Leishmaniasis is a vector-borne disease with a wide variety of parasite species, reservoirs, and vectors involved in transmission. It is caused by different species of the protozoa Leishmania and is transmitted to animals and humans through a bite of insects in the Psychodidae family. Its presence is directly linked to poverty, but social, environmental, and climatalogic factors directly influence the disease's epidemiology.
In the Americas, 15 of the 22 pathogenic types of Leishmania have been identified in man, and nearly 54 non-vector species may potentially be involved in transmission. The parasite is transmitted through the bite of female sand flies in the Lutzomyia family, colloquially known as "chiclero, asa branca, palomilla, mosquito palha, or torito" among others. This insect is active at night when it inoculates the parasite when it bites a human.
There are three different clinical manifestations of the disease: cutaneous, mucosal, and visceral. Visceral leishmaniasis is characterized by irregular episodes of fever, weight loss, hepatosplenomegaly, and anemia, which if not treated may cause death in more than 90% of the cases. Mucosal leishmaniasis can lead to partial or complete destruction of the mucous membranes in the nose and mouth and may cause severe disability, while cutaneous leishmaniasis is the most frequent form of this infection, causing mostly ulcerative lesions that leave scars for life.
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- Globally, leishmaniasis is among the top ten neglected tropical diseases with more than 12 million infected people, 0.9 to 1.6 million new cases each year, between 20,000 and 30,000 deaths, and 350 million people at risk of infection.
- The countries with the most cases of visceral leishmaniasis are India, South Sudan, Sudan, Brazil, Ethiopia, and Somalia.
- The Leishmania-HIV co-infection is present in 35 countries, which intensifies the burden of leishmaniasis due to greater difficulty in its clinical management and treatment.
- Of the 10 countries in the world with the highest number of cases of cutaneous leishmaniasis, four are in the Americas: Brazil, Colombia, Nicaragua and Peru.
- In the Americas, an average of 55,000 cases of cutaneous and mucosal leishmaniasis and 3,500 cases of visceral leishmaniasis are recorded each year, with an average case fatality rate of 7%. 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), and visceral leishmaniasis has been recorded in 13 countries (Argentina, Bolivia, Brazil, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela). In the Region of the Americas, 27% of cases of cutaneous leishmaniasis occur in border areas.
- Available tools for prevention and control are limited, which means that exposed individuals should take steps to reduce contact with the vector. Furthermore, the health authorities should implement surveillance actions and carry out public health interventions when necessary. Early diagnosis and proper treatment are essential for halting this disease.
- Recent studies reveal that leishmaniasis produces a disease burden of 2.35 million DALYs (years of life lost due to disability), of which 2.3% are in the Americas.
- In the Region of the Americas, cases of cutaneous leishmaniasis have been recorded from the southern United States to northern Argentina, with the exception of the islands of the Caribbean, Chile and Uruguay. Each year, an average of 55,000 cases of cutaneous and mucosal leishmaniasis and 3,500 cases of visceral leishmaniasis are diagnosed, with a 7% mortality rate. In the world, Leishmania and HIV coinfection has increased the burden of the disease due to the greater difficulty of clinical treatment.
- The diagnosis of the disease is essential to establish a specific treatment and to limit the progress of the disease, relieve signs and symptoms, and improve the quality of life of patients. If left untreated, the mucous and diffuse cutaneous forms can cause deformity and disfigurement, and the visceral form can cause death in more than 90% of untreated cases.
- PAHO/WHO provides technical cooperation to national health authorities, such as training in the surveillance, prevention, diagnosis, treatment, and control of the disease at the clinical, epidemiological, and laboratory level, including the development of guidelines on the clinical management of patients, epidemiological surveillance, and dissemination of knowledge. The Organization also collaborates with endemic countries to purchase drugs through the Strategic Fund and other supplies needed to implement actions for the prevention and control of the disease.
- PAHO/WHO is implementing the Plan of Action to Strengthen the Surveillance and Control of Leishmaniasis in the Americas 2017-2022, with the aim of consolidating actions to reduce morbidity and mortality from this disease, with a 50% reduction in the number of deaths from visceral leishmaniasis as well as in the number of cases of cutaneous leishmaniasis in children under the age of 10.