Occurrence of ticks (Acari: Ixodidae) on human hosts, in three municipalities in the State of Pará, Brazil

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

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

Human parasitism by the exotic tick Dermacentor variabilis (Parasitiformes: Ixodida) in Brazil: report of an imported case

In June 2012, a tick was found parasitizing a man in the city of São Paulo, who had recently returned from a visit to Pennsylvania, in the northeast of the United States. The tick was removed and sent to the São Paulo State Department of Health, where it was identified as a male of the species Dermacentor variabilis (Say, 1821), according to the literature and taxonomic keys. The tick was subjected to a PCR test to search for rickettsiae, but the result was negative. The fact that a human entered Brazilian territory unaware that he was parasitized by a hard tick not belonging to the national tick fauna is significant because of the possibility that an exotic species could be introduced and take hold in this country. Another major risk to public health is that this arthropod could be infected with the bacterium Rickettsia rickettsii, as this ectoparasite is the main vector of Spotted Fever on the East Coast of North America.

New Records of Ticks of Genus Amblyomma Koch, 1844 (Acari: Ixodidae) for Ecuador

PURPOSE

In Ecuador, knowledge of the diversity and geographic distribution of ticks, as well as their importance as vectors, is scarce. Within the family Ixodidae, the genus Amblyomma is the most diverse and parasitizes wild and domestic animals. This genus is represented by 19 species in Ecuador, 12 of which occur in the continental territory and 7 in the Galapagos Islands. In this way, the objective of this work was to update the diversity of ticks reported for Ecuador on wild and domestic animals.

METHODS

The specimens were collected manually on mammals and birds, in four localities belonging to the Sierra and Amazon of Ecuador and were kept in tubes with 96% ethyl alcohol. After that, all specimens were separated into immatures, males and females and were identified using their morphological characters.

RESULTS

This study records Amblyomma coelebs Neumann, 1899, Amblyomma longirostre (Koch, 1844) Neumann, 1905 and Amblyomma varium Koch, 1844 for the first time in Ecuador. Thus, the genus Amblyomma is currently represented by 22 species. In addition, their hosts, distribution, and importance are also discussed.

CONCLUSIONS

Knowing the diversity of ticks that wildlife possesses, its interrelation with the domestic fauna, and the possible pathogens that could be transmitting could significantly contribute to wildlife's conservation.

Seasonal Dynamics, Record of Ticks Infesting Humans, Wild and Domestic Animals and Molecular Phylogeny of Rhipicephalus microplus in Khyber Pakhtunkhwa Pakistan

Although ticks prevalent in various agro-systems of Pakistan are associated with economic losses, information is still missing about the tick's diversity, hosts they infest, seasonal dynamics and molecular phylogeny of Rhipicephalus microplus in Khyber Pakhtunkhwa (KP) Pakistan. This study for the first time enlisted ticks infesting diverse hosts including humans in various regions of KP. A total of 8,641 ticks were collected across the northern, southern and central regions of KP and were morpho-taxonomically categorized into six genera comprising 17 species, R. microplus (n = 3,584, 42%), Hyalomma anatolicum (n = 2,253, 27%), Argas persicus (n = 1,342, 16%), Hya. impeltatum (n = 586, 7%), R. turanicus (n = 161, 2%), R. haemaphysaloides (n = 142, 2%), R. annulatus (n = 132, 2%), Hae. montgomeryi (n = 123, 1.4%), Hya. marginatum (n = 110, 1.3%), R. sanguineus (n = 34, 0.4%), and Hae. longicornis (n = 31, 0.4%). Ticks infesting wild animals included Amblyomma gervaisi, Amb. exornatum, Amb. latum, Dermacentor marginatus, and Hae. indica, while ticks collected from humans included R. microplus, R. annulatus, Hya. anatolicum, Hya. marginatum, and Hae. punctata. The overall prevalence of ticks infesting domestic animals was 69.4% (536/772). Among animal hosts, cattle were found highly infested (87.2%, 157/180) followed by buffalos (79%, 91/114), domestic fowls (74.7%, 112/150), goats (68.3%, 82/120), dogs (66.7%, 32/48), horses (61.3%, 49/80), and sheep (16.3%, 13/80). Analysis revealed that the tick burden significantly differed among domestic animals and was found to be high in cattle, followed by buffalos, goats, sheep, domestic fowl, dogs, and horses. Seasonal patterns of ticks distribution showed highest prevalance in July, August, and September due to the prevailing high temperature and humidity during these months. The phylogenetic analysis of cattle tick R. microplus based on partial mitochondrial cytochrome oxidase subunit I (COX1), 16S ribosomal RNA (16S rRNA) and internal transcribed spacer 2 (ITS2) sequences, revealed that R. microplus prevalent in this region belongs to clade C which include ticks originating from Bangladesh, Malaysia, and India. Further large scale studies across the country are necessary to explore the molecular and cross breeding aspects at the geographical overlapping of various tick species and their associated pathogens to facilitate designing control strategies as well as awareness against tick infestation in the region.

