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Soft ticks (Argasidae) of the PavlovskyellaPospelova-Shtrom subgenus are important vectors of relapsing fever spirochetes, which are agents of disease globally. South American representatives of the Pavlovskyellasubgenus include 3 species: Ornithodoros(Pavlovskyella) brasiliensisAragão, Ornithodoros(Pavlovskyella) furcosusNeumann, and Ornithodoros(Pavlovskyella) rostratusAragão. Here, we describe a fourth species based on morphological and mitogenomic evidence of ticks collected in burrows of unknown hosts in central Chile. The larva of the new species separates from other South American soft ticks by the following combination of characters: 13 pairs of dorsolateral setae, dorsal plate hexagonal, hypostome blunt with denticles from apex almost to the base. Adults of this new species lack cheeks, possess a dorsoventral groove, and have humps, similar to O.(P.) brasiliensis; however, they lack bulging structures on the flanks of idiosoma. Moreover, females and males differ from O.(P.) rostratusby having 3 humps instead of spurs in tarsi I and from O.(P.) furcosusbecause of their smaller size and thinner anterior lip of the genital aperture in females. The phylogenetic analysis performed with mitogenomes of the Argasidae family depicts the new Pavlovskyellaspecies from Chile in a monophyletic clade with other South American species in the subgenus, confirming a regional group.

In this study, we present a morphological description of immature and adult specimens of Ornithodoros saraivain. sp., a tick associated with the frog Cycloramphus boraceiensis(Cycloramphidae) at São Sebastião island, located in the São Paulo state seaboard, Brazil. While larvae of O. saraivaiare ecologically related to Ornithodoros faccinii, another soft tick associated with cycloramphids, the combination of 7 sternal pairs, 16 dorsal pairs, a pyriform dorsal plate and a partially toothed hypostome constitute unique characters of the O. saraivailarvae. One undetermined nymphal instar and adults of O. saraivaiare similar to mature specimens of the Ornithodoros talajespecies group; however, the O. saraivaispecimens can be recognized by the presence of a robust bean-shaped spiracle with a large spiracular plate and more than two long seta in palpal article I. Identical partial sequences of the mitochondrial 16S rDNA gene confirmed the identity for all collected stages and for two cohorts of laboratory-reared larvae of O. saraivai. A Bayesian and Maximum Parsimony inferred phylogenetic trees support the position of O. saraivaiin a clade with O. faccinii, suggesting the existence of an Ornithodoroslineage that evolved in association with amphibians.

Tick abnormalities have been unusual in nature, and they can be divided into local and general. In the present study, external morphological anomalies were described in 31 individual adult ticks of 15 different species of Ixodidae, which were collected on wild hosts (20 ticks), domestic hosts (7 ticks), and in the environment (4 ticks) in 11 states of Brazil from 1998 to 2022. Among the 31 tick specimens, 14 (45%) were categorized as local anomalies, and 17 (55%) as general anomalies. The ticks were taxonomically identified into 14 species of Amblyomma,and one species of Rhipicephalus.Local anomalies included malformations of scutum/alloscutum, ectromely, leg atrophy, and a third ectopic spiracular plate. General anomalies included opisthosoma duplication, no expansion of dorsal alloscutum in engorged females, and gynandromorphism; the latter is described for 13 tick specimens. Morphological anomalies in Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma humeraleand Amblyomma longirostreare reported for the first time. Although the results herein expand the list of anomalous tick species in the Neotropics, future studies should be conducted to clarify the origin of these anomalies.

In 2020, adult hard ticks (males and females) were collected from great horned owls [Bubo virginianus(Gmelin, 1788)] in the coastal region in southern Brazil. The engorged females were allowed to oviposit in the laboratory and hatched larvae could be obtained. Analyses of the external morphology of the adult ticks revealed that they represent a new species, which was named Amblyomma monteiroaen. sp. Partial sequences of the mitochondrial 16S rRNA gene and the nuclear second internal transcribed spacer (ITS2) were generated from a male and a female. Their 16S rRNA haplotypes were identical to each other and closest (96% identity) to corresponding sequences of Amblyomma parvitarsumNeumann, 1901, and 90% identical to Amblyomma neumanniRibaga, 1902. Their ITS2 haplotypes were 95.8 to 96.0 identical to the single ITS-2 partial sequence of A. parvitarsumavailable in GenBank. In the phylogenetic trees inferred by both 16S rRNA and ITS2 partial sequences, A. monteiroaen. sp. formed a clade with A. parvitarsum,with A. neumannibranching sister to this clade. Amblyomma monteiroaen. sp. is genetically and morphologically related to A. parvitarsum.Both tick species are unique in combining the following morphological characters: scutum extensively ornate; eyes rounded and bulging; coxa I with two moderate pointed spurs, the external longer than the internal; a single triangular short spur on coxae II-III; presence of two spines on the tibia of legs II-IV; hypostomal dentition 3/3, trochanters without spurs. However, the males of the two species can be separated by specific features in palps and festoons, whereas the females differ in specific features of the coxal spurs. The larva of A. monteiroaen. sp. can be morphologically distinguished from A. parvitarsumonly by morphometry, with the former species being slightly smaller. Currently, A. monteiroaen. sp. is restricted to southern Brazil, and the only known host is B. virginianus(Strigiformes: Strigidae). The present study increases the AmblyommaBrazilian fauna to 34 species.

This study evaluated the species richness and seasonal dynamics of ticks and rickettsial agents infecting ticks in the largest natural Reserve of the Cerrado biome of Brazil, the Grande Sertão Veredas National Park. During 2012–2014, a total of 9531 host-seeking ticks were collected by dry ice traps and dragging, whereas 1563 ticks were collected from small mammals, and 1186 ticks from domestic animals. Overall, the following 12 tick species were identified: Amblyomma auricularium, Amblyomma dubitatum, Amblyomma naponense, Amblyomma ovale, Amblyomma parvum, Amblyomma sculptum, Amblyomma tigrinum, Amblyomma triste, Dermacentor nitens, Rhipicephalus microplus, Rhipicephalus sanguineussensu lato, and Ornithodoros mimon. The three most abundant tick species, A. sculptum, A. parvum,and A. triste,are likely to develop one generation per year, with adults predominating between spring and autumn, and immature ticks during autumn-winter. Small mammals seem to be important hosts for immature stages of A. parvum,and A. triste,but not for A. sculptum.Molecular analyses revealed the presence of the human pathogen Rickettsia parkeriin 10% of the A. tristeticks, whereas two agents of unknown pathogenicity, Rickettsia belliiand ‘CandidatusRickettsia andeanae’ were found in 7 and 5%, respectively, of the A. parvumticks. A fourth rickettsial agent, Rickettsia amblyommatis,was found in a single A. sculptumtick. Several Vero cell-established isolates of R. parkeriand R. belliiwere obtained from A. tristeand A. parvum,respectively. Serological analyses of small mammals suggest that they have been infected by R. parkeriand R. bellii,possibly via natural infestations by A. tristeand A. parvum,respectively. Because the Park has suffered low anthropic alterations, our results should provide baseline data that shall be used for future comparisons with other Cerrado areas with higher degree of anthropic changes.

Only one previous record of an exotic tick on a Brazilian traveler has been reported. Here, we report the detection of Dermacentor andersoni(Stiles) in Brazil while attached to a human traveler returning from the United States. This report is the fifth record of D. andersonias an exotic tick, and the second record of an exotic tick on a South American traveler.

