Detection of Rickettsia bellii and Rickettsia amblyommii in Amblyomma longirostre (Acari: Ixodidae) from Bahia state, Northeast Brazil

Ticks (Acari: Ixodidae) and tick-borne agents associated with domestic dogs in an environmental protection area in Brazil, with molecular evidence of Rhipicephalus linnaei (Audouin, 1826)

Wild animals and domestic dogs living in human dwellings near forested areas can share ectoparasites, including ticks. In this study, we surveyed ticks associated with dogs which tutors living in the Palmares Environmental Protection Area (EPA Palmares). Dogs were classified into three categories, domiciled, semi-domiciled and wandering dogs according to dog care/ type of dwelling. Ticks were collected monthly from January to December, 2020. Overall, 60 (33.9%) out of 177 examined dogs were infested by ticks. Six species of ticks were identified: Rhipicephalus linnaei, Amblyomma aureolatum, Amblyomma sculptum, Amblyomma ovale, Amblyomma dubitatum and Rhipicephalus microplus. The overall prevalence and presence in semi-domicilied+wandering dogs was higher for A. aureolatum than for R. linnaei by the Chi-square statistic tests. A random sample of 50 ticks, collected from 22 different dogs, were processed through molecular analyses. Ticks were submitted to DNA extraction and also by PCR, using specific primers in order to pathogens monitoring. Four males of A. aureolatum yielded DNA sequences (350 bp) that were 100% identical to the type strain of Rickettsia bellii in GenBank (CP000087).

Molecular survey of Rickettsia spp. in ticks infesting wild animals in six departments in Colombia

Ticks are a globally distributed group of hematophagous ectoparasites that parasitize terrestrial vertebrates such as amphibians, reptiles, birds, and mammals. Ticks are vectors and reservoirs of pathogens that play an important role in wildlife and human health. Rickettsia is one of the bacteria transmitted by ticks, which some pathogenic species can cause rickettsiosis, a zoonotic disease that can cause serious harm to humans and animals. More information is necessary on the interactions between ticks and wildlife despite the fifty-seven ticks species already identified in Colombia. The objective of the present study was to determine the associations between ticks parasitizing wildlife and bacteria of the genus Rickettsia in six departments of Colombia. One hundred eighty-five ticks (80 larvae, 78 nymphs, and 27 adults) were collected from 55 wildlife species (amphibians, birds, mammals, and reptiles). Nine tick species were identified, and Rickettsia bellii, Rickettsia felis, 'Candidatus Rickettsia colombianensi' and Rickettsia parkeri were detected. Our results contribute to the current knowledge of tick-associated rickettsiae and the role of wildlife in their transmission dynamics.

Survey of Rickettsia spp. in ticks (Acari: Ixodidae) infesting opossums (Didelphis albiventris) and capybaras (Hydrochoerus hydrochaeris) from an urban park in southeastern Brazil

Ticks are hematophagous arthropods and, during feeding, may transmit pathogens to vertebrate hosts, including humans. This study aimed to investigate the presence of Rickettsia spp. in ticks collected between 2010 and 2013 from free-ranging capybaras (Hydrochoerus hydrochaeris) and opossums (Didelphis albiventris) that inhabit Sabiá Park in Uberlândia, Brazil. Overall, 1,860 ticks were collected: 1,272 (68.4%) from capybaras (487 of the species Amblyomma sculptum, 475 adults and 12 nymphs; 778 Amblyomma dubitatum, 727 adults and 51 nymphs; and seven larva clusters of the genus Amblyomma); and 588 (31.6%) from opossums (21 A. sculptum, one adult and 20 nymphs; 79 A. dubitatum, all nymphs; 15 Ixodes loricatus, 12 adults and three nymphs; 457 Amblyomma sp. larva clusters; 15 Ixodes sp. larva clusters; and one Argasidae larva cluster). Out of 201 DNA samples tested for the presence of Rickettsia spp. DNA using polymerase chain reaction (PCR) 12 showed amplification of a gtlA gene segment that was specific to Rickettsia bellii, a bacterium non-pathogenic to humans. As there has been a report showing serological evidence of infections caused by Rickettsia species of the spotted fever group (SFG) in capybaras and opossums in the park, including Rickettsia rickettsii, the etiological agent of Brazilian spotted fever, and considering the presence of A. sculptum ticks, which are aggressive to humans, as well as these vertebrate hosts, which are amplifiers of R. rickettsii, it is important to monitor the presence of SFG rickettsiae in the Sabiá Park, which is visited daily by thousands of people.

New hard tick (Acari: Ixodidae) reports and detection of Rickettsia in ticks from Sierra Nevada de Santa Marta, Colombia

The Sierra Nevada de Santa Marta (SNSM), located in northern Colombia, is considered a geographical island with high levels of biodiversity and endemism. However, little is known about tick species and their associated microorganisms at the SNSM. In this study we sampled host-seeking ticks in areas of the town of Minca within the SNSM. We collected 47 ticks identified as Amblyomma pacae, Amblyomma longirostre, Amblyomma ovale, Amblyomma mixtum, Haemaphysalis juxtakochi, Ixodes sp. cf. Ixodes affinis and Ixodes sp. Of these ticks, we tested for Rickettsia spp. by amplifying the gltA, SCA1, and 16S rRNA genes via PCR. Rickettsia amblyommatis was detected in one pool of 3 larvae and in a female of A. pacae. Additonally, we isolated Rickettsia sp. belonging to the group of spotted fevers in larvae of A. longirostre. This study reports new findings of six species of ticks and two species of Rickettsia within the SNSM.

