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Editor’s note: In early October, the Los Angeles County Department of Public Health issued a press release about an outbreak of flea-borne typhus in downtown Los Angeles. National news coverage, including stories on CNN, NBC and CBS, followed. A slightly edited version of the LA Department of Public Health’s release appears here, as well as information about fleas and typhus from the Mallis Handbook of Pest Control.

Murine typhus is an important flea-transmitted human disease caused by Rickettsia typhi. Transmission occurs when the bodies of crushed fleas or their feces are scratched into an open wound or onto mucous membranes. Symptoms include fever, headache, rash and malaise.

Murine typhus is a cosmopolitan and endemic zoonosis, most prevalent in warm regions with suitable flea vectors along with rats and opossums serving as reservoirs. Although current prevalence of the disease is fewer than 100 cases per year, murine typhus is still the second most frequently reported rickettsial infection in the United States. Murine typhus is perceived as a clinically mild disease, and cases often go unrecognized.

In the U.S., murine typhus is most prevalent along the southeastern, southwestern and Gulf coasts, with Texas and regions of Southern California having the highest prevalence. Epidemiological studies have indicated that typhus reservoirs and vectors are spreading.

Historically, X. cheopis has been considered the main vector of murine typhus, but outbreaks of endemic typhus transmitted by cat fleas from opossums have been reported in suburban areas of Texas and California (Civen and Ngo 2008). A similar disease, flea-borne spotted fever caused by Rickettsia felis, is maintained in opossums and transmitted to humans by cat fleas (as well as C. canis and Pulex irritans) (Pérez-Osorio et al. 2008). Because symptoms of flea-borne spotted fever are similar to those of murine typhus, diagnoses may be misattributed. Flea-borne spotted fever appears to be cosmopolitan, occurring where cat fleas are found. Source: Mallis Handbook of Pest Control