Staphylococcus aureusis a multidrug-resistant bacterium responsible for several cases of hospital-acquired infections, which constitute a global public health problem. The introduction of new healthcare strategies and/or the discovery of molecules capable of inhibiting the growth or killing S. aureuswould have a huge impact on the treatment of S. aureus-mediated diseases. Herein, a Bowman–Birk protease inhibitor (LzaBBI), with strong in vitro antibacterial activity against S. aureus, was purified to homogeneity from Luetzelburgia auriculataseeds. LzaBBI in its native form is a 14.3 kDa protein and has a pI of 4.54, and its NH2-terminal sequence has high identity with other Bowman–Birk inhibitors. LzaBBI showed a mixed-type inhibitory activity against both trypsin and chymotrypsin, respectively, and it remained stable after both boiling at 98 °C for 120 min and incubation at various pHs. Scanning electron microscopy revealed that LzaBBI disrupted the S. aureusmembrane integrity, leading to bacterial death. This study suggests that LzaBBI is a powerful candidate for developing a new antimicrobial to overcome drug resistance toward reducing hospital-acquired infections caused by S. aureus.

More than seventy tick species have been reported in Brazil. Despite the emergence of tick-borne diseases in Neotropical region, there are still limited data available on tick species parasitizing humans in Brazil. Rio Grande do Sul is the southernmost state of Brazil, comprising the only part of Brazilian territory inside the Pampa biome, as well as the transition between subtropical and temperate zones. Here, we report on human parasitism by ticks in Rio Grande do Sul state between 2004 and 2017. Seventy cases of human parasitism by ticks were recorded, with a total of 81 tick specimens collected. These included 11 tick species belonging to three genera of Ixodidae (hard-ticks), Amblyomma, Haemaphysalisand Rhipicephalus; and one genus of Argasidae, Ornithodoros. The most prevalent tick species associated to cases of human parasitism were Amblyomma parkeri(24%), Rhipicephalus sanguineussensu lato (22%), Amblyomma aureolatum(15%) and Amblyomma ovale(12%). A spatial analysis showed two major hot spots of human parasitism by ticks in Rio Grande do Sul state. The findings of this study highlight the need for permanent monitoring of human parasitism by ticks in order to provide a better understanding of tick and tick-borne disease eco-epidemiology, and the early identification of potential cases of tick-borne diseases, particularly in spotted fever endemic regions.

Rickettsiosis are emerging or re-emerging diseases, with a worldwide distribution associated to transmission by arthropod vectors. Rickettsiaspecies belong to the spotted fever group (SFG) and are transmitted by hard ticks (Acari: Ixodidae) that may act as vectors and reservoirs. This study carried out a molecular detection of Rickettsiafrom 7 species of the family Ixodidae collected from domestic hosts by PCR amplification of fragments of the citrate synthase “gltA” gene and outer membrane protein “ompA” gene. Of the 204 samples analyzed, 11.3% (23) were positive for rickettsial infection. Three Rickettsiaspecies belonging to the SFG were found, constituting the first reports of Rickettsia rickettsiiin 2 departments of Colombia. Furthermore, we confirmed the first occurrence of CandidatusRickettsia andeanae in Colombia, a species with an unknown pathogenic role in humans. These results raise awareness regarding the need to increase epidemiological control measures, as well as to consider new endemic regions in Colombia for Rocky Mountain spotted fever (RMSF).

High similarity of morphological traits has historically overshadowed the identities and distributions of poultry-associated soft ticks Argas(Persicargas) miniatusand Argas(Persicargas) persicusin America. In order to model the occurrence of both parasites in the continent, in the current study we performed morphological and molecular analyses to identify ticks collected in hen houses from Brazil and northern Chile. Combining these results with literature data, and the examination of Argasallotments deposited in the tick collections “Coleção Nacional de Carrapatos Danilo Gonçalves Saraiva” (Brazil), the “Coleção Acarológica do Instituto Butantan São Paulo” (Brazil), and the “Colección Zoológica de la Academia de Ciencia de Cuba” (Cuba), we present a critical list with the localities where A. (P.) miniatusand A. (P.) persicushave been reported in the American continent. Our results confirmed the presence of A. (P.) miniatusin Brazil and Cuba, and A. (P.) persicusin Chile, which in particular, constitutes the first molecularly confirmed report of the later species for South America. Although A.(P.) miniatusand A. (P.) persicushave been documented in 21 American countries, the identity of some reports must still be considered as uncertain until detailed morphological and/or molecular studies are performed. When contrasted to a Köppen-Geiger climate classification, A. (P.) miniatuspredominantly occurs in equatorial and A. (P.) persicusin arid climates. However, until undetermined reports of both species are correctly identified, any conclusion on their geo-climatological occurrence throughout the American continent would be rather speculative.

The known tick fauna of Colombia includes 58 species (15 Argasidae and 43 Ixodidae). To add to the knowledge of the biology of ticks in Colombia, hard ticks (Ixodidae) were collected from domestic animals or vegetation during 2014–2016 in 10 of Colombia’s Departments. Ticks were identified to species through morphological examinations. Taxonomic identification was confirmed for some specimens by molecular methods, including phylogenetic analyses inferred from three tick genes (cytochrome c oxidase, 16S rDNA, second internal transcribed spacer). A total of 1745 tick specimens encompassing 8 species were collected. Overall, 5 tick species were recorded on cattle [Amblyomma dissimile, Amblyomma mixtum, Dermacentor nitens, Rhipicephalus microplus, Rhipicephalus sanguineussensu lato (s.l.)], 5 on dogs (Amblyomma maculatum, Amblyomma ovale, Amblyomma varium, R. microplus, R. sanguineuss.l.), 3 on horses (A. mixtum, D. nitens, R. sanguineuss.l.), 3 on donkeys (A. mixtum, D. nitens, R. microplus), 1 on pig (D. nitens), and 2 from vegetation (A. mixtum, A. dissimile). This included the first records of A. mixtumfrom two Colombian Departments, indicating that the distribution of this tick in Colombia may be broader than currently known. Phylogenetic analyses confirmed that R. sanguineuss.l. specimens from 8 Departments belong to the “tropical species”. Moreover, Colombian specimens of A. maculatumformed a large clade with GenBank sequences of A. maculatumand A. triste,although some Colombian specimens grouped with A. maculatumfrom the United States while others grouped with A. tristefrom Brazil. Significant polymorphisms were observed between specimens of A. ovaleor D. nitens; for the former species, it is noteworthy that two distinct clades were observed. Our study provides new records for 8 tick species parasitizing domestic animals in Colombia, including species with veterinary and medical importance in the Neotropical region, such as R. microplus, R. sanguineus, D. nitens, A. mixtum,and A. maculatum.Noteworthy, we provide the first record of A. variuminfesting a domestic mammal.

We report on the presence of the ixodid tick Amblyomma helvolumon three species of reptiles from Timor-Leste. Among a total of 21 host specimens (lizards: 18 four-fingered skinks, Carliasp. ‘Meleotegi’ and two forest skinks, Sphenomorphussp. ‘Meleotegi’; snake: one Coelognathus subradiatus) four were parasitized by ticks. Whereas nymphs were associated with the lizards, an adult male was retrieved from the snake. This report is the first of A. helvolumfor Timor-Leste, the first for the skink genera Carliaand Sphenomorphus, and the first for C. subradiatus. We present a comprehensive table with updated taxonomy of known associations between A. helvolumand other vertebrates.

•Absence of Cytauxzoonsp. in wild felids in a locality with the absence of the possible vector Amblyomma sculptum;.•High occurrence of Cytauxzoonspp. in wild felids infested by Amblyomma sculptum;.•Consolidation of the hypothesis that the jaguar is a natural reservoir of Cytauxzoonspp., related to the detection of parasitism for long periods and the absence of clinical and physiological changes.

