Approximately 8 million people worldwide are infected with Chagas disease, and it kills more than 10,000 people every year. While most cases are concentrated in Latin America, an estimated 288,000 people currently living in the United States carry the parasite, making it far more present in North America than most people realize.
Global Numbers
Chagas disease is caused by the parasite Trypanosoma cruzi, spread primarily through the feces of triatomine bugs (commonly called “kissing bugs”) that bite people at night. The 8 million infections worldwide are heavily concentrated in 21 Latin American countries where the bugs are endemic, stretching from Mexico through Central and South America to Argentina and Chile. But migration has carried the disease well beyond those borders. Cases now appear regularly in the United States, Canada, Europe, Japan, and Australia.
To put its impact in perspective: a 2025 analysis published in The Lancet estimated that the economic burden of Chagas heart disease in the United States alone reaches nearly $5 billion annually. The study found the disease burden was 1.9 times greater than HIV, 8.8 times greater than malaria, and 35.4 times greater than tuberculosis, yet research funding remains disproportionately low.
Chagas Disease in the United States
The CDC estimates that roughly 288,000 adults in the United States are living with Chagas disease, the vast majority being immigrants from Latin American countries where they were originally infected. Of those, about 57,000 have already developed Chagas-related heart disease, and roughly 43,000 are women of reproductive age who could potentially pass the infection to their children during pregnancy.
Local transmission also happens on U.S. soil, though it’s uncommon. Researchers estimate about 10,000 cases of locally acquired infection exist in the country. Triatomine bugs have been documented in at least 28 states, with established populations in Texas, Arizona, California, New Mexico, Florida, and as far north as Pennsylvania. The insects live in cracks in walls, under porches, and in outdoor dog kennels, feeding on both animals and humans.
Despite these numbers, fewer than 1% of infected people in the U.S. ever get tested or treated. The acute phase of infection is usually silent or resembles a mild flu, so most people have no idea they’re carrying the parasite. Blood donor screening has offered a glimpse at how widespread undetected infection may be: when the American Red Cross screened nearly 149,000 donations at centers in Los Angeles, Oakland, and Tucson, roughly 1 in 4,655 came back confirmed positive for the parasite. In Los Angeles, the rate was closer to 1 in 2,000.
Why Most Infections Go Unnoticed
Chagas disease has two phases. The acute phase begins shortly after infection and lasts a few weeks. Most people experience no symptoms at all during this stage, or they develop a mild fever, body aches, and fatigue that look identical to dozens of other common illnesses. A small swelling at the bite site or around the eye (called a chagoma or Romaña’s sign) sometimes appears, but many people never notice it.
After the acute phase passes, the infection enters a long, silent chronic stage called the “indeterminate” form. The parasite persists in the body, particularly in heart and digestive tissue, but causes no symptoms. This phase can last decades. Many people live their entire lives without knowing they’re infected, which is why the disease is sometimes called “the silent killer.”
Risk of Serious Complications
About one-third of people with chronic Chagas disease eventually develop serious complications, most commonly a form of heart disease called Chagas cardiomyopathy. The parasite gradually damages heart muscle, leading to irregular heartbeats, heart failure, and an increased risk of sudden cardiac death. This progression typically unfolds over 10 to 30 years after the initial infection, which is why many patients aren’t diagnosed until they show up with unexplained heart problems in middle age.
A smaller percentage develop problems with the digestive tract, where the parasite destroys the nerves that control the esophagus or colon. This can cause these organs to dilate dramatically, making swallowing or passing stool increasingly difficult. The remaining two-thirds of infected people stay in the indeterminate phase indefinitely and never develop organ damage, though they can still transmit the parasite through blood donation, organ transplant, or pregnancy.
Mother-to-Child Transmission
Congenital Chagas disease occurs when an infected mother passes the parasite to her baby during pregnancy or birth. This happens in 1% to 10% of pregnancies involving infected women, depending on factors like the mother’s level of parasites in the blood and her immune status. In the United States, researchers estimate 22 to 108 congenital infections occur each year, though most are never identified.
The Pan American Health Organization has made eliminating mother-to-child transmission a priority, incorporating Chagas into its framework alongside HIV, syphilis, and hepatitis B. The World Health Organization’s 2030 roadmap calls for interrupting all transmission routes in endemic countries and reaching 75% treatment coverage among eligible patients. Infants treated early in life have cure rates above 90%, making early detection especially valuable.
Who Should Be Aware
Chagas disease is most common among people who grew up in rural areas of Mexico, Central America, or South America, particularly in adobe or thatch-roof homes where kissing bugs nest easily. If you or your parents were born in an endemic country, testing is straightforward: a simple blood test checks for antibodies to the parasite. The challenge is that most doctors in the U.S. and Europe don’t think to order it, and most patients don’t know to ask.
People living in the southern United States who find triatomine bugs in or around their homes face a small but real risk of local transmission. The bugs are most active at night, attracted to light, and tend to bite exposed skin on the face. Infection doesn’t come from the bite itself but from the bug’s feces, which it deposits near the wound. Rubbing the feces into the bite, eyes, or mouth allows the parasite to enter the body. Sealing cracks in walls, using screens on windows, and keeping outdoor lights off near bedrooms all reduce exposure.