Survey for rickettsial infection of the spotted fever group in dogs, small mammals and ticks in endemic and non-endemic areas of the Pampa and Atlantic forest biomes in the state of Rio Grande do Sul.

Abstract

In 2005 the state of Rio Grande do Sul (RS) notified its first suspeted case of Brazilian spotted fever (BSF) to the Brazilian Ministry of Health. During 2005-2009, there were seven human confirmed cases, all from Cerro largo municipality, in the endemic area for spotted fever rickettsiosis (Data from Ministry of Health). In RS, there are various tick species of the genus Amblyomma, which are known vectors of spotted fever group (SFG) rickettsiae to humans and animals in other states. During 2006-2007, twenty tick specimens found attached to humans in Cerro Largo were sent to the laboratory, and identified as Amblyomma ovale. During the last few years, some studies demonstrated that A.ovale from Atlantic Forest areas in the states of São Paulo and Santa Catarina were infected with R. parkeri strain Atlantic rainforest, which is a novel pathogen responsible for a novel SFG rickettiosis in Brasil. In RS there are two biomes: Atlantic Forest and Pampa; the later is not present at any other Brazilian state. Until now, there has been only two serological studies on spotted fever in the state: one specifically in the municipality of Cerro Largo, an endemic area for the disease, and another in the Pelotas region. Both studies showed that health horses, dogs and humans were exposed to spotted fever group rickettsiosis. In this context, the present study aims to search for SFG rickettsial infection in dogs, horses, small mammals, and ticks in an endemic area (Cerro Largo) and non-endemic areas within the Pampa and Atlantic Forest biomes in RS. This will be the first comparative research on BSF between Pampa and Atlantic Forest biomes, and also the first one to apply molecular tools and attempts to isolation SFG rickettsiae in cell culture from samples collected in RS.