The goal of this work was to combine different lines of evidence besides that of molecular markers to delimit species in ticks when the molecular data are not totally congruent. Two groups (Argentina, Brazil) of South American populations of Amblyomma parvumwere compared to test whether the splitting of these two lineages suggested by genetic analyses is complete. Comparative studies of reproductive compatibility, morphological analyses of fixed characters, and comparison of population distributions in spatially defined ecological niches were performed.The morphological comparisons of both discrete and morphometric characters showed no differences among A. parvumticks from Argentina and Brazil. The intercrosses and backcrosses showed evidence of pre- and post-zygotic compatibility between the two groups. No significant differences in environmental traits were found which would justify the separation of the records of A. parvumin distinct groups. Although the gene flow between the two groups of populations is limited, the absence of reproductive barriers, the lack of significant morphological differences, and the absence of significant differences in the niche preferences indicate that populations of A. parvumfrom Argentina and Brazil should be treated as a single species. The speciation conjectures suggested by some analyses of mitochondrial DNA sequences were not supported when different lines of evidences were compared.

Up to some years ago, the taxon Amblyomma cajennenserepresented a single tick species in the New World, from southern United States to northern Argentina. Recent studies, based on genetic, reproductive and morphological data reorganized this taxon into a complex of the following 6 valid species: A. cajennensesensu stricto, Amblyomma mixtum, Amblyomma sculptum, Amblyomma interandinum, Amblyomma tonelliae, and Amblyomma patinoi. According to this classification, the A. cajennensecomplex is currently represented in Colombia by only one species, A. patinoi.Because the Colombian land is surrounded by confirmed records of A. mixtumin Panama and Ecuador, and by A. cajennenses.s. in Venezuela and the Brazilian Amazon, it is possible that these two species could also occur in Colombia. This study aimed to determine the occurrence of ticks of the A. cajennensecomplex in the Orinoquía region of Colombia. A total of 246 adult ticks of the Amblyommagenus were collected in three sampled regions: 71 females and 110 males in Arauca (Arauca Department), 27 females and 20 males in Nunchía (Casanare Department), and 10 females and 8 males in Yopal (Casanare Department). Based on morphological and molecular analyses, these ticks were identified as A. mixtum.Molecular analyses consisted of DNA sequences of two molecular markers, the nuclear second internal transcribed spacer (ITS2) and the mitochondrial cytochrome c oxidase subunit I gene (COI). The presence of A. mixtumin Colombia is of medical relevance, since this species is incriminated as a vector of Rickettsia rickettsiiin Central America.

Ornithodoros atacamensisn. sp. is described from larvae collected on the lizard Liolaemus bisignatusand from free-living adults collected in desert areas from the Pan de Azúcar and Llanos de Challe National Parks, in Northern Chile. Additionally, unengorged larvae were obtained from fertilized females, which laid eggs in the laboratory. Morphological and mitochondrial 16S rDNA sequence analyses were performed in order to compare this new soft tick species with other congeneric Neotropical representatives. Larvae of O. atacamensisare morphologically closely related to Ornithodoros talajesensu stricto, Ornithodoros puertoricensis, Ornithodoros rioplatensis, Ornithodoros guaporensisand Ornithodoros hasei, all belonging to the O. talajespecies group. The larval diagnostic characters for this species are a combination of a large pyriform dorsal plate with a length of approximately 300μm, 17 pairs of dorsal setae with five central pairs, hypostome with apex pointed and dental formula 2/2 in most rows, 3/3 apically, and capsule of the Haller’s organ oval in shape without reticulations. Phylogenetic analyses inferred from the mitochondrial 16S rRNA gene and a Principal Component Analysis based on morphometric characters provide additional support to the description of O. atacamensisas an independent lineage within the genus clustering within the O. talajespecies group.

Ticks collected in the last two decades from free-living and captive wild animals from 28 municipalities of the Brazilian state of Mato Grosso were identified and tested using molecular methods for the presence of rickettsial agents. A total of 4467 ticks (229 larvae, 1676 nymphs, 1565 males, 997 females) representing 27 ixodid species were collected from 235 species of amphibians, reptiles, birds, and mammals from three different ecoregions (Pantanal, Cerrado, and Amazonia). The species Amblyomma parkeri, Amblyomma romitii, Amblyomma variumand Ixodes luciaeare reported for the first time in the state of Mato Grosso. Amongst 538 ticks tested by molecular methods for rickettsial infection, we detected ‘CandidatusRickettsia amblyommii’ infecting Amblyomma cajennensesensu stricto and Amblyomma coelebs, Rickettsiasp. strain Atlantic rainforest infecting Amblyomma ovale, Rickettsiasp. strain NOD infecting Amblyomma nodosum, and ‘CandidatusRickettsia andeanae’ infecting Amblyomma sculptum. Our results represent an impressive expansion of knowledge on tick fauna and rickettsiae and are essential for understanding the ecology of ticks and tick-borne diseases in the Neotropical region, particularly in midwestern Brazil.

The involvement of different species of ticks and wild animals, such as birds, play an important role in the epidemiology of tick-borne diseases. Birds may serve as reservoirs for some tick-borne diseases, and may carry and spread hematophagous ectoparasites mechanically. This study aimed to show the diversity of ticks on birds and molecular detection of rickettsial infection in ticks from Pantanal and Cerrado, two similar Brazilian biomes characterized by hydrological seasons. During two years, August 2012 to May 2014, ticks were collected from birds and from the environment in total of 14 visits for collecting samples, distributed in all hydrological seasons. A total of 674 birds were captured representing 113 species from 26 families. In total, 71 birds were parasitized (10.5%), and 155 ticks of the following 7 tick species (in decreasing order of prevalence) were identified: Amblyomma longirostreKoch, Amblyomma nodosumNeumann, Amblyomma cajennenseFabricius sensu lato (s.l.), Amblyomma calcaratumNeumann, Ornithodoros mimonKohls, Clifford & Jones, Amblyomma ovaleKoch, and Amblyomma tristeKoch. Among free-living ticks collected in the environment, A. cajennenses.l. was the most common. This is the first occurrence of O. mimonon birds, and of A. tristeon Passeriformes in Brazil. Molecular analyses revealed that 6 A. longirostreticks were infected by ‘CandidatusRickettsia amblyommii’, whereas 1 A. nodosumwas infected by a Rickettsia parkeri-like agent, previously reported as Rickettsiasp. strain NOD. Spotted fever group (SFG) agents were, for the first time, reported in ticks from birds captured in Pantanal biome, and the potential involvement of these agents as human pathogens should be considered in further studies.

Ticks were collected from captive reptiles, wild birds, and incidentally from humans at two locations in Honduras and part of these were tested for the presence of Rickettsiausing polymerase chain reaction. The following species of ticks were found: Amblyomma dissimileon Iguanidae reptiles, Amblyomma longirostreand Amblyomma nodosumon birds, and Amblyomma mixtum(Amblyomma cajennensecomplex) on humans. A. dissimilewas infected with Rickettsiasp. strain Colombianensi. Both A. longirostreand A. mixtumwere infected with Candidatus‘Rickettsia amblyommii’. This study provides the first report of rickettsial infections in ticks from reptiles, birds and humans in Honduras. New host – Amblyommatick associations are documented.

