High prevalence of bancroftian filariasis and comorbidities in the eastern coalfield regions of West Bengal, India following COVID-19 disruption

Lymphatic filariasis (LF) is one of the most debilitating parasitic diseases worldwide, casting a shadow of socio-economic stigma over the affected underprivileged communities. The present study is a maiden investigation depicting LF prevalence in the previously unexplored remote eastern coalfield districts of West Bengal state, India during and after COVID-19 pandemic. A community-based cross-sectional survey (August 2021–March 2024) was conducted in four LF-endemic districts of West Bengal. Symptomatic cases were graded clinically, and asymptomatic infections confirmed by filaria-specific IgG/IgM and nocturnal microfilariae (mf) detection. Comorbidities were systematically recorded. Of 3705 individuals (50.7% females and 49.3% males) screened, the overall LF prevalence was 16.65% (95% CI:15.45% -17.85%, 617 individuals). Asymptomatic mf + ICT-positive cases accounted for 10.63% (95% CI, 9.64–11.62; n = 394), while 6.02% (95% CI, 5.30–6.82; n = 223) were symptomatic. Among the symptomatic cases, 144 had circulating mf, filaria-specific IgG/IgM (ICT positive) and clinical symptoms of lymphedema, most commonly Grade II (34.79%) and Grade III (43.48%). Chronic mf-negative lymphedema was observed in 2.13% (n = 79). Active LF prevalence, defined by mf and ICT positivity, was 14.52% (95% CI, 13.4–15.7; n = 538). Acute dermato-lymphangio-adenitis (ADLA) among the clinical categories was ranged between 8.71% and 39.79%. LF prevalence was higher in the rural areas, while hypertension, diabetes, and fungal infections as major comorbidities. The eastern coalfield region of West Bengal state presents heightened prevalence of severe chronic lymphedema and a marginal prevalence of new LF cases possibly due to interruption of mass drug administration in this neglected remote areas and poor morbidity management during COVID-19.