Researchers have identified a mutant form of the leishmaniasis parasite that can remain indefinitely in host animals and people without making them ill.
Leishmaniasis infects two million people a year, mainly in the developing world. After initial infection the parasite may persist in the body but can then be reactivated, causing the most severe forms of the disease. But little is known about the factors that enable the parasite to persist in this way.
The researchers say that the mutant form "may provide a new tool for the study of persistent Leishmania infections". So far it has been difficult to carry out such studies owing to the need for lengthy experiments. Their findings could also assist the development of effective vaccines and chemotherapy against the disease.
Reference: Science 301, 1241 (2003)