In vitro isolation and infection intensity of Rickettsia parkeri in Amblyomma triste ticks from the Paraná River Delta region, Argentina.

MONJE, L.D.; NAVA, S.; ANTONIAZZI, L.R.; COLOMBO, V.; BELDOMÉNICO, P.M.

Ticks and Tick-borne Diseases

Elsevier

Año: 2014 vol. 5 p. 924 - 927

In the present study, we report the first in vitro isolation and infection intensity of Rickettsia parkeri in Amblyomma triste ticks from Argentina. No genetic differences in the molecular targets evaluated were found between R. parkeri isolates from Argentina and those R. parkeri isolates reported in Uruguay and Brazil, both obtained from A. triste. Only a minor difference was observed when compared to R. park-eri isolated from Amblyomma maculatum from United States. Moreover, the prevalence of infection by R. parkeri in ticks collected from the vegetation in the Paraná Delta was high (20.4%). Interestingly, the distribution of R. parkeri infection intensity observed in A. triste ticks was distinctly bimodal, with approx-imately 60% of the infected ticks presenting high rickettsial loads (3.8 × 105?4.5 × 107 ompA copies/tick) and the remainder with low rickettsial levels (5.6 × 101?6.5 × 103 ompA copies/tick). This bimodality in R. parkeri infection intensity in ticks could determine differences in the severity of the disease, but also be important for the infection dynamics of this pathogen. Further research exploring the distribution of rickettsial infection levels in ticks, as well as its determinants and implications, is warranted. Rickettsia parkeri in Amblyomma triste ticks from Argentina. No genetic differences in the molecular targets evaluated were found between R. parkeri isolates from Argentina and those R. parkeri isolates reported in Uruguay and Brazil, both obtained from A. triste. Only a minor difference was observed when compared to R. park-eri isolated from Amblyomma maculatum from United States. Moreover, the prevalence of infection by R. parkeri in ticks collected from the vegetation in the Paraná Delta was high (20.4%). Interestingly, the distribution of R. parkeri infection intensity observed in A. triste ticks was distinctly bimodal, with approx-imately 60% of the infected ticks presenting high rickettsial loads (3.8 × 105?4.5 × 107 ompA copies/tick) and the remainder with low rickettsial levels (5.6 × 101?6.5 × 103 ompA copies/tick). This bimodality in R. parkeri infection intensity in ticks could determine differences in the severity of the disease, but also be important for the infection dynamics of this pathogen. Further research exploring the distribution of rickettsial infection levels in ticks, as well as its determinants and implications, is warranted.