Molecular evidence of Anaplasma phagocytophilum and Theileria equi coinfection in horses from Rio de Janeiro, Brazil

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Molecular evidence of coinfection with A. phagocytophilum and T. equi in horses in Brazil was confirmed for the first time by the detection of DNA from both agents.

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EGA should be included in differential diagnosis of tick-borne diseases in horses.

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Different clinical manifestations in horses may be due to coinfection.

The present study aims to determine the frequencies of Theileria equi and Anaplasma phagocytophilum antibodies among horses from the state of Rio de Janeiro, Brazil, and to detect the presence of DNA of these pathogens through molecular methods. A total of 98 serum samples of horses from the municipality of Seropedica were tested by indirect immunofluorescence antibody (IFA) to detect anti-A. phagocytophilum and anti-T. equi IgG antibodies. In addition, quantitative real-time PCR (qPCR) was used to detect these pathogens in the DNA extracted from the whole blood and buffy coat of horses. Bivariate analysis and odds ratio were performed to verify the possible association between positivity and characteristics related to the horses. As evaluated by IFA and qPCR, the frequency of animals that tested positive for T. equi was 89.8% (n = 88/98) and 91.8% (n = 90/98), whereas A. phagocytophilum was 17.4% (n = 17/98) and 1.0% (n = 1/98), respectively. Serological evidence of exposure to A. phagocytophilum and T. equi was observed in 16.3% (n = 16/98) of the horses; however, exposure was confirmed by qPCR in only 1.0% (n = 1/98). No statistical association was found in the bivariate and odds ratio analysis. This is the first study reporting the molecular detection of A. phagocytophilum DNA in horses from the state of Rio de Janeiro, and also the coinfection of A. phagocytophilum and T. equi in a horse from Brazil confirmed by molecular methods. Equine granulocytic anaplasmosis is circulating in Brazilian horses, together with T. equi, and should be included in the differential diagnosis of tick-borne diseases.

Human parasitism and toxicosis by Ornithodoros rietcorreai (Acari: Argasidae) in an urban area of Northeastern Brazil

The soft tick, Ornithodoros rietcorreai, is a parasite of the rodent, Kerodon rupestris, and, to a lesser extent, of bats living in rock cavities in Northeastern Brazil. This report describes the first recorded episodes of human parasitism by this argasid tick, reported to the Brazilian Ministry of Health in September 2017. We assessed outdoor environments, roofs, animal nests and chicken coops in five houses located in an urban area of Russas City, Ceará State, Brazil. Our results confirmed the presence of the tick in two of the assessed houses. The collected specimens were molecularly identified as O. rietcorreai. Of the ten individuals living in the investigated properties, three reported being parasitized by ticks. Although O. rietcorreai ticks were recovered from the evaluated houses, the primary hosts for the ticks were not identified. The retrospective medical records of parasitized individuals reported the following: local pruritus 3/3, malaise 3/3, local edema and erythema 3/3, local rash 3/3, local pain 3/3, slow lesion healing 3/3 and paresthesia 1/3. One of the individuals reported four parasitism episodes (March, June, July and August 2017) and required medical attention and the administration of anti-allergy and anti-inflammatory drugs. The aforementioned reports were the first to address human parasitism, with subsequent toxicosis, by this tick species in Brazilian urban areas. Attention was drawn to the potential consequences of such episodes to the health of previously exposed individuals.

