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1.
Exp Appl Acarol ; 88(3-4): 371-386, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36344862

RESUMO

From June 2013 to January 2014, blood sera samples and ticks were collected from domestic dogs and wild small mammals, and ticks from the vegetation in a preservation area of the Atlantic Forest biome (Turvo State Park), and the rural area surrounding the Park in Derrubadas municipality, state of Rio Grande do Sul, southern Brazil. Dogs were infested by Amblyomma ovale and Amblyomma aureolatum adult ticks, whereas small mammals were infested by immature stages of A. ovale, Amblyomma yucumense, Amblyomma brasiliense, Ixodes loricatus, and adults of I. loricatus. Ticks collected on vegetation were A. brasiliense, A. ovale, A. yucumense, Amblyomma incisum, and Haemaphysalis juxtakochi. Three Rickettsia species were molecularly detected in ticks: Rickettsia bellii in I. loricatus (also isolated through cell culture inoculation), Rickettsia amblyommatis in A. brasiliense, and Rickettsia rhipicephali in A. yucumense. The latter two are tick-rickettsia associations reported for the first time. Seroreactivity to Rickettsia antigens were detected in 33.5% (55/164) small mammals and 8.3% (3/36) canine sera. The present study reveals a richness of ticks and associated-rickettsiae in the largest Atlantic Forest Reserve of the state of Rio Grande do Sul, which is characterized by a rich fauna of wild mammals, typical of more preserved areas of this biome. Noteworthy, none of the detected Rickettsia species have been associated to human or animal diseases. This result contrasts to other areas of this biome in Brazil, which are endemic for tick-borne spotted fever caused by Rickettsia rickettsii or Rickettsia parkeri.


Assuntos
Carrapatos , Humanos , Cães , Animais , Brasil , Mamíferos
2.
Emerg Infect Dis ; 27(1): 322-324, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33350927

RESUMO

We conducted a molecular survey for Borrelia spp. in Ornithodoros ticks previously reported as biting humans. We collected specimens in natural ecosystems and inside human dwellings in 6 states in Brazil. Phylogenetic analyses unveiled the occurrence of 4 putatively new species of relapsing fever group borreliae.


Assuntos
Argasidae , Borrelia , Febre Recorrente , Animais , Borrelia/genética , Brasil/epidemiologia , Ecossistema , Humanos , Filogenia , Febre Recorrente/epidemiologia
3.
Exp Appl Acarol ; 83(4): 545-554, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33778915

RESUMO

From May to November 2013, ticks were collected from wild and domestic hosts that were sampled by convenience in different localities of El Salvador. Among 48 localities, in total 1181 ticks were collected from 200 vertebrate animals, comprising 13 species of wild hosts (amphibian, reptiles, mammals) and five species of domestic mammals, plus four samples from humans and four samples from the environment. Through morphological analysis (corroborated by molecular analyses in a few cases), the following ten tick species were identified: Amblyomma dissimile, Amblyomma mixtum, Amblyomma ovale, Amblyomma cf. parvum, Amblyomma sabanerae, Amblyomma scutatum, Dermacentor dissimilis, Dermacentor nitens, Rhipicephalus microplus, and Rhipicephalus sanguineus sensu lato. Among a sample of 211 tick specimens tested for rickettsial infection by molecular methods, we identified: 'Candidatus Rickettsia colombianensi' in 10% of the A. dissimile ticks and 11% of the A. scutatum ticks; Rickettsia amblyommatis in 77% of the A. mixtum ticks, 50% of the A. cf. parvum ticks, 8% of the D. nitens ticks, and 11% of the Amblyomma spp. nymphs; and Rickettsia bellii in 3% of the A. dissimile ticks and 17% of the A. ovale ticks. The tick fauna of El Salvador is currently represented by 12 reported species.


