Description of a new Pavlovskyella species (Acari: Argasidae) from Chile

Experimental transmission of a novel relapsing fever group Borrelia harbored by Ornithodoros octodontus (Ixodida: Argasidae) in Chile

Tick-borne relapsing fever spirochetes of genus Borrelia thrive in enzootic cycles involving Ornithodoros spp. (Argasidae) mainly, and rodents. The isolation of these spirochetes usually involves a murine model in which ticks are fed and the spirochetes detected in blood several days later. Such an experiment also demonstrates that a given species of tick is competent in the transmission of the bacteria. Here, soft ticks Ornithodoros octodontus were collected in Northern Chile with the objective to experimentally determine its capacity to transmit a Borrelia sp. detected in a previous study. Two Guinea pigs (Cavia porcellus) were used to feed nymphs and adults of O. octodontus and the spirochetes in blood were inspected by dark-field microscopy and nested PCR. Although spirochetes were not seen in blood, DNA was detected in only one animal 11 days after the ticks were fed. Genetic sequences of Borrelia flaB, clpX, pepX, recG, rplB, and uvrA genes retrieved from DNA extraction of positive blood were employed to construct two phylogenetic analyses. On the one hand, the flaB tree showed the Borrelia sp. transmitted by O. octodontus clustering with Borrelia sp. Alcohuaz, which was previously detected in that same tick species. On the other hand, concatenated clpX-pepX-recG-rplB-uvrA demonstrated that the characterized spirochete branches together with "Candidatus Borrelia caatinga", a recently discovered species from Brazil. Based on the genetic profile presented in this study, the name "Candidatus Borrelia octodonta" is proposed for the species transmitted by O. octodontus. The fact that spirochetes were not observed in blood of guinea pigs, may reflect the occurrence of low spirochetemia, which could be explained because the susceptibility of infection varies depending on the rodent species that is used in experimental models. Although the vertebrate reservoir of "Ca. Borrelia octodonta" is still unknown, Octodon degus, a rodent species that is commonly parasitized by O. octodontus, should be a future target to elucidate this issue.

Noteworthy records of the ticks Ornithodoros rostratus and Amblyomma sculptum parasitizing Pteronura brasiliensis in the central-western region of Brazil, with pathogen investigation notes

A male of Pteronura brasiliensis (Carnivora: Mustelidae) was found dead on the banks of the Rio Negro, in the Pantanal wetlands of Mato Grosso do Sul state, Aquidauana municipality. Two ticks found attached to its skin were morphologically identified as a second-instar nymph of Ornithodoros rostratus (Argasidae) and a male of Amblyomma sculptum (Ixodidae). In order to complement the morphological identification, these tick specimens were subjected to DNA extraction, and tested using PCR assays to confirm the molecular identity the specimens. Also, the tick DNA samples were tested and were negative in the PCR assays for all the pathogens tested. We also examined 30 batches, consisting of 174 individuals of O. rostratus deposited in the Acari Collection of the Butantan Institute, and we found material from four Brazilian states, including one batch containing 2 males and 2 females from Aquidauana, of Mato Grosso do Sul state, collected from the soil. This was therefore the first record of O. rostratus parasitizing P. brasiliensis and the first locality record (Aquidauana). Likewise, A. sculptum is commonly found in the Pantanal and is reported here for the second time parasitizing the giant otter, which is a host little studied regarding the ectoparasites.