New records of tick-associated spotted fever group Rickettsia in an Amazon-Savannah ecotone, Brazil

Abstract

Human rickettsiosis has been recorded in the Amazon Biome. However, the epidemiological cycle of causative rickettsiae has not been fully accounted for in the Amazon region. This study investigates the presence of spotted fever group (SFG) Rickettsia spp. in free-living unfed ticks of the Amblyomma genus. The study was conducted in seven municipalities in Rondonia State, Brazil, where the main biomes are Amazon forest, Brazilian Savannah and their ecotones (areas of ecological tension between open ombrophilous forest and savannah). The following tick species were collected: Amblyomma cajennense (sensu lato) s.l., A. cajennense (sensu stricto) s.s., A. coelebs, A. naponense, A. oblongoguttatum, A. romitii, A. scalpturatum and A. sculptum. A total of 167 adults, 248 nymphs and 1004 larvae were subjected to DNA extraction and polymerase chain reaction (PCR) to determine the presence of SFG Rickettsia spp. PCR-positive samples included: one A. cajennense s.s. female and one A. cajennense s.l. male from a rural area in Vilhena Municipality; 10 nymphs and a sample of larvae of A. cajennense s.l. from a peri-urban area in Cacoal Municipality; and an A. oblongoguttatum adult male from a rural area of Pimenta Bueno Municipality. All sequences obtained exhibited 100% identity with Rickettsia amblyommatis sequences. This is the first confirmation of SFG Rickettsia in an A. oblongoguttatum tick. Furthermore, this is the first record of SFG Rickettsia in the municipalities targeted by this study. These results warn that SFG Rickettsia circulation poses a threat in Rondonia State (among Amazon-Savannah ecotones), and that this threat is increased by the fact that SFG Rickettsia infect a human-biting tick species hitherto unconfirmed as a vector.

Dubious presence of Bartonella bacilliformis in ticks from Madre de Dios, Peru

“…Our work describes a specific event with a specific finding as reported in other scientific publications of the same type, whose primary objective is not to determine the dynamics of the expansion of a disease.The fact that a pathogen such as B. bacilliformis is present in these ticks and transported by these mammals does not mean that Carrion’s disease expands rapidly. Any disease and particularly those transmitted by vectors, depend on the environment, agent and guest, which makes their transmission and expansion complex.The geographic expansion of ticks and isolations of disease-causing bacteria from these is constantly reported [19, 20], B. bacilliformis would not be the exception.Dr. Ruiz mentions the geographical distribution of ticks and postulates how the disease can potentially spread and the reasons why it does not happen. Bartonella bacilliformis is a notifiable disease, however due to the lack of diagnostic resources is not usually made in time and the government uses mainly thick blood smear; although molecular tests are recently being implemented.…”

“…The geographic expansion of ticks and isolations of disease-causing bacteria from these is constantly reported [19, 20], B. bacilliformis would not be the exception.…”

A checklist of the tick of vultures, with the first record of the brown dog tick, Rhipicephalus linnaei (Acari: Ixodidae) from the Indian vulture, Gyps indicus (Falconiformes: Accipitridae)

“…(2013); Mathison and Pritt (2014); Savage et al (2015); Godsey Jr. et al (2016); Levin et al (2017); Savage et al (2017); Godsey Jr. et al (2020); Madison-Antenucci et al (2020) Parker et al (1933); Labruna et al (2004); Guede et al (2005); Sangioni et al (2005); Pacheko et al (2007); Labruna et al (2008); Horta et al (2009); Labruna (2009); Bermúdez et al (2011); Melo et al (2015); Soares et al (2015); Witter et al (2016); Costa et al (2017);Aguirre et al (2018) …”