Information of Visceral Leishmaniasis Human Disease

The visceral leishmaniasis, also known as kala-azar, is an infectious disease caused by a protozoan parasite of the genus Leishmania, affects man and different animal species, primarily the dog. It is the most severe form of leishmaniasis and a major cause of mortality worldwide, with 200,000 to 400,000 cases occurring in humans per year.

Causal Agent

There are two species of Leishmania that can cause visceral leishmaniasis. In East Africa and India the cases are caused by Leishmania donovani, while in Europe, North Africa and Latin America the agent is Leishmania infantum, also known as Leishmania chagasi.

Epidemiology

It is endemic in East Africa and India. 90% of cases worldwide occur in only 6 countries: Brazil, Ethiopia, Sudan, South Sudan, India and Bangladesh.

Transmission

Transmission is caused by bites of previously infected Phlebotomus or Lutzomyia genera.

Bio-epidemiological cycle

Leishmanias are located and multiply in the cells of the mononuclear phagocytic system of mammals and reptiles. The biological cycle needs the existence of insects that act as transmitters, in whose digestive tract the leishmania multiplies. Some leishmania will go to the insect's mouth area and be inoculated when it bites a mammal. In the New World, vector insects belong to the genus Lutzomyia and in the Old World to the genus Phlebotomus.

Leishmaniasis is a zoonosis, that is to say, that some animal species are the reservoir and from them it can pass to man through the bite of vector insects. Carnivorous animals, especially dogs are the main reservoirs, although many other species of mammals such as anteaters, sloths and opossums may be involved. Infection in vertebrates occurs when females of infected phlebotomes bite an animal or human to ingest their blood, transmitting leishmania during the process.

Symptomatology

The onset is insidious and the incubation period is very long, usually several months. The main symptoms are fever, enlargement of the spleen (splenomegaly) and liver (hepatomegaly), anemia and decrease in the total number of leukocytes in blood (leukopenia) with relative increase in monocytes. The evolution without treatment is fatal, malnourished children and patients infected with the human immunodeficiency virus are high-risk population, in them the disease is usually more serious.

Diagnosis

The diagnosis is suspected by the symptoms and is confirmed by laboratory studies, either by direct methods seeking the presence of leishmania or by indirect methods.

The direct diagnosis is based on the demonstration of leishmania in material from the biopsy of lymph nodes, bone marrow, liver or spleen. You can make a direct smear of the sample or perform a culture in the middle of Senekjie.

Indirect diagnosis is made with a blood sample, practicing immunochromatography of the rK39 antigen or performing the polymerase chain reaction (PCR) technique or the direct agglutination test.

Treatment

The most commonly used treatments are pentavalent antimonials, both meglumine antimony and sodium stibogluconate, also called sodium antimony gluconate, both are administered parenterally. Depending on the geographic area may be recommended other treatments. In India there is a high failure rate with the treatment of pentavalent antimonials, so other treatments such as amphotericin B and liposomal amphotericin B are frequently used, the latter is an amphotericin B encapsulated in liposomes which considerably decreases renal toxicity of the drug.