Chagas disease, a parasitic infection that can cause heart disease and stroke, has spread from South and Central America to the United States in recent decades, according to a statement from the American Heart Association (AHA) published this week in the journal Circulation. The statement aims to help U.S. doctors better recognize, diagnose, and treat the infection, which is transmitted by an insect called the kissing bug.
About one-third of people who are infected with the parasite that causes Chagas disease develop chronic heart problems at some point in their lives. The infection often goes undiagnosed until it’s too late, experts say, which is why early screening and prevention practices are so important.
To learn more about Chagas disease, Health spoke with Paula Stigler-Granados, PhD, assistant professor at Texas State University's School of Health Administration. Stigler-Granados was not involved in the AHA’s new statement, but she has researched Chagas disease extensively. Here’s what she, and the AHA, want people to know about this scary-sounding and often silent disease.
What is Chagas disease, and how is it spread?
Chagas disease is an infection caused by Trypanosoma cruzi, a parasite that lives in the gut of the triatomine insect—also known as the kissing bug because of its tendency to sometimes (but not always) bite humans near their mouths, while they sleep.
The T. cruzi parasite isn’t spread through the kissing bug’s bite in the same way that mosquito-borne viruses are; it’s spread through its feces. “If the kissing bug bites you and it has a blood meal and then it defecates, and then you scratch that area and rub it into the wound or rub your eyes, you could become infected,” says Stigler-Granados. (“Yes, it’s disgusting,” she adds.)
In other words, says Stigler-Granados, “all the stars have to align,” for someone to become infected. Those who do may have no symptoms at all, or may develop a mild flu-like illness that can last a few weeks. After that, they can feel fine, and be completely healthy, for a period of time. “For some people this period lasts a year, for some it’s 30 years, and for some it’s a lifetime,” says Stigler-Granados.
But eventually, 30% to 40% of people who are infected get sick: They can develop cardiovascular disease, heart failure, or life-threatening arrhythmias, and suffer strokes or cardiac arrest. “We still don’t really know what makes a person susceptible to developing full-blown Chagas disease versus never getting it at all,” says Stigler-Granados.
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How prevalent is Chagas disease in the United States?
The Centers for Disease Control and Prevention (CDC) estimates that there are about 300,000 people living in the U.S. with Chagas disease and that most of them acquired it in other countries. But Stigler-Granados says that number is a calculation based on immigrant populations moving to the United States, not on actual documented cases. Some experts, she says, believe the true number is closer to 1 million.
Kissing bugs are common in Central and South America, but they’ve also been reported in 27 states in the Southern U.S. And according to Stigler-Granados’ research, about 60% of the bugs tested here are infected with T. cruzi.
Trypanosoma cruzi, the parasite that causes Chagas disease, in a blood smear under a microscope
Smith Collection/Gado/Getty Images
According to the AHA, Chagas disease has spread to the United States and other new countries over the past 40 years. But some experts think the disease has been here longer than that.
“There’s some research on suspected cases that date back to the early 1900s,” says Stigler-Granados. “It’s possible that it’s always been here, and we just haven’t been looking for it. We’ve probably had quite a few misdiagnosed cardiovascular disease cases over the years that were actually Chagas disease.”
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Who is at risk?
Anyone living in Latin America, or who has spent significant amounts of time there, is at increased risk for Chagas disease. But Stigler-Granados says that people who live or have lived in the southern United States are, as well—especially those living in rural or poor areas.
People living in low-income, substandard housing facilities may be more exposed to bugs, especially while they sleep at night. But being wealthy doesn’t make you immune. “It’s a complete myth that [kissing bugs] are only found in mud huts,” Stigler-Granados says. “We see them everywhere, including million-dollar homes.”
Chagas disease can’t be transmitted from person to person through touching or saliva. But it can be transmitted through blood transfusions or organ transplants, or passed on from a pregnant woman to her baby. Rarely, it can also be passed through food or beverage that’s been contaminated with kissing-bug feces.
How can you protect yourself?
Anyone who lives in a state where kissing bugs have been identified should know what they look like and what to do if you find one, says Stigler-Granados. In her previous position at the University of Texas, she co-authored an image-based consumer guide—in English and Spanish—about how to identify kissing bugs and what people should know about Chagas disease.
Three species of kissing bugs found in the Southern United States: Triatoma protracta, Triatoma gerstaeckeri, and Triatoma sanguisuga
Curtis-Robles et al. (doi:10.1371/journal.pntd.0004235) [CC BY 4.0 (https://creativecommons.org/licenses/by/4.0)], via Wikimedia Commons
The bugs are large—usually larger than a penny–and most species have a band of orange or red stripes around the edge of their bodies. In Texas, if people find kissing bugs in their homes, they can mail them in for free testing; if the bug comes back positive for T. cruzi, anyone living in that home can get a blood test to see if they’ve been infected, as well.
Stigler-Granados notes that the kissing bug does have several lookalikes, including its relative, the assassin bug. “One way to tell the difference is that bites from the kissing bug are painless, but bites from the assassin bug hurt like hell,” she says. “If it hurts when they bite you, it’s probably not a kissing bug.”
Stigler-Granados believes that pregnant women living in the South or who have lived in South or Central American countries should be screened for Chagas disease; so should anyone who has a parent or sibling who’s been diagnosed.
Animals, including dogs, can also get Chagas disease. Anyone with a pet who’s been diagnosed should also be screened, says Stigler-Granados, since they’re living in the same environment and have likely been exposed to kissing bugs, as well.
One problem, however, is that many doctors don’t know much about Chagas disease. “If you ask for a test, most doctors will tell you you’re crazy, or that you don’t need it, or that they don’t know even know where to start,” says Stigler-Granados. “They think it’s a tropical disease that we don’t have here in the United States.”
That’s why Stigler-Granados is excited about the AHA’s statement and hopes that doctors will become increasingly familiar with Chagas disease and what’s needed to diagnose and treat it. “Just getting them up to speed on how to order the test and how to bill for it is half the battle,” she says.
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How is Chagas disease treated?
Medications are available to treat Chagas disease if it’s caught in the early stage, before damage to the heart and cardiovascular system is done. Unfortunately, that means it has to be screened for and diagnosed before symptoms appear—either because a person knows they were bitten by or exposed to kissing bugs, or because a doctor recognizes that they’re at high risk.
The current treatment options available have a 60% to 90% success rate, according to the AHA, depending on when a patient is diagnosed and treated. The drugs can also have side effects and aren’t recommended for people over 50, says Stigler-Granados, but for many people, they can be a life-saving.
There aren’t currently medications available for dogs or other animals—who can also die of Chagas disease—but Stigler-Granados says that clinical trials are in the works. “I’m hoping in the next year or two we get more traction and see more advances,” she says, “in both animal and human research.”