Association patterns of ticks (Acari: Ixodida: Ixodidae, Argasidae) of small mammals in Cerrado fragments, western Brazil

Rickettsial Infection in Ticks from a National Park in the Cerrado Biome, Midwestern Brazil

This study was carried out from February 2020 to September 2021 in Parque Nacional das Emas (PNE), a national park located in the Cerrado biome, midwestern Brazil, as well as in surrounding rural properties. Serum and tick samples were collected from dogs, terrestrial small mammals, and humans. Ticks were also collected from the environment. Dogs were infested with Rhipicephalus linnaei adults, whereas small mammals were infested by immature stages of Amblyomma spp., Amblyomma triste, Amblyomma dubitatum, and Amblyomma coelebs. Ticks collected from vegetation belonged to several species of the genus Amblyomma, including A. coelebs, A. dubitatum, Amblyomma naponense, Amblyomma sculptum, and A. triste. Two Rickettsia species were molecularly detected in ticks: Rickettsia parkeri in A. triste from the vegetation and a Rickettsia sp. (designated Rickettsia sp. strain PNE) in A. sculptum and A. triste collected from lowland tapirs (Tapirus terrestris). Based on short gltA gene fragments, this rickettsial organism showed 99.7-100% to Rickettsia tillamookensis. Seroreactivity to Rickettsia antigens was detected in 21.9% of dogs, 15.4% of small mammals, and 23.5% of humans. The present study reveals the richness of ticks and demonstrates the circulation of rickettsial agents in one of the largest conservation units in the Cerrado biome in Brazil. To our knowledge, this is the first report of a rickettsial phylogenetically related to R. tillamookensis in Brazil.

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.

Ticks on humans in an Atlantic rainforest preserved ecosystem in Brazil: Species, life stages, attachment sites, and temporal pattern of infestation

We herein describe exposure and tick attachment to researchers and field staff within the greatest preserved inland Atlantic rainforest, located in Brazil, over a non-consecutive period of five years. Overall, 433 ticks from five species were collected, Amblyomma coelebs (n = 281), Amblyomma brasiliense (n = 79), Amblyomma incisum (n = 43), Amblyomma ovale (n = 4), Haemaphysalis juxtakochi (n = 4). Clusters of larvae belonged to the genus Amblyomma (n = 21) and Haemaphysalis (n = 1). Both Haemaphysalis and Amblyomma species were observed crawling on humans but only ticks from the latter genus were found attached. Most recovered ticks (59%) were found attached and, whereas A. brasiliense was the main host-seeking tick species in the forest, A. coelebs nymphs were the ones that overwhelmingly attached to humans (70% of all attachments). At the same time only 0.4% of human bites were of A. ovale, the Rickettsia parkeri strain Atlantic rainforest vector tick in Brazil. Tick attachment sites were recorded for 132 ticks and lower/upper limbs and the trunk were more parasitized than the head/neck. Tick bites were recorded throughout the year; while larvae did not show an evident seasonal pattern, nymphs attached to humans mainly in autumn and winter and the few adult bites were recorded in spring. Our results highlighted A. coelebs nymphs as major human-biters and evidenced the necessity of studies that discern human tick bites that occur after exposure to host-seeking ticks from those that occur after tick displacement from hosts that carry ticks to human dwellings.

Didelphis spp. opossums and their parasites in the Americas: A One Health perspective

Medium sized opossums (Didelphis spp.) are among the most fascinating mammals of the Americas, playing important ecological roles (e.g., dispersal of seeds and control of insect populations) in the environment they inhabit. Nevertheless, as synanthropic animals, they are well adapted to human dwellings, occupying shelters within the cities, peripheral areas, and rural settings. These marsupials can harbor numerous pathogens, which may affect people, pets, and livestock. Among those, some protozoa (e.g., Leishmania infantum, Trypanosoma cruzi, Toxoplasma gondii), helminths (e.g., Ancylostoma caninum, Trichinella spiralis, Alaria marcianae, Paragonimus spp.) and arthropods (e.g., ticks, fleas) present substantial public health and veterinary importance, due to their capacity to cause disease in humans, domestic animals, and wildlife. Here, we reviewed the role played by opossums on the spreading of zoonotic parasites, vectors, and vector-borne pathogens, highlighting the risks of pathogens transmission due to the direct and indirect interaction of humans and domestic animals with Didelphis spp. in the Americas.