We examined the presence of borreliae and rickettsiae bacteria in ticks from wild passerine birds on three islands of the Archipelago of the Azores, the westernmost region of Palearctic. A total of 266 birds belonging to eight species from seven families were examined on São Miguel, Santa Maria and Graciosa islands in 2013. Ticks collected from these birds consisted of 55 Ixodes frontalis(22 larvae, 32 nymphs, 1 adult female) and 16 Haemaphysalis punctatanymphs. Turdus merulaand Erithacus rubeculawere the birds most infested with both tick species. Three T. merulain Santa Maria were infested with 4 I. frontalisinfected with Borrelia turdi. No rickettsiae were found in the ticks. We report for the first time the presence of I. frontalisand B. turdion the Azores islands and we showed that the spatial distribution reaches further west than previously thought.

The aim of this study was to document the presence of Rickettsiaspp. in ticks parasitizing wild birds in Costa Rica. Birds were trapped at seven locations in Costa Rica during 2004, 2009, and 2010; then visually examined for the presence of ticks. Ticks were identified, and part of them was tested individually for the presence of Rickettsiaspp. by polymerase chain reaction (PCR) using primers targeting fragments of the rickettsial genes gltAand ompA. PCR products were DNA-sequenced and analyzed in BLAST to determine similarities with previously reported rickettsial agents. A total of 1878 birds were examined, from which 163 birds (9%) were infested with 388 ticks of the genera Amblyommaand Ixodes. The following Amblyomma(in decreasing order of abundance) were found in immature stages (larvae and nymphs): Amblyomma longirostre, Amblyomma calcaratum, Amblyomma coelebs, Amblyomma sabanerae, Amblyomma varium, Amblyomma maculatum, and Amblyomma ovale. Ixodesticks were represented by Ixodes minorand two unclassified species, designated here as Ixodessp. genotype I, and Ixodessp. genotype II. Twelve of 24 tested A. longirostreticks were found to be infected with ‘CandidatusRickettsia amblyommii’, and 2 of 4 A. sabaneraewere found to be infected with Rickettsia bellii. Eight of 10 larval Ixodes minorwere infected with an endosymbiont (a novel Rickettsiasp. agent) genetically related to the Ixodes scapularisendosymbiont. No rickettsial DNA was found in A. calcaratum, A. coelebs, A. maculatum, A. ovale, A. varium, Ixodessp. I, and Ixodessp. II. We report the occurrence of I. minorin Costa Rica for the first time and a number of new bird host–tick associations. Moreover, ‘CandidatusR. amblyommii’ and R. belliiwere found in A. longirostreand A. sabanerae, respectively, in Costa Rica for the first time.

The present study evaluated the infection of rickettsiae in 151 Rhipicephalus sanguineus, 59 Amblyomma ovale, 166 Amblyomma triste, one Amblyomma dissimileand four Amblyomma dubitatumticks collected in the municipality of Poconé, State of Mato Grosso, within the Pantanal biome of Brazil. Ticks were individually processed by the hemolymph test with Gimenez staining, isolation of rickettsia in Vero cell culture by the shell vial technique, and polymerase chain reaction (PCR) targeting the citrate synthase rickettsial gene. Through the shell vial technique, rickettsiae were successfully isolated and established in Vero cell culture from one free-living A. tristefemale tick, which previously showed to contain Rickettsia-like organisms by the hemolymph test. Molecular characterization of the rickettsial isolate was achieved through DNA partial sequences of three rickettsial genes (gltA, ompA, ompB), which showed to be all 100% identical to Rickettsia parkeri. After testing all ticks by PCR, the frequency of R. parkeriinfection was 7.23% (12/166) in A. tristeadult ticks. The remaining ticks were negative by PCR. This is the first report of in vitro isolation of R. parkeriin the Pantanal biome, confirming the occurrence of this emerging rickettsial pathogen in this natural area of South America.

In the present study, we provide morphological descriptions of the nymph of Amblyomma parvitarsum, A. tonelliae, and redescriptions of A. argentinaeand A. sculptum. A taxonomic key, with relevant morphological characters illustrated by scanning electron micrographs, is provided for nymphs of the 24 species of the genus Amblyommaoccurring in Argentina. Species included are A. argentinae, A. aureolatum, A. auricularium, A. boeroi, A. brasiliense, A. calcaratum, A. coelebs, A. dissimile, A. dubitatum, A. incisum, A. longirostre, A. neumanni, A. nodosum, A. ovale, A. parvitarsum, A. parvum, A. pseudoconcolor, A. pseudoparvum, A. rotundatum, A. sculptum, A. tigrinum, A. tonelliae, A. tristeand A. varium.Principal morphological characters used for discrimination among species are presence/absence of auriculae, cornua and festoons with tubercles, size and shape of spurs of coxa I, margin and punctations of scutum, shape of basis capituli and length of cervical grooves. The geographical distribution of each tick species included in this work is presented and the importance of an accurate determination to species level of the Amblyommanymphs to make epidemiological inferences is also discussed.

Ticks were collected from wild birds at 3 locations in Paraguay during the South American winter in August and September 2012. In total, 480 birds belonging to 106 species were examined. Overall, 31 (6.5%) birds representing 21 species were found parasitized by ticks which were identified as Amblyomma calcaratumNeumann (2 larvae, 20 nymphs), Amblyomma longirostre(Koch) (17 larvae, 3 nymphs), Amblyomma parvumAragão (7 nymphs), Amblyomma aureolatum(Pallas) (1 nymph), Amblyomma ovaleKoch (1 nymph), Amblyomma tigrinumKoch (1 larva), and Amblyommaspp. (4 larvae). Ticks collected accidentally on humans at the study locations during field work included 1 nymph of Amblyomma coelebsNeumann and 54 nymphs of Amblyomma cajennense(Fabricius). Most ticks were individually tested for the presence of Rickettsiaspecies by polymerase chain reaction targeting rickettsial genes gltAand ompAand by amplicon sequencing. Two (12%) out of 17 A. longirostrelarvae were found infected with Candidatus‘Rickettsia amblyommii’, and 2 (33%) out of 6 A. parvumnymphs were infected with Candidatus‘Rickettsia andeanae’. This study provides the first report of rickettsial infections in Paraguayan ticks.

The external morphology of the nymph of Amblyomma geayiNeumann is described by optical and scanning electron microscopy. Unfed nymphs were obtained from an engorged A. geayifemale, which had been collected on a sloth (Bradypus variegatus) from Belém municipality, State of Pará, northern Brazil, and was kept under laboratory conditions. With the present description, we propose a modification of a taxonomic key published in 2010 for the Amblyommanymphs that occur in Brazil, through the inclusion of A. geayi. The nymph of A. geayiis morphologically very similar to the nymph of Amblyomma parkeriFonseca and Aragão, with only slight morphological differences related to scutal surface and punctuations (more shagreened and less punctuated in A. geayi). These 2 nymphs differ from all other known Amblyommanymphs from Brazil by the combination of auriculae present as small posterolateral rounded projections, eyes located at the level of the scutal midlength, and a rounded hypostome. These nymphal similarities as well the morphology of the adult stage corroborate previous studies that showed that A. geayiand A. parkeriare genetically closely related. Unpublished host records of the nymphs of both A. geayiand A. parkeriare provided. Established populations of A. geayiand A. parkeriseem to be geographically separated, since all confirmed records of A. geayiare from the northern half of South America (mainly the Amazonian region) and Central America, whereas all known records of A. parkeriare from the Atlantic rainforest biome in northeastern, southeastern, and southern Brazil.

