Community-based active case detection of hidden visceral leishmaniasis and post-kala-azar dermal leishmaniasis cases to support the elimination of visceral leishmaniasis in Bihar, India

Abstract Background: Visceral leishmaniasis (VL), commonly known as kala azar, remains a serious parasitic disease and a critical public health concern in India. Bihar alone accounts for nearly 70% of the global VL burden. Despite sustained elimination efforts, the disease persists, primarily due to underreporting and undiagnosed cases, particularly post-kala-azar dermal leishmaniasis (PKDL), which serves as a concealed reservoir for continued transmission. Methods: Between February 2016 and February 2019, the Government of Bihar, in collaboration with multiple partners, implemented a proactive active case detection (ACD) strategy. This multifaceted approach included door-to-door screening, training of private healthcare providers, diagnostic camps, community mobilization, and vector control interventions such as Indoor Residual Spraying and single-dose ambisome therapy. Findings: Under this initiative, healthcare workers screened 2,493,778 individuals across 960 villages, identifying 7504 suspected cases—5786 of VL and 1718 of PKDL. Diagnostic confirmation led to the detection of 959 positive cases, with PKDL accounting for 40.2%. As a result of the ACD program, the number of reported VL cases in Bihar sharply declined from over 14,000 in 2012 to just 335 by 2023. Interpretation: The ACD strategy played a pivotal role in reducing VL incidence by actively identifying and treating hidden cases of VL and PKDL, thereby breaking the chain of transmission. Its integrated approach—encompassing vector control, accurate diagnostics, and active community participation—demonstrates a replicable model for eliminating other neglected tropical diseases (NTDs). Conclusion: The ACD initiative in Bihar has led to a substantial decline in VL burden, offering a scalable and effective strategy for disease elimination. By closing critical gaps in surveillance, diagnosis, treatment, and PKDL management, this community-based model provides a robust framework for addressing NTDs on a national and global level.