Rickettsialpox is zoonotic disease caused by Rickettsia akari. It is transmitted to humans from house mice or other rodents via mites. Symptoms are an initial local skin lesion and a generalized papulovesicular rash. Diagnosis is by serology, immunofluorescence antibody assay, and polymerase chain reaction (PCR) testing. Treatment is not always necessary, but doxycycline can reduce symptom duration.
Rickettsialpox, a rickettsial disease, occurs in many areas of the United States and in Russia, Korea, and Africa.
The vector, a small, colorless mite (Liponyssoides sanguineus), is widely distributed. It infects the house mouse and some species of wild mice. Humans may be infected by mite larvae (chiggers) or adult mite bites.
This colorized image shows a mite larva (chigger) on human skin. Trombicula transmit Rickettsia akari, the causative agent of rickettsialpox.
DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY
This image shows a house mite, Liponyssoides sanguineus, which transmits Rickettsia akari, the causative agent of rickettsialpox.
CDC
Symptoms and Signs of Rickettsialpox
Approximately 1 week before fever onset, a small papule 1 to 1.5 cm in diameter appears and then develops into a small eschar that leaves a scar when it heals. Regional lymphadenopathy is present.
An intermittent fever lasts approximately 1 week, with chills, profuse sweating, headache, photophobia, and myalgias. Early in the febrile course, a generalized maculopapular rash with intraepidermal vesicles appears, sparing the palms and soles.
Diagnosis of Rickettsialpox
Diagnosis is primarily based on serology with acute and convalescent immunofluorescence assay (IFA) titers. Nucleic acid amplification tests (eg, PCR) of skin biopsies and cultures of eschar specimens are also available (1, 2).
For further details, see Diagnosis of Rickettsial and Related Infections.
Diagnosis references
1. Miller JM, Binnicker MJ, Campbell S, et al. A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis. 2018;67(6):e1-e94. doi:10.1093/cid/ciy381
2. Denison AM, Amin BD, Nicholson WL, Paddock CD. Detection of Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia akari in skin biopsy specimens using a multiplex real-time polymerase chain reaction assay. Clin Infect Dis. 2014;59(5):635-642. doi:10.1093/cid/ciu358
Treatment of Rickettsialpox
The disease is mild; no deaths have been reported.
Rickettsialpox is a self-limited disease; however, treatment with doxycycline for 5 days shortens the duration of systemic symptoms (1).
Treatment reference
1. Boyd AS. Rickettsialpox. Dermatol Clin. 1997;15(2):313-318. doi:10.1016/s0733-8635(05)70439-3
Prevention of Rickettsialpox
For prevention, mouse harborages must be destroyed, and the vector must be controlled by residual insecticides.
Drug Information for the Topic
