A Concise Review of the Epidemiology and Diagnostics of Rickettsioses: Rickettsia and Orientia spp

Abstract

Rickettsioses are globally distributed and caused by the family Rickettsiaceae, which comprise a diverse and expanding list of organisms. These include two genera, Rickettsia and Orientia Serology has been traditionally the mainstay of diagnosis, although this has been limited by cross-reactions among closely related members and diminished sensitivity/utility in the acute phase of illness. Other techniques, such as nucleic acid amplification tests using blood specimens or tissue swabs/biopsy specimens, sequencing, and mass spectrometry, have emerged in recent years for both pathogen and vector identification. This paper provides a concise review of the rickettsioses and the traditional and newer technologies available for their diagnosis.

Keywords: Orientia; Rickettsia; diagnostics; rickettsioses; scrub typhus; spotted fever; vector-borne diseases.

FIG 1

Major rickettsioses described by causative agent, clinical syndrome, and vector by region. From references , , , and and the CDC Yellow Book (https://wwwnc.cdc.gov/travel/yellowbook/2018/infectious-diseases-related-to-travel/rickettsial-spotted-and-typhus-fevers-and-related-infections-including-anaplasmosis-and-ehrlichiosis). The map was created using mapchart.net.

FIG 2

Illustration summarizing samples that can be obtained from patients and invertebrates and the testing that can be conducted with respect to sample type.