Experts Say Chagas Disease Has Quietly Spread Across the U.S.; Call for Endemic Label Change

Public health experts are urging officials to reconsider the United States’ designation as nonendemic for Chagas disease, saying increasing evidence of the parasite and its insect vectors challenges the long-held classification and contributes to low awareness and underreporting.

In a report published this month in the Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal, researchers said that the parasites that cause Chagas disease and the triatomine insects that transmit them — commonly called “kissing bugs” — have been identified widely across the country. The CDC estimates roughly 280,000 people in the United States live with Chagas disease, a parasitic infection that can remain dormant for years and later cause severe cardiac and digestive illness in a proportion of infected people.

The report notes that kissing bugs have been identified in 32 states and that autochthonous — locally acquired — human cases have been confirmed in at least eight states: California, Arizona, Texas, Tennessee, Louisiana, Missouri, Mississippi and Arkansas. The authors acknowledged that data are currently inadequate to prove a clear increase in the insects’ presence, but said encounters with kissing bugs are being recognized more frequently because of greater human contact and increased research attention.

Chagas disease is caused by the parasite Trypanosoma cruzi. Transmission typically occurs when a triatomine bug bites a person and then defecates near the bite site; parasites in the bug’s feces can enter the body through the eyes, mouth or an open wound. Infection can also happen through consumption of food contaminated with infected bug feces, from infected donor blood or organs, or from contact with infected wild animals. Person-to-person transmission is not the usual route for Chagas disease.

Many people who become infected show no symptoms during the acute or chronic phases. When symptoms do occur soon after infection, they are often mild and short-lived, including swelling at the site of infection, fever, rash and muscle aches. Without treatment, the parasite can persist in the body. The CDC and medical sources report that about 20% to 30% of infected people eventually develop serious complications, sometimes 10 to 20 years after infection. Those complications can include life-threatening heart problems such as heart failure or arrhythmias and digestive tract disorders, including enlargement of the esophagus or colon that can interfere with eating and bowel function.

Public health experts who authored the report argued that continuing to label the United States as non–Chagas disease–endemic perpetuates low awareness and underreporting, which can impede diagnosis, treatment and prevention efforts. The paper called for increased surveillance, more comprehensive data collection and heightened clinical awareness so that cases acquired in the United States are not missed.

There are currently no vaccines to prevent Chagas disease. Preventive measures recommended for people living in or traveling to higher-risk areas include reducing indoor insect habitats, using bed nets treated with insecticide, applying insecticides around dwellings and using insect repellent on exposed skin. Avoiding sleeping in structures made of mud or thatch is also advised in settings where triatomine bugs thrive.

Clinicians and public health authorities note challenges in detection and reporting. Because many infected people are asymptomatic for years and because the disease has historically been associated with other countries in the Americas, cases acquired domestically can be missed. The report’s authors said redefining the United States as endemic could prompt stronger diagnostic, screening and treatment strategies and encourage funding for research and vector control.

The extent of Chagas disease in the United States remains incompletely characterized. The CDC’s estimate of roughly 280,000 infected residents reflects available data on people who acquired the infection abroad and those identified in the United States, but gaps in surveillance and testing mean the actual number could differ. The Emerging Infectious Diseases report does not claim an immediate surge in vector populations; rather, it emphasizes that increased recognition of triatomine insects and confirmed local cases merit a reassessment of the country’s nonendemic status.

Medical organizations and public health agencies say that clinicians should consider Chagas disease in patients with compatible clinical signs or relevant exposure histories and that people with concerns about exposure seek medical advice. Steps to reduce contact with kissing bugs and to limit opportunities for parasite transmission are the primary current means of prevention while research into diagnostics, treatments and potential vaccines continues.