Chagas Disease: An Overlooked Threat in the U.S.

Chagas disease might not be on your radar, but it’s present in California and 29 other states throughout the country.

This illness claims more lives annually in Latin America than malaria, and it’s estimated that around 300,000 individuals in the U.S. may have it without even knowing. The problem is that it often remains dormant for years, only revealing itself when it leads to serious health issues like heart attacks or strokes.

Chagas disease results from the parasite Trypanosoma cruzi, spread by bloodsucking insects known as kissing bugs. In the U.S., there are about a dozen species of kissing bugs, with four of them found in California that can carry this parasite. Studies indicate that in some locations, like Griffith Park in Los Angeles, nearly a third of kissing bugs may be infected.

This has prompted a group of epidemiologists and medical professionals to urge the World Health Organization and Centers for Disease Control and Prevention to categorize the disease as endemic in the U.S. They believe that doing so would foster awareness, education, and more public health investment in a disease that has long been stigmatized, often associated with impoverished migrants from tropical regions.

“This is a disease that has been neglected and has been impacting Latin Americans for many decades,” noted Norman Beatty, a medical epidemiologist at the University of Florida and a Chagas expert. “But it’s also here in the United States.”

Dr. Salvadore Hernandez, a cardiologist in Northern California, shared a case of a child from the Hollywood Hills who contracted the disease without ever leaving the country, likely infected by local kissing bugs.

Moreover, the parasite has been discovered in various local animals like wood rats, skunks, and mice in Griffith Park, as well as bats, raccoons, and even black bears across the state.

“Kissing bugs are pretty indiscriminate in who they feast on,” said Sarah Hamer, an epidemiologist at Texas A&M University. She highlighted a range of animals that attract these bugs, from ocelots to amphibians, indicating a large reservoir for T. cruzi.

California accounts for the highest number of Chagas infections in the U.S., estimated between 70,000 and 100,000 cases. This is largely due to its population, which includes many individuals from regions where the disease is common. Additionally, the parasite and its vector reside here, suggesting some cases might originate locally.

A small study by the California Department of Public Health revealed that between 2013 and 2023, 31 out of 40 reported human cases—roughly 78%—were acquired abroad. For the remaining instances, local transmission couldn’t be ruled out.

Chagas is not officially reportable in California, meaning there’s no requirement for health professionals to track it like they do with illnesses such as influenza or malaria. However, in Los Angeles and San Diego counties, it is reportable; Los Angeles was the first county in the state to implement this requirement.

From 2019 to 2023, about 18 cases were confirmed in L.A. County, although officials noted that many more likely go undiagnosed. Most identified cases were contracted internationally, though some appeared to be acquired locally.

Gabriel Hamer, an entomologist at Texas A&M, suggests that the actual number of infected individuals in the U.S. is likely much higher. “There’s no standardized reporting system. There’s no active surveillance,” he remarked.

Many people discover their infection only when they attempt to donate blood, as was the case for Janeice Smith, a retired teacher in Florida. She received a notification from her local donation center in 2022, prompting her to seek medical advice.

Smith believes she got infected back in 1966 during a family trip to Mexico, returning home with severe symptoms that went undiagnosed for years. Now, she runs a nonprofit focused on raising awareness about Chagas.

While the proteins in kissing bugs’ saliva can lead to immediate reactions, such as swelling or anaphylaxis, the long-term effects of the Chagas parasite are the most dangerous. It’s common for individuals to visit doctors with symptoms that resemble other health issues, such as heart arrhythmias or seizures, without ever having been screened for Chagas.

“The disease is definitely underdiagnosed,” Dr. Hernandez stated. “If we screened for it and caught it early, a lot of patients could be treated effectively. But the sad truth is that we don’t, and that leads to devastating outcomes.”

Anti-parasitic medications can halt the disease’s progression, but Chagas also affects pets, particularly dogs, who show similar symptoms of heart failure or arrhythmia.

“We often see younger dogs, even puppies, severely impacted by acute infections. Then there are older dogs coming in that are also in heart failure,” said Ashley Saunders, a veterinary cardiologist from Texas A&M. Dogs typically contract the disease by ingesting kissing bugs, receiving a higher dose of the parasite than from bites alone.