A new species of soft tick from dry tropical forests of Brazilian Caatinga

Isolation and molecular characterization of a novel relapsing fever group Borrelia from the white-eared opossum Didelphis albiventris in Brazil

This study aimed to detect, isolate and to characterize by molecular methods a relapsing fever group (RFG) Borrelia in white-eared opossums (Didelphis albiventris) from Brazil. During 2015-2018, when opossums (Didelphis spp.) were captured in six municipalities of the state of São Paulo, Brazil, molecular analyses revealed the presence of a novel RFG Borrelia sp. in the blood of seven opossums (Didelphis albiventris), out of 142 sampled opossums (4.9% infection rate). All seven infected opossums were from a single location (Ribeirão Preto municipality). In a subsequent field study in Ribeirão Preto during 2021, two new opossums (D. albiventris) were captured, of which one contained borrelial DNA in its blood. Macerated tissues from this infected opossum were inoculated into laboratory animals (rodents and rabbits) and two big-eared opossums (Didelphis aurita), which had blood samples examined daily via dark-field microscopy. No spirochetes were visualized in the blood of the laboratory animals. Contrastingly, spirochetes were visualized in the blood of the two D. aurita opossums between 12 and 25 days after inoculation. Blood samples from these opossums were used for a multi-locus sequencing typing (MLST) based on six borrelial loci. Phylogenies inferred from MLST genes positioned the sequenced Borrelia genotype into the RFG borreliae clade basally to borreliae of the Asian-African group, forming a monophyletic group with another Brazilian isolate, "Candidatus B. caatinga". Based on this concatenated phylogenetic analysis, which supports that the new borrelial isolate corresponds to a putative new species, we propose the name "Candidatus Borrelia mimona".

New records of soft ticks (Acari: Argasidae) from caves in Brazil, with a morphological study of Ornithodoros fonsecai and an analysis of the taxonomic status of Antricola inexpectata

In this study, we report soft ticks from bat-inhabiting caves in different areas of Brazil. From 2010 to 2019, we collected 807 tick specimens from nine caves located in four Brazilian states among two biomes. Ticks were morphologically identified as Antricola guglielmonei (282 specimens), Ornithodoros cavernicolous (260 specimens), and Ornithodoros fonsecai (265 specimens). Whereas A. guglielmonei was collected on bat guano in hot caves, O. cavernicolous and O. fonsecai were collected in cracks and crevices on the walls of cold caves, sometimes in the same chamber. Morphological identifications were corroborated by molecular and phylogenetic analyses inferred from tick mitochondrial 16S rRNA gene partial sequences. The sequences of A. guglielmonei, O. cavernicolous and O. fonsecai collected in this study clustered with conspecific GenBank sequences from different localities of Brazil. Remarkably, a clade containing 12 sequences of O. fonsecai was clearly bifurcated, denoting a degree of genetic divergence (up to 5 %) of specimens from Cerrado/Atlantic Forest biomes with the specimens from the Caatinga biome. To further evaluate this divergence, we performed morphometric analysis of the larval stage of different O. fonsencai populations by principal component analysis, which indicated that the larvae from Caatinga populations were generally smaller than the larvae from other biomes. Some of the present A. guglielmonei specimens were collected from the type locality of Antricola inexpectata. Comparisons of these specimens with the type specimens of A. inexpectata and A. guglielmonei indicated that they could not be separated by their external morphology. Hence, we are relegating A. inexpectata to a synonym of A. guglielmonei. This proposal is corroborated by our phylogenetic analysis.

Ticks (Ixodida) associated with bats (Chiroptera): an updated list with new records for Brazil

Bats harbor diverse groups of ectoparasites, such as insects and mites like ticks (Ixodida). Some species of ticks with records for bats and humans have already been reported with the occurrence of pathogens. This research article aims to document new geographical and host records of ticks infesting bats in Rio de Janeiro state, Southeastern Brazil, and provides a list of tick species associated with bats in Brazil. We counted 12 argasid ticks and five ixodid ticks associated with six individuals of bats. Larvae of Amblyomma sp., Ixodes sp., Ornithodoros sp., and Ornithodoros hasei and one nymph of Amblyomma sculptum parasitizing Artibeus obscurus, Phyllostomus hastatus, Micronycteris sp., Molossus fluminensis, and Carollia perspicillata in different localities of Rio de Janeiro state were studied. We carried out a systematic review with the descriptors: tick bat Brazil. We considered data from 42 articles in the systematic review. We compiled eleven records of Ixodidae, and 160 records of Argasidae. Ornithodoros cavernicolous were the most recorded tick species. Overall, we registered 171 tick-bat or roost-bat associations with 85 records of these infesting bats. The review also shows the occurrence of tick species associated with bats, and we present new records on ticks parasitizing bats in Brazil.

