The parasite that causes Chagas disease is transmitted to people through the faeces of 'kissing bugs'

Marcelo de Campos Pereira

Research into new treatments for Chagas disease has picked up pace following years of stagnation, according to an article published in Science.

One drug is entering a phase I trial next year, and two others are entering phase II trials to determine whether they clear the parasite from chronically infected people.

"It's been decades since there was a clinical trial of a new drug for Chagas disease, so that is very exciting," Frederick Buckner, a biochemist at the University of Washington, United States, tells Science magazine.

Researchers hope this is the beginning of a new drive to find even more compounds. The Drugs for Neglected Diseases Initiative (DNDi), a nonprofit organisation based in Switzerland, hopes to have at least one drug against the disease approved by 2014.

"I'm optimistic that there's going to be a lot of progress in the next decade," says Peter Hotez, dean of the new National School of Tropical Medicine at the Baylor College of Medicine, United States. But he cautioned that this movement "is all relative".

Chagas disease is one of the tropical diseases that drug companies have traditionally overlooked, even though there is no vaccine against the parasite, Trypanosoma cruzi, and efforts to curb the 'kissing bugs' that carry it have proved hit and miss.

Currently available drugs can trigger serious side effects and need to be taken for up to 90 days. Additionally, it is not clear whether they work in the later stages of the disease — when people become aware they need treatment.

Researchers are therefore putting their hopes into new drugs, despite the slow progress. "It's like we are going from zero to 20 [miles per hour]," Hotez says. "It's not zero to 60."

And James McKerrow, a biochemist at the University of California, San Francisco, says: "If you look at the history of drug development, more than 50 per cent of drug candidates fail when they go into people … We need to have the next generation of compounds ready to go".

But one of the major challenges is the lack of a practical way to determine when a drug is successful in humans.

"We don't have an endpoint indicator that says, 'Ha, that cures people'," says parasite immunologist Rick Tarleton of the University of Georgia, Athens, United States. The usual method of measuring disappearance from the blood of antibodies against the parasite is unfeasible for drug trials because it may take the Chagas parasite ten years or more to fully clear from blood. One of DNDi's projects aims to find new biomarkers that can more quickly signal when the pathogen has been vanquished.