Rare Disease Is Circulating In CA: How Kissing Bugs Are Playing A Role

A rare but deadly parasitic disease is spreading in California, and researchers estimate that about 300,000 people in the U.S. may already have it but are unaware.

Now, scientists are urging the U.S. to recognize Chagas disease as endemic.

The disease is caused by the parasite Trypanosoma cruzi, which is carried by blood-sucking insects known as triatomines, or “kissing bugs” — a type of conenose bug, according to the Centers for Disease Control and Prevention.

Chagas is especially dangerous because it can remain silent for years, only surfacing when it causes a heart attack, stroke or death. In California alone, experts suspect tens of thousands may be infected — more than any other state.

While there are about a dozen kissing bug species across the country, four found in California are known to carry the parasite. In some places, such as Griffith Park, roughly one in three kissing bugs is infected, according to the Los Angeles Times.

A recent California Department of Public Health study looked at kissing bugs collected across the state between 2013 and 2023. Of the 226 insects tested, about 28 percent carried the parasite Trypanosoma cruzi. The findings suggest that infected bugs are not only present in California, but relatively widespread — reinforcing concerns that residents may be at risk of contracting Chagas disease without ever leaving the state.

The same study also reviewed 40 confirmed human Chagas cases in California. While the majority were linked to exposure abroad, nearly a quarter could not be definitively tied to travel outside the U.S., leaving open the possibility that those infections were acquired locally. Researchers said the lack of standardized reporting and surveillance makes it difficult to know the true scope of transmission.

While the University of Florida reports that Chagas disease is considered rare in the United States, it's quite difficult to know exactly how many cases there are and how frequently it’s transmitted since it is not tested or reported to most state health departments.

“The biggest need is awareness, and that is the focus of our publication — to share the scientific perspective that Chagas disease is endemic in the U.S.,” said Gabriel Hamer, Ph.D., an entomologist with Texas A&M AgriLife Research. “Too often, medical and veterinary training programs dismiss Chagas as only a tropical disease, irrelevant to public and animal health in the U.S.”

Hamer is among the researchers and epidemiologists who recently published findings in the CDC’s September issue of Emerging Infectious Diseases, where a team from the University of Florida, Texas A&M, UC Berkeley, and the Texas Department of State Health Services urged the U.S. to recognize Chagas disease as endemic in order to strengthen surveillance, research and public health response.

Each year, Chagas disease claims more lives in Latin America than malaria. What's more, the disease is often stigmatized as one that is only contracted by poor rural residents of tropical nations.

“Too often, medical and veterinary training programs dismiss Chagas as only a tropical disease and irrelevant to public and animal health in the U.S.," Hamer said. “But kissing bug vectors, the parasite and locally acquired human cases are here. It is critical for our next generation of doctors and veterinarians to be aware of this vector-borne disease to assist with the diagnosis of humans and animal patients.”

It has long been thought that Chaga is a disease mostly contracted in far-off countries. But Hamer and his research team believe some cases are homegrown in the U.S.

Salvador Hernandez, a cardiologist with Kaiser Permanente in Northern California, told the Times that a kid from the Hollywood Hills recently contracted the disease. Since the child had not traveled out of the country, Hernandez said its likely that he got bitten by a kissing bug in his affluent neighborhood.

Hamer says there's no standardized reporting system or active surveillance in the U.S. In fact, many find out they have the disease after trying to donate blood, he told the LA Times.

Here are the symptoms of Chagas disease:

• Swelling at the infection site.
• Fever.
• Tiredness.
• Rash.
• Body aches.
• Eyelid swelling.
• Headache.
• Loss of appetite.
• Nausea, diarrhea or vomiting.
• Swollen glands.
• A larger liver or spleen.

If the disease is left untreated, symptoms of a "chronic phase" could appear after about 10 to 20 years, according to the Mayo Clinic. These symptoms include:

• Irregular heartbeat.
• Heart failure.
• Sudden cardiac arrest.
• Trouble swallowing.
• Stomach pain or trouble passing stool, called constipation.

The disease is curable with antiparasitic medications if caught early, but health experts say it isn't if it reaches the chronic phase. Once Chagas becomes more serious, medicines may be offered to help slow the disease and its most serious complications, according to the Mayo Clinic.

Kissing bugs spread the parasite in a roundabout way. After feeding on blood, the insects defecate near the bite site, leaving parasite-laden stool on the skin. The parasites can then enter the body through the eyes, mouth, a cut or scratch, or even the wound itself. Scratching or rubbing the bite — something that often happens while a person is asleep — makes it easier for the parasite to slip inside.

Chagas disease cannot be passed from simply being near an infected person. But transmission can occur in other ways: by eating uncooked food contaminated with infected bug feces, being born to a mother carrying the parasite, receiving blood or an organ from an infected donor, handling the parasite in a laboratory, or encountering infected wild animals such as raccoons or opossums.

Kissing bugs mostly bite animals, but when they bite people, they tend to bite on the face and near the mouth.

“Kissing bugs are pretty equal opportunity when it comes to who they take a blood meal from,” Sarah Hamer, an epidemiologist at Texas A&M University’s College of Veterinary Medicine and Biomedical Sciences, told the Times. She listed a variety of animals, such as ocelots, bobcats, coyotes, birds, reptiles and amphibians.

Chagas disease is also common in dogs, which can develop heart failure or dangerous arrhythmias much like humans. Dogs typically become infected by eating the bugs.

“We’ll see these acutely infected, usually young dogs that might be puppies, or dogs less than 1 or 2 years of age that are really adversely affected," Ashley Saunders, a Texas A&M veterinary cardiologist, told the Times." And then we would have dogs that would come in older, and they might be in heart failure."