Chagas disease, a parasitic illness often associated with rural areas in Latin America, is drawing increased attention in the United States. The disease is caused by the parasite Trypanosoma cruzi and spread by triatomine insects, commonly called “kissing bugs.”
“Chagas disease is caused by a parasite called Trypanosoma cruzi, and while it’s often associated with rural areas in Latin America, evidence is mounting that it’s likely more common in the U.S. than we think,” says Dr. Wesley Long, medical director of diagnostic microbiology at Houston Methodist.
Recent findings from the Centers for Disease Control and Prevention (CDC) suggest Chagas disease should be considered endemic to the U.S., particularly in southern states such as Texas.
The transmission occurs when kissing bugs feed on infected animals or people and then defecate during feeding. If their feces enter a bite wound or mucous membranes, infection can result.
A systematic review found 29 confirmed and 47 suspected cases of locally acquired Chagas disease in the U.S. between 2000 and 2018. However, experts believe these numbers do not reflect the actual number of infections because most states have not started tracking cases systematically.
“While some states, like Texas, Arizona and Arkansas, have started tracking Chagas cases in the last decade, most states haven’t — making it difficult to understand the full scope of the disease,” adds Dr. Long.
Kissing bugs have been identified in 29 U.S. states, and studies indicate about half carry the Chagas parasite. While most infections occur in Latin America, locally acquired cases have been documented in eight U.S. states including Texas.
“There’s a general lack of familiarity about the disease, from both the public at large but also health care providers,” adds Dr. Long. “The reality is that most infections likely go undiagnosed and subsequently unreported.”
Chagas disease has two stages: acute and chronic. In its early phase, symptoms may include fever, fatigue, body aches, headache, diarrhea or vomiting; one distinctive sign is swelling of an eyelid known as Romaña’s sign if infection enters through the eye.
After this stage passes without detection or treatment—something experts say happens frequently—the chronic stage can last for years without symptoms before about 20% of those infected develop serious heart or digestive complications.
“Yes, it’s rare, but Chagas disease is something doctors should be thinking about in the right patients,” warns Dr. Long. “This is what’s needed to catch the disease before cardiac symptoms appear and become severe.”
Early diagnosis improves outcomes significantly but remains challenging due to limitations with antibody-based tests that sometimes produce false positives.
“A drawback of serological tests is that you’re looking for antibodies that react against the parasite, but you may have antibodies that aren’t due to the infection but still react with the test, giving you a false positive,” explains Dr. Long.
Dr. Long recommends follow-up testing when unexplained cardiac or gastrointestinal symptoms are present along with risk factors such as residence in southern states where kissing bugs are common; other risk factors include living rurally or engaging frequently in outdoor activities like hunting or camping.
To reduce risk from kissing bugs—and thus potential exposure to Chagas—public health guidance emphasizes sealing homes against insect entry points such as windows and doors; inspecting living spaces regularly; using tents with netting while outdoors; keeping pets’ sleeping areas clean; and situating kennels away from brushy zones.
