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The frequent use of acaricides against the tick Rhipicephalus microplus increases the risk of development of resistance. Recent studies have revealed that Neoglaziovia variegata, an indigenous plant species known in Brazil as 'caroá', has a deleterious effect against R. microplus. In the current study, extracts of N. variegata were studied for their possible acaricidal properties. A hexane extract of N. variegata leaves was fractionated in a chromatography column and the fractions were tested in adult tick immersion tests in triplicate using three concentrations (5, 10 and 25 mg/ml). All the fractions had harmful effects on the ticks. However, three fractions were more efficaceous. Phytochemical analysis indicated that stigmast-5-en-3-ol and stigmastanol were most abundant; they might be responsible for the acaricidal effects, making them potentially useful as alternative agents to control the tick R. microplus. [ABSTRACT FROM AUTHOR]

This study aimed to determine the AR of gastrointestinal nematodes (GIN) to commercial drugs in sheep flocks naturally infected, grazing in irrigated (IA) and dry (DA) areas of the semiarid region in northeastern Brazil. Fecal egg count reduction tests (FECRT) were performed at 10 farms. From each flock, 36 adult sheep were selected and divided into five groups (G1 (0.08% ivermectin), G2 (10% albendazole), G3 (5% levamisole), G4 (1% moxidectin), G5 (10% closantel) and one control group, G6). All the commercial drugs were found to reduce the number of eggs per gram of feces (EPG). Resistance to ivermectin (37.1%), albendazole (52.1%), and levamisole (52.0%) was detected at all the farms, but nematodes proved to be susceptible to moxidectin (87.9%) and closantel (83.9%). The overall average efficacy of the commercial drugs was significantly higher (P < 0.05) in DA (49.2%), where moxidectin (90.4%) showed high effectiveness. The presence of the parasite Haemonchus contortus predominated at all the farms. The variables irrigated area (P = 0.002), intensive breeding (P = 0.018), uncovered enclosures (P = 0.05), cultivated (P = 0.043) and native/cultivated (P = 0.007) pastures, and rotational grazing (P = 0.013) were significantly associated with GIN infection; irrigated area (P = 0.009), semi-intensive breeding (P = 0.05), rotational grazing (P = 0.045), cultivated (P = 0.021) and native/cultivated (P = 0.04) pastures, and estimated weighing of animals (P = 0.002) were significantly associated with AR. Therefore, improved management practices and strategic deworming must be implemented to prevent the development of AR. [ABSTRACT FROM AUTHOR]

The genetic structure of populations of the tick Amblyomma ovale from five distinct areas of the Brazilian Atlantic rainforest was evaluated via DNA sequencing and associated with the presence of domestic dogs acting as hosts at the edge of forest fragments. Ticks were collected from domestic dogs and from the environment between 2015 and 2017. Four collection areas were located in the surroundings and within the Serra do Mar State Park, São Paulo State (23°37′21"S, 45°24′43"W), where dogs were bimonthly monitored along 2 years using camera traps and GSM trackers. To determine the spatial limits of genetic structure, ticks collected upon dogs living near the Serra do Baturié, Ceará State (4°15′40"S, 38°55′54"W) were included as well. A total of 39 haplotypes of 16S rRNA and Cox 1 mitochondrial genes sequences were observed, with 27 of them coming from areas within the Serra do Mar State Park. No haplotype was shared between the Serra do Mar and the Serra do Baturié indicating isolation of tick populations at the scale of 2000 km. Although three different haplotype lineages of A. ovale occurred within the Serra do Mar State Park, no genetic structure was found across the study sites within this park, suggesting high tick gene flow across a range of 45 km. Monitoring data from domestic dogs and wild carnivores showed that these species share the same habitats at the forest edge, with dogs playing a likely limited role in tick dispersal. Our findings have important implications for understanding the genetic structure of wide spread A. ovale along Brazilian rainforest remnants, which can further be associated to tick-borne infectious agents, such as Rickettsia parkeri, and used for predicting future patterns of tick diversity in the Brazilian Atlantic rainforest. [ABSTRACT FROM AUTHOR]

