title: Epidemiology of Rickettsia sp. strain Atlantic rainforest in a spotted fever-endemic area of southern Brazil.
abstract: The present study was performed in Vila Itoupava, an area of the state of Santa Catarina, southern Brazil, in which a tick-borne spotted fever illness has been endemic since 2003. Notably, both the etiological agent and the vector of these spotted fever cases remain unknown. During January 2011, humans, domestic dogs, and their ticks were sampled in households that are typically surrounded by highly preserved Atlantic rainforest fragments. Ticks collected from dogs were Amblyomma ovale (34% prevalence), Amblyomma aureolatum (18.9%), and Rhipicephalus sanguineus (3.8%). A total of 7.8% (6/77) A. ovale and 9.3% (4/43) A. aureolatum were infected by Rickettsia sp. strain Atlantic rainforest, a Rickettsia parkeri-like agent recently shown to cause spotted fever illness in southeastern Brazil. Overall, 67.3% (35/52) of the dogs were seroreactive to spotted fever group rickettsiae, mostly with highest endpoint titers to R. parkeri. Among humans, 46.7% (7/15) reacted serologically to rickettsiae at low to moderate endpoint titers. Because canine seroreactivity to R. parkeri was strongly associated with frequent contact with forests (the preferred habitat for A. ovale and A. aureolatum), it is concluded that sampled dogs have been infected by strain Atlantic rainforest through the parasitism of these tick species. The present study provides epidemiological evidence that the spotted fever in the study area has been caused by Rickettsia sp. strain Atlantic rainforest, transmitted to humans by either A. ovale or A. aureolatum. Further studies encompassing direct diagnostic methods on clinical specimens from patients are needed to confirm the above epidemiological evidence.
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Amalia R M
authors.initials: AR
authors.lastname: Barbieri
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Jonas M
authors.initials: JM
authors.lastname: Filho
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Fernanda A
authors.initials: FA
authors.lastname: Nieri-Bastos
authors.affiliation: Regional University of Blumenau, FURB, Blumenau, SC, Brazil.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Souza
authors.affiliation: Federal University of Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Matias P J
authors.initials: MP
authors.lastname: Szabó
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil. Electronic address: labruna@usp.br.
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Labruna
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology*; D001483:Base Sequence; D001938:Brazil / Q000453:epidemiology; D004283:Dog Diseases / Q000453:epidemiology* / Q000382:microbiology; D004285:Dogs; D017753:Ecosystem; D019353:Endemic Diseases; D006801:Humans; D026863:Ixodidae / Q000382:microbiology*; D008969:Molecular Sequence Data; D065947:Rainforest; D048508:Rhipicephalus sanguineus / Q000382:microbiology; D012281:Rickettsia / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D012282:Rickettsia Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D012307:Risk Factors; D017422:Sequence Analysis, DNA / Q000662:veterinary; D017282:Tick-Borne Diseases / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*
keywords: Amblyomma aureolatum; Amblyomma ovale; Rickettsia; Risk factors; Southern Brazil; Spotted fever