Mumbai (PTI): Scientists from the National Institute of Immunology (NII) have identified a crucial protein that has an important role in regulating the infectivity, survival and drug response of the parasite that causes visceral leishmaniasis or the dreaded `Kala-azar'.

The scientists found that higher level of an enzyme called cytosolic tryparedoxin peroxidase (cTXNPx), at a certain stage of the L. donovani life cycle made the parasite more virulent. Laboratory tests also showed a higher parasite burden in immune cells, according to Jitesh P Iyer, of New Delhi based NII scientist.

Kala-azar or black fever, is the most severe form of leishmaniasis, a disease caused by the parasite Leishmania donovani and transmitted to people through sandfly bite.

Kala-azar is endemic in four Indian states, the worst affected being Bihar. The disease infects about 300,000 people and kills 20,000 in India every year.

This discovery assumes significance and paves way for developing a new drug molecule targeting this enzyme, pharmaceutical experts said.