Background: The rock cavy Kerodon rupestris (Wied-Neuwied, 1820) is a rodent species endemic to northeastern Brazil. Earlier studies have associated the argasid tick Ornithodoros talaje (Guérin-Méneville, 1849) with rocky cavy; however, a recent study proposed that O. talaje is not established in Brazil, where previous reports of this species were possibly misidentifications of closely related species, yet to be properly determined. Here, we describe a new species of Ornithodoros Koch, 1844 associated with rock cavies in northeastern Brazil. Methods: During 2012-2013, Ornithodoros ticks were collected from K. rupestris resting places in Paraíba State (PB) and Piauí State (PI), northeastern Brazil. These ticks were brought alive to the laboratory, and used to form two laboratory colonies (PB and PI ticks). Field-collected adults and laboratory-reared larvae were used for morphological description through light and scanning electron microscopy. DNA sequences of the mitochondrial 16S rRNA gene were generated from nymphal ticks and used to conduct phylogenetic analyses along with other Ornithodoros spp. sequences from GenBank. Reproductive compatibility of crosses between PB and PI adult ticks was evaluated, as well as analyses of hybrid ticks through larval morphology by a principal components analysis (PCA) and DNA sequences of the second internal transcribed spacer (ITS2) region from adult ticks. Results: Morphological analysis allowed recognizing these ticks as a new species, Ornithodoros rietcorreai n. sp. The larva of O. rietcorreai is distinct from those of other Ornithodoros spp. by the combination of the following character states: 14 pairs of dorsal setae, dorsal plate pyriform, hypostome with pointed apex and dental formula 3/3 anteriorly, 2/2 posteriorly, and anal valves with long and pointed leaf-shaped ends. There were a few larval morphological differences between PB and PI ticks, and their mitochondrial 16S rDNA sequences diverged by 3.3 %. On the other hand, cross-mating experiments showed that PB and PI ticks were reproductive compatible, indicating that they represent a single species. Analyses of ITS2 sequences and PCA corroborated this assumption. Conclusion: Ornithodoros rietcorreai is described as a new species associated with K. rupestris in Brazil, increasing the Brazilian tick fauna to 70 species. [ABSTRACT FROM AUTHOR]

Background: Until recently, Amblyomma cajennense (Fabricius, 1787) was considered to represent a single tick species in the New World. Recent studies have split this taxon into six species. While the A. cajennense species complex or A. cajennense (sensu lato) (s.l.) is currently represented by two species in Brazil, A. cajennense (sensu stricto) (s.s.) and Amblyomma sculptum Berlese, 1888, their geographical distribution is poorly known. Methods: The distribution of the A. cajennense (s.l.) in Brazil was determined by morphological examination of all lots of A. cajennense (s.l.) in two large tick collections of Brazil, and by collecting new material during three field expeditions in the possible transition areas between the distribution ranges of A. cajennense (s.s.) and A. sculptum. Phylogenetic analysis inferred from the ITS2 rRNA gene was used to validate morphological results. Morphological description of the nymphal stage of A. cajennense (s.s.) is provided based on laboratory-reared specimens. Results: From the tick collections, a total 12,512 adult ticks were examined and identified as 312 A. cajennense (s.s.), 6,252 A. sculptum and 5,948 A. cajennense (s.l.). A total of 1,746 ticks from 77 localities were collected during field expeditions, and were identified as 249 A. cajennense (s.s.), 443 A. sculptum, and 1,054 A. cajennense (s.l.) [these A. cajennense (s.l.) ticks were considered to be males of either A. cajennense (s.s.) or A. sculptum]. At least 23 localities contained the presence of both A. cajennense (s.s.) and A. sculptum in sympatry. DNA sequences of the ITS2 gene of 50 ticks from 30 localities confirmed the results of the morphological analyses. The nymph of A. cajennense (s.s.) is morphologically very similar to A. sculptum. Conclusion: Our results confirmed that A. cajennense (s.l.) is currently represented in Brazil by only two species, A. cajennense (s.s.) and A. sculptum. While these species have distinct distribution areas in the country, they are found in sympatry in some transition areas. The current distribution of A. cajennense (s.l.) has important implications to public health, since in Brazil A. sculptum is the most important vector of the bacterium Rickettsia rickettsii, the etiological agent of Brazilian spotted fever. [ABSTRACT FROM AUTHOR]

