Abstract
Brazilian spotted fever (BSF), caused by Rickettsia rickettsii, is endemic in the municipality of Americana, southeastern Brazil, where the disease is transmitted by the tick Amblyomma cajennense. This study evaluated the tick fauna and rickettsial infection in free-living ticks that were captured monthly using dry ice traps in areas endemic for BSF in Americana, from July 2009 to June 2010. Two tick species were captured: A. cajennense (6,122 larvae; 4,265 nymphs; 2,355 adults) and Amblyomma dubitatum (7,814 larvae; 3,364 nymphs; 1,193 adults). The immature stages of A. cajennense and A. dubitatum had similar distribution through the 12-month period, with larvae of both species collected in highest numbers between April and July, and nymphs between June and October. The highest numbers of A. cajennense adults were collected between October and December, whereas A. dubitatum adults were collected in relatively similar numbers throughout the 12-month period. Rickettsial infection was evaluated by means of PCR in 1,157 A. cajennense and 1,040 A. dubitatum ticks; only 41 (3.9%) A. dubitatum were found to be infected by Rickettsia bellii. The present study showed that the areas of Americana that are endemic for BSF are characterized by high environmental burdens of A. cajennense and A. dubitatum.
Highlights
The bacterium Rickettsia rickettsii is the etiological agent for the deadliest form of rickettsiosis in the world, namely Brazilian spotted fever (BSF) (LABRUNA, 2009)
Brazilian spotted fever (BSF), caused by Rickettsia rickettsii, is endemic in the municipality of Americana, southeastern Brazil, where the disease is transmitted by the tick Amblyomma cajennense
Rickettsial infection was evaluated by means of PCR in 1,157 A. cajennense and 1,040 A. dubitatum ticks; only 41 (3.9%) A. dubitatum were found to be infected by Rickettsia bellii
Summary
The bacterium Rickettsia rickettsii is the etiological agent for the deadliest form of rickettsiosis in the world, namely Brazilian spotted fever (BSF) (LABRUNA, 2009) Americana is a municipality located in the eastern part of the state of São Paulo It has a population of 212,791 inhabitants, mostly living in a 92 km urban area surrounded and crossed by water courses, namely the Salto Grande reservoir (9.3 km2) and four rivers: Piracicaba, Jaguari, Atibaia and Ribeirão Quilombo (FELICIANO, 2012). From 2004 to 2012, there were ten confirmed cases of BSF with a 60% fatality rate in Americana, indicating endemicity for BSF All these cases were related to tick bites acquired along the water courses of the municipality, where there are established populations of capybaras (BRITESNETO, 2011). The present study aimed to evaluate the tick fauna of these risk areas, and to investigate rickettsial infection in these ticks
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