San Diego County Confirms First Locally Acquired Chagas Disease Case in Asymptomatic Blood Donor
San Diego County health officials have confirmed the region’s first locally acquired case of Chagas disease, detected during routine screening of a blood donation from a person who showed no symptoms at the time.
The confirmation marks a notable development for a disease that has historically been associated with rural Latin America. While Chagas remains far more prevalent in those regions, the case serves as a reminder that the infection can be acquired closer to home — particularly for people with outdoor exposure in areas where the insect responsible for transmission is present.
How Chagas spreads and why this case is significant
Chagas disease is caused by a parasite transmitted primarily through the bite of triatomine insects, commonly known as kissing bugs. In Latin America, these insects typically inhabit homes made of mud, adobe, or thatch, making rural and low-income housing a significant risk factor. The kissing bug species found in San Diego County behaves differently — it tends to live in rodent nests and wild habitats rather than inside homes, meaning camping and outdoor activities represent the most likely exposure routes locally.
San Diego County made Chagas disease locally reportable in 2024 to improve surveillance and raise awareness. Since then, officials have received 22 reports, four of which have been confirmed. This fourth confirmed case is the first determined to have been acquired locally rather than through travel or residence in an endemic country.
“Identifying a locally acquired Chagas case reminds us that this disease is not limited to Latin America,” said Dr. Sayone Thihalolipavan, County Public Health Officer. “Our priority is making sure residents and healthcare providers have the information they need to stay protected.”
Symptoms, risks and long-term complications
One of the most significant challenges with Chagas disease is that early infection frequently produces no symptoms at all, or only mild ones that are easily mistaken for other illnesses — including fever, headache, cough, abdominal pain, or localised swelling near the bite site.
People who have lived in countries where Chagas is endemic may have been infected years or even decades ago without knowing it. If untreated, the disease can be passed from a pregnant person to their infant during pregnancy.
The long-term consequences can be serious. Approximately 30 to 40 percent of people with untreated Chagas infection will go on to develop significant heart or gastrointestinal complications — sometimes decades after the initial infection occurred, often with no warning signs in the intervening years.
Who should consider being screened
County health officials are particularly encouraging people who have lived in Latin America to speak with a healthcare provider about screening, with pregnant women identified as a priority group given the risk of transmission during pregnancy.
For those travelling to areas where Chagas is endemic, health officials recommend wearing protective clothing, using insect repellent, sleeping indoors, using insecticide-treated bed nets, and avoiding unpeeled or uncooked fruits and vegetables that could carry contamination.
Anyone experiencing symptoms that might be consistent with Chagas disease is advised to contact a healthcare provider promptly. County Public Health is continuing to work with healthcare providers across the region to investigate cases, monitor for additional transmission, and provide clinical guidance.
Further information is available through San Diego County’s Chagas disease and kissing bug public health webpages.
