Rickettsialpox

An acute, self-limiting, febrile illness

Caused by Rickettsia akari, a parasite of mice, transmitted by the mite Liponyssoides sanguineus

Infections are reported globally

Crowded conditions and mouse-infested housing allow transmission of the pathogen to humans

Has also been found in farming communities

Primary lesion is a painless red papule that vesiculates and forms a black eschar followed by an incubation period of 7–12 days

Onset of symptoms is sudden, with chills, fever, headache, photophobia, and disseminated aches and pains

Widespread papular eruption appears 2–4 days later

Rash becomes vesicular and forms crusts that are shed in about 10 days

Early lesions may resemble those of chickenpox (typically vesicular versus papulovesicular in rickettsialpox)

Pathologic findings include dermal edema, subepidermal vesicles, and a lymphocytic vasculitis

Transient leukopenia and thrombocytopenia and acute hepatitis can occur

A fourfold rise in serum antibody titers to rickettsial antigen, detected by complement fixation or indirect fluorescent assays

Conjugated antirickettsial globulin can identify antigen in punch biopsies of skin lesions

Polymerase chain reaction (PCR) detection of rickettsial DNA in fresh tissue

R akari can also be isolated from eschar biopsy specimens

Oral doxycycline (100 mg twice daily) for 2–5 days until defervescence

Severe symptoms may require hospitalization

Control requires the elimination of mice from human habitations and insecticide applications