Ecology of a tick-borne spotted fever in southern Brazil

Abstract

Rio Grande do Sul is the southernmost state of Brazil, bordering Uruguay. Clinical cases of spotted fever group (SFG) rickettsiosis were recently reported in Rio Grande do Sul. None of these cases was lethal, and all were confirmed by seroconversion to R. rickettsii antigens. Because serological cross-reactions are well known to occur between different SFG agents, the SFG agent responsible for the clinical cases remains unknown in Rio Grande do Sul, where no rickettsial agent is known to infect ticks. During 2013-2014, ticks and blood sera samples were collected from domestic dogs and wild small mammals, and from the vegetation in a SFG-endemic area of Rio Grande do Sul. Dogs were infested by Amblyomma ovale adult ticks, whereas small mammals were infested by immature stages of A. ovale, Ixodes loricatus, and adults of I. loricatus. Ticks collected on vegetation were adults of A. ovale, and immature stages of A. ovale, Amblyomma dubitatum, and Amblyomma longirostre. Three Rickettsia species were detected: Rickettsia bellii in I. loricatus, Rickettsia amblyommii in A. longirostre, and a Rickettsia parkeri-like agent (Rickettsia sp. strain Atlantic rainforest) in A. ovale. Seroreactivity to SFG antigens were detected in 19.7 % (27/137) canine and 37.5 % (15/40) small mammal sera, with highest titers to R. parkeri. Results indicate that the R. parkeri-like agent, strain Atlantic rainforest, is circulating between A. ovale ticks, dogs and small mammals in the study area, suggesting that this SFG pathogen could be one of the etiological agents of SFG clinical cases in Rio Grande do Sul.

Ticks parasitizing wild mammals in Atlantic Forest areas in the state of Rio de Janeiro, Brazil

“…All tick-host associations recorded here had previously been reported elsewhere in Brazil (BARROS-BATTESTI et al, 2006;SARAIVA et al, 2012;SZABÓ et al, 2013;GUGLIELMONE et al, 2014;OLIVEIRA et al, 2014;KRAWCZAK et al, 2016b;MARTINS et al, 2016;, except for records of A. longirostre on Trinomys dimidiatus and B. torquatus. This tick species has wide distribution throughout the Neotropical region, and its adults have commonly been reported parasitizing rodent species, especially of the genus Coendou (BARROS-BATTESTI et al, 2006;NAVA et al, 2010;.…”

First molecular detection of Rickettsia sp. strain Atlantic rainforest in Amblyomma ovale ticks from Espírito Santo state, Brazil

“…Research to unveil its epidemiology has identified the tick Amblyomma ovale as its main vector (KRAWCZAK et al, 2016a). The results based on experimental models and field-collected material indicate that this tick species is naturally infected with strain Atlantic rainforest in several states of the south (Rio Grande do Sul, Santa Catarina and Paraná), southeast (São Paulo and Rio de Janeiro) and northeast (Bahia and Ceará) regions of Brazil (KRAWCZAK et al, 2016b;NIERI-BASTOS et al, 2016;MOERBECK et al, 2016;LUZ et al, 2017).…”

Febre Maculosa No Brasil: Situação Epidemiológica Atual E a Distribuição Geográfica De Carrapatos Em Cenários De Mudanças Climáticas

“…(Szabo et al, 2013;Barbieri et al, 2014;Vizzoni et al, 2016;Krawczak et al, 2016c). (Souza et al 2006;Souza et al, 2008;Almeida et al, 2011;Brites-Neto et al, 2015).…”