In Pursuit of a Vaccine for Chagas Disease
How TMC researchers are developing a vaccine to treat Chagas
In the past few weeks, Chagas disease has made headlines with reports of new cases popping up around Texas and — most recently — with controversial pharmaceutical executive Martin Shkreli gouging prices of a medication commonly used to treat the disease.
Chagas disease, known as American trypanosomiasis, is a parasitic infection classified as one of the 17 neglected tropical diseases prioritized by the World Health Organization. Chagas and other NTDs have, for the most part, been eliminated in more developed areas of the world but remain a looming threat in impoverished global communities.
The potentially life-threatening disease is transmitted by triatomine bugs, colloquially called “kissing bugs,” which are typically found in cracks of poorly constructed homes in poorer communities. Though its nickname may sound harmless, the critter is far less innocuous than its name would imply, affecting approximately 8 million people worldwide, with most of the cases concentrated in Latin America — including Argentina, Brazil, Mexico and Bolivia. In the United States, an estimated 300,000 people are infected with Chagas, with reports of infections coming from Arkansas, Arizona, Missouri, Tennessee and Texas.
According to the U.S. Centers for Disease Control, there were 351 cases of Chagas in animals, primarily dogs, reported in 2013–2014 from about 20 percent of Texas counties. In that same period, 39 human cases were reported, 24 of which were acquired in another country, while 12 were acquired locally and the remaining three are unknown.
Peter J. Hotez, M.D., Ph.D., founding dean of the National School of Tropical Medicine at Baylor College of Medicine, explained that the blood-sucking triatomines are considered “silent feeders,” oftentimes coming out at night and biting victims — both humans and dogs — on the face or anywhere on the body where skin is exposed. But the infection doesn’t occur like a mosquito bite, which infects the host with its saliva. Instead, the parasite Trypanosoma cruzi responsible for Chagas disease lives inside the feces of the kissing bugs.
“What happens is, not very elegantly, they defecate their whole blood meal out and you rub the bug feces into your mucus membrane, [such as] your mouth, your eye or abrasion on the skin,” Hotez said.
Because the T. cruzi parasites circulate in the bloodstream once the triatomines’ fecal matter enters the body, Chagas can be transmitted from infected mothers to newborns during pregnancy or childbirth. In that same vein, infected donors of blood transfusions or organ transplants can also pass along the disease to recipients.
