Abstract
BackgroundRickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases. While these cases were epidemiologically associated with the tick Amblyomma ovale, in none of them the tick specimens that bit the patients could be identified.ResultsWe report a clinical case of spotted fever rickettsiosis that was acquired in an Atlantic forest area in Bahia state, northeast Brazil. The case was determined to be caused by R. parkeri strain Atlantic rainforest, based on molecular analysis of the crust removed from the tick bite site (inoculation eschar) of the patients’ skin. DNA extracted from the crust yielded partial sequences of three rickettsial genes (gltA, ompA and ompB), which were 99–100% identical to R. parkeri strain Atlantic rainforest. The tick specimen that was attached to patient skin was identified as a female of A. ovale.ConclusionsWe report the fourth confirmed case of spotted fever rickettsiosis caused by R. parkeri strain Atlantic rainforest, providing to our knowledge for the first time, direct evidence of R. parkeri strain Atlantic rainforest transmission by A. ovale.
Highlights
Rickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases
Tick-borne rickettsioses are zoonoses caused by bacteria of the genus Rickettsia, especially species belonging to the spotted fever group (SFG) [1]
While the identity of the agent of these three cases was initially reported as an unnamed Rickettsia species (Rickettsia sp.) with different strain names (Atlantic rainforest or Bahia), a recent phylogenetic study concluded that it corresponds to a single species and strain, named as R. parkeri strain Atlantic rainforest [6]
Summary
Rickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases While these cases were epidemiologically associated with the tick Amblyomma ovale, in none of them the tick specimens that bit the patients could be identified. The three confirmed cases of the disease in Brazil were epidemiologically associated with A. ovale, based on the findings of R. parkeri strain Atlantic rainforest-infected A. ovale ticks in the environment or/and infesting domestic dogs from the same areas da Paixão Sevá et al Parasites Vectors (2019) 12:471 where the patients reported to have acquired the infected ticks [8,9,10]. The tick specimens that bit the patients could not be identified in any of the three laboratory-confirmed cases
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