A Novel Relapsing Fever Group Borrelia Isolated from Ornithodoros Ticks of the Brazilian Caatinga

Tick-borne relapsing fever group (RFG) borreliosis remains neglected as a human disease and little is known on its maintenance in ticks and vertebrates, especially in South America. Therefore, this study investigated borrelial infection in Ornithodoros ticks collected in rodent-inhabited rock formations in the Brazilian semiarid region, within the Caatinga biome. Collected ticks (Ornithodoros rietcorreai and Ornithodoros cf. tabajara) were allowed to feed under laboratory conditions on guinea pigs, which had blood samples examined daily by dark-field microscopy. No spirochetes were visualized in the blood of any of four O. rietcorreai-infested guinea pigs. Contrastingly, spirochetes were visualized between 9 and 39 days after tick feeding in the blood of three guinea pigs, each infested with O. cf. tabajara ticks from a different locality. Guinea pig infection was confirmed by passages into experimental animals and by generating DNA sequences of Borrelia spp. from the blood of spirochetemic guinea pigs. Three O. cf. tabajara populations were infected by the same borrelial organism, which was characterized as a novel RFG agent (named as 'Candidatus Borrelia caatinga') based on 10 Borrelia loci (rrs, flaB, glpQ, gyrB, clpX, pepX, pyrG, recG, rplB and uvrA). We demonstrated that O. cf. tabajara is a competent vector of the novel Borrelia sp. isolates, although none of the infected rodents developed clinical illness.

Laboratory life cycle of Ornithodoros puertoricensis (Ixodida: Argasidae) collected in the Colombian Caribbean

Three studies on the biology of Ornithodoros puertoricensis are available in the literature, using different hosts and incubation temperatures. In a previous study, we identified O. puertoricensis in the Colombian Caribbean. The aim of the present work was to analyze life cycle data along one generation from these specimens under laboratory conditions. Eggs of O. puertoricensis were collected in between fragments of bahareque material in a rural dwelling in the municipality of Planeta Rica (Córdoba Department, Colombia), and transported to the laboratory. All post-egg stages (i.e., larvae, nymphs, and adults) were incubated at 27 °C and 85% RH and fed on laboratory mice (Mus musculus). Sixteen engorged larvae were obtained to start a laboratory colony. Average feeding period for larvae was 4.6 days (4-5). The first nymphal instar (N1) did not require feeding and the subsequent nymphal stages (N2, N3, and N4) and adults had feeding periods ranging from 55 to 75 min. Average pre-molting period in nymphs was 15 days (10-21). Most of the N3 molted to males and all N4 molted to females. Two gonotrophic cycles were recorded: the first had a preoviposition period of 12 days (7-18) and produced 190 eggs (171-223), the second lasted 6.6 days (6-7) and produced 146 eggs (104-201). The mean life cycle duration (from parental eggs to F1 eggs) was 70.7 days (58.7-82.7) without fasting periods. The collected data agree with previous studies even with differences in hosts and maintenance conditions.

Soft and hard ticks (Parasitiformes: Ixodida) on humans: A review of Brazilian biomes and the impact of environmental change

Records of accidental parasitism by ticks in humans from Brazil are scarce, with most being reported by researchers who are parasitized during their research and by professionals who work with animals. In order to compile these records, an extensive literature review was carried out. Our revision includes studies published between 1909 and 2022, including nine species of the Argasidae family and 32 species of the Ixodidae family that were reported biting humans in the six biomes of the Brazilian territory. The species with the highest number of records of human parasitism was Amblyomma sculptum, followed by Amblyomma coelebs, Amblyomma cajennense sensu stricto, and Amblyomma brasiliense. The Atlantic Forest was the most frequent biome where human parasitism occurred, probably due to the greater number of inhabitants, universities, and researchers in the region; however, this does not mean that this biome is more conducive to the development of ticks and their parasitism in humans. In addition to Amblyomma ovale, a vector of Rickettsia parkeri in the country, two of the main species that act as vectors of Rickettsia rickettsii, A. sculptum, and Amblyomma aureolatum, have been reported, which is quite worrying considering that the wide distribution of the species and life stages most frequently mentioned in parasitism (i.e., nymphs and adults) are the ones that favour pathogen transmission. This research provides a significant contribution to the knowledge of tick species associated with human parasitism in Brazil; however, due to environmental change potentiated by deforestation and fires, it is expected that there will be a geographic expansion of some tick species and the pathogens that use them as a vector and an increase in human parasitism.

