What is Visceral leishmaniasis?
Visceral leishmaniasis, also widely known by its common name kala-azar, is a progressive and systemic disease initiated by a single-celled parasite. Unlike other forms of leishmaniasis that are confined to the skin, the visceral form is defined by the parasite’s invasion of the body’s internal organs. The primary targets are the liver, the spleen, and the bone marrow.
Once inside the body, the parasite, belonging to the genus Leishmania, specifically colonizes cells within this network of vital organs. This internal assault disrupts normal organ function and severely compromises the body’s immune response. The resulting condition leads to a gradual but relentless decline in health, distinguishing it as the most life-threatening type of leishmaniasis.
Causes:- The Infectious Agent: The disease is initiated by protozoan parasites from the Leishmania donovani complex, which are single-celled organisms that cannot survive long outside of a host.
- The Transmission Vector: Humans acquire the parasite exclusively through the bite of an infected female phlebotomine sandfly. The sandfly first becomes a carrier by feeding on the blood of an already infected person or animal, and then transfers the parasite to a new host during its next blood meal.
- Geographic Exposure: The single greatest risk factor is living in or traveling to specific regions where the parasite and its sandfly vector are common, concentrated in parts of East Africa, the Indian subcontinent, and areas of South America.
- Nutritional Status: Malnutrition, particularly deficiencies in protein, iron, vitamin A, and zinc, severely weakens the immune system's ability to mount an effective defense against the Leishmania parasite after infection occurs.
- Socioeconomic Conditions: Poverty often correlates with higher risk due to factors like poor housing construction (e.g., mud walls, thatched roofs) that provide ideal breeding grounds and resting sites for sandflies, increasing human exposure.
- Immune Co-factors: Concurrent infections that compromise the immune system, most notably HIV, create a synergistic threat where each disease accelerates the progression and severity of the other.
