The Centers for Disease Control and Prevention of the United States announced in September 2025 that Chagas disease, also known as American trypanosomiasis, is now considered endemic within the country. This decision reflects evidence of ongoing local transmission and regular local occurrence rather than cases being solely imported from Latin America.
Chagas Disease Officially Declared Endemic in the United States by the U.S. Centers for Disease Control and Prevention
What is Chagas Disease and Where Does it Come From?
Chagas disease is a parasitic disease caused by the parasite Trypanosoma cruzi. This protozoan parasite is transmitted to humans and other mammals through the bite of kissing bugs or insects in the subfamily Triatominae. The insect bites human skin, often on the face, and later defecates near the wound, allowing parasites to enter when a person scratches.
Triatomine bugs are present across several U.S. regions. This raises concern about potential disease transmission. Studies in Texas have confirmed that some carry the parasite. In Los Angeles County, current research suggests local kissing bugs are unlikely to harbor the parasite, though changing environmental conditions could significantly alter transmission dynamics.
Kissing bugs typically thrive in the cracks of adobe or mud walls and frequently inhabit areas with rodents or domestic pets, which can act as alternate hosts for the parasite. Experts warn that climate change may expand their geographic distribution northward, increasing exposure risk in regions that previously experienced minimal concern about Chagas transmission.
The parasitic diseases can also spread through congenital transmission during pregnancy, via contaminated blood transfusions, organ transplants, or by consuming uncooked food containing the parasite. Note that blood donations in the U.S. have included screening for Chagas disease since 2007. 1 in 275000 blood donors tested positive. This is a substantial ratio.
Estimates from the CDC indicate that more than 300,000 people in the United States are currently infected with the parasite Trypanosoma cruzi. In Los Angeles County alone, public health officials estimate that about 45,000 residents are affected. However, fewer than 2 percent of these infected individuals are actually aware of their infection status or conditions.
Globally, Chagas disease affects an estimated 8 million people, the vast majority residing in Latin America, where transmission has been documented for decades. The acknowledgment of endemic transmission in the United States elevates public health concern, drawing attention to a condition historically concentrated in Mexico, Central America, and South America.
What Makes Chagas Disease a Serious Health Condition?
Symptoms of Chagas disease vary significantly depending on the stage of infection. During the acute phase, which usually lasts for about two months, individuals may present with fever, fatigue, headache, loss of appetite, diarrhea, vomiting, or a swollen eyelid, although many remain asymptomatic, delaying recognition, diagnosis, and timely treatment.
The chronic phase often remains silent for many years, yet approximately 20 percent of infected individuals ultimately develop serious and life-threatening complications. These may include an enlarged heart, progressive heart failure, sudden cardiac arrest, or digestive tract disorders such as an enlarged esophagus or colon. Diagnosis frequently occurs too late.
According to Judith S. Currier, Chief of Infectious Diseases at UCLA Health, delayed diagnoses remain common because many patients are unaware they are at risk. She underscored the need for the medical community to expand awareness campaigns and patient education, particularly among individuals from Latin America presenting with unexplained heart problems.
Shaun Yang, a professor of clinical microbiology at UCLA, further explained that scratching the bite wound or bitten area significantly increases the risk of Trypanosoma cruzi infection because it introduces parasite-containing insect waste into the body. He highlighted the need for clinicians to ask detailed travel and background questions during patient evaluations.
Current treatment options remain limited. Antiparasitic medications are primarily effective during the acute phase of infection or in cases of reactivation following organ transplantation. Once antibody tests confirm past exposure, drugs cannot reverse the condition, underscoring the critical importance of early detection to reduce severe long-term complications.
Moreover, in advanced cases of Chagas-related heart failure, heart transplantation remains a viable option. UCLA Health physician Joanna M. Schaenman stated that transplant patients with Chagas respond well. However, because reactivation may occur, continuous monitoring and antiparasitic treatment during reactivation are needed for successful outcomes.
FURTHER READINGS AND REFERENCES
- Beatty, N. L., Hamer, G. L., Moreno-Peniche, B., Mayes, B., and Hamer, S. A. 2025. “Chagas Disease, an Endemic Disease in the United States.” Emerging Infectious Diseases. 31(9). DOI: 3201/eid3109.241700
- S. 2 September 2025. “Chagas Disease, Which Can Be Deadly, is Now Considered Endemic in the U.S.” UCLA Health News. UCLA Health. Available online
Photo Credit: Heigen Villacarlos / Kissing Bug / 2022 / Adapted / CC BY-SA 4.0