Rickettsial infection in equids, opossums and ticks in the municipality of Monte Mor, state of São Paulo, Brazil

The aim of this study was to investigate rickettsial infection in equids, opossums and ticks in the municipality of Monte Mor, a place where a Brazilian spotted fever case occurred in 2005. In addition, characteristics possibly associated with seropositivity in horses were analyzed. Serum samples from horses, mules and opossums (Didelphis albiventris) were subjected to indirect immunofluorescence assay (IFA) against Rickettsia rickettsii. The ticks collected from the animals were identified and Amblyomma sculptum ticks from the equids were tested using PCR for Rickettsia spp. Anti-R. rickettsii antibodies were detected in 22.6% (14/62) of the horses, none of the mules and 21.7% (5/23) of the opossums. Among the variables analyzed, only age > 12 years showed a statistically significant association with seropositivity among horses. All of the 166 A. sculptum ticks tested using PCR were negative. The results showed that rickettsiae of the spotted fever group was circulating in the municipality of Monte Mor when the samples were collected and indicate a need for surveillance of Brazilian spotted fever in this region.

Ornithodoros cerradoensis n. sp. (Acari: Argasidae), a member of the Ornithodoros talaje (Guérin-Méneville, 1849) group, parasite of rodents in the Brazilian Savannah

Ornithodoros cerradoensis n. sp. is described from field-collected and laboratory reared nymphs, males, females, and larvae parasitizing the rodents Cavia aperea and Thrichomys sp. in the Brazilian Savannah. This new species is morphologically and genetically related with the Ornithodoros talaje group and can be separated from other Neotropical species using the following combination of characters: larva with 18 pairs of setae on dorsum (seven anterolateral, four central and seven posterolateral), hypostome with median dentition 2/2; adults provided with large mammillae; dorsal disks surrounded by bulked marginal ridges delimiting barely pebbled areas; three disks in the anterolateral file, and median disk not merging with the posteromedian file. Feeding assays in the laboratory demonstrated that (1) larvae of O. cerradoensis are slow-feeders (∼6 days), (2) first nymphal instar (N1) molts to second instar (N2) without feeding, and (3) N2 and third nymphal instar (N3) engorge rapidly (minutes). With the exception of Ornithodoros hasei nymphs that depict flattened bodies, O. cerradoensis N1, N2, and N3 highly resemble homologous instars of other species in O. talaje sensu lato, therefore are not suitable for morphological comparisons within the group. In addition to morphological signature of larvae and adults that separate this new species; results of cross-mating attempts between O. cerradoensis and Ornithodoros guaporensis a morphologically and phylogenetically closely related species that also parasitizes rodents in the Brazilian Savannah; a Principal Component Analysis using larval characters; and a phylogenetic analysis using mitochondrial markers, support O. cerradoensis as an independent lineage within the Ornithodorinae.

Retrospective and new records of ticks (Acari: Argasidae, Ixodidae) from the state of Maranhão, an Amazon-Cerrado transition area of Brazil

The Brazilian state of Maranhão is located in a transition area of the Amazon and Cerrado biomes, where there is a rich fauna of vertebrates. This study aimed to update the list of the ticks occurring in Maranhão, through a compilation of literature records and examination of three tick collections, plus the addition of unpublished collections of ticks from road-killed animals during recent years. Our results indicate that the tick fauna of Maranhão includes 26 species: seven in the family Argasidae (Antricola guglielmonei, Argas miniatus, Ornithodoros cavernicolous, Ornithodoros hasei, Ornithodoros mimon, Ornithodoros rietcorreai and Ornithodoros rudis); and 19 in the family Ixodidae (Amblyomma auricularium-provisional, Amblyomma cajennense sensu stricto, Amblyomma calcaratum, Amblyomma dissimile, Amblyomma geayi, Amblyomma longirostre, Amblyomma naponense, Amblyomma nodosum, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma parvum, Amblyomma rotundatum, Amblyomma sculptum, Amblyomma triste, Dermacentor nitens, Ixodes luciae, Haemaphysalis juxtakochi, Rhipicephalus microplus, and Rhipicephalus sanguineus sensu lato). Eleven of the above species are reported for the first time in Maranhão. We consider previous reports of Ornithodoros talaje and Amblyomma pseudoconcolor in Maranhão as misidentification with O. hasei and A. auricularium, respectively. Until 1958, only 11 tick species were reported in Maranhão, with no additional reports until 2009. During 2010-2019, 15 additional species were reported. We also highlight the importance of ticks for public and veterinary health in Maranhão.