Assuntos
Ixodidae , Rickettsia , Carrapatos , Animais , El Salvador , Rickettsia/genética
5.
Exp Appl Acarol ; 82(1): 151-159, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32869112

RESUMO

Rickettsia amblyommatis has been reported infecting various tick species throughout the western hemisphere, including Amblyomma cajennense sensu stricto (s.s.). The present study aimed to evaluate whether R. amblyommatis can be maintained by transovarial transmission and transstadial passage in A. cajennense s.s. ticks, and whether these ticks are competent vectors of this rickettsial agent. We selected engorged females that were naturally infected or uninfected by R. amblyommatis, and reared their offspring (infected and control groups, respectively). Immature ticks were allowed to feed on guinea pigs, whereas adults fed on rabbits. All stages and individuals of each generation of the infected group yielded rickettsial DNA, which was not detected in any tick from the control group. No host from the control group seroconverted to R. amblyommatis. Among 16 guinea pigs and eight rabbits infested with R. amblyommatis-infected ticks, only one guinea pig seroconverted to R. amblyommatis. Some unfed adult ticks of the infected group were dissected, and DNA was extracted from their salivary glands and from their carcasses. DNA of R. amblyommatis was detected in all carcasses, but not in the salivary glands. Results of this study indicate very low vector competence of A. cajennense s.s. for R. amblyommatis. Previous studies reported domestic animals with high titers to R. amblyommatis in areas where these animals are naturally infested chiefly by A. cajennense s.s. ticks. One may consider that the vector competence of A. cajennense s.s. for R. amblyommatis could vary among tick populations and/or rickettsial strains.


Assuntos
Vetores Artrópodes/microbiologia , Infecções por Rickettsia/veterinária , Rickettsia/isolamento & purificação , Carrapatos/microbiologia , Animais , Brasil , Feminino , Cobaias , Coelhos
6.
Emerg Infect Dis ; 25(12): 2322-2323, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31742533

RESUMO

In São Paulo metropolitan area, Brazil, Amblyomma aureolatum ticks are the main vector of Rickettsia rickettsii, which causes Brazilian spotted fever. In 2013, a boy in São Paulo died of Brazilian spotted fever associated with household dogs and A. aureolatum ticks. Prompt recognition and treatment of this illness might prevent deaths.


Assuntos
Vetores Aracnídeos/microbiologia , Rickettsia rickettsii , Febre Maculosa das Montanhas Rochosas/microbiologia , Febre Maculosa das Montanhas Rochosas/transmissão , Carrapatos/microbiologia , Animais , Brasil/epidemiologia , Gatos , Criança , Cães , Evolução Fatal , Humanos , Masculino , Rickettsia rickettsii/classificação , Rickettsia rickettsii/genética , Febre Maculosa das Montanhas Rochosas/diagnóstico , Febre Maculosa das Montanhas Rochosas/epidemiologia
7.
Emerg Infect Dis ; 24(11): 2041-2048, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30334709

RESUMO

Amblyomma aureolatum ticks are vectors of Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever in Brazil. Maintenance of R. rickettsii in nature depends on horizontal transmission along tick generations. Although such transmission is known to occur when uninfected and infected ticks feed simultaneously on susceptible animals (co-feeding systemic transmission), we investigated co-feeding nonsystemic transmission, which was based on R. rickettsii-infected and -uninfected A. aureolatum ticks feeding simultaneously on guinea pigs immune to R. rickettsii. Our acquisition and transmission infestations demonstrated that horizontal transmission of R. rickettsii by co-feeding ticks on immune hosts with no systemic infection did not occur when uninfected larvae fed distantly from infected nymphs but did occur in a few cases when uninfected larvae fed side-by-side with infected nymphs, suggesting that they shared the same feeding site. The co-feeding nonsystemic transmission type might have no epidemiologic importance for Rocky Mountain spotted fever.