A review of the genus Rickettsia in Central America

In this paper, we present a historical review of rickettsiosis in Central America and also the most recent findings of Rickettsia in ectoparasites. All countries of Central America have records of rickettsiosis. Regarding the typhus group rickettsioses, there is clinical or serological evidence of Rickettsia prowazekii in Guatemala, Rickettsia typhi in Panama, Guatemala, and Costa Rica and unidentified species of the typhus group in El Salvador. Concerning spotted fever group rickettsiosis, there is serological evidence of infection by Rickettsia akari in Costa Rica and confirmed cases involving Rickettsia rickettsii in Panama and Costa Rica. There are also reports of spotted fever group rickettsiosis in acute patients from Guatemala, Honduras, and Nicaragua. Serological studies in Central America show reactivity of Rickettsia ambyommatis, Rickettsia bellii, Rickettsia felis, Rickettsia rhipicephali, and R. rickettsii in domestic and wild mammals. Eight species of Rickettsia have been detected in ectoparasites from Central America: R. africae (or very similar), R. amblyommatis, R. asembonensis, R. bellii, R. felis, R. parkeri, R. rhipicephali, and R. rickettsii, in addition to undescribed strains such as Atlantic Rainforest, Colombianensi, IbR/CRC, Barva, Aragaoi, and Candidatus "Rickettsia nicoyana;" the latter being the only one associated with Argasidae (Ornithodoros knoxjonesi). R. amblyommatis is the most common species in Central America, seeing as it has been reported in 10 species of ticks and one of fleas in five of the seven countries of the region. In this study, we demonstrate that the genus Rickettsia is widely distributed in Central America and that rickettsiosis could be an underestimated problem in the absence of greater diagnostic efforts in undetermined febrile cases.

Rickettsia (Rickettsiales: Rickettsiaceae) Vector Biodiversity in High Altitude Atlantic Forest Fragments Within a Semiarid Climate: A New Endemic Area of Spotted-Fever in Brazil

Rickettsioses are re-emerging vector-borne zoonoses with a global distribution. Recently, Rickettsia sp. strain Atlantic rainforest has been associated with new human spotted-fever (SF) cases in Brazil, featuring particular clinical signs: eschar formation and lymphadenopathy. These cases have been associated with the tick species, Amblyomma ovale From 2010 until 2015, the Brazilian Health Department confirmed 11 human SF cases in the Maciço de Baturité region, Ceará, Brazil. The present study reports the circulation of Rickettsia spp. in vectors from this entirely new endemic area for SF. A total of 1,727 ectoparasites were collected in this area from the environment, humans, and wild and domestic animals. Samples (n = 887) were screened by polymerase chain reaction (PCR), targeting the gltA and ompA rickettsial genes. Sequencing and phylogenetic analyses of gltA gene amplicons were carried out for 13 samples positive for both screening PCRs. Fragments of gltA and ompA from three samples were cloned, sequenced, and analyzed further. A. ovale and Rhipicephalus sanguineus specimens, collected from dogs, were found to be infected with Rickettsia sp. str. Atlantic rainforest, suggesting the importance of dogs in the epidemic cycle. Candidatus Rickettsia andeanae, Rickettsia felis, and Rickettsia bellii were also found infecting ticks and fleas in five municipalities, demonstrating the broad diversity of rickettsiae in circulation in the studied area. This study reports, for the first time, evidence of infection with Rickettsia sp. strain Atlantic rainforest in A. ovale and R. sanguineus in Ceará, and Ca. R. andeanae in an Atlantic rainforest environment of Brazil.

