Title : Risk of visceral leishmaniasis resurgence in India: A compartmental modelling study
Abstract:
Visceral leishmaniasis (VL) is a neglected tropical disease (NTD) caused by the parasite Leishmania donovani and transmitted by sandflies. In India, the elimination target for VL is defined as less than 1 case per 10,000 population per year at the block level. As the country approaches VL elimination, a critical challenge is mitigating the risk of disease resurgence. While VL cases have fallen below the elimination threshold across all blocks, post-kala-azar dermal leishmaniasis (PKDL) persists as a significant reservoir, posing a considerable threat to sustained elimination. To address this, it is essential to establish the PKDL threshold required to sustain VL elimination. This study represents the first attempt to propose such a threshold, addressing a critical gap in existing research. To determine the optimal PKDL level necessary to prevent resurgence within a specified time frame, we modified an established deterministic model of VL transmission. We choose realistic model parameters, such as the vector-to-human ratio, the proportion of the susceptible population, and a range of epidemiological rates, from existing estimates. Our findings indicate that these factors significantly influence the average time to resurgence. The results of this study provide critical insights for policymakers, enabling the design of region-specific targeted control measures to sustain VL elimination.
