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BioMed Research International
Volume 2013 (2013), Article ID 402737, 6 pages
Research Article

Comparative Evaluation of Infected and Noninfected Amblyomma triste Ticks with Rickettsia parkeri, the Agent of an Emerging Rickettsiosis in the New World

1Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Avenida Prof. Orlando Marques de Paiva 87, Cidade Universitária, 05508-270 São Paulo, SP, Brazil
2Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal de Uberlândia, Avenida Pará 1720, Campus Umuarama-Bloco 2T, 38400-902 Uberlândia, MG, Brazil
3Faculdade de Agronomia e Medicina Veterinária, Universidade Federal do Mato Grosso, Avenida Fernando Corrêa da Costa 2367, Boa Esperança, 78060-900 Cuiabá, MT, Brazil

Received 6 April 2013; Revised 18 June 2013; Accepted 19 June 2013

Academic Editor: Georgios Theodoropoulos

Copyright © 2013 F. A. Nieri-Bastos et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The distribution of Rickettsia parkeri in South America has been associated with Amblyomma triste ticks. The present study evaluated under laboratory conditions two colonies of A. triste: one started from engorged females that were naturally infected by R. parkeri (designated as infected group); the other started from noninfected females (designated as control group). Both colonies were reared in parallel for five consecutive generations. Tick-naïve domestic rabbits were used for feeding of each tick stage and generation. R. parkeri was preserved by transstadial maintenance and transovarial transmission in A. triste ticks for five consecutive generations, because all tested larvae, nymphs, and adults from the infected group were shown by PCR to contain rickettsial DNA. All rabbits infested by larvae, nymphs, and adults from the infected group seroconverted, indicating that these tick stages were all vector competent for R. parkeri. Expressive differences in mortality rates were observed between engorged nymphs from the infected and control groups, as indicated by 65.9% and 92.4% molting success, respectively. Our results indicate that A. triste can act as a natural reservoir for R. parkeri. However, due to deleterious effect caused by R. parkeri on engorged nymphs, amplifier vertebrate hosts might be necessary for natural long-term maintenance of R. parkeri in A. triste.