COMET-LF: a compartmental model of dynamics of infection, disease, and elimination strategies for lymphatic filariasis

Lymphatic filariasis (LF) is a mosquito-borne disease caused by filarial worms. The WHO has targeted LF elimination by 2030. Mathematical models can help evaluate and guide elimination strategies. We developed a new compartmental model—COmpartmental Modelling of Elimination strategies and Transmission of Lymphatic Filariasis (COMET-LF)—to assess the impact of mass drug administration (MDA) on LF elimination. Our model incorporates efficacy data from clinical trials and generates estimates of disease (lymphoedema and hydrocele) prevalence. The model is calibrated to publicly available microfilaria (Mf) and disease prevalence data (2008-2013), and validated using programmatic data (2018-2019) from ten endemic districts of Bihar, India. COMET-LF simulation projected that at 85% coverage with a two- or three-drug regimen, six rounds of MDA should be sufficient to achieve elimination for baseline Mf prevalence up to 10%, consistent with the existing models - EPIFIL and LYMFASIM. The impact of MDA on disease burden, generated using COMET-LF, suggest that the disease prevalence reduces over much longer timescales - 20 years for a reduction of 8%-11.5% following 5 rounds of MDA. To investigate the role of migration, we implemented COMET-LF within a meta-population model. We found that high Mf prevalence in the spatial neighbourhood can require up to 3 additional rounds for the two-drug regimen. Migration between non-endemic and adjacent endemic regions (>5% Mf) may lead to a significant risk of resurgence. Our COMET-LF model can capture LF transmission dynamics and estimate the number of MDA rounds required to reach elimination. MDA coverage, baseline Mf prevalences and human migration are the determinants of the required rounds of MDA. Our model can be easily tailored to specific blocks and districts to guide programmatic intervention for LF elimination and disease management.