The possibility of the brown dog tick (Rhipicephalus linnaei) dispersing through veterinary facilities in urban areas

Rhipicephalus linnaei is the most important tick infesting dogs in urban areas of many tropical and subtropical regions of the world, where it can complete its life cycle within human dwellings. This study evaluated the role of veterinary facilities (hospitals, clinics, pet shops) and green areas (parks, public squares) as sources of dispersal of R. linnaei to households. During February 2021-September 2023, we visited 34 veterinary facilities and 51 green areas within São Paulo city. In each facility we inspected the internal premises (waiting/reception, inpatient and exam rooms) for the presence of ticks in cracks, holes and crevices in the structures. When ticks were found, they were collected and taken to laboratory for identification and molecular testing for Ehrlichia canis. Epidemiological information was obtained from each facility via a questionnaire. In the 51 green areas, all with high daily frequency of visiting dogs, the search for ticks was carried out by cloth dragging (60 min/area) and dry ice traps (10 or 11/area). Overall, 12 (37.5 %) veterinary facilities reported seeing ticks at least once in the premises, and 28 (87.5 %) facilities reported seeing ticks on dogs at least once. During our visits, R. linnaei ticks were found on the premises of five (15.6 %) facilities, significantly associated with the high number of animals treated per day. All developmental stages of R. linnaei (including eggs, ticks at premolting period, ovipositing females, and nymphal exuvia) were found in the veterinary facilities, suggesting that this tick species was able to complete its life cycle within the facility. Ticks from three facilities were found infected by E. canis. In the green areas, ticks were collected from six (11.8 %) areas and were all identified as Amblyomma spp. The results of this study support the hypothesis that veterinary facilities are an important source of acquisition and dispersal of the R. linnaei tick among dogs in urban areas. The results also serve as a basis for invalidating the widespread popular belief that, in urban areas, dogs are infested with ticks only when they frequent green areas.