In the Americas, leishmaniasis is a vector-borne disease that causes a set of clinical syndromes in humans that can affect the skin, mucous membranes, and viscera. It is caused by 22 species of protozoan parasites of the Leishmania genus and is transmitted to animals and humans through the bite of female sand flies of the Psychodidae family, colloquially known as chiclero, asa branca, palomilla, mosquito palha, or torito, among other names.
The disease can present in three clinical forms: cutaneous, mucosal, and visceral.
The cutaneous form of the disease has several different clinical manifestations; the most frequent one causes localized or multiple skin ulcers.
The clinical diffuse cutaneous form can result in disfigurement similar to leprosy and is difficult to cure, with frequent relapses after treatment. Mucosal leishmaniasis can partially or totally destroy the mucous membranes of the nose, mouth, throat cavities, and surrounding tissues.
The visceral form, which is the most severe, causes fever, weight loss, inflammation of the spleen and liver, and anemia, and can be fatal in 90% of cases, if not properly treated.
Many factors affect transmission of the disease: Poverty, resulting in poor housing and sanitation conditions (e.g. garbage and open sewers) may increase insect breeding and resting sites and facilitate transmission to humans. Leishmaniasis is associated with migration and the movement of people to areas with existing transmission cycles.
Environmental and climate changes such as deforestation, rainfall, temperature, and humidity influence the incidence of leishmaniasis; and the incursion of farming, road construction, hydroelectric power plants, and settlements in forest areas have led to an increase in the number of cases.
Individual and collective measures to avoid being bitten are recommended to reduce contact with the vector. These include using insect repellant and mosquito netting, cleaning up the environment, and when necessary, spraying long-lasting insecticides. Early diagnosis and proper treatment are indicated for all confirmed cases.
- Globally, it is estimated that there are 0.9 to 1.6 million new cases of leishmaniasis and 20,000 to 30,000 deaths each year.
- In the Americas, an average of 56,000 cases of cutaneous and mucosal leishmaniasis and 3,800 cases of visceral leishmaniasis are recorded each year. Cutaneous leishmaniasis has been recorded in 20 countries, and is endemic in 18 of them (Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, French Guyana, Guyana, Honduras, Nicaragua, Mexico, Panama, Paraguay, Peru, Suriname, and Venezuela). In the Region of the Americas, 27% of cases of cutaneous leishmaniasis occur in border areas.
- Visceral leishmaniasis is present in 12 countries, although 96% of the cases are concentrated in Brazil. Cases have also been frequently recorded in Argentina, Colombia, Paraguay, and Venezuela, with sporadic cases reported in Bolivia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, and Nicaragua.
- The PAHO Strategic Fund helps endemic countries in the Americas to purchase medicines and other supplies needed to treat the disease.
- PAHO provides technical training in the surveillance, prevention, diagnosis, treatment, and control of the disease at the clinical, epidemiological, and laboratory level, and produces guidelines for the clinical management of patients, epidemiological surveillance, and dissemination of knowledge.
(Last update: October 2017.)