Molecular detection of Rickettsia spp. and Ehrlichia chaffeensis in Amblyomma ticks collected in Santiago del Estero, Argentina

TOMASSONE L; NUÑEZ P,; GÜRTLER R.E.; CEBALLOS L.A; KITRON U; FARBER M

Cordoba – Argentina

Congreso; XI Congreso Argentino de Microbiologia; 2007

Asociación Argentina de Microbiología

In November-December 2006, ticks were collected from the vegetation and on the host (humans, wild and domestic animals) in a rural area in the semiarid argentinian Chaco of Argentina, to evaluate their potential role as vectors of tick-borne pathogens to humans. A total of 233 adult ticks, identified as  Amblyomma parvum, Amblyomma tigrinum and Amblyomma pseudoconcolor, were collected and subjected to PCR to look for Rickettsia spp.. A subset (n=65) was further analyzed by PCR and ReverseLineBlot Hybridization (RLBH) to detect Ehrlichia and Anaplasma spp.. 31.3% of  ticks resulted positive for the PCR assay using specific primers for a region of the Rickettsial OmpA gene, suggesting the presence of Spotted Fever Group rickettsiae in A. parvum. Moreover, PCR assay using specific primers for Citrato Sintase gene (CS) allowed us to detect Rickettsia bellii in a host-seeking male of Amblyomma tigrinum . This result was confirmed by sequencing. By RLBH, 13.8% of samples showed a positive signal to E. chaffeensis probe, and sequencing confirmed this finding in three A. parvum collected from fox, cow and goat respectively. A. parvum is widespread in the area and could constitute a potential threat to human health in our study area, where tick-borne diseases are possibly present in mild forms and miss-diagnosed.