Rickettsia parkeri: a Rickettsial pathogen transmitted by ticks in endemic areas for spotted fever rickettsiosis in southern Uruguay

At first Rickettsia conorii was implicated as the causative agent of spotted fever in Uruguay diagnosed by serological assays. Later Rickettsia parkeri was detected in human-biting Amblyomma triste ticks using molecular tests. The natural vector of R. conorii, Rhipicephalus sanguineus, has not been...

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Bibliographic Details
Published in:Revista do Instituto de Medicina Tropical de São Paulo
Main Authors: José M. Venzal, Agustín Estrada-Peña, Aránzazu Portillo, Atilio J. Mangold, Oscar Castro, Carlos G. De Souza, María L. Félix, Laura Pérez-Martínez, Sonia Santibánez, José A. Oteo
Format: Article in Journal/Newspaper
Language:English
Published: Universidade de São Paulo (USP) 2012
Subjects:
Rhipicephalus sanguineus
Amblyomma triste
Rickettsia parkeri
Spotted fever group (SFG)
Uruguay
Arctic medicine. Tropical medicine
RC955-962
Infectious and parasitic diseases
RC109-216
Arctic
Online Access:https://doi.org/10.1590/S0036-46652012000300003
https://doaj.org/article/6097c22fbfdc4fa4bd566a2ca5f6b0fd
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Summary:At first Rickettsia conorii was implicated as the causative agent of spotted fever in Uruguay diagnosed by serological assays. Later Rickettsia parkeri was detected in human-biting Amblyomma triste ticks using molecular tests. The natural vector of R. conorii, Rhipicephalus sanguineus, has not been studied for the presence of rickettsial organisms in Uruguay. To address this question, 180 R. sanguineus from dogs and 245 A. triste from vegetation (flagging) collected in three endemic localities were screened for spotted fever group (SFG) rickettsiosis in southern Uruguay. Tick extracted DNA pools were subjected to PCR using primers which amplify a fragment of the rickettsial gltA gene. Positive tick DNA pools with these primers were subjected to a second PCR round with primers targeting a fragment of the ompA gene, which is only present in SFG rickettsiae. No rickettsial DNA was detected in R. sanguineus. However, DNA pools of A. triste were found to be positive for a rickettsial organism in two of the three localities, with prevalences of 11.8% to 37.5% positive pools. DNA sequences generated from these PCR-positive ticks corresponded to R. parkeri. These findings, joint with the aggressiveness shown by A. triste towards humans, support previous data on the involvement of A. triste as vector of human infections caused by R. parkeri in Uruguay.

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