Zheng Qi  2021-03-11

Leishmaniasis poses a severe, long-lasting threat to human health across 98 endemic countries, with vastly different impacts depending on its three clinical forms. Cutaneous leishmaniasis, the most widespread variant, causes persistent painless skin ulcers that often leave permanent, disfiguring scars on exposed body parts, triggering lifelong social stigmatization, chronic psychological stress and social exclusion for survivors. Mucocutaneous leishmaniasis progressively erodes the mucous membranes of the nose, mouth and throat, leading to irreversible facial mutilation that severely impairs breathing, eating and normal social interaction. Visceral leishmaniasis, the deadliest form, causes persistent high fever, severe anemia, massive enlargement of the liver and spleen, and drastic weight loss; without timely treatment, its untreated mortality rate can reach 95%, making it the second most lethal parasitic disease globally after malaria. The parasite’s long, often asymptomatic incubation period that can extend up to 10 years, combined with limited clinical awareness among medical staff in non-endemic regions and sparse access to specialized health services in remote areas, frequently delays diagnosis for months or even years, allowing the disease to progress to advanced, life-threatening stages before intervention.

Vicious Cycle of Poverty

The disease is deeply intertwined with structural poverty, creating a self-reinforcing cycle that traps vulnerable communities in long-term impoverishment. Multiple poverty-linked factors drastically elevate infection risk: poor housing conditions that offer no protection against sandfly bites, inadequate environmental sanitation that supports dense sandfly breeding sites, lack of affordable personal protective measures, and large-scale economic migration that brings non-immune migrant workers into active transmission zones. Malnutrition, co-infections with other diseases, and HIV co-infection which increases the risk of developing symptomatic leishmaniasis by over 1000 times, further weaken host immunity and push asymptomatic infections to progress to severe clinical disease. When public health systems do not offer free diagnosis and treatment, affected families are forced to sell productive assets, take on high-interest loans, and divert limited household funds away from food, education and other basic needs to cover medical costs, pushing them deeper into poverty.

Global Public Health Priority

Leishmaniasis is classified as one of the world’s 20 major neglected tropical diseases, with over 50,000 to 90,000 new visceral leishmaniasis cases recorded globally every year, 90% of which are concentrated in just 10 high-burden countries. The WHO has set a clear target to eliminate visceral leishmaniasis as a public health problem in 64 countries by 2030, defined as a local primary case mortality rate below 1%. Targeted public investment in leishmaniasis control not only directly reduces avoidable deaths and disfiguring disabilities, but also breaks the disease-poverty cycle, delivering far-reaching socioeconomic benefits for marginalized endemic communities. Even in regions that have achieved historical elimination targets, sustained surveillance remains critical, as shifting sandfly habitats, growing stray dog populations and cross-border population mobility can easily reignite local transmission and trigger new outbreaks.

Edited by: Secretariat of the Asia-Pacific Network for Drug and Diagnostics Innovation
Produced by: Zheng Qi
Reviewed by: Zhang Haobing
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