Fast facts

• Cause: Trypanosoma cruzi parasite (not a virus or bacterium).
• Main vector: Triatomine “kissing” bugs; infection occurs when parasite-laden bug feces enter a bite wound or the eyes/mouth.
• U.S. presence: Kissing bugs occur in many southern and some mid-Atlantic states; most U.S. infections were acquired in Latin America, but rare local transmission has been documented, especially in Texas.
• Global burden: About 6–7 million people are infected worldwide; in the U.S., an estimated 300,000 people live with Chagas disease.
• Health impact: Often silent for years; 20–30% may develop serious heart disease, and a smaller number develop gastrointestinal complications.
• Treatment: Antiparasitic medications (benznidazole or nifurtimox) are most effective early but can still benefit many chronically infected people.

What is Chagas disease?

Chagas disease is a parasitic infection that can be acute (early) or chronic (long-term). The acute phase often causes mild or no symptoms. After this phase, most people enter a prolonged “indeterminate” stage without symptoms. Years or decades later, some develop chronic disease, most often affecting the heart (arrhythmias, cardiomyopathy, heart failure) and less commonly the digestive system (enlarged esophagus or colon).

How it spreads

• Insect-borne: Triatomine bugs feed on blood at night, typically around the face. The bugs can defecate near the bite, and the parasite enters the body if the feces are rubbed into the skin, eyes, or mouth.
• Congenital: A pregnant person with Chagas can pass the parasite to the baby during pregnancy or delivery.
• Blood/organ exposure: Before universal screening, transfusions and organ transplants were risks. U.S. blood donations are now screened, which greatly reduces the danger.
• Foodborne (rare in U.S.): Contamination of food or drink with the parasite can cause outbreaks.

Where are kissing bugs found in the U.S.?

Several species of kissing bugs live in the southern and southwestern U.S., with documented presence in parts of Texas, Arizona, New Mexico, California, and across the Gulf Coast and Southeast, extending into some mid-Atlantic states. Not every bug carries the parasite, and not every bite leads to infection. However, studies have found varying infection rates in captured bugs, and infected wildlife and dogs can serve as local reservoirs.

Most U.S. human infections are still in people who previously lived in or traveled to areas of Latin America where the disease is endemic. Locally acquired infections in the U.S. are uncommon but have been reported, especially in Texas.

Symptoms: what to watch for

Acute phase (days to weeks after infection)

• Fever, headache, fatigue, body aches
• Swelling at the bite site (chagoma) or painless swelling around one eye (Romana’s sign)
• Rash, swollen glands; occasionally liver/spleen enlargement
• Often mild or unnoticed

Chronic phase (years to decades later)

• Cardiac: irregular heartbeat, palpitations, fainting, chest pain, shortness of breath, heart failure, risk of stroke or blood clots
• Digestive (less common in the U.S.): trouble swallowing, reflux, chronic constipation from enlargement of the esophagus or colon
• Many remain asymptomatic but still infected

Who is at higher risk?

• People born in or who spent prolonged time in Mexico, Central America, or South America
• Infants born to mothers with Chagas disease
• People with unexplained cardiomyopathy or certain conduction abnormalities
• Recipients of blood transfusion or organ transplant in countries or eras without screening
• Residents of rural areas in southern U.S. with frequent exposure to kissing bugs or to outdoor structures that can harbor them (kennels, barns, chicken coops)

Diagnosis

• Acute infection: PCR or direct parasite detection in blood; prompt testing is crucial if acute Chagas is suspected.
• Chronic infection: Blood tests (serology). Because no single test is perfect, two different antibody tests are usually used to confirm.
• Congenital infection: Specialized testing for newborns of mothers with Chagas; negative early tests are typically followed by repeat testing later in infancy.

If you believe you are at risk, ask your clinician about testing. Testing and treatment are often coordinated with infectious diseases or cardiology specialists familiar with Chagas disease.

