Leishmaniasis

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Leishmaniasis facts

  • Leishmaniasis is caused by a parasite that is spread to humans through the bite of infected sand flies.
  • Leishmaniasis exists in many temperate and tropical countries of the world. The disease is most common in India, Bangladesh, Nepal, Sudan, Ethiopia, Afghanistan, Algeria, Iran, Saudi Arabia, Syria, Brazil, Colombia, Peru, and Bolivia.
  • The most common type of leishmaniasis is cutaneous leishmaniasis. This causes nodules or sores to form on the skin, including the skin of the face. Affected people may have a single lesion or many lesions. Sores heal slowly over months to years and leave scars.
  • Another type is called visceral leishmaniasis. Parasites infect the tissues of key organs, especially the liver, spleen, and bone marrow. Serious cases are usually fatal if not treated.
  • Uncommonly, people who have had cutaneous leishmaniasis may get new sores in the mucous membranes of the mouth, nose, and larynx even years after the cutaneous leishmaniasis has resolved. This is called mucocutaneous leishmaniasis and only occurs in limited areas of the New World.
  • Treatment consists of medications that are specific to the type of leishmaniasis, the species of the parasite, and to the country in which the disease was acquired.
  • Consultation with the CDC and an infectious-disease consultant is strongly recommended for assistance with diagnosis and treatment of cases imported into the United States.
  • Those who work in or travel to affected areas can reduce their risk by using insect repellents, protective clothing, and bed nets. These precautions are especially important after dusk, because that is when the sand fly is most active.

What is leishmaniasis?

Leishmaniasis is an infection caused by a parasite that is spread to people through the bite of the female phlebotomine sand fly. The parasite exists in many tropical and temperate countries. Cases in the United States are almost always imported from other countries by travelers or immigrants. It has been estimated that there are 2 million new cases of leishmaniasis every year in the world, of which 1.5 million are categorized as cutaneous leishmaniasis and 0.5 million are visceral leishmaniasis. Epidemics occur when people are displaced into affected regions through war or migration or when people in affected regions experience high rates of disease or malnutrition.

Picture of a sand fly biting a human arm.
Figure 1: Picture of a sand fly biting a human arm. SOURCE: CDC/Frank Collins

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Leishmaniasis Transmission

How do people get infected with Leishmania parasites?

The main route is through the bite of infected female phlebotomine sand flies. Sand flies become infected by sucking blood from an infected animal or person. People might not realize that sand flies are present because:

  • They do not make noise when they fly;
  • They are small: they are only about one-third the size of typical mosquitoes or even smaller;
  • Their bites might not be noticed (the bites may be painless or painful).

Sand flies usually are most active in twilight, evening, and night-time hours (from dusk to dawn). Although sand flies are less active during the hottest time of the day, they may bite if they are disturbed (for example, if a person brushes up against the trunk of a tree or other site where sand flies are resting).

Some types (species) of Leishmania parasites may also be spread by blood transfusions or contaminated needles (needle sharing). Congenital transmission (spread from a pregnant woman to her baby) has been reported.

SOURCE: CDC

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