Comparative Evaluation of Infected and NoninfectedAmblyomma tristeTicks withRickettsia parkeri, the Agent of an Emerging Rickettsiosis in the New World

Abstract

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.

High prevalence of “Candidatus Rickettsia andeanae” and apparent exclusion of Rickettsia parkeri in adult Amblyomma maculatum (Acari: Ixodidae) from Kansas and Oklahoma

“…Rickettsia parkeri negatively impacts the survival of infected Amblyomma triste nymphs (Nieri-Bastros et al, 2013). At present there are no data regarding the impact of R. parkeri or “ Ca .…”

Rickettsia parkeri Rickettsiosis in Different Ecological Regions of Argentina and Its Association with Amblyomma tigrinum as a Potential Vector

“…4,15 In Argentina, A. triste is found predominantly in wetland environments in the provinces of Buenos Aires, Corrientes, Entre Ríos, and Formosa, where the immature stages parasitize a broad range of sigmodontine and caviid rodents and the adult stages parasitize many domesticated and wild large mammals. 6 A. triste is an efficient host and vector of R. parkeri, 26 and natural infections of this tick also occur in areas of Uruguay and Brazil, where R. parkeri rickettsiosis is endemic. [27][28][29][30][31] Có rdoba province, located in the central aspect of Argentina, is the second most populous province in the country and includes many scenic areas that are visited frequently by tourists.…”

Detection of tick-borne rickettsial pathogens in naturally infected dogs and dog-associated ticks in Medellin, Colombia

“…Dogs are considered important sentinel animals for human rickettsial infection since they may suffer a clinical illness similar to humans or may be asymptomatic and chronically infected, serving as reservoir host. Even if dogs are not the main reservoirs, or amplifying hosts for rickettsial pathogens, they may serve as definitive feeding hosts for ticks or carry ticks infected by these pathogens to human dwellings (Sabatini et al, 2010;Nieri-Bastos et al, 2013;Szabó et al, 2013).…”