Rickettsia parkeri Infection

Clinical signs in humans have been described with a febrile illness associated with headache, myalgia, a maculopapular rash, and multiple eschars (Paddock et al., 2004). It is assumed that the infection with R. parkeri has often been misdiagnosed as Rocky Mountain Spotted Fever (RMSF). Several compelling lines of evidence suggest that infections with R. parkeri, and probably one or more other tick-borne SFG rickettsiae, are responsible for at least some of the approximately 400-1,100 cases of RMSF reported each year in the United States. These include according to Paddock (2005): (1) cases of eschar-associated spotted fevers for which species-specific confirmatory data are lacking; (2) serologic evidence of subclinical or mild infections with spotted fever group rickettsiae in tick-exposed patients; and (3) the precedent recognition of multiple tick-borne rickettsial diseases in Europe, Africa, and Australia (Parola et al., 2005; Raoult, 2004).

Dogs have been shown to be infected with R. parkeri in serosurveys with prevalences between 0.65 and 1.83% in the Monte Negro region in Brazil (rural and urban) (Labruna et al., 2007) and 25.7% in Southern Brazil (Saito et al., 2008). However, clinical signs in dogs correlating with a R. parkeri infection have not been described yet.

For special areas, where the transmitting tick species is found to infest dogs as well as humans (rural areas in Monte Negro region, Brazil), dogs have ben described as sentinels (Labruna et al., 2007).

Further information

• Labruna MB, Horta MC, Aguiar DM, et al.: Prevalence of Rickettsia infection in dogs from the urban and rural areas of Monte Negro municipality, western Amazon, Brazil. Vector Borne Zoonotic Dis. 2007, 7, 249-55
• Paddock CD: Rickettsia parkeri as a paradigm for multiple causes of tick-borne spotted fever in the western hemisphere. Ann NY Acad Sci. 2005, 1063, 315-26
• Paddock CD, Sumner JW, Comer JA, et al.: Rickettsia parkeri: a newly recognized cause of spotted fever rickettsiosis in the United States. Clin Infect Dis. 2004, 38, 805-11
• Parola P, Paddock CD, Raoult D: Tick-borne rickettsioses around the world: emerging diseases challenging old concepts. Clin Microbiol Rev. 2005, 18, 719-56
• Raoult D: A new rickettsial disease in the United States. Clin Infect Dis. 2004, 38, 812-3
• Saito TB, Cunha-Filho NA, Pacheco RC, et al.: Canine infection by rickettsiae and ehrlichiae in southern Brazil. Am J Trop Med Hyg. 2008, 79, 102-8