Health officials say Chagas disease is now endemic in the U.S.; experts outline early signs

Health officials and researchers say Chagas disease, a parasitic infection spread by triatomine or "kissing" bugs, is now considered endemic in the United States, and they are urging awareness of key early warning signs so infections can be identified and treated before chronic complications develop.

The disease is caused by the parasite Trypanosoma cruzi and is typically transmitted when infected triatomine bugs defecate near a bite wound and the parasite is introduced into the body through the skin or mucous membranes. The bugs — blood-feeding insects about 0.5 to 1.25 inches long that hide during the day in dark crevices and come out to feed at night — have been detected in about 32 states. Human disease has been documented in eight states, and researchers estimate roughly 300,000 Americans have been infected, though the Centers for Disease Control and Prevention says the true number may be higher because up to 80 percent of infected people never develop symptoms.

Infections were first identified in Texas in 1955, and researchers say cases have spread to other parts of the country. While most infected people remain asymptomatic for years or decades, an acute phase in the weeks to months after infection can produce nonspecific symptoms such as fever, fatigue, body aches, rash, loss of appetite, diarrhea and vomiting. A distinct sign in some cases is Romaña's sign, a swollen, red and inflamed eyelid on the side of the bite when the parasite enters near the eye.

When Chagas disease progresses to its chronic phase it can cause serious and lasting damage. Cardiac complications include inflammation that injures cardiac muscle cells, scarring that impairs the heart's ability to pump and disruptions to electrical signaling that can cause irregular heart rhythms, heart failure and enlargement of the heart. Inflammation can also promote formation of blood clots that travel to the brain and cause stroke. In some patients chronic infections produce progressive damage to the enteric nervous system, enlarging the esophagus or colon, which can make swallowing and bowel movements difficult and contribute to malnutrition or intestinal blockages.

Two antiparasitic drugs, benznidazole and nifurtimox, are approved for treatment of Trypanosoma cruzi infection and are most effective when given in the early stages of disease. There is currently no vaccine to prevent Chagas disease. Health officials emphasize that timely detection and treatment can reduce the risk of long-term cardiac and gastrointestinal complications.

Experts say the disease was historically concentrated in parts of Latin America but has moved northward through a combination of migration, environmental change and other factors. Some scientists have pointed to deforestation and climate-related shifts, including warmer temperatures and increased rainfall, as potential contributors to expansion of triatomine habitats. Because Chagas is not closely tracked in the United States, public health authorities and researchers have warned that cases may be undercounted and that greater surveillance and awareness are needed.

State-level analyses indicate that California, Texas and Florida account for the highest estimated burdens of chronic Chagas disease in the United States, with researchers from the University of Florida estimating 70,000 to 100,000 people in California may be living with the infection. The CDC has said the recorded number of deaths linked to Chagas in the country appears to be low, but the precise toll is unclear.

Awareness of typical early symptoms and of the vector's habits — hiding in household cracks and emerging at night to feed — may help clinicians and patients identify infections sooner. Public health officials have called for improved screening in at-risk populations, expanded tracking of vector distribution, and education to help prevent transmission and ensure timely treatment when infections are detected.