Prevalence of Antibodies to Spotted Fever Group Rickettsiae in Humans and Domestic Animals in a Brazilian Spotted Fever-Endemic Area in the State of São Paulo, Brazil: Serologic Evidence for Infection by Rickettsia Rickettsii and Another Spotted Fever Group Rickettsia

Abstract

In serum samples obtained from all the healthy humans, horses, dogs, and donkeys present on three farms in the Pedreira Municipality, an endemic area for Brazilian spotted fever, an indirect immunofluorescence assay (IFA) detected antibodies against Rickettsia rickettsii in 17 (77.3%) horses, 5 (31.3%) dogs (titers ranging from 64 to 4,048), and none of 4 donkeys or 50 humans. Five canine and eight equine sera with high antibody titers to R. rickettsii were also tested by IFA against R. bellii, R. akari, and R. africae antigens. Sera from two horses and two dogs that showed similar high antibody titers against two rickettsial antigens were evaluated after cross-absorption. Sera from seven horses and two dogs contained antibodies specific for R. rickettsii, and one dog serum had antibodies against a Rickettsia species very closely related to R. africae. The latter may have been caused by infection with the recently identified COOPERI strain.

First identification of natural infection of Rickettsia rickettsii in the Rhipicephalus sanguineus tick, in the State of Rio de Janeiro

“…Although other species of Rickettsia have been described in the Brazilian territory, as Rickettsia parkeri (Horta et al 2004 and Rickettsia felis (Cardoso et al 2006, Oliveira et al 2008, only R. rickettsii has been identified in BSF human cases.…”

Serological evidence of Rickettsia parkeri as the etiological agent of rickettsiosis in Uruguay

“…Each of the absorbed sera was then tested by IFA to either R. parkeri or R. rickettsii crude antigens. If serum absorbed with one Rickettsia species showed no or minimal reaction against both antigens, and a strong reaction to only one of the two antigens when absorbed with the second Rickettsia species, this serum was considered to contain antibodies stimulated by the Rickettsia species (or a very closely related species) that elicited the strong reaction in the second cross-absorption and had absorbed all the antibodies in the first reaction 6 . After absorption with R. rickettsii, the serum demonstrated a 1,024 titer against R. parkeri and no antibodies against R. rickettsii, but after absorption with R. parkeri, there was no reaction against either of the two Rickettsia antigens.…”

Anticorpos anti-rickettsias do grupo da febre maculosa em equídeos e caninos no norte do Estado do Paraná, Brasil

“…Além disso, é uma das mais importantes doenças rickettsiais no Brasil (Horta et al, 2004). É causada por rickettsias do grupo da febre maculosa (GFM) e tem como principal agente causal Rickettsia rickettsii, responsável também pela febre maculosa das Montanhas Rochosas (FMMR) nos Estados Unidos da América (Paddock, 2002).…”

“…É causada por rickettsias do grupo da febre maculosa (GFM) e tem como principal agente causal Rickettsia rickettsii, responsável também pela febre maculosa das Montanhas Rochosas (FMMR) nos Estados Unidos da América (Paddock, 2002). Outras rickettsias do GFM têm sido isoladas, no Brasil, em carrapatos e pulgas, entre elas a R. belli (Horta et al, 2004), R. parkeri (Silveira et al, 2007) e R. felis (Sangioni, 2003). Embora o antígeno mais utilizado em inquéritos sorológicos no Brasil seja o de R. rickettsii, pesquisas recentes (Silveira et al, 2007) revelaram a presença de R. parkeri no Brasil, a qual tem sido comprovada como causadora de febre maculosa nos Estados Unidos, e possivelmente no Uruguai (Paddock, 2005 (Labruna et al, 2002), especialmente nas fases de larva e ninfa (Lemos et al, 1996), que usualmente fazem o repasto sanguíneo em cães, equinos, capivaras, antas e humanos (Labruna et al, 2002;Paddock et al, 2002).…”