Scientists close in on vaccine for Chagas disease

Mexico : A team of scientists has taken a step closer to developing a vaccine for the potentially life-threatening Chagas disease, which is transmitted by so-called "kissing bugs" and has infected millions in Latin America.

Emilio Malchiodi, professor of immunology at the University of Buenos Aires, said a molecule engineered to contain three antigens had been shown in mice to reduce the number of Trypanosoma cruzi parasites that cause Chagas, as well as the amount of tissue damage they inflict.

The development could help cut the cost of a potential vaccine, he said. "Otherwise you have to produce three different antigens, and now you have to produce just one," said Malchiodi, who led the research.

Chagas, which kills some 12,000 people a year, is caused by a parasite transmitted by the cockroach-like, blood-sucking triatomine bug endemic to Latin America that hides in the adobe houses with straw roofs lived in by many of the rural poor.

The World Health Organization says up to 7 million people, mostly in Latin America, have been infected by the parasite. Chagas is on its list of 17 neglected tropical diseases in need of more investment and research, which receive scant attention from pharmaceutical companies.

Malchiodi, whose team's work was published by Nature's "npj Vaccines" journal this week, said developing a vaccine was imperative as increased migration meant an estimated 300,000 to 500,000 people in the United States and up to 70,000 in Europe were infected by the parasite.

Charity Medecins Sans Frontieres says nearly one in three with Chagas develop life-threatening problems such as heart disease, cardiac arrest and intestinal complications, but it can take more than 30 years before chronic health issues manifest.

Laboratory analysis of blood samples is needed to diagnose infection, and while treatment can be nearly 100 percent effective for newborn babies and acute cases, it becomes harder to treat as the time between infection and diagnosis increases, according to MSF.

More than 100 years after Brazilian doctor Carlos Chagas discovered the disease, little headway has been made in developing new treatments apart from the drugs benznidazole and nifurtimox which are used today.

According to a study published in Nature last year, scientists at the Genomics Institute of the Novartis Research Foundation found a single class of drugs that can kill the parasites responsible for Chagas, leishmaniasis and sleeping sickness tropical diseases that affect millions in Africa, Asia and Latin America.

Malchiodi said his team's work has focused on developing a prophylactic vaccine, but the next step will be to develop a therapeutic vaccine to treat the chronic stage of the disease.