Assuntos
Vetores Aracnídeos/microbiologia , Ixodidae/microbiologia , Rickettsia rickettsii/fisiologia , Febre Maculosa das Montanhas Rochosas/transmissão , Animais , Brasil , Suscetibilidade a Doenças , Feminino , Cobaias , Humanos , Larva , Ninfa , Febre Maculosa das Montanhas Rochosas/microbiologia
8.
Exp Appl Acarol ; 70(2): 219-29, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27392739

RESUMO

Rio Grande do Sul is the southernmost state of Brazil, bordering Uruguay. Clinical cases of spotted fever group (SFG) rickettsiosis were recently reported in Rio Grande do Sul. None of these cases was lethal, and all were confirmed by seroconversion to R. rickettsii antigens. Because serological cross-reactions are well known to occur between different SFG agents, the SFG agent responsible for the clinical cases remains unknown in Rio Grande do Sul, where no rickettsial agent is known to infect ticks. During 2013-2014, ticks and blood sera samples were collected from domestic dogs and wild small mammals, and from the vegetation in a SFG-endemic area of Rio Grande do Sul. Dogs were infested by Amblyomma ovale adult ticks, whereas small mammals were infested by immature stages of A. ovale, Ixodes loricatus, and adults of I. loricatus. Ticks collected on vegetation were adults of A. ovale, and immature stages of A. ovale, Amblyomma dubitatum, and Amblyomma longirostre. Three Rickettsia species were detected: Rickettsia bellii in I. loricatus, Rickettsia amblyommii in A. longirostre, and a Rickettsia parkeri-like agent (Rickettsia sp. strain Atlantic rainforest) in A. ovale. Seroreactivity to SFG antigens were detected in 19.7 % (27/137) canine and 37.5 % (15/40) small mammal sera, with highest titers to R. parkeri. Results indicate that the R. parkeri-like agent, strain Atlantic rainforest, is circulating between A. ovale ticks, dogs and small mammals in the study area, suggesting that this SFG pathogen could be one of the etiological agents of SFG clinical cases in Rio Grande do Sul.


Assuntos
Animais Domésticos , Animais Selvagens , Ixodidae/fisiologia , Infecções por Rickettsia/epidemiologia , Rickettsia/isolamento & purificação , Infestações por Carrapato/veterinária , Animais , Brasil/epidemiologia , DNA Bacteriano/genética , Feminino , Ixodidae/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , RNA Ribossômico 16S/genética , Rickettsia/genética , Infecções por Rickettsia/microbiologia , Análise de Sequência de DNA , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/parasitologia
9.
J Med Entomol ; 52(1): 28-37, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26336277

RESUMO

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.


Assuntos
Arvicolinae/parasitologia , Didelphis/parasitologia , Ixodidae/classificação , Ixodidae/fisiologia , Animais , Brasil , Feminino , Ixodidae/genética , Ixodidae/crescimento & desenvolvimento , Masculino , Dados de Sequência Molecular , Ninfa/classificação , Ninfa/fisiologia , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA/veterinária
10.
Exp Appl Acarol ; 62(1): 121-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23975565

RESUMO

From 2005 to 2012, ticks were collected from different hosts at different localities of the state of Rondônia. The following 16 ixodid tick species were identified: Ixodes fuscipes, Amblyomma auricularium, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma geayi, Amblyomma humerale, Amblyomma latepunctatum, Amblyomma longirostre, Amblyomma naponense, Amblyomma nodosum, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma romitii, Amblyomma rotundatum, Amblyomma scalpturatum, and Amblyomma varium. From these, A. auricularium, A. dubitatum, and A. geayi are reported for the first time in the state of Rondônia. We provide the following tick-host associations that have not been reported anywhere: A. longirostre on Pteroglossus bitorquatus, A. rotundatum on Hydrodynastes gigas, and A. latepunctatum and A. scalpturatum on Hydrochoerus hydrochaeris. An adult male specimen of A. rotundatum is reported on Boa constrictor, comprising only the fourth male specimen to be recorded for this obligate parthenogenetic tick species. We also report the presence of the argasid species Ornithodoros kohlsi for the first time in Brazil, based on larval specimens collected on bats Molossops (Neoplatymops) mattogrossensis in Monte Negro, Rondônia. The present study increases the Brazilian tick fauna to 65 species, from which 34 species (52 %) are now registered to Rondônia. Such high diversity of ticks in a relatively small state, associated with increasing environmental alteration due to deforestation and human occupation, makes Rondônia a potential source of tick-borne diseases.