The tick-borne bacterium Rickettsia rickettsii is the aetiological agent of Brazilian spotted fever (BSF). The present study evaluated tick infestations on wild and domestic animals, and the rickettsial infection in these animals and their ticks in 7 forest areas adjacent to human communities in the São Paulo Metropolitan Area (SPMA). The results were compared to ecological traits of each sampled area. Two main tick species, Amblyomma aureolatum and Rhipicephalus sanguineus, were collected from dogs. The major ticks found on small mammals and birds were Ixodes loricatus and Amblyomma longirostre, respectively. Both anti-R. rickettsii antibodies and R. rickettsii-infected ticks were detected on dogs from only 2 areas in the southern part of the SPMA, which were considered to be endemic for BSF; the remaining 5 areas were considered to be non-endemic. Ecologically, the BSF-endemic areas clearly differed from the non-endemic areas by the presence of significantly more degraded forest patches in the former. The present results corroborate historical observations that have indicated that all human cases of BSF in the SPMA were contracted in the southern part of this metropolitan area. However, not all forest patches in the southern part of the SPMA were shown to be associated with BSF endemism. [ABSTRACT FROM AUTHOR]

Oocyte maturation in the thelytokous parthenogenetic tick Amblyomma rotundatumwas examined for the first time using light and scanning electron microscopy. The panoistic ovary lacks nurse and follicular cells and is a single continuous tubular structure forming a lumen delimited by the ovarian wall. Oocytes of tick species are usually classified according to cytoplasm appearance, the presence of germinal vesicle, the presence of yolk granules, and the chorion. However, for this species, we also use oocyte size as an auxiliary tool since most oocytes were in stages I–III and were histologically very similar. Oocytes were classified into five development stages, and specific characteristics were observed: mature oocytes with thin chorion, pedicel cells arranged forming an epithelium with two or more oocytes attached by the same structure, and a large number of oocytes in the process of reabsorption.

Between December 2007 and March 2009, small mammals were captured in 6 Atlantic Forest patches in Brazil. We assessed tick-host associations and whether they differ among forest strata, sites, seasons, and host age classes or between sexes. Moreover, we assessed the exposure of animals to Rickettsia spp. In total, 432 animals were captured and 808 ticks were found on 32·9% of them. Significant differences were found among host species, collection sites, and forest strata; microhabitat preference was a strong risk factor for tick infestation. The highest tick density rates were recorded in forest fragments settled in rural areas; 91·3% of the ticks were collected from animals trapped in these forest fragments. A high prevalence (68·8%) of antibodies to Rickettsia spp. was detected among animals. This study suggests that disturbed Atlantic Forest fragments provide an environment for ticks and small mammals, which are highly exposed to rickettsiae. It also indicates that forest patches settled in rural areas are usually associated with higher small mammal diversity as well as with higher tick density rates. [ABSTRACT FROM PUBLISHER]

Sera of 320 dogs from urban and rural areas of a Pantanal region of Brazil were evaluated for rickettsial (Rickettsia rickettsii, R. parkeri, R. amblyommii, R. rhipicephali, R. felis, and R. bellii) and ehrlichial (Ehrlichia canis) infection by the immunofluorescence assay (IFA). Risk factors for ehrlichiosis or rickettsiosis were also evaluated. Positive reaction against Ehrlichiaspp. was detected in 227 (70.9%) dogs, 119 (74.3%) from an urban area and 108 (67.5%) from rural areas (P0.05). For Rickettsiaspp., 152 (47.5%) dogs were positive, 31 (19.3%) from urban and 121 (75.6%) from rural areas (P<0.05). Highest anti-Rickettsiaspp. endpoint titers were observed for R. amblyommii, suggesting homologous reactions to this agent or a very closely related organism. While most of the urban dogs were found parasitized by the tick Rhipicephalus sanguineus, infestations on rural dogs were predominated by Amblyomma cajenennse. Rickettsial infection was significantly higher (P<0.05) in rural dogs, in dogs with hunting practice, or in A. cajennense-infested dogs.

Together with the larval stage, the nymphal stage of ticks of the genus Amblyommaare the most aggressive ticks for humans entering areas inhabited by wildlife and some domestic animals in Brazil. However, due to the absence of morphological descriptions of the nymphal stage of most Brazilian Amblyommaspecies, plus the lack of an identification key, little or nothing is known about the life history of Amblyommaspp. nymphs in the country. In the present study, morphological description of the nymphal stage, illustrating important external characters through scanning electron microscopy, is provided for nymphs of 15 Amblyommaspecies that occur in Brazil, for which the nymphal stage had never been described: A. aureolatum, A. auricularium, A. calcaratum, A. coelebs, A. fuscum, A. humerale, A. incisum, A. latepunctatum, A. naponense, A. nodosum, A. ovale, A. pacae, A. pseudoconcolor, A. scalpturatum, A. varium. In addition, the nymphal stage of 12 Amblyommaspecies, which had been previously described, are redescribed: A. brasiliense, A. cajennense, A. dissimile, A. dubitatum, A. longirostre, A. oblongoguttatum, A. parkeri, A. parvum, A. romitii, A. rotundatum, A. tigrinum, A. triste. The descriptions and redescriptions totalized 27 species. Only 2 species (A. geayi, A. goeldii) out of the 29 Amblyommaspecies established in Brazil are not included in the present study. A dichotomous identification key is included to support taxonomic identification of the nymphal stage of 27 Amblyommaspecies established in Brazil.

We studied communities of small mammals and their ticks in endemic (E) and non-endemic (NE) areas for Brazilian spotted fever (BSF), aiming to infer if diversity parameters of parasites and hosts could be related to occurrence and prevalence of rickettsial infection, especially Rickettsia rickettsii. We compared E and NE areas in human-modified landscapes (HMLs) and natural areas (BIO) with no report of BSF cases. Composition and equitability were important components of diversity explaining differences among areas. The marsupial Didelphis albiventriswas dominant in HMLs, but not in natural areas, and this opossum was the main host for the tick Amblyomma sculptum, principal vector of R. rickettsii, especially in E areas. Communities of ticks were dominated by A. sculptum, followed by Amblyomma dubitatumin E areas.In NE areas, this dominance was inverted, with more A. dubitatumthan A. sculptuminfesting small mammals, but the numbers of ticks were much lower than in E areas. Composition and abundance of ticks in natural areas were very dissimilar from HMLs, with the lowest tick burdens. Didelphis albiventrisin E areas presented higher seroprevalence and endpoint titres against R. rickettsiithan in other areas. At least three Rickettsiaspecies, non-pathogenic to humans, were detected in natural areas (Rickettsia bellii, Rickettsia amblyommatisand ‘CandidatusRickettsia andeanae’), and only one non-pathogenic species in HMLs (R. bellii). Our results suggest that higher diversity of ticks, hosts and rickettsiae could be relevant factors in buffering the effect in BSF occurrence. Particularly for D. albiventris, its importance has to be quantified in further studies considering the epidemiological scenario of BSF.

