Your Guide to
Neglected Tropical Diseases

Leishmaniasis is a group of diseases caused by parasites that spread through sandfly bites. There are three main forms-the most common form affects the skin, causing ulcers that leave permanent scars, often on the face and arms. These scars can cause stigma, especially for women and girls. Another form affects the mouth, nose, and throat, destroying tissue and causing severe disfigurement if left untreated. The most serious form attacks internal organs like the spleen, liver, and bone marrow, causing fever, weight loss, and severe anemia.

Without treatment, this form is almost always fatal. Leishmaniasis is one of the most prominent neglected tropical diseases, affecting large numbers of people living in impoverished areas where access to healthcare is limited. It is deeply linked to health inequality, disparities in healthcare resources, and discrimination and prejudice.

Leishmaniasis spreads within a region through bites from sand flies that have become infected after feeding on blood from reservoir animals, including humans. The sand fly is a small insect measuring 2-3 mm in length, and is most active from dusk until dawn. When a sandfly bites someone with leishmaniasis, it picks up parasites. The parasites develop inside the sandfly, then spread to the next person the sandfly bites. Once in the body, parasites invade cells and multiply. Depending on the parasite type and the person's immune system, the infection may cause skin sores, spread to the mouth and nose, or travel to internal organs. Many infected people never develop symptoms.

Sandflies breed in warm, humid places like cracks in walls, animal shelters, and piles of organic material. People living in rural areas near sandfly habitats face the highest risk.

Geographic scope:

• Almost all continents and tropical regions where the sand fly is found. Endemic in approximately 100 countries across the Americas, Africa, Asia, southern Europe, and the Middle East.
• The disease primarily affects remote rural populations, although some cases occur in cities.
• In 2023, Bangladesh became the first country to eliminate the serious form as a public health problem.

Population affected:

• More than 1 billion people live in areas where they could get leishmaniasis.
• Approximately 700,000 to 1 million new skin cases occur every year.
• An estimated 30,000-90,000 new internal organ cases occur annually.
• More than 12 million people are currently infected worldwide.
• Over 40 countries have reported cases in people also living with HIV, making treatment more difficult.

Treatment depends on the form of disease, where the infection was acquired, and overall health. The serious internal organ form requires medication given through IV or oral pills. Common medications can cause nausea, vomiting, and kidney problems. Treatment cannot completely remove the parasite from the body, so people with weakened immune systems may get sick again. Some oral medications cannot be used during pregnancy because they cause birth defects. Treatment effectiveness varies by region, with some areas showing resistance to certain medications.

Prevention focuses on avoiding sandfly bites. Use insect repellent, wear long-sleeved shirts and pants, and stay indoors from dusk to dawn when sandflies are most active. Sleep under insecticide-treated bed nets and keep window screens in good repair. No vaccine is available.