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Mario J. Grijalva, Ph.D.

Discovery could help control life-threatening disease

International research team announces break from 30 years of dogma for ancient disease agent. 

(ATHENS, Ohio) A discovery by a team of researchers from Ecuador, the United Kingdom and the Ohio University College of Osteopathic Medicine (OU-COM) could prove key to creating control programs for a parasite that causes a life-threatening disease in humans.

The findings were published in the article, “Sex, Subdivision, and Domestic Disperal of Trypanosoma cruzi Lineage I in Southern Ecuador,” in the most recent version of the on-line journal PLoS Neglected Tropical Diseases (  

The team, which includes Mario J. Grijalva, Ph.D., associate professor of microbiology and director of the OU-HCOM Tropical Disease Institute, found novel evidence that the population of protozoan parasites in Southern Ecuador reproduce sexually, in stark contrast to populations across the continent and contradicting a belief held for thirty years that sex is largely absent from this organism.

Of sex in this protozoan, Grijalva said “This was the first time this had been found in the field, and it is a very important basic scientific discovery.”

The parasite, called Trypanosoma cruzi, is transmitted by bloodsucking insects known as triatomines, and it commonly infects wild and domestic mammals in South and Central American, including humans. Human infection with T. cruzi, known as Chagas disease, is a major public health concern in Latin America, affecting more than 13 million people, including more than 200,000 Ecuadorians.

“Understanding the complex dynamics of parasite spread between wild and domestic environments is essential to design effective control measures to prevent the spread of Chagas disease,” the authors wrote. 

The researchers also discovered that the parasites in southern Ecuador are of a genetically different population than those in others parts of Central and South America, Grijalva said. “They have entirely different characteristics,” he said.

“Our findings indicate that the parasite circulates in two largely independent cycles: one corresponding to the sylvatic environment and one related to the domestic/peridomestic environment,” Grijalva said. “Furthermore, our data indicate that human activity might promote parasite dispersal among communities.”

Besides Grijalva, other authors of the paper included Sofia Ocana-Mayorga and Jaime A. Costales of the Center for Infectious Disease Research at the Pontificia Universidad Catolica del Ecuador in Quito, Ecuador, and Martin S. Llewellyn and Michael Miles of the London School of Hygiene and Tropical Medicine in London, United Kingdom. This research was supported by the National Institutes of Health and the Chagas Epidemiological Network. 

Each year, Grijalva leads a team of more than 40 researchers, scientists and medical students, including several from OU-HCOM, to study tropical diseases in Ecuador. The World Health Organization has cited this program as an example of how to develop a new strategy for a global fight against this disease.

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Last updated: 01/28/2016