Socio-economic and environmental factors associated with high lymphatic filariasis morbidity prevalence distribution in Bangladesh

BackgroundLymphatic filariasis (LF) is a vector-borne parasitic disease which affects 70 million people worldwide and causes life-long disabilities. In Bangladesh, there are an estimated 44,000 people suffering from clinical conditions such as lymphoedema and hydrocoele, with the greatest burden in the northern Rangpur division. To better understand the factors associated with this distribution, this study examined socio-economic and environmental factors at division, district, and sub-district levels. MethodologyA retrospective ecological study was conducted using key socio-economic (nutrition, poverty, employment, education, house infrastructure) and environmental (temperature, precipitation, elevation, waterway) factors. Characteristics at division level were summarised. Bivariate analysis using Spearman's rank correlation coefficient was conducted at district and sub-district levels, and negative binomial regression analyses were conducted across high endemic sub-districts (n = 132). Maps were produced of high endemic sub-districts to visually illustrate the socio-economic and environmental factors found to be significant. ResultsThe highest proportion of rural population (86.8%), poverty (42.0%), tube well water (85.4%), and primary employment in agriculture (67.7%) was found in Rangpur division.Spearman's rank correlation coefficient at district and sub-district level show that LF morbidity prevalence was significantly (p<0.05) positively correlated with households without electricity (district r(s) = 0.818; sub-district r(s) = 0.559), households with tube well water (sub-district r(s) = 0.291), households without toilet (district r(s) = 0.504; sub-district r(s) = 0.40), mean annual precipitation (district r(s) = 0.695; sub-district r(s) = 0.503), mean precipitation of wettest quarter (district r(s) = 0.707; sub-district r(s) = 0.528), and significantly negatively correlated with severely stunted children (district r(s) = -0.723; sub-district r(s) = -0.370), mean annual temperature (district r(s) = -0.633.; sub-district r(s) = 0.353) and mean temperature (wettest quarter) ((district r(s) = -0.598; sub-district r(s) = 0.316)Negative binomial regression analyses at sub-district level found severely stunted children (p = <0.001), rural population (p = 0.002), poverty headcount (p = 0.001), primary employment in agriculture (p = 0.018), households without toilet (p = <0.001), households without electricity (p = 0.002) and mean temperature (wettest quarter) (p = 0.045) to be significant. ConclusionsThis study highlights the value of using available data to identify key drivers associated with high LF morbidity prevalence, which may help national LF programmes better identify populations at risk and implement timely and targeted public health messages and intervention strategies. Author summaryLymphatic Filariasis (LF) is particularly associated with poverty and living in a rural area, where disease transmitting mosquito vectors thrive. To better understand the socio-economic and environmental factors associated with the LF morbidity prevalence distribution in Bangladesh, this study examined publicly available data and used descriptive, statistical, and mapping methods to highlight key associations. Results found that high risk populations were those living in rural areas, employed in agriculture, with high levels of poverty, and houses without electricity or toilets, and where temperatures in the rainy season were lower than other regions of the country. These findings will help to inform public health messages and implement interventions for people affected by LF morbidity, but also to help reduce any current and future risk of transmission. This will support progress to achieving WHO elimination targets, leading to a future free of suffering for people affected by LF associated morbidity.