Assuntos
Carrapatos , Animais , Biodiversidade , Brasil , Feminino , Masculino
11.
Vet Res Commun ; 48(2): 1161-1169, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38227179

RESUMO

The current work assessed the infection with Ehrlichia and Anaplasma species, and exposure to Rickettsia spp. in free-ranging capybaras in the Iberá wetlands ecoregion in Argentina. By indirect immunofluorescence assay, 37 out of 51 (73%) capybara sera were seropositive to Rickettsia spp., with 23.5% and 4% samples considered homologous to Rickettsia parkeri and Rickettsia bellii, respectively (or very closely related serotypes). Anaplasmataceae DNA was found to be highly prevalent in capybaras, with 33 out of 62 samples positive for Anaplasma sp. with Ct values of 28.64 ± 0.35 (average ± standard error), and 12 samples positive for Ehrlichia sp. with Ct values of 31.74 ± 0.87. Anaplasma sp. from capybaras was closely related to Anaplasma sp. reported to infect Amblyomma dubitatum in Iberá wetlands and to Anaplasma odocoilei, while the detected Ehrlichia sp. was closely related to "Candidatus Ehrlichia hydrochoerus" previously reported to infect capybaras in Brazil and A. dubitatum in Iberá wetlands. Structures compatible with Anaplasma morulae were observed in the cytoplasm of platelets from Anaplasma-positive capybaras. Our findings show that capybaras from the Iberá wetlands were exposed to Rickettsia species related to R. bellii and to the pathogen R. parkeri, and were infected with "Ca. Ehrlichia hydrochoerus" and a novel Anaplasma species, herein named "Candidatus Anaplasma capybara".


Assuntos
Rickettsiaceae , Roedores , Animais , Áreas Alagadas , Argentina , Brasil
12.
J Med Entomol ; 50(3): 674-8, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23802466

RESUMO

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.


Assuntos
Doenças do Cão/epidemiologia , Infestações por Pulgas/veterinária , Infestações por Piolhos/veterinária , Infestações por Carrapato/veterinária , Amblíceros/classificação , Amblíceros/fisiologia , Animais , Brasil/epidemiologia , Ctenocephalides/classificação , Ctenocephalides/fisiologia , Doenças do Cão/parasitologia , Cães , Meio Ambiente , Feminino , Infestações por Pulgas/epidemiologia , Infestações por Pulgas/parasitologia , Ixodidae/classificação , Ixodidae/fisiologia , Infestações por Piolhos/epidemiologia , Infestações por Piolhos/parasitologia , Masculino , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/parasitologia
13.
Parasitology ; 139(10): 1283-300, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22716923

RESUMO

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.


Assuntos
Doenças das Aves/epidemiologia , Doenças do Cão/epidemiologia , Febre Maculosa das Montanhas Rochosas/epidemiologia , Árvores , Animais , Animais Selvagens , Anticorpos Antibacterianos/sangue , Biodiversidade , Aves , Brasil/epidemiologia , Doenças do Cão/microbiologia , Cães , Ixodidae/microbiologia , Mamíferos , Dados de Sequência Molecular , Doenças Parasitárias em Animais/epidemiologia , Doenças Parasitárias em Animais/microbiologia , Prevalência , RNA Ribossômico 16S , Rhipicephalus sanguineus/microbiologia , Rickettsia rickettsii/genética , Rickettsia rickettsii/isolamento & purificação , Rickettsia rickettsii/fisiologia , Estudos Soroepidemiológicos , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/microbiologia
14.
Parasit Vectors ; 15(1): 196, 2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35676728

RESUMO

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


Assuntos
Argasidae , Borrelia , Doenças do Gato , Doenças do Cão , Ixodidae , Ornithodoros , Febre Recorrente , Animais , Aves , Gatos , Bovinos , Cães , América Latina/epidemiologia , Mamíferos , Febre Recorrente/diagnóstico , Febre Recorrente/epidemiologia , Febre Recorrente/veterinária
15.
Vet Sci ; 8(8)2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34437487