This study investigated the prevalence of Rickettsia spp. and Ehrlichia canis infection in dogs and their ectoparasites from rural and urban areas of two municipalities, Petrolina and Juazeiro, within a semiarid region (Caatinga biome) of northeastern Brazil, by immunofluorescence assay (IFA) and polymerase chain reaction (PCR). Overall, 12.1% (61/504) and 23.0% (116/504) of canine plasma samples had antibodies reactive to Rickettsia spp. and E. canis. E. canis DNA was detected by PCR in 8.3% (42/504) of canine blood samples, whereas no blood sample was positive for Rickettsia spp. The infection by E. canis was determined by PCR in 4.9% (14/285) Rhipicephalus sanguineus sensu lato (s.l.) ticks and by Rickettsia felis in 1.1% (3/285) and 40.6% (74/182) ticks and fleas, respectively. Multivariate regression analyses revealed that canine seropositivity to Rickettsia spp. was associated statistically with the variables 'to reside in Petrolina' and 'presence of ectoparasites.' Our results indicate that canine infection by E. canis might be endemic in the Caatinga biome as it is in other Brazilian biomes. Although no previous serosurvey for Rickettsia spp. has been conducted on dogs from the Caatinga biome, our values are much lower than the ones reported for rural dogs from other Brazilian biomes. These differences are likely related to the semiarid climate of the aatinga biome, which minimizes the exposure of rural dogs to Amblyomma spp. ticks, the most common vectors of Rickettsia spp. in Brazil. Considering that dogs are excellent sentinels for human exposure to Rickettsia spp., we can infer that the risks of human acquiring tick-borne rickettsiosis in the Caatinga region of the present study are low. The rickettsial infection rates in fleas and ticks were not related to canine seropositivity; i.e., areas with higher Rickettsia infection rates in fleas had the lowest canine seroreactivity to Rickettsia spp. [ABSTRACT FROM AUTHOR]

Rickettsia species antibodies have been detected in some cats but it is unknown whether infected cats develop clinical signs. The prevalence of Rickettsia species deoxyribonucleic acid (DNA) in blood from clinically ill cats has not been determined. The objective of this study was to determine if cats with fever (body temperature ≥102.5°F [39.2°C]) were more likely to have evidence of rickettsial infection than healthy, age-matched, control cats with a body temperature<102.5°F. Rickettsia species polymerase chain reaction (PCR) assays were performed to detect rickettsial DNA extracted from blood (71 paired samples), indirect immunofluorescence assays (IFA) were performed to detect serum antibodies against Rickettsia felis (90 paired samples) and Rickettsia rickettsii (91 paired samples), and the results between pairs were compared. All samples were negative for Rickettsia species DNA. More cats with fever were seropositive for R felis or R rickettsii than control cats, but results were not statistically significant. Results of this pilot study failed to show an association between Rickettsia species DNA or Rickettsia species antibodies and fever. [Copyright &y& Elsevier]

An Ixodes loricatus engorged female, infected with Rickettsia bellii, was collected from an opossum ( Didelphis aurita) in Mogi das Cruzes, São Paulo State, Brazil. Two consecutive laboratory tick generations (F1 and F2) reared from this single engorged female were evaluated for Rickettsia infection by polymerase chain reaction (PCR) targeting specific Rickettsia genes. Immature ticks fed on naïve Wistar rats ( Rattus norvegicus) and adult ticks fed on opossum ( D. aurita), both free of ticks and rickettsial infection. PCR performed on individual ticks from the F1 (20 larvae, 10 nymphs, and 10 adults) and the F2 (30 larvae, 30 nymphs, and 15 adults) yielded expected bands compatible with Rickettsia. All the PCR products that were sequenced, targeting gltA gene, resulted in sequences identical to each other and 99.7% (349/350) similar to the corresponding sequence of R. bellii in GenBank. The R. bellii infection on ticks from the second laboratory generation (F2) was confirmed by other PCR protocols and successful isolation of R. bellii in cell culture. We report for the first time a Rickettsia species infecting I. loricatus, and the first report of R. bellii in the tick genus Ixodes. We conclude that there was an efficient transovarial transmission and transstadial survival of this Rickettsia species in the tick I. loricatus. Our results suggest that R. bellii might be maintained in nature solely by transovarial transmission and transstadial survival in ticks (no amplifier vertebrate host is needed), since there has been no direct or indirect evidence of infection of vertebrate hosts by R. bellii. [ABSTRACT FROM AUTHOR]

Clinical illness caused by Rickettsia rickettsii in dogs has been reported solely in the United States. We report 2 natural clinical cases of Rocky Mountain spotted fever in dogs in Brazil. Each case was confirmed by seroconversion and molecular analysis and resolved after doxycycline therapy. [ABSTRACT FROM AUTHOR]

We evaluated the presence of Rickettsia infection among fleas collected on domestic dogs in two Guarani Indian communities in the suburban area of São Paulo Municipality, Brazil. A total of 114 Ctenocephalides felis felis and 47 Ctenocephalides canis were collected from 40 dogs. A total of 41 C. felis felis (36.0%) and 9 C. canis (19.1%) fleas yielded expected bands by PCR, which were all shown by DNA sequencing to be indentical to the corresponding sequence of a fragment of the Rickettsia felis gltA gene deposited in GenBank. The overall prevalence of R. felis was 31.0% (49/161). [ABSTRACT FROM AUTHOR]