Molecular Detection of Rickettsia parkeri Strain Atlantic Rainforest in Ticks Parasitizing Small Mammals in Northeastern Brazil.

PURPOSE: Small mammals are important reservoirs of ticks and their pathogens in nature. However, studies reporting these associations are still rare in Brazil. In the present study, we investigated the presence of Rickettsia DNA in ticks parasitizing rodents and marsupials captured in different areas throughout the Atlantic rainforest biome, Bahia, Northeastern (NE), Brazil. METHODS: The study was conducted in five municipalities within of the Atlantic Forest biome, Bahia state, in NE Brazil. Two campaigns were done in each municipality. For host captures Sherman and Tomahawk traps were used, and pitfall traps. After being captured, the hosts were anesthetized and their entire body examined for ticks. When ticks were detected, they were manually removed and stored in eppendorf tubes (1.5 ml) containing absolute PA ethanol for future laboratory analysis (identification of ticks and detection of Rickettsia spp.). RESULTS: A total of 609 mammals were captured. Overall, 208 ticks of the genus Amblyomma and Ixodes were collected: A. ovale, I. loricatus and A. varium. Rickettsia DNA was detected in A. ovale and it was 99-100% of identity to the sequence deposited in GenBank as Rickettsia parkeri strain Atlantica rainforest. CONCLUSION: These results suggest that R. parkeri strain Atlantic rainforest occurs in the region, and A. ovale is likely the vector.

Diversity of ticks and detection of Rickettsia amblyommatis infecting ticks on wild birds in anthropogenic landscapes in Bahia state, northeast Brazil.

Birds are important hosts in the maintenance and spread of ticks worldwide, including several species of Amblyomma which harbor rickettsial agents as members of the spotted fever group (SFG). The current survey shows the diversity of tick and rickettsial agents infecting ticks on wild birds from an Atlantic rainforest in the state of Bahia, Brazil. A total of 365 birds were captured, representing two orders, 22 families and 51 species, among which 68 specimens (18.6%) were parasitized. Overall, 132 immature ticks (81 larvae and 51 nymphs) were identified to species level, representing six recognized species of the genus Amblyomma: Amblyomma longirostre (n = 45), Amblyomma nodosum (n = 40), Amblyomma varium (n = 5), Amblyomma parkeri (n = 2), Amblyomma coelebs (n = 3) and Amblyomma calcaratum (n = 1). Amplification by PCR and sequencing of rickettsial genes (gltA and ompA), detected the presence of Rickettsia DNA in 12 (9.1%) of the ticks. Rickettsia amblyommatis was the only agent detected in nine larvae and two nymphs of A. longirostre and one nymph of A. varium with 99-100% similarity.

Serologic and molecular survey of Rickettsia spp. in dogs, horses and ticks from the Atlantic rainforest of the state of Bahia, Brazil.

Tick-borne spotted fever in Brazil is known to be caused by two agents, Rickettsia rickettsii and Rickettsia parkeri. Nothing was known about these agents in one area of the Atlantic rainforest biome of Bahia state, where during March to June 2016, 356 rural dogs and 69 horses were sampled and their sera were processed through indirect immunofluorescence assay against antigens of R. rickettsii, R. parkeri, Rickettsia amblyommatis and Rickettsia bellii. Ticks collected from these dogs and horses were molecularly tested for the presence of rickettsial DNA. Overall, 16.4% (58/356) dogs and 24.6% (17/69) horses were seroreactive to Rickettsia spp. Five tick species, Rhipicephalus sanguineus sensu lato (s.l.), Amblyomma ovale, A. sculptum, R. microplus, and A. naponense, were collected from dogs, whereas horses were infested by A. sculptum and Dermacentor nitens. A total of 242 ticks from dogs and 62 from horses were analyzed by PCR targeting rickettsiae, which were detected in only 4/27 (14.8%) A. ovale. Fragments of the rickettsial gltA and ompA genes from these four ticks were 100% identical to the Atlantic rainforest strain of R. parkeri. The presence of A. ovale on dogs was positively associated with local canine seroreactivity to R. parkeri. Our results provide evidence for the transmission of R. parkeri strain Atlantic rainforest from A. ovale to domestic dogs within the rural area of Ilhéus, similarly to other areas of the Atlantic rainforest biome of Brazil, where human cases of R. parkeri-caused spotted fever have been reported.