On Sept. 3, 2025, California health officials confirmed the presence of Chagas disease in the state, a parasitic infection caused by Trypanosoma cruzi spread by triatomine or “kissing” bugs; public-health experts warn the Bay Area could face increased risk if infected insects expand northward.
Key Takeaways
- State officials have confirmed Chagas disease has been detected in California as of Sept. 3, 2025.
- The parasite Trypanosoma cruzi is carried by triatomine (kissing) bugs; contact with infected feces at a bite site causes transmission.
- World Health Organization estimates more than 7 million people are infected worldwide and over 10,000 die annually from Chagas-related complications.
- Infected kissing bugs have been increasingly reported in Southern California counties, raising concerns about northward spread.
- San Francisco health officials say there is currently no evidence of increased Chagas activity within the city.
- Early symptoms can be mild or localized; chronic infection may cause severe cardiac and gastrointestinal damage years later.
- Screening is recommended for people from endemic regions and for those with suspicious symptoms after rural exposures; antiparasitic treatment is most effective when started early.
Verified Facts
Chagas disease is caused by the parasite Trypanosoma cruzi and is usually transmitted when an infected triatomine insect feeds on a person and parasite-containing feces enter the bite wound or mucous membranes. The World Health Organization estimates over 7 million people are infected globally, with more than 10,000 deaths each year attributable to the disease.
Health authorities and infectious disease specialists have confirmed the parasite has been identified in California in 2025. News reports and regional surveillance have documented increases in infected kissing bugs in Los Angeles and San Diego counties, signaling a wider presence of the parasite among local insect populations.
Clinically, acute Chagas can produce localized swelling (sometimes around the eye), fever or rash. The most serious risk is chronic disease: heart muscle damage that disrupts electrical conduction and can lead to heart failure, and enlargement of the esophagus or colon that impairs swallowing and digestion. Antiparasitic drugs can clear infection if administered early, reducing long-term complications.
Context & Impact
Triatomine insects are native across much of California, especially in rural, foothill and mountain habitats where they often nest near wood rats and other wildlife. Experts caution that once infected insects become established in a new area, local transmission to humans or domestic animals can follow if preventive measures are not taken.
Public-health implications include the need to expand surveillance, increase clinician awareness, and update testing protocols. Some clinics, such as UCSF’s infectious disease service, already screen patients from regions where Chagas is common; broader screening strategies may be considered if local transmission grows.
For outdoor enthusiasts, campers and residents of rural areas, practical measures include reducing rodent habitat near homes, using bed nets in rustic sleeping situations, sealing cracks in housing, and avoiding sleeping directly on the ground where bugs may feed at night. Early recognition of signs after a suspected bite can prompt testing and timely treatment.
Official Statements
“Currently there are no signs of increased activity of Chagas disease in San Francisco.”
San Francisco Department of Public Health
“Chronic Chagas can be dangerous,” said an infectious disease specialist noting risks of heart rhythm problems, heart failure and esophageal enlargement.
Dr. Monica Gandhi, UCSF
Unconfirmed
- Precise number of infected triatomine insects detected across California and the specific counties with confirmed positive insects or human cases have not been published publicly.
- Extent and timing of any locally transmitted human Chagas cases in northern California or the Bay Area remain unclear.
- California Department of Public Health’s detailed statement and data were not available at the time of initial reports.
Bottom Line
The confirmed presence of Trypanosoma cruzi in California is a public-health concern that warrants enhanced surveillance, clinician awareness and public education—especially for people living or traveling in rural and foothill regions. Early testing and treatment reduce risks, so clinicians should consider Chagas in relevant clinical contexts and residents should take simple measures to reduce insect and rodent exposure.