Leishmaniasis is caused by infection with a parasite after being bitten by a sandfly. 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.
The skin sores of leishmaniasis can take months or even years to heal without treatment, and can leave ugly scars. The disfigurement causes stigmatization and isolation of people who could normally be treated. Not treating this disease can lead to advanced forms, frequently resulting in death. Leishmaniasis occurs often in large outbreaks and this frequently compromises access to medicines for those who need it.
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What causes Leishmaniasis
Leishmaniases are a group of vector-borne diseases caused by protozoan parasites from more than 20 Leishmania species. Some 70 animal species, including humans, make up the natural reservoir for Leishmania parasites.
In most parts of the world, a bite from an infected Phlebotomus sandlfy is considered the vector of leishmaniasis.
There are three forms of leishmaniasis: visceral (also called Kala-azar or Black fever), cutaneous, and mucocutaneous. The cutaneous form is the most common form of the disease. The cutaneous form of the disease is caused by more than 15 species of Leishmania. Visceral disease is usually caused by Leishmania donovani, L. infantum, or L. chagasi.
Where is Leishmaniasis found
Cutaneous leishmaniasis occurs in Americas, the Mediterranean basin, the Middle East and Central Asia. Countries where the disease is common are Afghanistan, Algeria, Bolivia, Brazil, Colombia, Iran, Iraq, Pakistan, Peru, Saudi Arabia, Syria and Tunesia.
Most cases of mucocutaneous leishmaniasis occur in Bolivia, Brazil, Ethiopia and Peru.
Visceral leishmaniasis occurs most in Bangladesh, Brazil, India and East Africa.
Risk factors include poverty, malnutrition, deforestation, lack of sanitation, suppressed immune system and urbanization.
What are the symptoms of Leishmaniasis
The symptoms of leishmaniasis are skin sores which erupt weeks to months after the person is bitten by infected sand flies.
- Cutaneous leishmaniasis is the most common form, which causes an open sore at the bite sites. This will eventually heal spontaneously in a few months to a year and half, leaving life-long scars and serious disability or stigma.
- Diffuse cutaneous leishmaniasis produces widespread skin lesions which resemble leprosy, and may not heal on its own.
- Mucocutaneous leishmaniasis causes both skin and mucosal ulcers with damage primarily to the nose and mouth.
- Visceral leishmaniasis, also known as kala-azar or black fever is the most serious form, and is generally fatal if untreated.
Other consequences, which can occur a few months to years after infection, include fever, damage to the spleen and liver, and anemia. Leishmaniasis is considered one of the classic causes of a markedly enlarged and palpable spleen. The organ, which is not normally felt during examination of the abdomen, may become larger than the liver in severe cases.
How can Leishmaniasis be prevented
Prevention is by avoiding bites of sandflies. Leishmaniasis can be partly prevented by using nets treated with insecticide while sleeping. To provide good protection against sandflies, fine mesh sizes of 0.6 mm or less are required. Covering doors and windows with nets is also recommended. Programs of fumigation to reduce the number of sandflies by using insecticides are highly successful and locally reduce the risk.
How is Leishmaniasis diagnosed
Leishmaniasis is usually diagnosed by evaluation of clinical signs and direct visualization of peripheral blood or aspirates from marrow, spleen, lymph nodes, or skin lesions. However, the retrieval of tissue samples is often painful for the patient and identification of the infected cells can be difficult.
The most sensitive tests for leishmaniasis are polymerase chain reaction (PCR) tests, such as the ones made available by the WoIDMo. With this method, very low parasite loads can be detected and only a minimal amount of sample is required.
In cutaneous and mucocutaneous forms of leishmaniasis PCR tests have limited value since clinical manifestation along with tissue visualization usually confirms a diagnosis.
Early diagnosis and fast treatment reduces the prevalence of the disease and prevents disabilities and death.
How is Leishmaniasis treated
The treatment of leishmaniasis depends on several factors including type of disease, parasite species and geographic location. Patients should have a competent immune-system to fight the disease.
For visceral leishmaniasis in India, South America, and the Mediterranean, liposomal amphotericin B is the recommended treatment and is often used as a single dose. In India, almost all infections are resistant to pentavalent antimonials.
In Africa, a combination of pentavalent antimonials and paromomycin is recommended.
Miltefosine, an oral medication, is effective against both visceral and cutaneous leishmaniasis. It does not appear to work for L. major or L. braziliensis.
Cutaneous leishmaniasis caused by L. tropica should be treated with pentavalent antimonials, combined with local wound care. Oral fluconazole or itraconazole appears effective in L. major and L. tropica.
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