This study evaluated ticks and tick-borne agents in 104 captures of the maned wolf Chrysocyon brachyurus(50 different individuals and 54 recaptures) in the Serra da Canastra National Park (SCNP), a Cerrado preserved area in southeastern Brazil, from 2005 to 2012. From the 104 capture events, a total of 1,206 ticks were collected on 94 occasions (90.4 %), and identified into five species: Amblyomma tigrinum(77.3 % of all collected ticks), Amblyomma sculptum(16.6 %), Amblyomma ovale(0.1 %), Amblyomma brasiliense(0.1 %), Rhipicephalus microplus(0.1 %), and Amblyommaspp. larvae (5.8 %). Molecular analyses of A. tigrinumadult ticks revealed the presence of ‘CandidatusRickettsia andeanae’, Rickettsia parkerisensu stricto, two different haplotypes of ‘Ca.Midichloria sp.’, and a Hepatozoon canishaplotype. Molecular analyses of maned wolf blood samples revealed two distinct haplotypes of Hepatozoonspp., one identical to the H. canisgenotype that was detected in the A. tigrinumticks, and a Hepatozoon americanum-like haplotype. None tick or blood samples yielded amplicons through PCR assays targeting the genera Ehrlichia, Anaplasma, Babesia, Rangelia, Cytauxzoon, and Theileria. Maned wolf serum samples were tested by immunofluorescence assay against antigens of five Rickettsiaspecies (R. parkeri, R. rickettsii, R. amblyommatis, R. rhipicephali, and R. bellii) and Ehrlichia canis.Among 78 serum samples (45 captures plus 33 recaptures), 74 (95 %) were reactive to at least one Rickettsiaspecies, with R. parkerieliciting the highest endpoint titers. Some maned wolves that were recaptured during the study were shown to seroconvert to R. parkeri.Serum-reactiveness to E. caniswas detected in 36 % (16/45) maned wolves. During the study, general clinical signs of tick-borne diseases were not found in any of the captured animals, indicating that they were under a good health status in the SCNP, despite of been exposed to ticks (mostly A. tigrinum) and some tick-borne agents (Rickettsia, Hepatozoon, Ehrlichia). The results of the present study might represent baseline data for the conservation of the maned wolf in its natural habitat, which should be used to interpret further studies about ticks and tick-borne diseases in maned wolves within human-modified landscapes.

This study evaluated ticks and rickettsial exposure in 220 free-ranging lowland tapirs, Tapirus terrestris,from 2006 to 2018 in selected areas of three major biomes of Brazil – Atlantic Forest, Pantanal, and Cerrado. Overall, a total of 5,970 tick specimens representing the following nine species were collected from tapirs: Amblyomma brasiliense, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma ovale, Amblyomma parvum, Amblyomma sculptum, Amblyomma triste, Haemaphysalis juxtakochi,and Rhipicephalus microplus. Amblyomma sculptumwas the most prevalent and abundant tick species in all three biomes; however, mean intensity values for A. sculptumwere significantly lower in Atlantic Forest than in the Pantanal or Cerrado, and at the same time, statistically similar among tapirs from Pantanal and Cerrado. Contrastingly, mean intensity values for A. coelebswere significantly higher in the Atlantic Forest than in the other biomes. The remaining tick species were collected in lower numbers, or were exclusive for one biome, e.g., A. brasilienseand H. juxtakochionly in the Atlantic Forest. A total of 177 blood sera (123 individuals plus 54 recaptures) were collected from tapirs and tested for the presence of reactive antibodies to six Rickettsiaspecies by immunofluorescence assay. Overall, 69% (9/13), 49% (62/126), and 66% (25/38) tapir sera from Atlantic Forest, Pantanal and Cerrado, respectively, were seroreactive to at least one Rickettsiaspecies, with no significant difference between the three areas. Although many tapir sera reacted simultaneously to ≥2 Rickettsiaspecies, Rickettsia parkerielicited highest % seroprevalence and endpoint titers, and was incriminated as the possible agent involved in a homologous reaction in tapirs from the three biomes, where A. ovalewas previously found infected by R. parkeri.In fact, seroconversion to R. parkeriwas demonstrated in five tapirs that were captured at least twice during the study. This study demonstrated that tapirs were found to be constantly infested by several tick species in the Atlantic Forest, Pantanal and Cerrado biomes; however, the richness of tick infestations was concordant to the tick species known to be established in each biome. Under natural conditions, lowland tapirs were shown to be exposed to tick-borne spotted fever group rickettsiae.

Brazilian spotted fever (BSF) is the deadliest rickettsiosis in the world. Although the epidemiology of the disease has been established in Brazil, there are still limited data available on distribution of tick vectors and tick species parasitizing humans in the country, particularly in Paraná State. The State of Paraná is located in the southern region of the country and is covered by two biomes: Atlantic rainforest and Cerrado. Thus, the aims of this study were i) to map the distribution of SF tick vectors, ii) to describe and map the distribution of human parasitism by ticks, and iii) to map the distribution of fatal and non-fatal spotted fever (SF) cases in Paraná State, southern Brazil. Data were reviewed and compiled from previous published reports, and also from two scientific collections of Paraná State. SF cases were retrieved from the Brazilian Notifiable Diseases Information System. A total of 50 cases of human parasitism by ticks were recorded, with a total of 64 (22 males, 12 females, 30 nymphs) ticks collected. The following 12 tick species were identified: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma calcaratum, Amblyomma dubitatum, Amblyomma incisum, Amblyomma longirostre, Amblyomma ovale, Amblyomma parkeri, Amblyomma scalpturatum, Amblyomma sculptum, Haemaphysalis juxtakochiand Rhipicephalus sanguineussensu lato (s.l.). The most prevalent tick species associated to cases of human parasitism were A. sculptum(13/50; 26 %), A. aureolatum(10/50; 20 %), A. brasiliense(5/50; 10 %), A. ovale(5/50; 10 %) and A. parkeri(4/50; 8%). A total of 51 non-fatal and five fatal SF cases were recorded. Data from this study highlights the need for monitoring ticks parasitizing humans aiming early detection of tick-borne diseases cases, particularly BSF in Paraná State, southern Brazil.

Ticks of the family Ixodidae are vectors of important pathogens in human and animal health. Birds are involved in long-distance transport and dispersion of hard ticks. Tick infestations on wild birds mostly involve species within the genera Amblyomma, Ixodes,and Haemaphysalis. In Colombia, tick research is scarce and there are no studies to date about the associations between wild birds and ticks. We aimed to contribute to the knowledge of the associations between wild birds and hard ticks based on the collection of 2314 wild birds belonging to 29 families in Caldas – Colombia between 2015 and 2019. In total, we collected 133 hard ticks that were found parasitizing 78 birds representing 45 species and 14 wild bird families. We report at least seven tick species on birds confirmed by morphological and molecular methods: Amblyomma longirostre, Amblyomma varium, Amblyomma dissimile, Amblyomma ovale, Amblyomma nodosum, Amblyomma calcaratumand Haemaphysalis leporispalustris.In addition, we recorded three Ixodesspecies, which yielded DNA sequences that did not have high identity (≤ 95 %) to any species in GenBank. Ticks were found infesting resident and migratory boreal birds. This is the first study addressing the associations between wild birds and hard ticks in Colombia. We describe new associations between birds and ticks in the Americas.

The removal of ectoparasites is a common behavior found across animal taxa and is a determinant to avoid the negative effects of parasites’ presence. Eventually, the elimination of ectoparasites is associated with mutualistic interactions. Cleaner birds remove ectoparasites, providing benefits to its mutualistic host by reducing parasite burden while they obtain a protein food source. Here we report some evidence that giant cowbirds (Molothrus oryzivorus) may have an important role as a cleaner bird. We found 74 adult ticks inside the ventriculus of one male giant cowbird. The ticks belonged to three different species: Amblyomma dubitatum, A. sculptumand A. triste. We found that the sex-ratio of the consumed adult ticks was not different from 1:1. Although additional data are necessary, the large number of ticks found suggests that the giant cowbird may have developed a mutualistic association with large, social mammals such as capybaras (Hydrochoerus hydrochaeris), since this animal is an important host species for the three tick species found in the present study.

