Endemic (Murine) Typhus in Returned Travelers from Asia, a Case Series: Clues to Early Diagnosis and Comparison with Dengue

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Two cases of endemic typhus are described in detail with a clinical summary of eight cases in returned travelers. Compared with a similar cohort of patients with dengue, typhus cases had higher CRP and less neutropenia. These findings may guide empirical therapy and improve use of definitive diagnostic tests. A report of the GeoSentinel Network identified rickettsial infection in 280 (1.5%) of around 14,000 febrile travelers.1 Only 10 individuals were considered to have endemic (murine) typhus caused by flea-borne infection with Rickettsia typhi. In a Swedish cohort of febrile returned travelers, 1% of 1,049 patients with routine testing and 4% of 383 patients with additional serological investigation were diagnosed with typhus group (R. prowazekii or R. typhi) rickettsiosis.2 Thirty-two cases of endemic typhus were identified in a retrospective analysis of all samples sent to the World Health Organization (WHO) Collaborative Center for Rickettsial Diseases and Other Arthropod-Borne Bacterial Diseases, Marseille, France, over a 3-year period.3 Of these cases, 13 individuals had traveled to Africa, and 12 individuals had traveled to Southeast Asia. There have been sporadic case reports of endemic typhus in tourists returning from Southeast Asia, including seven cases acquired in Indonesia,4–7 one case acquired in Thailand, and one case acquired in Vietnam.8,9 Conclusions from these reports are that endemic typhus remains a rare but probably underdiagnosed cause of febrile illness in returned travelers, severe presentations do occur,7and Southeast Asia is the main source. Indonesia is the most popular holiday destination for Western Australians, accounting for 259,737 (42% of total) annual short-term overseas departures according to the Australian Bureau of Statistics (2011). Since 2009, we have diagnosed endemic typhus in eight returned travelers. Here, we present two illustrative cases and a clinical summary of the series. Because it is a rare condition presenting as a non-specific febrile illness and most commonly diagnosed serologically, definitive diagnosis is often retrospective, requiring early treatment with doxycycline to provide adequate empiric cover. Because dengue fever was the most common working diagnosis in our series of patients, we compared initial laboratory parameters of endemic typhus patients with those parameters of a similar cohort of dengue patients to identify features that may help clinicians differentiate between these two infections.