Ectoparasites of small mammals in a fragmented area of the southern Amazonia: interaction networks and correlations with seasonality and host sex

The present work aimed to analyze the ectoparasite-host interaction network and possible differences of this interaction related to two seasonal periods and host sex. During November 2016 and July 2017, non-flying small mammals were captured in 17 forest fragments located in the southern portion of the Amazon biome. We captured 96 individuals belonging to 10 host species that were parasitized with a total of 3668 ectoparasites. Overall, we identified 24 ectoparasite taxa belonging to the mite and insect groups Ixodida (ticks), Mesostigmata, Sarcoptiformes, Trombidiformes (mites), Phthiraptera (lice), and Siphonaptera (fleas). The interaction network between all ectoparasites and hosts showed significant deviation from random, with moderately high specialization index (H2' = 0.80). There was seasonal difference in prevalence for Amblyomma cajennense (Fabricius) sensu stricto (s.s), Amblyomma coelebs Neumann and larvae of Amblyomma. This difference was also found in the mean intensity of infestation of Amblyomma larvae and the mite Tur aragaoi (Fonseca). Only mean intensity of infestation differed in relation to host sex for the species Marmosa constantiae Thomas. Our results demonstrate that specificity between ectoparasites and small mammals in this region is moderately high and that the pattern of aggregation of some ectoparasite taxa differed between two seasons, as well as between sexes in M. constantiae.

Description of a new soft tick species (Acari: Argasidae: Ornithodoros) parasite of Octodon degus (Rodentia: Octodontidae) in northern Chile

A new argasid (Argasidae) tick is herein described based on morphology and molecular data obtained from larvae parasitizing Octodon degus and from ticks collected inside burrows in northern Chile. Unfed laboratory-reared larvae were mounted in slides for morphometrical and morphological analyses. Larvae of Ornithodoros octodontus n. sp. share morphological traits with Ornithodoros quilinensis and 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. octodontus lack 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. octodontus forms a monophyletic group with O. xerophylus and an unidentified Ornithodoros sp. from Bolivia, all of them associated with burrow-dweller rodents. Ornithodoros aragaoi and 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. octodontus revealed 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.

Ticks (Acari: Ixodidae) in the Serra da Canastra National Park in Minas Gerais, Brazil: species, abundance, ecological and seasonal aspects with notes on rickettsial infection

The Cerrado Biome is the second largest in Brazil covering roughly 2 million km², with varying features throughout its area. The Biome is endangered but it is also source of animal species for rural, green urban and degraded rainforest areas. Ticks are among Cerrado species that establish at anthropogenic sites and although information about them is steadily increasing, several features are unknown. We herein report tick species, abundance and some ecological relationships within natural areas of the Cerrado at higher altitudes (800-1500 m) within and around Serra da Canastra National Park, in Minas Gerais State Brazil. In total of 1196 ticks were collected in the environment along 10 campaigns held in 3 years (2007-2009). Amblyomma sculptum was the most numerous species followed by Amblyomma dubitatum and Amblyomma brasiliense. Distribution of these species was very uneven and an established population of A. brasiliense in the Cerrado is reported for the first time. Other tick species (Amblyomma ovale, Amblyomma nodosum, Amblyomma parvum, Ixodes schulzei and Haemaphysalis leporispalustris) were found in lesser numbers. Domestic animals displayed tick infestations of both rural and urban origin as well as from natural areas (Rhipicephalus sanguineus sensu lato, Rhipicephalus microplus, Dermacentor nitens, A. sculptum, A. ovale, Amblyomma tigrinum, Argas miniatus). Amblyomma sculptum had the widest domestic host spectrum among all tick species. DNA of only one Rickettsia species, R. bellii, was found in an A. dubitatum tick. Several biological and ecological features of ticks of the studied areas are discussed.

First record of Ornithodoros faccinii (Acari: Argasidae) on toads of genus Rhinella (Anura: Bufonidae) in Brazil

Although a group of soft ticks (Argasidae) associated with amphibians was recently discovered in Brazilian rainforests, parasitism by these ticks on cold-blooded animals remains less common than on mammal and bird species. In this study, we identified ticks that were collected from toads that had been caught in December 2016 and January 2017, at Itinguçú waterfall (22°54'05" S; 43°53'30" W) in the municipality of Itaguaí, state of Rio de Janeiro. Tick specimens were identified using a morphological and molecular approach. In total, twelve larvae of Ornithodoros ticks were collected from three individuals of Rhinella ornata and were identified as Ornithodoros faccinii. Our results include a longer 16S rRNA mitochondrial sequence for O. faccinii that supports its phylogenetic relatedness to Ornithodoros saraivai, and we report this tick species parasitizing Rhinella toads for the first time in Brazil.