A new argasid (Argasidae) tick is herein described based on morphology and molecular data obtained from larvae parasitizing Octodon degusand from ticks collected inside burrows in northern Chile. Unfed laboratory-reared larvae were mounted in slides for morphometrical and morphological analyses. Larvae of Ornithodoros octodontusn. sp. share morphological traits with Ornithodoros quilinensisand Ornithodoros xerophylus, two species associated with rodents in the Argentinean Chaco. However, a longer hypostome with two rows of 21 and 22 denticles each one, and conspicuous leaf-shaped anal plates separate O. octodontus. While nymphal stages of O. octodontuslack cheeks and possess a micromammillated dorsal integument, adults have cheeks and exhibit markedly irregular mammillae along their dorsal surface. Phylogenetic analyses of neotropical Argasidae based on mitochondrial 16S rDNA sequences point that O. octodontusforms a monophyletic group with O. xerophylusand an unidentified Ornithodorossp. from Bolivia, all of them associated with burrow-dweller rodents. Ornithodoros aragaoiand Ornithodoros davisi, two rare species collected once only in the Peruvian Andean Plateau during 1955 are morphologically closely related with adults and nymphs of O. octodontus. Biological observations of O. octodontusrevealed autogenic females. For the moment, subgeneric classification of this new species depends on further biological studies. The fauna of ticks occurring in Chile is now represented by 22 species, 11 belonging to the Argasidae family.

Since 2010, a new rickettsiosis caused by Rickettsia parkeri, a species included in the spotted fever group (SFG) and transmitted by the tick Amblyomma ovale, has been described in Brazil. Considering that A. ovaledoes occur in the Espírito Santo state (ES), the present study aimed at preliminarily describing the epidemiology of R. parkeriin the Atlantic forest of this state. Between June 2016 and September 2018, 33 villages from nine municipalities of the ES were included in a study for the molecular detection and isolation of SFG rickettsiae from adult Amblyommaticks collected on dogs with free access to the forest. Serologic screenings against SFG rickettsiae in these animals and their owners (humans) were performed through immunofluorescence assay (IFA) using antigens of Rickettsia rickettsiiand R. parkeri. Additionally, local health secretariats were informed on clinical manifestations of R. parkeriinfection and told to communicate any suspected case. A total of 280 adult ticks were collected and taxonomically classified as A. ovale(n = 152), Amblyomma aureolatum(n = 127) and Amblyomma sculptum(n = 1). Overall, RickettsiaDNA was detected in 12/266 ticks. The sequencing of PCR products revealed that 0.7% (1/144) and 0.8% (1/121) of the analyzed A. ovaleand A. aureolatumticks were infected by R. parkeristrain Atlantic rainforest, respectively, and 8.3% (10/121) of the A. aureolatumticks infected by Rickettsia bellii. Among the above PCR-positive ticks, only one isolate from one A. aureolatumtick was successfully established in the laboratory. DNA extracted from the third passage of this isolate was designated as strain M9A and molecularly characterized using primers targeting the Rickettsia gltAgene, whose sequence matched 100% the corresponding sequences of R. bellii. Seroprevalence against SFG rickettsiae in sampled dogs (n = 83) was 41% or 57%, depending on the rickettsial antigen (R. rickettsiistrain Taiaçu or R. parkeristrain Atlantic rainforest, respectively). A total of 37 (45%) canine sera showed titers to R. parkeriat least fourfold higher than to R. rickettsiiantigen. Among humans, 10% (4/41) of the samples reacted to at least one rickettsial antigen, with the highest endpoint titer varying from 64 to 128 for R. rickettsiiand R. parkeri; no human serum showed ≥4-fold difference between the highest endpoint titers. Finally, during the study period, suspicions on cases of R. parkeri-rickettsiosis were not informed by the health secretariats. Our results confirm the presence and exposure to R. parkeristrain Atlantic rainforest, associated with two anthropophilic tick species (A. ovaleand A. aureolatum) parasitizing domestic dogs with unrestrained access to forest areas. Consequently, the occurrence of R. parkeriinfection in humans inhabiting the Atlantic forests of ES should not be discarded.

Recent studies have reported several larvae of an unidentified Amblyommaspecies on passerine birds in Atlantic rainforest fragments in southeastern Brazil. These larvae yielded a unique 16S rRNA haplotype designated as Amblyommasp. haplotype Nazaré, which showed nucleotide identity levels of 91% to Amblyomma parkeriFonseca & Aragão, 1952 and 88% to Amblyomma longirostre(Koch, 1844). Herein, we describe Amblyommasp. haplotype Nazaré as a new species, Amblyomma romarioin. sp. Martins, Luz & Labruna, through a formal description of the male and female adult stages. Amblyomma romarioiis morphologically and genetically most closely related to A. parkeri, A. longirostreand Amblyomma geayiNeumann, 1899. Among males, the rectangular basis capituli and rounded coxa I spurs separates A. romarioifrom A. parkeri, A. longirostre,and A. geayi,which have basis capituli triangular or slightly hexagonal, and pointed coxa I spurs. Among females, the V-shaped genital aperture and coxa I rounded spurs of A. romarioicontrasts to the U-shaped genital aperture and coxa I pointed spurs in A. parkeri, A. longirostre,and A. geayi.Larvae of A. romarioihave been collected on 24 species of passerines. The few records of nymphs and adults were on the black-fronted titi monkey Callicebus nigrifrons(Spix, 1823). The current distribution of A. romarioiis restricted to the Brazilian Atlantic rainforest, southeastern Brazil, in areas with altitude between 363 and 1600 m, within the distribution of C. nigrifrons. We discuss ecological features of Amblyomma romarioi,comparatively to A. parkeri, A. longirostreand A. geayi.The present study increases the Brazilian tick fauna to 74 species.

In this study, Amblyomma ovale Koch ticks were collected from domestic dogs in two localities of the Atlantic rainforest biome of Brazil: 1) the Paty Valley of the Chapada Diamantina National Park, Bahia state (northeastern Brazil), and 2) Adriano´polis, Parana´ state (southern Brazil). Ticks were screened for the presence of Rickettsia-like structures by the hemolymph test with Gime´nez staining, and then processed for isolation of rickettsiae in Vero cell culture by the shell-vial technique. Rickettsiae were isolated from one A. ovale tick of each of the two localities. The two isolates were successfully established in the laboratory with several passages, each one reaching >90% infection of the cells. The two isolates were identified as the spotted fever group (SFG) agent Rickettsia sp. strain Atlantic rainforest, as their gltA (350 bp), ompB (781 bp), and ompA (567 bp) gene fragments were 100% equal to GenBank corresponding sequences of the original strain Atlantic rainforest, reported to be infecting a human in southeastern Brazil, and also 100% equal to the available ompA sequence of strain Bahia, reported to be infecting a human in Paty Valley, the same area of the present study in Bahia state. Ten dogs from Paty Valley were serologically tested against rickettsial antigens by the indirect immunofluorescence antibody test. At least 60% of them were seroreactive to SFG rickettsiae. The role of A. ovale as vector of Rickettsia sp. strain Atlantic rainforest in the Paty Valley area, as well as in other parts of Latin America, is discussed.

During 2013–2014, adult ticks were collected on the vegetation and subadult ticks were collected from small mammals [Didelphis aurita Wied-Neuwied, Sooretamys angouya (Fischer), Euryoryzomys russatus (Wagner), Akodon montensis Thomas, Oxymycterus judex Thomas] in an Atlantic rainforest reserve in southern Brazil. Analyses of the external morphology of the adult ticks revealed that they represent a new species, Amblyomma yucumense n. sp. Partial 16S rRNA sequences generated from males, females, and nymphs were identical to each other and closest (95% identity) to corresponding sequences of Amblyomma dubitatum Neumann. A. yucumense is morphologically and genetically closest related to A. dubitatum. Dorsally, male of these species can be separated by major longitudinal pale orange stripes associated with a pseudoscutum indicated by a pale stripe in A. yucumense, in contrast to pale creamy longitudinal stripes and absence of pseudoscutum in A. dubitatum. Ventrally, male coxal I spurs are separated by a space narrower than external spur width in A. yucumense, and wider than external spur width in A. dubitatum. Females of the two species can be separated by coxal I spurs, longer in A. yucumense than in A. dubitatum. In addition, the adult capitulum and ventral idiosoma of A. yucumense are generally dark brown colored, while A. dubitatum is yellowish or light brown colored. The nymph of A. yucumense differs from A. dubitatum by the scutal cervical groove length, slightly shorter in the former species. Currently, A. yucumense is restricted to southern Brazil.

