Leishmaniasis is a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. Leishmaniasis 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 leishmaniasis, which causes skin sores, and visceral leishmaniasis, which affects several internal organs (usually spleen, liver, and bone marrow).
Some people have a silent infection, without any symptoms or signs. People who develop clinical evidence of infection have one or more sores on their skin. The sores can change in size and appearance over time. The sores may start out as papules (bumps) or nodules (lumps) and may end up as ulcers (like a volcano, with a raised edge and central crater); skin ulcers may be covered by scab or crust. The sores usually are painless but can be painful. Some people have swollen glands near the sores (for example, under the arm, if the sores are on the arm or hand).
Some people have a silent infection, without any symptoms or signs. People who develop clinical evidence of infection usually have fever, weight loss, enlargement (swelling) of the spleen and liver, and abnormal blood tests. People may have low blood counts, including a low red blood cell count (anemia), a low white blood cell count (leukopenia), and a low platelet count (thrombocytopenia).
The number of new cases may vary or change over time and are difficult to estimate. For cutaneous leishmaniasis, estimates of the number of new cases per year have ranged from approximately 700,000 to 1.2 million or more. For visceral leishmaniasis, the estimated number of new cases per year may have decreased to <100,000, but previous estimates ranged up to 400,000 or more cases.
In the Old World (the Eastern Hemisphere), leishmaniasis is found in some parts of Asia, the Middle East, Africa (particularly in the tropical region and North Africa, with some cases elsewhere), and southern Europe. It is not found in Australia or the Pacific Islands.
In the New World (the Western Hemisphere), leishmaniasis is found in some parts of Mexico, Central America, and South America. It is not found in Chile or Uruguay.
Overall, leishmaniasis is found in parts of approximately 90 countries. 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. U.S. military personnel have become infected in various countries, such as Iraq and Afghanistan.
Not usually. Almost all of the cases of leishmaniasis diagnosed in the United States are in people who became infected while traveling or living in other countries.
Occasional cases of cutaneous leishmaniasis have been acquired in Texas and Oklahoma. No cases of visceral leishmaniasis are known to have been acquired in the United States.
The main way 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 any noise;
- They are small: on average, they are only about one fourth the size of mosquitoes or even smaller; and
- Their bites might not be noticed (the bites can 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 some other site where sand flies are resting).
Some types (species) of Leishmania parasites also may be spread via contaminated needles (needle sharing) or blood transfusions. Congenital transmission (spread from a pregnant woman to her baby) has been reported.
People of all ages are at risk for infection if they live or travel where leishmaniasis is found. Leishmaniasis usually is more common in rural than in urban areas, but it is found in the outskirts of some cities. The transmission risk is highest from dusk to dawn because this is when sand flies generally are the most active. Examples of people who may have an increased risk for infection (especially with the cutaneous form) include adventure travelers, ecotourists, Peace Corps volunteers, missionaries, soldiers, ornithologists (people who study birds), and other people who do research (or are active) outdoors at night/twilight.
Some people have a silent infection, without any symptoms or signs.
The skin sores of cutaneous leishmaniasis usually develop within a few weeks or months of the sand fly bite.
People with visceral leishmaniasis usually become sick within months (sometimes as long as years) of when they were bitten.
See your health care provider. Be sure to say where you have traveled and to mention the possibility of leishmaniasis.
The first steps are to check if you have been in a part of the world where leishmaniasis is found and if you have any symptoms or signs that might be from leishmaniasis.
CDC staff can advise your health care provider and can help with the laboratory testing for leishmaniasis. Tissue specimens—for example, 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 by molecular tests.
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 (or its DNA) usually also are done.
Your health care provider can talk with CDC staff about whether your case of leishmaniasis should be treated and, if so, with what type of therapy.
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, mouth, or throat (mucosal leishmaniasis). Mucosal leishmaniasis might not be noticed until years after the original sores healed. Ensuring adequate treatment of the cutaneous infection may help prevent mucosal leishmaniasis.
If not treated, severe (advanced) cases of visceral leishmaniasis typically are fatal.
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).
- 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).
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.
Yes. Some people have had cutaneous leishmaniasis more than once. Therefore, you should follow the preventive measures listed above whenever you are in an area where leishmaniasis is found.