India is closing in on eliminating kala-azar, but a skin sequel could undo it

The Indian subcontinent is on the verge of eliminating visceral leishmaniasis — kala-azar, a parasitic disease that is fatal in more than 95% of cases if left untreated — as a public health problem, a goal pursued for two decades. Bangladesh was validated by the World Health Organization in 2023 as the first country in the world to reach that milestone, and India is now nearing the same threshold, though a lingering skin complication of the disease threatens to keep transmission alive [s1][s3].

Visceral leishmaniasis is caused by Leishmania parasites transmitted by the bite of infected sandflies, and it attacks the internal organs, typically causing prolonged fever, weight loss, an enlarged spleen and anaemia. WHO estimates 50,000 to 90,000 new cases occur worldwide each year, with most concentrated in Brazil, East Africa and India [s1]. Because untreated visceral leishmaniasis kills more than 95% of the people it infects, driving case numbers down is measured directly in lives, not just in incidence [s1]. In the WHO South-East Asia Region, "elimination as a public health problem" has a precise definition: fewer than one case per 10,000 people at the district level in Nepal and the sub-district level in Bangladesh and India [s1]. Reaching that number is not the end of the work — sustaining it is.

What sustained elimination looks like on the ground

A window into the maintenance phase comes from Malda district in West Bengal, one of India's historically endemic areas, analysed through routine programme data for 2018 to 2022 [s2]. There, confirmed visceral leishmaniasis cases fell from 19 in 2018 to seven in 2022 [s2]. All 15 endemic blocks in the district held below the elimination target throughout the period, and 11 of them reported no VL cases at all in 2022 [s2]. Treatment completion exceeded 90% every year, and indoor residual spraying — the insecticide campaign that suppresses sandflies — reached more than 91% of the target population [s2]. On the headline metric, the programme is working.

The caseload also shows who is left. Adults older than 15 accounted for 89.9% of visceral leishmaniasis cases and 92.2% of the skin cases, and tribal populations made up between 40% and 71% of reported cases each year [s2]. As overall numbers fall, the residual burden concentrates in specific, marginalised groups — a pattern that makes the last cases the hardest to find and treat, and the elimination target easiest to lose sight of.

The skin sequel that could reverse the gains

The figure that complicates Malda's success is the other line on the chart. While visceral cases fell, post-kala-azar dermal leishmaniasis (PKDL) — a skin manifestation that can appear months or years after apparently successful treatment — rose from 40 cases in 2018 to 55 in 2022, and by 2022 PKDL made up the majority of all kala-azar cases reported in the district [s2]. That matters beyond the individual patient. People with PKDL carry parasites in their skin and can act as a reservoir, seeding new sandfly infections long after the visceral epidemic appears to have ended. An elimination programme that counts only the dramatic visceral cases while the skin reservoir quietly grows is measuring the wrong thing.

Why the finish line is not the end

India's path to formal WHO validation is conditional: the country must sustain the elimination threshold for three consecutive years before it can be certified [s3]. Analysts argue that in the post-elimination phase, case counts alone are an inadequate gauge, because residual transmission and preventable deaths can go undetected in settings marked by poverty, poor housing and population mobility [s3]. Two fixes are being pushed. Housing support under India's Pradhan Mantri Awas Yojana scheme is framed as a structural intervention — better housing limits the mud-and-thatch conditions where sandflies breed and bite indoors — and integrating verbal autopsy into routine surveillance is proposed to catch deaths the case-reporting system misses [s3].

The Malda analysis is a single district over five years, built on secondary programme data, and its small numbers mean year-to-year swings should not be over-read [s2]. But its central tension is the one the whole subcontinent now faces. The visceral disease is being driven down toward elimination; the surveillance question is whether the programmes can hold the line for the three years validation demands, keep active case-finding running in the tribal and remote pockets where the last cases hide, and track the PKDL reservoir that could reintroduce the parasite once vigilance relaxes [s2][s3]. Bangladesh has shown the target is reachable [s1]. Whether it stays reached is the harder test.

This article is informational and is not medical advice.

Sources

• [s1] World Health Organization, "Leishmaniasis — fact sheet." https://www.who.int/news-room/fact-sheets/detail/leishmaniasis
• [s2] Cureus, "Sustaining the Elimination of Visceral Leishmaniasis: A Secondary Data Analysis of the National Kala-Azar Elimination Programme in Malda District, West Bengal, India (2018–2022)," published 12 July 2026. https://doi.org/10.7759/cureus.112553
• [s3] Journal of Vector Borne Diseases, "Efforts to sustain post-kala-azar elimination in India: surveillance, mortality monitoring, and housing support under the Pradhan Mantri Awas Yojana," published 10 September 2026. https://doi.org/10.4103/jvbd.jvbd_36_26