RickettsiaSpecies InfectingAmblyomma cooperiTicks from an Area in the State of São Paulo, Brazil, Where Brazilian Spotted Fever Is Endemic

Abstract

Owing to the potential role of the tick Amblyomma cooperi in the enzootic cycle of Rickettsia rickettsii, the etiologic agent of Brazilian spotted fever (BSF), this study evaluated infection by Rickettsia species in A. cooperi ticks collected from an area in Brazil where BSF is endemic. Among a total of 40 A. cooperi adult ticks collected in an area of BSF endemicity in the state of São Paulo, PCR analysis detected DNA of Rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positive for a previously unidentified spotted-fever-group (SFG) rickettsia. Cultivation in Vero cell cultures by the shell vial technique with individual A. cooperi ticks resulted in two isolates of R. bellii and one isolate genotypically characterized as an SFG rickettsia. The two R. bellii isolates were established in Vero cell cultures in the laboratory and were confirmed to be R. bellii by molecular analysis of the gltA and 17-kDa protein-encoding genes and by electron microscopic analysis. The SFG rickettsial isolate could not be stably passaged in cell culture in the laboratory, but molecular analysis of early passages suggested that it was closely related to Rickettsia parkeri, Rickettsia africae, and Rickettsia sibirica. These results do not support the role of A. cooperi in the ecology of R. rickettsii in the area studied, but they add two more species of rickettsiae to the poorly developed list of species occurring in ticks in South America.

Importance of Common Wall Lizards in the Transmission Dynamics of Tick-Borne Pathogens in the Northern Apennine Mountains, Italy

“…Detection of Rickettsia spp. in ticks was performed by targeting the citrate synthase (gltA) [22], OmpA [41] and OmpB genes [46]. Rickettsia spp.…”

Infección por rickettsia en capibaras (Hydrochoerus hydrochaeris) de São Paulo, Brasil: evidencia serológica de infección por Rickettsia bellii y Rickettsia parkeri

“…Each spleen was subjected to DNA extraction using the DNeasy Tissue Kit (Qiagen, Chatsworth, CA) following the manufacturer's protocol, and tested by PCR using the primers CS-5 (forward) and CS-6 (reverse) that amplify a 147 bp fragment of the citrate synthase gene (gltA). These primers have a sensitivity for detection of a single copy of R. rickettsii DNA and 10 copies of R. bellii (7). PCR conditions were as described previously (17).…”

“…The indirect immunofluorescence assay (IFA) used crude antigens derived from three Rickettsia isolates from Brazil: R. rickettsii strain Taiaçu, R. parkeri strain At24, and R. bellii strain Mogi. These three rickettsiae comprise the Rickettsia species known to infect Amblyomma ticks that infest capybaras in Brazil (7,17).…”

“…Spotted fever caused by R. parkeri seems to have milder clinical manifestations than the classical BSF, with no fatal cases yet reported (5,6). In Brazil, human cases due to R. parkeri have not been reported; however the infection by R. parkeri and a closerelated genotype (strain COOPERI) have been reported in the ticks A. triste and Amblyomma dubitatum (=Amblyomma cooperi), respectively, in the state of São Paulo (7,8). In addition, serological evidence of R. parkeri infection has been reported in dogs, horses, and opossums in the state of São Paulo (9, Horta MC, Labruna MB, Pinter A, Linardi PM, Schumaker TT.…”

“…These include the SFG species R. amblyommii in the state of Rondônia (10) and R. rhipicephali in Rondônia and São Paulo (11,12). R. bellii, a species classified neither in the TG or SFG, has also been reported in Rondônia and São Paulo (7,10,12). While serological evidence of canine infection due to R. amblyommii and R. rhipicephali has been reported in the state of Rondônia (13) there has been no evidence for R. bellii natural infection in vertebrate hosts.…”