Candidatus Rickettsia andeanae in Amblyomma parvum attached to humans in a high-altitude forest refuge within the Caatinga biome, Brazil

Objective. This studied aimed to report Amblyomma parvum ticks parasitizing humans in a high-altitude forest within the Caatinga biome, Brazil, with notes on rickettsial infection. Materials and methods. The study was carried out in the Metropolitan Region of Sobral, in the Serra of Meruoca, within the Municipality of Meruoca (3° 32' 20” S; 40º 26' 56” W; altitude 650 m), in the northwest region of the State of Ceará, Brazil. All ticks were identified morphologically under stereomicroscope. Some of the collected ticks were tested molecularly for the presence of DNA of bacteria of the genus Rickettsia, with PCR protocols targeting two rickettsial genes: citrate synthase gene (gltA) and outer membrane protein gene (ompA). Results. A total of 78 ticks were collected on humans, identified as adults of Amblyomma parvum (62 females and 16 males). Of these, 20 females were tested, of which 15 (75%) were infected by ‘Candidatus Rickettsia andeanae'. Conclusions. The present study confirms one more area at human risk for tick bites in Brazil, also for the non-pathogenic rickettsia ‘Ca. Rickettsia andeanae'