Scrub typhus and rickettsial diseases in international travelers: A review

Abstract

Physicians caring for febrile returned travelers face the difficult task of recognizing the typical and atypical features of more than 16 known rickettsial diseases and separating these diseases from potentially serious nonrickettsial diseases. Currently available diagnostic tools are inadequate for timely diagnosis. This review summarizes the English-language literature concerning imported rickettsial diseases in international travelers and describes important clinical principles in diagnosis and treatment of these illnesses. -Travelers with imported rickettsial disease often become sick before or within a few days of return from an endemic region. Illness that begins more than 18 days after return is unlikely to be rickettsial in origin. The absence of a skin rash or exposure to a vector should not dissuade clinicians from considering the possibility of a rickettsial disease in a returned traveler. Finally, if empiric therapy does not result in defervescence within 48 hours, an alternative nonrickettsial illness should be strongly considered.

Rickettsial Infections in Southeast Asia: Implications for Local Populace and Febrile Returned Travelers

“…Because the incubation period for most rickettsial infections is 6-20 days, an illness that begins more than 18 days after return from a disease-endemic area is unlikely to be rickettsial in origin. 11,41 Because clinical features of rickettsial infections are nonspecific, many common febrile illnesses can mimic rickettsioses. 46 Differential diagnoses are wide and include viral infections, such as dengue, chikungunya, Epstein-Barr virus, cytomegalovirus, other herpesviruses, enteroviruses, flaviviruses, viral hepatitis, and human immunodeficiency virus; bacterial infections, such as typhoid fever, leptospirosis, disseminated gonococcal infections, and syphilis; and parasitic infections, such as malaria and toxoplasmosis.…”

“…Endemic (murine) typhus caused by R. typhi occurs in tropical and temperate climates. 11 It is carried by rat flea X. cheopis and typically thrives in markets, grain stores, breweries, and garbage depots where rats (mainly R. rattus or R. norvegicus) serve as the main reservoir. However, other rodent species and cats have also been implicated as reservoirs and cats fleas can also transmit the infection.…”

“…Infections have been reported among city dwellers in more affluent countries such as Singapore, and immigrant workers living in poor and unhygienic conditions seemed to be at a higher risk. 11,12,16,52,53 However, no associated seasonal or festive variation with murine typhus has been observed. 16,19,28,54 Flea bites and contamination of excoriated skin or respiratory tract with flea feces cause infections, and R. typhi can remain infectious in dried flea feces for 100 days.…”

“…41 Of all rickettsial diseases, scrub typhus is more likely to present with a severe clinical picture because of a more prominent inflammatory response, 42 which causes multiorgan dysfunction, meningoencephalitis, coma, and persistent neurologic deficits. 11,66 Pulmonary involvement occurs in up to 50% of patients 28,65 but clinical manifestation of acute respiratory distress syndrome is rare. [67][68][69][70] Mortality rates can be up to 25% and scrub typhus could be potentially mistaken for melioidosis or leptospirosis, which are more common in the region.…”

“…5,10 Physicians caring for the local populace and febrile returned travelers face the extremely difficult task of recognizing and differentiating rickettsial infections from other equally prevalent and important diseases. 11 The greatest challenge lies in diagnosing rickettsioses in a timely manner early in the course, when antibiotic use is most effective. 12 This report aims to provide a comprehensive review on the prevalence of rickettsial infections in Southeast Asia, with particular emphasis on the characteristics and clinical features of Rickettsia typhi, Orientia tsutsugamushi, and spotted fever group rickettsiae (SFGR).…”