Arsenic contamination of water supplies may have played a significant role in the development of widespread resistance in the Indian subcontinent to an important drug used to treat leishmaniasis, the second-largest parasitic killer in the world.
Visceral leishmaniasis infects around half a million people across the world every year and close to one-in-ten of those die.
One of the main treatments for the disease is a group of drugs known as antimonial preparations. However, by the end of the 20th century their effectiveness in treating the disease in the Bihar region, which houses ninety per cent of India’s leishmaniasis victims, was so low that use of the drugs was no longer recommended.
Now researchers at the Universities of Dundee and Aberdeen have concluded that arsenic contamination of the water supply may have played a significant role in building resistance to the drugs.
“The Indian subcontinent is the only region where arsenic contamination of drinking water coexists with widespread resistance to antimonial drugs which are used to treat visceral leishmaniasis,” said Professor Alan Fairlamb, of the University of Dundee.
“The water supply in Bihar has been found to be affected by contamination from naturally occurring arsenic in the ground water. What we have been able to show through experiments is that arsenic contamination of water can build resistance in Leishmania parasites to antimonial treatments.
“This is important as we need to be sure of why resistance to drugs develops. Leishmaniasis is a neglected disease that has a devastating effect across the developing world and there is a desperate need for better drugs to treat it. What we cannot afford is for the existing treatments to be compromised while we search for new ones.”
Meghan Perry, a Wellcome Trust-funded clinical PhD student working on the project, has also carried out field research in Bihar.
Meghan said, “Arsenic contamination of the groundwater is a serious issue in Bihar. Many villagers continue to drink arsenic contaminated water as they have no alternative. Knowledge of the dangers of arsenic pollution is low and mitigation projects are not reaching all of those in need. Arsenic can lead to a myriad of health issues and our research adds to this long list. Community education and alternative drinking water sources are desperately needed."
Professor Jörg Feldmann, Head of Chemistry at the University of Aberdeen, said, “As an environmental chemist I have always been interested in arsenic exposure through drinking water and food, but to show the influence of arsenic on an the efficacy of a drug based on antimony, an element chemically similar to arsenic, is fascinating. This only adds to the many detrimental effects arsenic has on the human being and shows how complex the arsenic biochemistry can be.
The research is published in a paper in the journal PNAS (Proceedings of the National Academy of Sciences of the United States of America).