RESUMO

The capybara, Hydrochoerus hydrochaeris, is the largest extant rodent of the world. To better understand the correlation between size and body mass, and biochemical parameters of capybaras from areas with different degrees of anthropization (i.e., different food supplies), we sampled free-ranging capybaras from areas of natural landscapes (NLs) and human-modified landscapes (HMLs) in Brazil. Analyses of biometrical and biochemical parameters of capybaras showed that animals from HMLs were heavier (higher body mass) than those from NL, a condition possibly related to fat deposit rather than body length, as indicated by Body Condition Index (BCI) analyses. Biochemical parameters indicated higher serum levels of albumin, creatine kinase, cholesterol, fructosamine and total protein among capybaras from HMLs than from NLs; however, when all adult capybaras were analyzed together only cholesterol and triglycerides were positively correlated with body mass. We propose that the biochemical profile differences between HMLs and NLs are related to the obesity condition of capybaras among HMLs. Considering that heavier animals might live longer and reproduce more often, our results could have important implications in the population dynamics of capybaras among HMLs, where this rodent species is frequently represented by overgrowth populations that generate several levels of conflicts with human beings.

16.
Ticks Tick Borne Dis ; 12(6): 101805, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34411793

RESUMO

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 albiventris was 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 dubitatum in E areas. In NE areas, this dominance was inverted, with more A. dubitatum than A. sculptum infesting 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 albiventris in E areas presented higher seroprevalence and endpoint titres against R. rickettsii than in other areas. At least three Rickettsia species, non-pathogenic to humans, were detected in natural areas (Rickettsia bellii, Rickettsia amblyommatis and 'Candidatus Rickettsia 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.


Assuntos
Ixodidae , Mamíferos , Rickettsia/isolamento & purificação , Febre Maculosa das Montanhas Rochosas/veterinária , Animais , Brasil/epidemiologia , Ixodidae/microbiologia , Ixodidae/fisiologia , Prevalência , Febre Maculosa das Montanhas Rochosas/epidemiologia , Febre Maculosa das Montanhas Rochosas/microbiologia , Estudos Soroepidemiológicos
18.
Vet Parasitol Reg Stud Reports ; 22: 100448, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33308714

RESUMO

In this work we performed a field study in a spotted fever-endemic area of the Pampa biome in Rio Grande do Sul, the southernmost state of Brazil (Rosário do Sul municipality), with the aim to evaluate the serological status of dogs for spotted fever group (SFG) rickettsiae, to attempt the isolation rickettsiae from A. tigrinum ticks, and to further perform a multi-genic molecular characterization of the rickettsial isolate. For this purpose, we collected blood serum samples and ticks from 18 rural dogs during 2016-2017. By immunofluorescence assay, all 18 dogs (100%) reacted serologically to SFG rickettsiae, with highest endpoint titers to R. parkeri, suggesting that at least part of these dogs have been infected by R. parkeri. Among 23 ticks collected from the dogs (13 A. tigrinum and 10 Rhipicephalus sanguineus sensu stricto), 46% (6/13) A. tigrinum contained DNA of R. parkeri, which was successfully isolated in Vero cell culture from one of these ticks. Partial sequences of five genes (gltA, ompA, virB4, dnaA, dnaK) and 3 intergenic spacers (mppA-purC, rrl-rrf-ITS, rpmE-tRNAfMet) were generated from this rickettsial isolate, and were all 100% identical to corresponding sequences of R. parkeri s.s. We provide the first report of a viable isolate of R. parkeri from A. tigrinum, confirming that this isolate belongs to the strain R. parkeri s.s., as it has already been demonstrated for other two tick species of the Amblyomma maculatum species complex (A. maculatum and Amblyomma triste).


