Los Angeles County, California, 2022
Alarcón J, Sanosyan A, Contreras ZA, et al. MMWR Morb Mortal Wkly Rep 2023;72:838–843. DOI: http://dx.doi.org/10.15585/mmwr.mm7231a1
Abstract. Fleaborne typhus (also known as murine typhus), a widely distributed vectorborne zoonosis caused by Rickettsia typhi, is a moderately severe, but infrequently fatal illness; among patients who receive doxycycline, the case-fatality rate is <1%. Fleaborne typhus is a mandated reportable condition in California. Reported fleaborne typhus cases in Los Angeles County have been increasing since 2010, with the highest number (171) reported during 2022. During June–October 2022, Los Angeles County Department of Public Health learned of three fleaborne typhus–associated deaths. This report describes the clinical presentation, illness course, and methods used to diagnose fleaborne typhus in these three cases. Increased health care provider and public health awareness of the prevalence and severity of fleaborne typhus and of the importance of early doxycycline therapy is essential for prevention and treaogy oftment efforts.
Comment. For detailed accounts on the evolution and extent of this problem in Los Angeles and Orange Counties see Cummings et al. (2022: PMVCAC 90: 33-42). As reviewed, the epidemiology and etiology of typhus has been somewhat confounded by the occurrence of two rickettsia with differing life cycles and transmission patterns. However, the expansion of urban rodent, opossum and feral cat populations clearly have exacerbated the problem. The spread of homeless encampments is a related issue. Clinical research is needed to identify which rickettsia are involved in human disease, to delineate the extent of human infection in California, and to identify risk factors that may be targets for public health/vector control district intervention. Although human cases mostly seem confined to southern California, Rickettsia felis most likely is present wherever cat flea populations are found.
[Submitted by the Vector and Vectorborne Disease Committee]