Ticks parasitizing wild mammals in Atlantic Forest areas in the state of Rio de Janeiro, Brazil

Mammals captured in the Serra dos Órgãos National Park (PARNASO) and the Pedra Branca State Park (PBSP) between 2012 and 2015 were examined for the presence of ticks. In total, 140 mammals were examined, and 34 specimens were found to be parasitized by ticks. Didelphis aurita, Akodon montensis and Oligoryzomys nigripes were the species most parasitized. From these specimens, 146 ticks were collected, including 10 larvae. The ticks belonged to eight species: one in the genus Ixodes and seven in the genus Amblyomma. This study reports new associations of ticks and wild mammals in Brazil.

Biological parameters of Amblyomma coelebs Neumann, 1906 (Acari: Ixodidae) under experimental conditions

Abstract One generation of Amblyomma coelebs life cycle under experimental conditions was evaluated. Ten tick pairs were allowed to feed on rabbits under laboratory conditions (LC), resulting six engorged females with a mean weight of 1,403.9 mg. Two females were maintained in a forest reserve under natural conditions (NC), and four were maintained in incubators (LC). The engorgement period lasted 10.33 days. Pre-oviposition periods were 10.75 (NC) and 22 days (LC). The mean egg-mass weight was 514.76 mg, and the blood meal conversion index was 36.67% (LC). Incubation period under NC and LC were 91 and 56.33 days and hatching rates were 50% and 28.33%, respectively. Larval engorgement period ranged from 4 to 10 days, with average weight of 1.1 mg. Engorged larvae were incubated under NC and LC, with a premolt period of 27 to 36 days and molting rate of 7.1% and 28.7%, respectively. Nymphal engorgement period ranged from 5 to 7 days, with a mean weight of 18.8 mg and a recovery rate of 54.54%. In LC, the ecdysis mean period was 24.5 days, and molting rate was 44.44%, resulting in 24 adult A. coelebs. Our results show a life cycle of 187.45 (NC) and 149 (LC) days.

CAPIVARAS (Hydrochoerus hydrochaeris) E A PRESENÇA DO CARRAPATO (Amblyomma sculptum) NO CAMPUS DA UFSCAR-ARARAS, SÃO PAULO

Resumo Capivaras são territoriais e vivem em grupos sociais, ocorrendo comumente em áreas antropizadas. Em algumas regiões do Brasil, estes animais apresentam infestação por carrapatos do gênero Amblyomma, que por sua vez são considerados como principal vetor biológico e reservatório natural da bactéria Rickettsia rickettsii, agente causador da Febre Maculosa Brasileira. Na UFSCar campus Araras, a interação entre capivaras, carrapatos e comunidade acadêmica é frequente, ocorrendo principalmente durante a estação seca. Este estudo teve como objetivo realizar um censo populacional das capivaras que ocupam o campus, identificando sua área de uso e se estes roedores se encontravam infestados por carrapatos. Realizou-se observação direta das capivaras, captura-marcação e recaptura com uso de um brete, e também coleta dos carrapatos nas capivaras e no ambiente. Registrou-se um total de 56 capivaras, com densidade de 1,50 ind./ha. Foram capturados 24 animais, sendo 25% machos e 75% fêmeas, dos quais 25% eram adultos, 45,8% jovens e 29,2% filhotes. A espécie de carrapato amplamente encontrada infestando tanto os animais como o ambiente foi A. sculptum. Conclui-se que o grupo de capivaras apresentou um número elevado de indivíduos por causa da abundância de recursos e ausência de predadores, e também com grande infestação por carrapatos.