The aim of the study was to evaluate exposure of equids to rickettsial agents (Rickettsia rickettsii, Rickettsia parkeri, ‘Candidatus Rickettsia amblyommii’, Rickettsia rhipicephali, and Rickettsia bellii) and rickettsial infection in ticks of a Pantanal region of Brazil. Sera of 547 equids (500 horses and 47 donkeys) were evaluated by indirect immunofluorescence assay. In total, 665 adults and 106 nymphal pools of Amblyomma cajennense F. sensu lato, 10 Dermacentor nitens Neumann ticks, and 88 larval pools of Amblyomma sp. were tested by polymerase chain reaction (PCR). Overall, 337 (61.6%) equids were reactive (titer =64) to at least one antigen of Rickettsia spp. The prevalence values for Rickettsia were 66%, and the highest endpoint titers were observed for ‘Ca. R. amblyommii’. By PCR 3 (0.45%) A. cajennense s.l. females were positive for ‘Ca. R. amblyommii’. Minimum infection rates of 0.75% for nymphs and 0.34% for larvae were calculated. Positive samples of ticks have had a fragment of the 16S mitochondrial rRNA gene sequenced and sequences showed 99% identity to Amblyomma sculptum Berlese. This study reports a wide exposure of equids to Rickettsia agents, and PCR evidence of infection with ‘Ca. R. amblyommii’, for the first time, in A. sculptum.

This study evaluated for the first time, ectoparasite infestations on dogs from urban and rural areas of the continental land of the state of Maranhão, northeastern Brazil. In total, 622 dogs were examined for ectoparasite infestations. Overall, 392 (63.0%) were infested with ectoparasites, 154 (51.3%) of 300 urban dogs and 238 (73.9%) of 322 rural dogs. Five species of ectoparasites were found, three ticks [Rhipicephalus sanguineus (Latreille), Amblyomma ovale Koch, and Amblyomma cajennense (F.)], one flea [Ctenocephalides felis (Bouché)], and one louse [(Heterodoxus spininger (Enderlein)]. The frequency of infestation by R. sanguineus tended to be higher in urban than in rural areas, whereas infestations by Amblyomma ticks and C. felis fleas tended to be higher among rural dogs. Louse (H. spininger) infestations were similarly low among all areas. Mixed infestations by at least two species of ectoparasites on the same dog were significantly more frequent on rural than on urban dogs. The most frequent mixed infestation was by R. sanguineus and C. felis, found on 11.4% of the dogs. Further studies are warranted to evaluate canine vector-borne agents in Maranhão, especially because most of the ectoparasites here reported are vectors of major vector-borne diseases, including zoonoses of continental importance.

During 2008–2010, ticks were collected from road-killed wild animals within the Serra dos Órgãos National Park area in the state of Rio de Janeiro, Brazil. In total, 193 tick specimens were collected, including Amblyomma dubitatum Neumann and Amblyomma cajennense (F.) from four Hydrochoerus hydrochaeris (L.), Amblyomma calcaratum Neumann and A. cajennense from four Tamandua tetradactyla (L.), Amblyomma aureolatum (Pallas) and A. cajennense from five Cerdocyon thous L., Amblyomma longirostre (Koch) from one Sphiggurus villosus (Cuvier), Amblyomma varium Koch from three Bradypus variegatus Schinz, and A. cajennense from one Buteogallus meridionalis (Latham). Molecular analyses based on polymerase chain reaction targeting two rickettsial genes (gltA and ompA) on tick DNA extracts showed that 70.6% (12/17) of the A. dubitatum adult ticks, and all Amblyomma sp. nymphal pools collected from capybaras were shown to contain rickettsial DNA, which after DNA sequencing, revealed to be 100% identical to the recently identified Rickettsia sp. strain Pampulha from A. dubitatum ticks collected in the state of Minas Gerais, Brazil. Phylogenetic analysis with concatenated sequences (gltA-ompA) showed that our sequence from A. dubitatum ticks, referred to Rickettsia sp. strain Serra dos Órgãos, segregated under 99% bootstrap support in a same cluster with Old World rickettsiae, namely R. tamurae, R. monacensis, and Rickettsia sp. strain 774e. Because A. dubitatum is known to bite humans, the potential role of Rickettsia sp. strain Serra dos Órgãos as human pathogen must be taken into account, because both R. tamurae and R. monacencis have been reported infecting human beings.

From September 2008 to March 2010, 397 ticks (315 larvae, 33 nymphs, 23 females, and 26 males) were collected from captive and free-living wildlife species in northeastern Brazil. Six tick species were identified, including Amblyomma auricularium (Conil) on Tamandua tetradactyla (L.), Amblyomma dubitatum Neumann on Hydrochaeris hydrochaeris (L.), Nectomys rattus (Pelzen) and T. tetradactyla, Amblyomma parvum Aragão on T. tetradactyla, Amblyomma rotundatum Koch on Boa constrictor L., Chelonoidis carbonaria (Spix), Kinosternon scorpioides (L.) and Rhinella jimi (Stevaux), Amblyomma varium Koch on Bradypus variegatus Schinz, and Rhipicephalus sanguineus (Latreille) on Lycalopex vetulus (Lund). Nectomys rattus and T. tetradactyla are new hosts for A. dubitatum. This study extends the known distribution of A. dubitatum in South America and provides evidence that its geographical range has been underestimated because of the lack of research. Four (A. dubitatum, A. parvum, A. rotundatum, and R. sanguineus) of six tick species identified in this study have previously been found on humans in South America, some of them being potentially involved in the transmission of pathogens of zoonotic concern.

The current study compared the susceptibility of larval stages of Amblyomma cajennense (F.), Amblyomma aureolatum (Pallas), and Rhipicephalus sanguineus (Latreille) to infection by a Brazilian strain of Rickettsia rickettsii. Guinea pigs experimentally infected by R. rickettsii were simultaneously infested by larvae of the three tick species. Recovered engorged larvae were allowed to molt to nymphs and held in an incubator at 23°C and 85–90% RH. Subsequent flat nymphs were tested for rickettsial infection by polymerase chain reaction (PCR). Concomitant infestations with sibling ticks on noninfected guinea pigs (control) were done. While 10-60% of the A. cajennense nymphs were shown to be infected by R. rickettsii, both A. aureolatum and R. sanguineus were highly susceptible to R. rickettsii, since 80–100% of their nymphs were shown to be infected in the corresponding trials. Most of the engorged larvae (≈70–95%), regardless of being infected or not, successfully molted to nymphs. Mortality rates for engorged larvae tended to be statistically similar (P > 0.05) for ticks recovered from R. rickettsii-infected and noninfected guinea pigs, within each tick species. The only exceptions were the significantly higher mortalities (P < 0.05) for engorged A. cajennense larvae recovered from two infected guinea pigs. Therefore, A. cajennense was less susceptible to R. rickettsii infection than A. aureolatum and R. sanguineus, while feeding on rickettsemic guinea pigs. These two later species were similarly highly susceptible.