Leishmaniasis

What is leishmaniasis?
Leishmaniasis (LEASH-ma-NIGH-a-sis) is a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. It is caused by infection with Leishmania parasites, which are spread by the bite of infected sand flies. There are several different forms of leishmaniasis in people. The most common forms are cutaneous (cue-TAY-knee-us) leishmaniasis, which causes skin sores, and visceral (VIS-er-al) leishmaniasis, which affects some of the internal organs of the body (for example, spleen, liver, and bone marrow).

What are the signs and symptoms of cutaneous leishmaniasis?
People who have cutaneous leishmaniasis have one or more sores on their skin. The sores can change in size and appearance over time. They may end up looking somewhat like a volcano, with a raised edge and central crater (ulcer). Some sores are covered by a scab. The sores can be painless or painful. Some people have swollen glands near the sores (for example, under the arm if the sores are on the arm or hand).

What are the signs and symptoms of visceral leishmaniasis?
People who have visceral leishmaniasis usually have fever, weight loss, and an enlarged spleen and liver (typically, the spleen is bigger than the liver), and some abnormal blood tests. For example, patients usually have low blood counts, including a low red blood cell count (anemia), low white blood cell count, and low platelet count.

How common is leishmaniasis in the world?
The number of new cases of cutaneous leishmaniasis each year in the world is thought to be about 1.5 million. The number of new cases of visceral leishmaniasis is thought to be about 500,000.

In what parts of the world is leishmaniasis found?
In the New World (the Western Hemisphere), leishmaniasis is found in some parts of Mexico, Central America, and South America (Latin America). It is not found in Chile or Uruguay.

In the Old World (the Eastern Hemisphere), leishmaniasis is found in some parts of Asia, the Middle East, Africa, and southern Europe. It is not found in Australia or the Pacific Islands.

Overall, leishmaniasis is found in focal areas of about 88 countries. Some of these countries account for most of the world’s cases of leishmaniasis:

Over 90 percent of the cases of cutaneous leishmaniasis occur in parts of Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, and Syria (in the Old World) and in Brazil and Peru (in the New World);
Over 90 percent of the cases of visceral leishmaniasis occur in parts of India, Bangladesh, Nepal, Sudan, and Brazil.
However, the cases of leishmaniasis evaluated in the United States reflect travel and immigration patterns. For example, cases in U.S. civilian travelers typically are cases of cutaneous leishmaniasis (rather than of visceral leishmaniasis) acquired in common tourist destinations in Latin America (rather than in places in the Old World).

How do people get infected with Leishmania parasites?
The main way is through the bite of infected female phlebotomine sand flies. (Sand flies become infected by biting 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.