Infestação por carrapatos Argasidae e Ixodidae em pequenos mamíferos silvestres da Estação Experimental Rafael Fernandes, Mossoró/RN

RESUMO: Poucos estudos avaliaram a diversidade de ectoparasitos e a associação deles com seus hospedeiros que ocorrem no bioma Caatinga, Nordeste do Brasil. Considerando-se essa falta de conhecimento, este estudo objetivou identificar e determinar a ocorrência de carrapatos coletados de pequenos mamíferos da Estação Experimental Rafael Fernandes, no Rio Grande do Norte, Brasil. De janeiro de 2014 a fevereiro de 2015 foram capturados 52 marsupiais (38 Gracilinanus agilis e 14 Monodelphis domestica) e 10 roedores (5 Wiedomys sp., 4 Thrichomys sp. e 1 Rattus norvegicus). Foram identificados os carrapatos Amblyomma auricularium, Amblyomma parvum, Amblyomma sp., Ornithodoros mimon e Ornithodoros sp., empregando estudo morfológico, chaves taxonômicas e sequenciamento parcial do gene mitocondrial 16S rDNA de carrapatos. Todas as associações carrapato-hospedeiro encontradas neste estudo são relatadas pela primeira vez no Rio Grande do Norte e constituem novos dados ecológicos aplicáveis aos ectoparasitos de pequenos mamíferos no nordeste do Brasil.

Ectoparasites of small-mammals: determinants of community structure in South American savannah

This study aimed to assess the contribution of hosts characteristics (rodents and marsupials) in the organization of ectoparasite communities present in woodland patches in western central Brazil. We verified the effect of host species, sex, body mass and vertical strata in addition to the role of seasonality on the ectoparasite composition, richness and abundance. The total sampling effort was 22 032 trap-nights equally distributed in 54 woodland patches. Variance partition and principal coordinate analysis were used to verify the existence of significant relationships between response variables and predictors. As expected, host species was the most important variable in ectoparasite community assembly. The composition, richness and abundance of mites and lice were highly influenced by host species, although higher for mites than for lice. Host body mass had a determining role on the richness and abundance of tick species. Vertical stratification and seasonality had weak influence, while the sex of the host had no influence on the organization of these communities. The results are closely related to the evolutionary characteristics of the species involved, as well as with local environmental characteristics of the study area.

Microorganisms in ticks (Acari: Ixodidae) collected on marsupials and rodents from Santa Catarina, Paraná and Mato Grosso do Sul states, Brazil

Information about tick fauna and monitoring of pathogen prevalences in ticks (Acari: Ixodidae) in various habitat types can enhance knowledge about the epidemiology of tick-borne pathogens in Brazil. This work shows the results of a study of tick parasitism of wild rodents and marsupials collected in seven localities in the southern part of Brazil, within Atlantic Forest and Cerrado biomes. A total of 61 ticks were collected from small mammals, and after identification to the species level, the ticks were individually tested for the presence of bacteria of the genera Rickettsia, Borrelia, family Anaplasmataceae, and protozoa of the genus Babesia. The following species of ticks were found: Amblyomma ovale Koch, 1844, Amblyomma dubitatum Neumann, 1899, Amblyomma fuscum Neumann, 1907, Ixodes aragaoi Fonseca, 1935, Ixodes fuscipes Koch, 1844, Ixodes loricatus Neumann, 1899, and Ixodes schulzei Aragão and Fonseca, 1951. Among tested ticks, no DNA of Borrelia, Babesia or Anaplasmataceae was detected. Two nymphs of A. ovale were found infected with Rickettsia bellii and four nymphs of I. aragaoi with Rickettsia sp., genetically close to Rickettsia monacensis, Rickettsia tamurae and the endosymbiont Rickettsia spp., previously found in various Ixodidae. In one nymph of A. fuscum, DNA of a novel Hepatozoon sp. was found. Additionally we provide novel tick-host associations.

CARRAPATOS EM ANIMAIS SILVESTRES DO BIOMA CERRADO TRIADOS PELO CETAS, IBAMA-GOIÁS

Resumo O Bioma Cerrado possui por volta de 320 mil espécies de animais e ocupa aproximadamente 25% do território brasileiro. Por sua grande diversidade de espécies, excita o tráfico ilegal de animais silvestres. O Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) apreende animais traficados e encaminha-os para o Centro de Triagem de Animais Silvestres (CETAS), onde passam por triagem, são identificados e submetidos a testes diagnósticos e à quarentena, antes de serem encaminhados a uma destinação final. A identificação de ectoparasitas, possíveis vetores de zoonoses, está entre um dos procedimentos preconizados. Foi realizada, durante o ano de 2013, a colheita e identificação de carrapatos encontrados em animais silvestres encaminhados ao CETAS. As respectivas espécies foram identificadas: Amblyomma longirostre em ouriço-caxeiro (Coendou prehensilis); Amblyomma rotundatum em jiboia (Boa constrictor); Amblyomma sculptum e Rhipicephalus microplus em veado-mateiro (Mazama americana); Amblyomma sculptum em lobo-guará (Chrysocyon brachyurus); Amblyomma sculptum e Amblyomma dubitatum em capivara (Hydrochoerus hydrochaeris); Amblyomma nodosum em tamanduá-mirim (Tamandua tetradactyla); Amblyomma sculptum em bugio (Alouatta guariba). Amblyomma foi o principal gênero encontrado. Este é o gênero mais disperso entre os animais silvestres da América. Animais silvestres frutos de apreensão apresentaram baixo número de carrapatos. Isto pode ter acontecido pela forma como são manejados nos criatórios.

