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Ticks Tick Borne Dis. 2014 Oct;5(6):848-53. doi: 10.1016/j.ttbdis.2014.07.010. Epub 2014 Aug 7.

Epidemiology of Rickettsia sp. strain Atlantic rainforest in a spotted fever-endemic area of southern Brazil.

Author information

1
Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil.
2
Regional University of Blumenau, FURB, Blumenau, SC, Brazil.
3
Federal University of Uberlândia, Uberlândia, MG, Brazil.
4
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.

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.

KEYWORDS:

Amblyomma aureolatum; Amblyomma ovale; Rickettsia; Risk factors; Southern Brazil; Spotted fever

PMID:
25108786
DOI:
10.1016/j.ttbdis.2014.07.010
[Indexed for MEDLINE]

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