Kala-azar (Leishmaniasis) – Causes and symptoms

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Kala-azar, Oriental sore, Delhi boil, or Leishmaniasis is an infection in the body of animals and humans caused by protozoa that belongs to the family known as Leishmania.

Kala-azar (Leishmaniasis) – Causes and symptomsLeishmaniasis is quite common in several tropical and temperate countries including India. There are 23 leishmania species cause leishmaniasis in humans. The three forms of the disease are as follows:

  • Cutaneous (skin), the most common form
  • Mucocutaneous (mucous membranes)
  • Visceral (internal organs), a very rare form.

Leishmaniasis is found in approximately 90 countries but more than 90% of the world’s cases of visceral leishmaniasis occur in India, Bangladesh, Nepal, Sudan, and Brazil. Leishmaniasis is classified as one of the "most neglected diseases". This observation stems from the basis of limited resources invested in diagnosis, treatment and control of Leishmaniasis, and its strong association with poverty.

Causes of leishmaniasis

Leishmaniasis is caused by a parasite which spreads from one person to another through the bite of an infected female phlebotomine sand fly. The sand fly can pick up the parasite leishmania from many common reservoir hosts such as domestic dogs, rats and humans. The infection spreads when the sand fly feeds on an uninfected human, usually at dusk or during the night.  Certain species of leishmania parasites may spread through blood transfusions or contaminated needles if shared. Spread of infection from a pregnant woman to her baby has also been reported.

Symptoms of leishmaniasis

Commonly, leishmaniasis manifests only as cutaneous leishmaniasis and nodules or sores on the skin and face. These symptoms may begin weeks or months after the bite of an infected sand fly. At the site of the bite, a papule is formed which eventually ulcerates. The centre of the ulcer appears as a crater and the edges are raised almost giving the ulcer, a volcano like resemblance. These lesions may be solitary or multiple. Healing is very slow and may take over months to years. A few leishmaniasis ulcers may also be covered by a scab. The associated lymph nodes in that area may also swell and lead to inflammation. It may also leave a residual scar.

Mucocutanoues leishmaniasis refers to the condition when the cutaneous form spreads to involve the mucous membranes of the mouth and inner tissues of the nose, mouth and throat. This can appear very disfiguring and the specie of leishmania found in Central and South America causes this.

In the rarer form called visceral leishmaniasis, key organs such as the liver, spleen, and bone marrow are infected and this may be more serious and sometimes fatal. This severe form can cause fever, weakness, anemia, weight loss, skin lesions, and enlargement of organs of the body. If untreated, it can be fatal. This can occur after two to eight months after getting bitten by an infected sand fly.

Photograph via sxc.hu

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