Assuntos
Doenças do Cão/epidemiologia , Infecções por Rickettsia/veterinária , Rickettsia/isolamento & purificação , Animais , Brasil/epidemiologia , Doenças do Cão/microbiologia , Cães , Ecossistema , Feminino , Rickettsia/genética , Rickettsia/fisiologia , Infecções por Rickettsia/epidemiologia , Infecções por Rickettsia/microbiologia , Estudos Soroepidemiológicos
19.
J Med Entomol ; 57(1): 308-311, 2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31504641

RESUMO

The bacterium Rickettsia rickettsii is the agent of Brazilian spotted fever (BSF), a highly fatal disease that is transmitted in Brazil mainly by the tick Amblyomma sculptum Berlese, which uses capybaras (Hydrochoerus hydrochaeris Linnaeus) as major hosts. In 2015, we captured nine capybaras in a BSF-endemic area of southeastern Brazil. From each capybara, we collected blood sera that were tested through the immunofluorescence assay using Rickettsia spp. antigens, and A. sculptum ticks, processed for isolation of R. rickettsii through guinea pig inoculation. All capybaras (100%) were seroreactive to Rickettsia spp., with highest titers to R. rickettsii. A total of 166 A. sculptum ticks were macerated and inoculated into nine guinea pigs, from which only one presented high fever and seroconverted to R. rickettsii. Blood from this febrile animal was inoculated into additional guinea pigs (guinea pig passages), which also became febrile and seroconverted, or when euthanized during the fever period, their internal organs (spleen, lung) were shown to contain R. rickettsii DNA. The present rickettsial isolate has been maintained cryopreserved as infected guinea pig organs. There was at least one R. rickettsii-infected tick among the 166 macerated ticks, giving a minimal infection rate of 0.6% (1/166). This infection rate is within the range of previous studies, which reported that only 0.05% to at most 1.28% A. sculptum ticks were infected by R. rickettsii in other BSF-endemic areas. These low infection rates support the low incidence of BSF, despite of A. sculptum being the most frequent human-biting tick in southeastern Brazil.


Assuntos
Ixodidae/microbiologia , Rickettsia rickettsii/isolamento & purificação , Febre Maculosa das Montanhas Rochosas/veterinária , Doenças dos Roedores/epidemiologia , Roedores , Animais , Brasil/epidemiologia , Feminino , Incidência , Masculino , Ninfa , Febre Maculosa das Montanhas Rochosas/epidemiologia , Febre Maculosa das Montanhas Rochosas/microbiologia , Doenças dos Roedores/microbiologia
20.
PLoS One ; 15(8): e0229277, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817698

RESUMO

Human activities are changing landscape structure and function globally, affecting wildlife space use, and ultimately increasing human-wildlife conflicts and zoonotic disease spread. Capybaras (Hydrochoerus hydrochaeris) are linked to conflicts in human-modified landscapes (e.g. crop damage, vehicle collision), as well as the spread and amplification of Brazilian spotted fever (BSF), the most human-lethal tick-borne disease in the world. Even though it is essential to understand the link between capybaras, ticks and BSF, many knowledge gaps still exist regarding the effects of human disturbance in capybara space use. Here, we analyzed diurnal and nocturnal habitat selection strategies of capybaras across natural and human-modified landscapes using resource selection functions (RSF). Selection for forested habitats was higher across human-modified landscapes, mainly during day- periods, when compared to natural landscapes. Across natural landscapes, capybaras avoided forests during both day- and night periods. Water was consistently selected across both landscapes, during day- and nighttime. Distance to water was also the most important variable in predicting capybara habitat selection across natural landscapes. Capybaras showed slightly higher preferences for areas near grasses/shrubs across natural landscapes, and distance to grasses/shrubs was the most important variable in predicting capybara habitat selection across human-modified landscapes. Our results demonstrate human-driven variation in habitat selection strategies by capybaras. This behavioral adjustment across human-modified landscapes may be related to increases in A. sculptum density, ultimately affecting BSF.


Assuntos
Ecossistema , Roedores/psicologia , Animais , Animais Selvagens , Brasil , Meio Ambiente , Pradaria , Interações Hospedeiro-Parasita/fisiologia , Humanos , Febre Maculosa das Montanhas Rochosas/epidemiologia , Carrapatos , Água , Zoonoses
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