In vitroisolation fromAmblyomma ovale(Acari: Ixodidae) and ecological aspects of the Atlantic rainforestRickettsia, the causative agent of a novel spotted fever rickettsiosis in Brazil

Abstract

Recently, a novel human rickettsiosis, namely Atlantic rainforest spotted fever, was described in Brazil. We herein report results of a survey led around the index case in an Atlantic rainforest reserve in Peruibe municipality, southeastern Brazil. A Rickettsia parkeri-like agent (Rickettsia sp. Atlantic rainforest genotype) and Ricketsia bellii were isolated from adult Amblyomma ovale ticks collected from dogs. Molecular evidence of infection with strain Atlantic rainforest was obtained for 30 (12.9%) of 232 A. ovale adult ticks collected from dogs. As many as 88.6% of the 35 examined dogs had anti-Rickettsia antibodies, with endpoint titres at their highest to R. parkeri. High correlation among antibody titres in dogs, A. ovale infestations, and access to rainforest was observed. Amblyomma ovale subadults were found predominantly on a rodent species (Euryoryzomys russatus). From 17 E. russatus tested, 6 (35.3%) displayed anti-Rickettsia antibodies, with endpoint titres highest to R. parkeri. It is concluded that Atlantic rainforest genotype circulates in this Atlantic rainforest area at relatively high levels. Dogs get infected when bitten by A. ovale ticks in the forest, and carry infected ticks to households. The role of E. russatus as an amplifier host of Rickettsia to A. ovale ticks deserves investigation.

Ticks infesting wild small rodents in three areas of the state of São Paulo, Brazil

“…In this study, immature A. ovale were reported on four species of rodents, which includes the first records for O. flavescens, O. nigripes and S. agouya. Generally, the values of prevalence and mean intensity of A. ovale reported in this study were similar or within the range reported for other species of small rodents in the state of São Paulo (SZABÓ et al, 2013) and Mato Grosso do Sul (SPoNCHIADo et al, 2015).…”

“…Previous studies indicated that immature A. ovale parasitize mainly rodents of the family Cricetidae (SZABÓ et al, 2013;SPoNCHIADo et al, 2015) and echimyidae (SARAIVA et al, 2012), whereas the adult stage parasitizes chiefly wild carnivores and domestic dogs (GUGLIeLMoNe et al, 2003). In this study, immature A. ovale were reported on four species of rodents, which includes the first records for O. flavescens, O. nigripes and S. agouya.…”

“…once A. ovale is vector of Hepatozoon canis for domestic dogs (FoRLANo et al, 2005) and a causative agent of spotted fever (Rickettsia sp. strain Atlantic Forest) for humans in the state of São Paulo (SZABÓ et al, 2013), studies such as the present one are essential for a better understanding of the natural history of A. ovale and its associated pathogens. …”

“…In the case of Amblyomma spp. larvae, collected samples were compared morphologically with Amblyomma ovale larvae originated from a laboratory colony, as previously described (BARBIeRI et al, 2008;SZABÓ et al, 2013.). The morphological identification of these larvae was confirmed by molecular analysis of a few specimens, which had the DNA extracted by the guanidine isothiocyanate method (SANGIoNI et al, 2005) and tested by polymerase chain reaction (PCR) targeting a fragment of 460 nucleotides of the tick mitochondrial 16S rDNA gene, according to MANGoLD et al (1998).…”

Infestação por carrapatos Argasidae e Ixodidae em pequenos mamíferos silvestres da Estação Experimental Rafael Fernandes, Mossoró/RN

“…Em cada estação foi colocada uma armadilha Tomahawk (45 x 17,5 x 15,0cm) ou Sherman (31 x 8 x 9cm), de forma alternada e no solo, com distância de 20m entre armadilhas. Em cada mês de coleta, as sessões de captura foram realizadas durante seis noites consecutivas (Szabó et al 2013). Como isca foi usada uma mistura feita com pasta de amendoim, sardinha, flocos de milho e banana (Almeida et al 2013), distribuída antes do ocaso do sol (16 horas) e recolhida no início da manhã (5:30 horas) (Kim et al 2010).…”