Leishmaniasis is caused by infection with Leishmania parasites, which are spread by the bite of phlebotomine sand flies. There are several different forms of leishmaniasis in people. The most common forms are cutaneous leishmaniasis, which causes skin sores, and visceral leishmaniasis, which affects several internal organs (usually spleen, liver, and bone marrow).

Epidemiology & Risk Factors

Leishmaniasis is found in people in focal areas of more than 90 countries in the tropics, subtropics, and southern Europe. The ecologic settings range from rain forests to deserts. Leishmaniasis usually is more common in rural than in urban areas, but it is found in the outskirts of some cities. Climate and other environmental changes have the potential to expand the geographic range of the sand fly vectors and the areas in the world where leishmaniasis is found.
Leishmaniasis is found on every continent except Australia and Antarctica.

The number of new cases per year is not known with certainty. For cutaneous leishmaniasis, estimates of the number of cases range from approximately 0.7 million (700,000) to 1.2 million (1,200,000). For visceral leishmaniasis, estimates of the number of cases range from approximately 0.2 million (200,000) to 0.4 million (400,000). The cases of leishmaniasis evaluated in the United States reflect travel and immigration patterns. For example, many of the cases of cutaneous leishmaniasis in U.S. civilian travelers have been acquired in common tourist destinations in Latin America, such as in Costa Rica.
Overall, infection in people is caused by more than 20 species (types) of Leishmania parasites, which are spread by about 30 species of phlebotomine sand flies; particular species of the parasite are spread by particular sand flies. The sand fly vectors generally are the most active during twilight, evening, and night-time hours (from dusk to dawn).
In many geographic areas where leishmaniasis is found in people, infected people are not needed to maintain the transmission cycle of the parasite in nature; infected animals (such as rodents or dogs), along with sand flies, maintain the cycle. However, in some parts of the world, infected people are needed to maintain the cycle; this type of transmission (human—sand fly—human) is called anthroponotic. In areas with anthroponotic transmission, effective treatment of individual patients can help control the spread of the parasite.

Diagnosis

Various laboratory methods can be used to diagnose leishmaniasis—to detect the parasite as well as to identify the Leishmania species (type). Some of the methods are available only in reference laboratories. In the United States, CDC staff can assist with the testing for leishmaniasis.
Tissue specimens—such as from skin sores (for cutaneous leishmaniasis) or from bone marrow (for visceral leishmaniasis)—can be examined for the parasite under a microscope, in special cultures, and in other ways. Blood tests that detect antibody (an immune response) to the parasite can be helpful for cases of visceral leishmaniasis; tests to look for the parasite itself usually also are done.

Treatment

Before considering treatment, the first step is to make sure the diagnosis is correct.
Treatment decisions should be individualized. Health care providers may consult CDC staff about the relative merits of various approaches. Examples of factors to consider include the form of leishmaniasis, the Leishmania species that caused it, the potential severity of the case, and the patient's underlying health.
The skin sores of cutaneous leishmaniasis usually heal on their own, even without treatment. But this can take months or even years, and the sores can leave ugly scars. Another potential concern applies to some (not all) types of the parasite found in parts of Latin America: certain types might spread from the skin and cause sores in the mucous membranes of the nose (most common location), mouth, or throat (mucosal leishmaniasis). Mucosal leishmaniasis might not be noticed until years after the original sores healed. The best way to prevent mucosal leishmaniasis is to ensure adequate treatment of the cutaneous infection.
If not treated, severe (advanced) cases of visceral leishmaniasis typically are fatal.

Prevention & Control

No vaccines or drugs to prevent infection are available. The best way for travelers to prevent infection is to protect themselves from sand fly bites. To decrease the risk of being bitten, follow these preventive measures:
Avoid outdoor activities, especially from dusk to dawn, when sand flies generally are the most active.
When outdoors (or in unprotected quarters):

• Minimize the amount of exposed (uncovered) skin. To the extent that is tolerable in the climate, wear long-sleeved shirts, long pants, and socks; and tuck your shirt into your pants. (See below about wearing insecticide-treated clothing.)
• Apply insect repellent to exposed skin and under the ends of sleeves and pant legs.
• Follow the instructions on the label of the repellent. The most effective repellents generally are those that contain the chemical DEET (N,N-diethylmetatoluamide).

Note:

Bed nets, repellents, and insecticides should be purchased before traveling and can be found in hardware, camping, and military surplus stores. Bed nets and clothing that already have been treated with a pyrethroid-containing insecticide also are commercially available.

When indoors:

• Stay in well-screened or air-conditioned areas.
• Keep in mind that sand flies are much smaller than mosquitoes and therefore can get through smaller holes.
• Spray living/sleeping areas with an insecticide to kill insects.
• If you are not sleeping in a well-screened or air-conditioned area, use a bed net and tuck it under your mattress. If possible, use a bed net that has been soaked in or sprayed with a pyrethroid-containing insecticide.
• The same treatment can be applied to screens, curtains, sheets, and clothing (clothing should be retreated after five washings.