Detection of rickettsiae in fleas and ticks from areas of Costa Rica with history of spotted fever group rickettsioses

Outbreaks of spotted fevers have been reported in Costa Rica since the 1950s, although vectors responsible for transmission to humans have not been directly identified. In this study, species of Rickettsia were detected in ectoparasites from Costa Rica, mostly from five study sites where cases of spotted fevers have been reported. Ticks and fleas were collected using drag cloths or directly from domestic and wild animals and pooled according to species, host, and location. Pools were analyzed initially by PCR to detect a fragment of Rickettsia spp. specific gltA gene, and those positive were confirmed by detection of htrA and/or ompA gene fragments. Partial sequences of the gltA gene were obtained, as well as at least one ompA and/or ompB partial sequence of each species. Rickettsia spp. were confirmed in 119 of 497 (23.9%) pools of ticks and fleas analyzed. Rickettsia rickettsii was identified in one nymph of Amblyomma mixtum and one nymph of Amblyomma varium. Other rickettsiae present were 'Candidatus Rickettsia amblyommii' in A. mixtum, Amblyomma ovale, Dermacentor nitens, and Rhipicephalus sanguineus s. l.; Rickettsia bellii in Amblyomma sabanerae; Rickettsia felis in Ctenocephalides felis; and Rickettsia sp. similar to 'Candidatus R. asemboensis' in C. felis, Pulex simulans, A. ovale, and Rhipicephalus microplus. Results show the presence of rickettsiae in vectors that may be responsible for transmission to humans in Costa Rica, and evidence suggests exposure to rickettsial organisms in the human environment may be common. This is the first study to report R. rickettsii in A. varium and in A. mixtum in Costa Rica.

Rhipicephalus sanguineus sensu lato (Ixodidae) in synantropic rodents in Rio Grande do Sul, Brazil

Rhipicephalus sanguineus, the brown dog tick, is responsible for maintaining and transmitting various pathogens, both in animals and human beings, and it is of great sanitary importance. This communication reports the first occurrence of Rhipicephalus sanguineus sensu lato parasitizing Rattus norvegicus in the state of Rio Grande do Sul, Brazil, and it is also the first record of this tick species parasitizing Rattus rattus in Brazil. The rodents were captured from the port area, located in the city of Pelotas, Rio Grande do Sul, Brazil. We collected 6 larvae of this tick species from 2 male R. rattus individuals, and 3 larvae from 2 female R. norvegicus individuals; parasitized specimens of both rodent species were captured from different sites within the experimental area. This record broadens the number of Rhipicephalus sanguineus sensu lato hosts in urban areas, indicating the need for continued monitoring on population density for both R. sanguineus and synanthropic rodents.

Rhipicephalus sanguineus (ACARI: IXODIDAE) BITING A HUMAN BEING IN PORTO ALEGRE CITY, RIO GRANDE DO SUL, BRAZIL

We report the finding of a female brown dog tick, Rhipicephalus sanguineus (Acari: Ixodidae) on the scalp of a male patient inPorto Alegre, Rio Grande do Sul, Brazil. Human parasitism by this tick is rare and has seldomly been reported in the literature, despite its recognized importance since it can act as a vector of Rickettsia rickettsii, the agent of spotted fever.

Brazilian Spotted Fever with an Approach in Veterinary Medicine and One Health Perspective

There is increasing interaction between man and pathogens transmitted by arthropods, especially by ticks. It is on this background that a holistic approach stands out, for the sake of Public Health. Brazilian Spotted Fever is an endemic disease at the country's southeast, with Amblyomma sculptum as its major contributor, followed by A. aureolatum and potentially Rhipicephalus sanguineus. Dogs have been considered sentinels, and in some areas the disease in dogs can precede human disease. Considering the importance of this disease for human health, the serological evidence in dogs, and the transmission of ticks between dogs and their owners, this review aimed to elucidate the importance of the epidemiological investigation, the diagnosis in dogs, and the role of veterinarians in Public Health to control vector-borne zoonotic diseases. We encourage veterinarians to include this rickettsial infection in the diagnosis of febrile diseases of common occurrence in dogs.