Historical overview and update on relapsing fever group Borrelia in Latin America

Relapsing fever group Borrelia (RFGB) are motile spirochetes transmitted to mammalian or avian hosts through the bite of hematophagous arthropods, such as soft ticks (Argasidae), hard ticks (Ixodidae) and the human clothing lice. RFGB can infect pets such as dogs and cats, as well as birds, cattle and humans. Borrelia recurrentis, B. anserina and B. theileri are considered to have worldwide distribution, affecting humans, domestic birds and ruminants, respectively. Borrelia spp. associated with soft ticks are transmitted mainly by Ornithodoros ticks and thrive in endemic foci in tropical and subtropical latitudes. Nowadays, human cases of soft tick-borne relapsing fever remain neglected diseases in several countries, and the impact these spirochetes have on the health of wild and domestic animals is largely understudied. Human infection with RFGB is difficult to diagnose, given the lack of distinguishing clinical features (undifferentiated febrile illness). Clinically, soft tick or louse-borne relapsing fever is often confused with other etiologies, such as malaria, typhoid or dengue. In Latin America, during the first half of the twentieth century historical documents elaborated by enlightened physicians were seminal, and resulted in the identification of RFGB and their associated vectors in countries such as Mexico, Panama, Colombia, Venezuela, Peru and Argentina. Almost 80 years later, research on relapsing fever spirochetes is emerging once again in Latin America, with molecular characterizations and isolations of novel RFGB members in Panama, Bolivia, Brazil and Chile. In this review we summarize historical aspects of RFGB in Latin America and provide an update on the current scenario regarding these pathogens in the region. To accomplish this, we conducted an exhaustive search of all the published literature for the region, including old medical theses deposited in libraries of medical academies. RFGB were once common pathogens in Latin America, and although unnoticed for many years, they are currently the focus of interest among the scientific community. A One Health perspective should be adopted to tackle the diseases caused by RFGB, since these spirochetes have never disappeared and the maladies they cause may be confused with etiologies with similar symptoms that prevail in the region.

Ornithodoros cf. mimon infected with a spotted fever group Rickettsia in Brazil

Ornithodoros mimon is an argasid tick primarily associated with bats that also infest other animals including birds, opossums and humans. In this paper, we report the finding of an argasid species resembling O. mimon, which similarly may be found in human dwellings and parasitize humans in Brazil. We also provide molecular evidence that this argasid tick species may carry a rickettsial organism, whose pathogenicity remains unknown. A total of 16 ticks (two females, two males and 12 nymphs) were collected in the bedroom and in the attic of a human house, where cases of "insect" bites have been recurrent. These ticks were identified morphologically and genetically as Ornithodoros cf. mimon. Upon PCR testing, four of these ticks (one female and three nymphs) were positive for human blood and for a bacterium closely related to "Candidatus Rickettsia paranaensis". In conclusion, we report for the first time in Brazil an argasid tick species morphologically and genetically related to O. mimon, which feeds on humans and carry a rickettsial organism belonging to the spotted fever group. Further studies are needed to formally assess the taxonomic status of this tick species and also to investigate the pathogenicity of its associated rickettsial organism.

New records of soft ticks (Acari: Argasidae) in the Caatinga biome of Brazil, with a phylogenetic analysis of argasids using the nuclear Histone 3 (H3) gene

In Brazil, 19 species of the genus Ornithodoros (Acari: Argasidae) have been reported. The medical and veterinary importance of Ornithodoros ticks has increased substantially in recent decades, with the discovery of various relapsing fever Borrelia infecting Ornithodoros ticks. Herein, argasid ticks were collected during 2019-2020 from caves, abandoned nests and homes in various regions of Ceará State, Brazilian semiarid-Caatinga biome. In total, 289 ticks were collected and identified into five species: Ornithodoros cavernicolous (176 specimens), Ornithodoros fonsecai (81), Ornithodoros mimon (12), Ornithodoros rietcorreai (4), and a fifth species provisionally retained as Ornithodoros sp. Ubajara. Tick identifications were corroborated by a phylogenetic analysis inferred using the 16S rRNA gene. To extend the molecular characterization, DNA samples were tested by an additional PCR assay targeting the nuclear Histone 3 (H3) gene. Because there were no H3 sequences of argasids in GenBank, we extended this PCR assay for additional Ornithodoros species, available in our laboratory. In total, 15 partial sequences of the H3 gene were generated for 10 Ornithodoros species, showing 0% intraspecific polymorphism, and 1.5-11.6% interspecific polymorphism. Phylogenetic analyses inferred segregated Ornithodoros sp. Ubajara as a potential novel species. Our results also highlight the potential of the H3 gene for deeper phylogenetic analyses of argasids. The present study provides new data for argasid ticks of the genus Ornithodoros in the Caatinga biome. Because some of these tick species are human-biting ticks, active surveillance for the incidence of human infection due to Ornithodoros-borne agents is imperative in the Caatinga biome.