The antimalarial drug artemisinin shows promise as a treatment for leishmaniasis, according to Indian researchers.

The research was published in the September issue of the Journal of Medical Microbiology.

Visceral leishmaniasis — also known as kala-azar — is caused by the Leishmania parasite and transmitted to humans through biting insects such as sand flies. The parasite lowers immunity and causes persistent fever, anaemia, liver and spleen enlargement, and is lethal if left untreated.

It infects 500,000 people worldwide, according to the WHO. There is no vaccine for the disease and there are signs of increasing resistance to the few effective drug treatments.

Researchers evaluated the efficacy of artemisinin against the Leishmania donovani parasite. They found that the drug kills the parasite at both stages of its growth, particularly the disease-causing 'amastigote' form of the parasite.

Lead researcher Mitali Chatterjee, from the India-based Institute of Postgraduate Medical Education and Research, said the fact that artemisinin is more effective against the amastigote form suggests that the drug acts via macrophages, immune cells that engulf and kill harmful organisms that invade the body.

Chatterjee said it is likely that artemisinin not only directly kills the parasite but additionally activates the macrophage so it can clear itself of the parasite.

The study also indicated that artemisinin was safer than the existing antileishmanial drugs pentamidine — which can cause diabetes — and miltefosine, which has been linked to birth defects.  

Chatterjee said the advantage of artemisinin is that it is already a licensed drug, so toxicity studies have already been completed.

Swapan Jana, secretary of India-based nongovernmental organisation Society for Social Pharmacology, said the prospect of using artemisinin was "very encouraging given leishmaniasis is endemic in India and existing antileishmanial drugs show side-effects".

But Neena Valecha, deputy director of the National Institute of Malaria Research in India, warned that any expanded use of artemisinin must not affect malaria management.

"We have to consider that artemisinin is the valuable drug for acute illnesses like malaria," Valecha told SciDev.Net.

Link to abstract in Journal of Medical Microbiology

Reference: Journal of Medical Microbiology 56, 1213 (2007)