of Rickettsialpox
Pathophysiology...
R akari is an obligate intracellular gram- negative coccobacillus. Its vector is the colorless mite Liponyssoides sanguineus (formerly Allodermanyssus sanguineus), which is found on mice (most commonly the house mouse [Mus musculus]) and other rodents. These hosts serve as the reservoir for the disease. A sanguineus will bite humans when murine hosts are scarce. About 7- 10 days after the painless bite, a papular skin lesion appears at the bite location and becomes vesicular with a surrounding area of erythema. An eschar forms and slowly heals. About 3-7 days after the initial skin lesion develops, patients may suddenly develop high-grade fever, chills, headaches, and myalgias with subsequent development of a sparse generalized papulovesicular rash. The disease is mild and self-limited and usually persists for about a week.
History...
Following a mite bite, R akari proliferates locally in the skin. After 7-10 days, a firm, red papule 1-1.5 cm in diameter appears; in a few days, it vesiculates with a surrounding area of erythema.The lesion then ulcerates,forms an eschar,and slowly heals.
About 3-7 days after the appearance of the skin lesion, rickettsialpox may manifest as a sudden onset of high fever, chills, sore throat, rigor and profuse sweating, myalgias (especially backache),anorexia,and photophobia. Untreated, fever may last a week. Vertigo, conjunctival injection, cough, rhinorrhea, nausea, and vomiting sometimes occur. Headaches and neck stiffness may be severe. Regional lymphadenopathy at the draining site of the eschar is common, and generalized lymphadenopathy has also been reported. Lymphangitis is not a feature of rickettsialpox.
Approximately 2-3 days after the onset of systemic symptoms, the generalized papulovesicular rash of rickettsialpox erupts. This can involves palms and soles and is occasionally accompanied by an oropharyngeal enanthem. This rash typically lasts a week.
Mortality/Morbidity...
Rickettsialpox is a benign, self-limited disease. No fatalities have been reported. The incubation period varies from 10-21 days. Rickettsialpox usually resolves within 14-21 days; however, headache and lassitude may persist for another 1-2 weeks.