Chagas Disease Case Confirmed in San Diego County

In a significant development, San Diego County has reported its first case of Chagas disease, with the infection acquired locally.

This case emerged during a routine blood donation screening and involved a donor who, interestingly enough, showed no symptoms, according to county spokesperson Fernanda Lopez Halvorson.

Chagas disease is caused by the Trypanosoma cruzi parasite, often transmitted when infected feces from the triatomine insect—commonly called a kissing bug—enter a bite wound. While more prevalent in Latin America, instances have been rising in California recently.

It’s worth noting that the type of triatomine found in California differs from those in Latin America. These insects typically inhabit rodent nests instead of homes, which could make outdoor activities, like camping, somewhat risky. However, infectious disease expert Dr. Peter Chin-Hong emphasizes that there’s no need for panic. In California, kissing bugs are less likely to invade homes, often choosing to dwell near wood rat nests.

“California infection is quite rare,” Chin-Hong elaborated. “People usually have to venture into the woods to encounter these bugs. It’s not a cause for alarm, but caution is always wise, similar to the hantavirus situation.”

Chin-Hong also pointed out that local transmission of the disease is infrequent. In most regions where kissing bugs are found, they tend to defecate while biting, letting the parasites enter through the wound. However, in California, these insects often leave the host first, which reduces the chances of parasite-laden feces being introduced into the bite area.

Additionally, blood donation screenings have been crucial in identifying individuals who might be unaware of their infection, as many can remain symptom-free for years.

Since the introduction of mandatory reporting for Chagas disease in San Diego County in 2024, health officials have tracked 22 reports, confirming four cases so far, including this newly identified local infection.

Dr. Sayone Thihalolipavan, the county’s public health officer, noted that this case serves as a reminder that Chagas isn’t just confined to Latin America anymore.

A review published in 2025 by the Centers for Disease Control and Prevention highlighted the increasing prevalence of Chagas disease in the U.S., suggesting it shouldn’t be viewed as solely a foreign illness. Researchers documented kissing bugs in 32 states and confirmed locally acquired human cases in seven, leading to new reporting requirements in both San Diego and Los Angeles counties.

While early stages of Chagas can result in mild, flu-like symptoms—including fever and swelling at the bite site—long-term complications can become serious. About 30% to 40% of those infected may face significant heart or gastrointestinal issues over time.

Chin-Hong is particularly concerned about heart complications, which can manifest years after the initial infection, potentially leading to heart failure or irregular heart rhythms. To mitigate risks, he advises minimizing contact with rodents and their nests, sealing entry points in homes, and seeking professional identification of any kissing bugs found indoors. People diagnosed with the disease can receive antiparasitic treatment or supportive care if symptoms worsen.