Kala azar (also known as visceral leishmaniasis) is the second largest parasitic killer in the world—only malaria is more deadly. Along with Chagas disease and sleeping sickness, kala azar is one of the most dangerous neglected tropical diseases (NTDs).
Kala azar is endemic in 76 countries with approximately 200 million people at risk of infection.
The parasite is spread to humans through the bite of infected female sand flies. It attacks the immune system, and is almost always fatal if not treated.
What causes kala azar?
Kala azar is caused by bites from female phlebotomine sandflies—the vector (or transmitter) of the leishmania parasite.
The sand flies feed on animals and humans for blood, which they need for developing their eggs.
If blood containing leishmania parasites is drawn from an animal or human, the next person to receive a bite will then become infected and develop leishmaniasis.
Months after this initial infection the disease can progress into a more severe form, called visceral leishmaniasis or kala azar.
Symptoms of kala azar
Initially, leishmania parasites cause skin sores or ulcers at the site of the bite. If the disease progresses, it attacks the immune system.
Kala azar presents after two to eight months with more generalized symptoms including prolonged fever and weakness.
Diagnosing kala azar
The most effective diagnostic tests for leishmaniasis are invasive and potentially dangerous, where tissue samples are required from the spleen, lymph nodes, or bone marrow. These tests require lab facilities and specialists not readily available in resource-poor, endemic areas.
The most common method of diagnosing kala azar is by dipstick testing. However, this method is highly problematic. In endemic areas, people can become infected with kala azar but it may not develop into the disease. Therefore, no treatment will be required.
Unfortunately, dipstick testing only establishes whether a patient is immune to kala azar—so if the parasite is present it would appear that the patient has the disease. Because of this, dipstick testing can’t be used to see if the patient is cured, is re-infected, or has relapsed.
Treating kala Azar
There are different treatment options available for kala azar, with varying effectiveness and side effects. Pentavalent antimonials are usually the first line group of drugs, given as a 30 day course of intramuscular injections.
While antimonials are quite toxic and present a risk to patients receiving treatment, those who are cured for kala azar almost always develop immunity for life. Researchers hope to identify ways to simplify treatment regimes, improve their safety, and reduce the risk of drug resistance.
Since 1989 Doctors Without Borders/Médecins Sans Frontières (MSF) has treated around 100,000 patients with kala azar. MSF is also campaigning for more research into suitable diagnostic techniques and affordable drugs to treat this neglected disease.
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