Treatment

Two antiparasitic drugs, benznidazole and nifurtimox, can clear the parasite. Treatment is most effective in the acute and congenital phases, but many chronically infected patients—especially younger adults without advanced heart disease—may still benefit.

• Benznidazole: Generally first-line in many cases; course lasts several weeks.
• Nifurtimox: Alternative option; also given for several weeks.

Side effects (such as rash, gastrointestinal upset, weight loss, insomnia, or neuropathy) are not uncommon and should be monitored by a clinician. Treatment during pregnancy is typically deferred, with close follow-up and testing of the newborn. People with Chagas cardiomyopathy need cardiac evaluation and management in addition to antiparasitic therapy considerations.

Prevention and home protection

• Seal entry points: Caulk cracks and gaps in walls, windows, doors, rooflines, and around utility penetrations. Install and repair window/door screens.
• Outdoor habitat management: Reduce wood, brush, and rock piles; keep firewood away from the house; tidy sheds and crawlspaces.
• Lighting: Minimize outdoor lighting at night or use yellow “bug” lights to reduce attraction.
• Pet areas: Keep dog kennels and chicken coops well-maintained and away from the home; consider elevating kennels, using tight-fitting screens, and reducing clutter where bugs can hide.
• Bed and sleeping areas: In endemic travel settings, use bed nets and keep sleeping areas sealed. In the U.S., ensure indoor sleeping spaces are well screened.
• Insect control: Work with local vector-control or pest professionals if kissing bugs are found; approved residual insecticides may be recommended in and around structures where bugs are detected.
• Blood and organ safety: U.S. blood donations are screened, which reduces risk. If you are a potential organ donor/recipient with exposure risk, discuss screening with your transplant team.

What to do if you find a kissing bug or think you were bitten

• Do not crush the bug with bare hands. If safe, place it in a clean, sealable container (or a bag) for identification. You can also take clear photos.
• Contact your state health department or university extension for identification guidance. Some public health labs or academic centers accept specimens.
• If a bite occurred, wash the area with soap and water. Seek medical advice if you develop fever, swelling at the bite, or other symptoms.
• If you believe you may have been exposed or are at risk because of where you lived or traveled, ask a clinician about testing for Chagas disease.

Pets and Chagas

Dogs can become infected and may develop heart disease. If you live in an area with kissing bugs:

• Keep kennels clean, in good repair, and away from the home’s exterior walls.
• Remove nearby brush piles and rodent nests that can attract bugs and wildlife reservoirs.
• Ask your veterinarian about regional risks. There is no approved vaccine or curative therapy for dogs, so prevention and environmental control are key.

Myths vs. facts

• Myth: “Every kissing bug bite gives you Chagas.” Fact: Many bugs are not infected, and even if infected, transmission requires parasite-containing feces to enter the body.
• Myth: “Chagas always causes severe symptoms right away.” Fact: Most infections are silent at first; serious complications often arise years later.
• Myth: “There’s no treatment.” Fact: Two medications can treat the infection, especially early; specialty care also manages heart or digestive complications.

When to seek medical care

• You have lived in or spent significant time in Latin America and have never been tested.
• You are pregnant or planning pregnancy and have risk factors for Chagas disease.
• Your infant was born to a mother with Chagas disease.
• You have unexplained heart rhythm problems or cardiomyopathy and an exposure history.
• You had a suspected kissing bug exposure with subsequent fever, swelling at the bite site, or other acute symptoms.

Learn more

• CDC: Chagas Disease (American trypanosomiasis) — https://www.cdc.gov/parasites/chagas/
• WHO: Chagas disease (American trypanosomiasis) — https://www.who.int/news-room/fact-sheets/detail/chagas-disease-(american-trypanosomiasis)
• American Heart Association Scientific Statements on Chagas cardiomyopathy
• Local/state health department vector control and university extension services

Note: This explainer is for general information and does not replace professional medical advice. If you have concerns about Chagas disease, consult a qualified healthcare professional.