Rickettsial infection in ticks infesting wild birds from two eco-regions of Argentina

FLORES FS; COSTA FB; NAVA S; DIAZ LA; LABRUNA MB

REVISTA BRASILEIRA DE PARASITOLOGIA VETERINáRIA

BRAZILIAN COLL VETERINARY PARASITOLOGY

Año: 2016

0103-846X

Several tick-borne Rickettsia species are recognized human pathogens in Argentina. Herein we evaluated rickettsial infection in ticks collected on passerine birds during 2011-2012 in two eco-regions of Argentina. Ticks were processed by molecular analysis through PCR detection and DNA sequencing of fragments of two rickettsial genes, gltA and ompA. A total of 594 tick specimens (532 larvae and 62 nymphs), representing 5 species (Amblyomma tigrinum, Ixodes pararicinus, Heamaphysalis juxtakochi, Heamaphysalis leporispalustris, and Amblyomma hadanii), were evaluated for rickettsial infection. One Amblyomma tigrinum larva, collected on Coryphospingus cucullatus in Chaco Seco, was infected with Rickettsia parkeri, whereas at least 12 Ixodes pararicinus, collected from Troglodytes aedon, Turdus amaurochalinus,Turdus rufiventris,Coryphospingus cucullatus, Zonotrichia capensis and Turdus rufiventris, were infected with an undescribed Rickettsia agent, genetically related to several rickettsial endosymbionts of ticks of the Ixodes ricinus complex from other continents. No rickettsia was detected in the remaining tick species. The present study provides molecular evidence of two rickettsial agents infecting ticks that were parasitizing birds in Argentina. At least one of these agents, R. parkeri, is a recognized human pathogen in several countries of the Americas, including Argentina, where a recent study incriminated A. tigrinum as the potential vector of R. parkeri to humans. Birds could possibly play an important role in dispersing R. parkeri-infected A. tigrinum ticks, what could expand the distribution area of human exposure to these ticks, and consequently, increasing the risks of human rickettsiosis.We report for the first time a rickettsial agent infecting I. pararicinus ticks.