Survey of canine tick-borne diseases in Lábrea, Brazilian Amazon: ‘accidental’ findings of Dirofilaria immitis infection

Blood samples were collected from 99 domestic dogs from the urban and rural areas of the Lábrea municipality, state of Amazonas, Brazil. Canine serum samples were tested by immunofluorescence assay against Rickettsia spp., which revealed that only 3.0% (1/33) and 7.6% (5/66) of the dogs from urban and rural areas, respectively, reacted positively to at least one Rickettsia species. DNA was extracted from canine blood and tested by a battery of PCR assays targeting protozoa of the genera Babesia and Hepatozoon, and bacteria of the genera Rickettsia and Ehrlichia and family Anaplasmataceae. All samples were negative in the PCR assays targeting the genera Babesia, Hepatozoon, Ehrlichia and Rickettsia. For Anaplasmataceae, 3% (1/33) and 39.4% (26/66) of the urban and rural dogs, respectively, yielded amplicons that generated DNA sequences 100% identical to the corresponding sequence of Wolbachia endosymbiont of Dirofilaria immitis. Because of these results, all canine DNA samples were further tested in a PCR assay targeting filarial nematodes, which was positive for 18.2% (6/33) and 57.6% (38/66) urban and rural dogs, respectively. Filarial-PCR products generated DNA sequences 100% identical to D. immitis. While tick-borne infections were rare in Lábrea, D. immitis infection rates were among the highest reported in South America.

Dogs, cats, parasites, and humans in Brazil: opening the black box

Dogs and cats in Brazil serve as primary hosts for a considerable number of parasites, which may affect their health and wellbeing. These may include endoparasites (e.g., protozoa, cestodes, trematodes, and nematodes) and ectoparasites (i.e., fleas, lice, mites, and ticks). While some dog and cat parasites are highly host-specific (e.g., Aelurostrongylus abstrusus and Felicola subrostratus for cats, and Angiostrongylus vasorum and Trichodectes canis for dogs), others may easily switch to other hosts, including humans. In fact, several dog and cat parasites (e.g., Toxoplasma gondii, Dipylidium caninum, Ancylostoma caninum, Strongyloides stercoralis, and Toxocara canis) are important not only from a veterinary perspective but also from a medical standpoint. In addition, some of them (e.g., Lynxacarus radovskyi on cats and Rangelia vitalii in dogs) are little known to most veterinary practitioners working in Brazil. This article is a compendium on dog and cat parasites in Brazil and a call for a One Health approach towards a better management of some of these parasites, which may potentially affect humans. Practical aspects related to the diagnosis, treatment, and control of parasitic diseases of dogs and cats in Brazil are discussed.

New tick records from the state of Rondônia, western Amazon, Brazil

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.

Serosurvey for tick-borne diseases in dogs from the Eastern Amazon, Brazil

Canine ehrlichiosis and babesiosis are the most prevalent tick-borne diseases in Brazilian dogs. Few studies have focused attention in surveying tick-borne diseases in the Brazilian Amazon region. A total of 129 blood samples were collected from dogs living in the Brazilian eastern Amazon. Seventy-two samples from dogs from rural areas of 19 municipalities and 57 samples from urban stray dogs from Santarém municipality were collected. Serum samples were submitted to Indirect Immunofluorescence Assay (IFA) with antigens ofBabesia canis vogeli, Ehrlichia canis, and six Rickettsia species. The frequency of dogs containing anti-B. canis vogeli, anti-E. canis, and anti-Rickettsia spp. antibodies was 42.6%, 16.2%, and 31.7%, respectively. Anti-B. canis vogeli antibodies were detected in 59.6% of the urban dogs, and in 29.1% of the rural dogs (P < 0.05). For E. canis, seroprevalence was similar among urban (15.7%) and rural (16.6%) dogs. ForRickettsia spp., rural dogs presented significantly higher (P < 0.05) prevalence (40.3%) than urban animals (21.1%). This first study on tick-borne pathogens in dogs from the Brazilian eastern Amazon indicates that dogs are exposed to several agents, such asBabesia organisms, mostly in the urban area; Spotted Fever group Rickettsia organisms, mostly in the rural area; andEhrlichia organisms, in dogs from both areas studied.