy for control of LF after the stoppage of MDA.