Ticks infesting bats (Mammalia: Chiroptera) in the Brazilian Pantanal

Ticks associated with bats have been poorly documented in the Neotropical Zoogeographical Region. In this study, a total of 1028 bats were sampled for tick infestations in the southern portion of the Brazilian Pantanal. A total of 368 ticks, morphologically identified as Ornithodoros hasei (n = 364) and O. mimon (n = 4), were collected from the following bat species: Artibeus planirostris, Platyrrhinus lineatus, Phyllostomus hastatus, Mimon crenulatum and Noctilio albiventris. Morphological identification of O. hasei was confirmed by molecular analysis. Regarding the most abundant bat species, only 40 (6.2%) out of 650 A. planirostris were infested by O. hasei, with a mean intensity of 7.2 ticks per infested bat, or a mean abundance of 0.44 ticks per sampled bat. Noteworthy, one single P. hastatus was infested by 55 O. hasei larvae, in contrast to the 2.5-7.2 range of mean intensity values for the whole study. As a complement to the present study, a total of 8 museum bat specimens (6 Noctilio albiventris and 2 N. leporinus), collected in the northern region of Pantanal, were examined for tick infestations. These bats contained 176 ticks, which were all morphologically identified as O. hasei larvae. Mean intensity of infestation was 22, with a range of 1-46 ticks per infested bat. Our results suggest that A. planirostris might play an important role in the natural life cycle of O. hasei in the Pantanal.

Comparative evaluation of Amblyomma ovale ticks infected and noninfected by Rickettsia sp. strain Atlantic rainforest, the agent of an emerging rickettsiosis in Brazil

In 2010, a novel spotted fever group rickettsiosis was reported in the Atlantic rainforest coast of Brazil. The etiological agent was identified as Rickettsia sp. strain Atlantic rainforest, and the tick Amblyomma ovale was incriminated as the presumed vector. The present study evaluated under laboratory conditions four colonies of A. ovale: two started from engorged females that were naturally infected by Rickettsia sp. strain Atlantic rainforest (designated as infected groups); the two others started from noninfected females (designated as control groups). All colonies were reared in parallel from F0 engorged female to F2 unfed nymphs. Tick-naïve vesper mice (Calomys callosus) or domestic rabbits were used for feeding of each tick stage. Rickettsia sp. strain Atlantic rainforest was preserved by transstadial maintenance and transovarial transmission in A. ovale ticks for at least 2 generations (from F0 females to F2 nymphs), because nearly 100% of the tested larvae, nymphs, and adults from the infected groups were shown by PCR to contain rickettsial DNA. All vesper mice and rabbits infested by larvae and nymphs, and 50% of the rabbits infested by adults from the infected groups seroconverted, indicating that these tick stages were vector competent for Rickettsia sp. strain Atlantic rainforest. Expressive differences in mortality rates and reproductive performance were observed between engorged females from the infected and control groups, as indicated by 75.0% and 97.1% oviposition success, respectively, and significantly lower egg mass weight, conversion efficiency index, and percentage of egg hatching for the infected groups. Our results indicate that A. ovale can act as a natural reservoir for Rickettsia sp. strain Atlantic rainforest. However, due to deleterious effect caused by this rickettsial agent on engorged females, amplifier vertebrate hosts might be necessary for persistent perpetuation of Rickettsia sp. strain Atlantic rainforest in A. ovale under natural conditions.

Rickettsial infection in ticks (Acari: Ixodidae) of wild animals in midwestern Brazil

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 varium and Ixodes luciae are reported for the first time in the state of Mato Grosso. Amongst 538 ticks tested by molecular methods for rickettsial infection, we detected 'Candidatus Rickettsia amblyommii' infecting Amblyomma cajennense sensu stricto and Amblyomma coelebs, Rickettsia sp. strain Atlantic rainforest infecting Amblyomma ovale, Rickettsia sp. strain NOD infecting Amblyomma nodosum, and 'Candidatus Rickettsia 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.