Tejal Somvanshi
Recent scientific findings support classifying Chagas disease as endemic in the United States. A September 2025 report in the Centers for Disease Control and Prevention’s (CDC) journal Emerging Infectious Diseases calls for the U.S. to officially classify the disease as endemic, highlighting its growing presence across the country.
Researchers have documented the disease-causing parasite Trypanosoma cruzi in 32 states, with human infections confirmed in eight states: Arizona, Texas, Louisiana, Missouri, Mississippi, Arkansas, Tennessee and California. Texas has reported the most locally-acquired human cases.
“This is a disease that has been neglected and has been impacting Latin Americans for many decades,” said Norman Beatty, a medical epidemiologist at the University of Florida. “But it’s also here in the United States.”
Chagas disease is transmitted primarily through the “kissing bug” – a blood-sucking insect that typically bites people near their face while they sleep. The parasite lives in the bug’s feces, which can enter the body when a person scratches a bite. The disease can also spread from mother to child during pregnancy, through blood transfusions, organ transplants, and rarely through contaminated food.
Health experts estimate more than 300,000 people in the U.S. are infected with Chagas disease, including approximately 45,000 in Los Angeles County alone. Alarmingly, fewer than 2% of infected individuals know they carry the parasite.
“Most people living with Chagas disease are unaware of their diagnosis, often until it’s too late to have effective treatment,” said Judith Currier, chief of infectious diseases at UCLA Health.
The disease develops in two phases. During the acute phase, which lasts about two months after infection, symptoms may include fever, fatigue, body aches, headache, loss of appetite, diarrhea, and vomiting. A hallmark sign is severe swelling of the eyelid, according to Shaun Yang of UCLA’s David Geffen School of Medicine.
What makes Chagas particularly dangerous is its chronic phase. While many infected people remain symptom-free for years, about 20-30% eventually develop serious heart or digestive problems. The disease can cause an enlarged heart, heart failure, cardiac arrest, stroke, or an enlarged colon or esophagus.
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Gabriel Hamer notes that confirmed cases likely represent only a fraction of actual infections due to the lack of standardized reporting and active surveillance.
The disease is only reportable in eight states and two California counties (Los Angeles and San Diego), which means healthcare providers elsewhere aren’t required to report cases to public health authorities.
Salvador Hernandez, a cardiologist with Kaiser Permanente in Northern California, emphasizes that early detection is crucial: “If we screened for it and caught it early, most patients could be cured. The problem is we don’t, and people end up dying or requiring terrifically expensive care.”
Researchers found that in some areas, such as Los Angeles’ Griffith Park, about one-third of kissing bugs harbor the Chagas parasite. The insects have also been found in various wild animals, including wood rats, skunks, and bats, creating a large reservoir for the brain-affecting disease.
Scientists advocate for the U.S. to be classified as “hypoendemic” for Chagas disease, a designation that would increase awareness, improve surveillance, enhance research funding, and support better public health responses. Classification as endemic would also help medical schools properly educate future doctors about the disease.
Hamer emphasizes that the vectors and parasite are present in the U.S., local infections occur, and public health messaging should reflect this reality.
