Overview

Flea-borne typhus, a disease that many may consider outdated, is experiencing a resurgence in certain areas of Southern California. Health officials have noted a significant increase in cases in Los Angeles and Orange Counties, while San Diego County has reported minimal occurrences.

Last year, Los Angeles County recorded a historic high of 220 cases, a rise from 187 the previous year. In contrast, San Diego County has maintained a low incidence of the disease, with no cases reported in 2025 or thus far in 2026.

Key details

  • Flea-borne typhus is caused by the bacteria Rickettsia typhi.
  • The disease is transmitted by infected fleas, which are often found on animals such as rats, opossums, and stray cats.
  • Individuals do not contract the disease directly from flea bites.
  • Infection occurs when bacteria from flea droppings enter the skin.
  • Symptoms of flea-borne typhus can appear one to two weeks after exposure.
  • Common symptoms include fever, headaches, body aches, vomiting, and rash.
  • Los Angeles County has seen a dramatic increase in cases, with a record number reported last year.
  • Orange County is also experiencing a rise in flea-borne typhus cases.
  • San Diego County has reported few cases in recent years.
  • No cases of flea-borne typhus have been reported in San Diego County for 2025 or 2026.
  • Dr. Anne Kjemtrup, a research scientist and epidemiologist, provided insights into the transmission and symptoms of the disease.
  • Flea droppings can infect individuals when scratched into a wound.

Context

The rise in flea-borne typhus cases in parts of Southern California highlights a public health concern, particularly in areas where the disease is more prevalent. The contrast with San Diego County's low case numbers suggests a localized issue that may require further investigation.

What happens next

Health officials may continue to monitor the situation in Southern California, particularly in Los Angeles and Orange Counties, while maintaining awareness in San Diego County to prevent any potential outbreaks.

What we don't know yet

Details regarding the specific factors contributing to the rise in cases in Los Angeles and Orange Counties are not confirmed. Additionally, it is unclear what measures, if any, will be implemented to address the increasing cases in those areas.