Scientists are calling on health authorities to classify Chagas disease – sometimes known as the "kissing bug disease" – as endemic to the United States.
Chagas disease, a parasitic infection spread by bugs, mostly infects people in Central and South America. Still, human cases have been reported in Missouri and seven other states, and the bug that carries the parasite has been found in both Missouri and Illinois.
In an article published this month in the Journal of Emerging Infectious Diseases, the article’s authors called for doctors, public officials and health agencies to classify Chagas as endemic – or regularly occurring – to the United States.
“The United States is often labeled as nonendemic, and this designation permeates the scientific literature, the Centers for Disease Control and Prevention (CDC) website, the media, pest professional websites, and the general community of researchers and physicians,” the authors wrote. “Labeling the United States as non–Chagas disease-endemic perpetuates low awareness and underreporting.”
After patients contract the parasite that causes Chagas, they can develop a fever, rash, swelling and other symptoms. Over time, Chagas can cause serious cardiac and digestive issues.
Classifying the disease as endemic could improve surveillance, research and public health responses, said Phil Budge, an infectious disease doctor at Washington University.
“I think it's been several years now where folks have been kind of recognizing, ‘Hey, this is probably happening at low levels, and we catch it sometimes,’” he said. “But officially, it has not been considered endemic here in the U.S.”
Budge said that the article shouldn’t scare residents about getting sick. Instead, the authors are calling for a new understanding about the disease that would improve diagnostics and research.
The CDC publishes the journal in which the article appeared, but its authors are from academic institutions in Florida, California and Texas.
Chagas is caused by a parasite that lives in a kissing bug’s feces. Humans can contract the parasite when the feces gets in a wound or bug bite, or gets into a person’s eye or mouth.
The bugs are moving north into the southern parts of the country, said Daniel Hoft, director of St. Louis University’s Division of Infectious Diseases, Allergy and Immunology and the head of the school’s Center for Vaccine Development.
“Over the last 10 years, there has been a slow creep of the insect vector from Latin America into the United States,” said Hoft, who has studied Chagas for decades.
Kissing bugs have been found throughout the St. Louis region, said Ellen Santos, an epidemiologist and researcher. While she was a professor at Southern Illinois University Edwardsville, Santos and her coauthors published a study showing where the bug is found.
The study, published in 2023 in the Journal of Medical Entomology, noted the bugs were found in dozens of counties in Missouri and Illinois. Some of the bugs found in the region carried the parasite that causes Chagas disease.
“I think the takeaway is that it is technically possible for it to happen, because we do have all the right players all in the same place,” Santos said. “We have the bugs, we have the parasites, we have people and animals.
“However, even though it's possible, it's probably still not likely, and that is largely because of the way that the parasite is actually transmitted to people,” she said.
People in the United States are less likely to sleep outside and are thus less likely to be bit by the bugs. The species of kissing bugs in the U.S. also doesn’t defecate as readily as others after feeding, so it is less likely to spread the parasite, she explained.
“It's really gross, it's fascinating,” Santos said.
Because Chagas symptoms can be mild and resemble those of other illnesses, many people don’t know they have the parasite, only finding out when their blood is tested during medical procedures or blood donation.
That’s what happened to a Missouri patient in 2017, according to state health officials. In a case study published in the CDC’s Morbidity and Mortality Weekly Report in 2020, a person's donated blood tested positive for the disease. She had no travel history, which indicated the infection had originated in Missouri.
After the patient learned she had Chagas, she was screened for heart problems, which showed she had a chronic case of infected cardiac tissue. The patient was treated with anti-parasite medication.
According to the Missouri Department of Health and Senior Services, it’s the only case of Chagas the state has documented in a resident.
Labeling the disease as endemic could lead doctors to consider such screenings, said Budge, of Wash U. That could mean patients like the Missouri woman could get treatment before serious health problems pop up.
“I think the target audience [for the article] was … public health officials, politicians, infectious disease specialists and other doctors trying to raise the awareness that when you have someone that has compatible signs and symptoms, you should think about this,” he said.
Hoft said he hoped the article would spur more interest in the disease. His lab has developed two potential human vaccines for Chagas, but they haven’t moved beyond preliminary testing.
“The hardest thing for me to get funded is Chagas,” Hoft said.
