ARS | Publication request: Epidemiological and biological aspects on Ornithodoros brasiliensis (mouro tick), an argasidae tick only found on the highlands region of Rio Grande do Sul state, southern Brazil

Submitted to: Livestock Insect Worker's Conference Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 13, 2011
Publication Date: N/A

Technical Abstract: The soft tick Ornithodoros brasiliensis (Acari: Argasidae) is present in farms along the highlands of Rio Grande do Sul state in southern Brazil. Reports of human parasitism by O. brasiliensis drew the attention of local health authorities. A preliminary epidemiological survey was conducted to identify areas of incidence of this tick species in the region, as well as to ascertain the occurrence of tick bites in humans. O. brasiliensis was found in five out of the thirty farms sampled. Surveys of previous human tick contact tick samples were collected and processed in the laboratory for taxonomic and biological analyses. Survey results indicated 28 people were bitten by this tick with 16 of the cases taking place during the last four years. Humans affected reported local pain, skin irritation, redness and swelling in the bitten area with slow healing of the bite lesion. Some people also reported systemic disturbances such as malaise and headache. Eleven dogs were bitten as well and three of the affected dogs died within three weeks of being bitten by the ticks. Tick-borne pathogens common in the region were not found in blood samples from the field, in laboratory animals parasitized by O. brasiliensis, or in tick specimens. Ticks were allowed to feed on rats and biological parameters such as feeding time, and size and aspect of local lesions at feeding sites were analyzed. Tissue samples were submitted for histopathological evaluation. Tick bites induced extensive hemorrhagic lesions on rats with local tissue degeneration, a slight myocardium alteration, and CPK increase. The blood meal took approximately 40 minutes. Tick weight increased four-fold during feeding. Studies are in progress to characterize the effects of O. brasiliensis saliva on endothelial cells. The re-emergence of this tick is of concern in southern Brazil. The risk exists for infestations in neighboring areas. Financial support: CNPq/CAPES.