Molecular detection of Babesia spp. and Rickettsia spp. in coatis (Nasua nasua) and associated ticks from midwestern Brazil

Procyonids are reservoirs of many zoonotic infectious diseases, including tick-borne pathogens. The role of coatis (Nasua nasua) in the epidemiology of piroplasmids and Rickettsia has not been fully addressed in Brazil. To molecularly study these agents in coatis and associated ticks, animals were sampled in two urban areas in Midwestern Brazil. Blood (n = 163) and tick (n = 248) DNA samples were screened by PCR assays targeting the 18S rRNA and gltA genes of piroplasmids and Rickettsia spp., respectively. Positive samples were further molecularly tested targeting cox-1, cox-3, β-tubulin, cytB, and hsp70 (piroplasmid) and ompA, ompB, and htrA 17-kDa (Rickettsia spp.) genes, sequenced and phylogenetically analyzed. All coatis' blood samples were negative for piroplasmids, whereas five pools of ticks (2%) were positive for two different sequences of Babesia spp.. The first from Amblyomma sculptum nymphs was close (i.e., ≥ 99% nucleotide identity) to a Babesia sp. previously found in capybaras (Hydrochoerus hydrochaeris); the second from Amblyomma dubitatum nymphs and Amblyomma spp. larvae was identical (100% nucleotide identity) to a Babesia sp. detected in opossums (Didelphis albiventris) and associated ticks. Four samples (0.8%) were positive by PCR to two different Rickettsia spp. sequences, being the first from Amblyomma sp. larva identical to Rickettsia belli and the second from A. dubitatum nymph identical to Rickettsia species from Spotted Fever Group (SFG). The detection of piroplasmids and SFG Rickettsia sp. highlights the importance of Amblyomma spp. in the maintenance of tick-borne agents in urban parks where humans and wild and domestic animals are living in sympatry.

Rickettsia amblyommatis in Ticks: A Review of Distribution, Pathogenicity, and Diversity

Rickettsia amblyommatis is a potentially pathogenic species of Rickettsia within the spotted fever group vectored by ticks. While many studies have been published on this species, there is debate over its pathogenicity and the inhibitory role it plays in diagnosing illnesses caused by other spotted fever group Rickettsia species. Many publications have recorded the high infection prevalence of R. amblyommatis in tick populations at a global scale. While this species is rather ubiquitous, questions remain over the epidemiological importance of this possible human pathogen. With tick-borne diseases on the rise, understanding the exact role that R. amblyommatis plays as a pathogen and inhibitor of infection relative to other tick-borne pathogens will help public health efforts. The goal of this review was to compile the known literature on R. amblyommatis, review what we know about its geographic distribution, tick vectors, and pathogenicity, assess relatedness between various international strains from ticks by phylogenetic analysis and draw conclusions regarding future research needed.

Detection of Rickettsia spp. in ticks of wildlife fauna from Costa Rica: First report of Rickettsia rhipicephali in Central America

In the past two decades, new species of Rickettsia have been detected and described worldwide, some of them considered pathogenic for humans. Although Costa Rica is considered a biodiversity hotspot, the knowledge about rickettsiae in sylvatic ecosystems and wild animals is scarce. The aim of this preliminary study was to detect and identify species of Rickettsia in ticks collected from wild animals in Costa Rica. A total 119 ticks were collected from 16 animal host species belonging to diverse vertebrate families (Didelphidae, Procyonidae, Felidae, Choloepodidae, Bradypodidae, Myrmecophagidae, Tayassuidae, Tapiridae, Phyllostomidae, Bufonidae, Geoemydidae, Boidae, Colubridae), and they were grouped into 43 pools to detect the presence of Rickettsia spp. DNA by PCR targeting the gltA gene. In positive pools, amplicons of the ompA, sca5 (ompB), and/or htrA genes were also amplified to identify the species present. The identification of some ticks was also confirmed by molecular methods. Four species of Rickettsia were detected in eight (19%) tick pools: Rickettsia amblyommatis in four pools of Amblyomma geayi (host: Caluromys derbianus) and one pool of Amblyomma cf. parvum (host: Nasua narica), Rickettsia rhipicephali in one pool of Dermacentor latus (host: Tayassu pecari), 'Candidatus Rickettsia colombianensi' in one pool of Amblyomma sp. nymphs (host: Boa constrictor), and Rickettsia sp. genotype IbR/CRC in one pool of Ixodes cf. boliviensis (host: Puma concolor). This is the first molecular detection of R. rhipicephali in Central America, and of 'Candidatus R. colombianensi' in Costa Rica. Results show that diverse wild animals and their ticks are associated with several species of rickettsiae in Costa Rica, which may come in contact with humans and other domestic animals in sylvatic environments.

High Prevalence of Rickettsia bellii in Mosquitoes From Eastern China

Mosquitoes are the most important vectors carrying significant numbers of human pathogens. Recent studies implicated that mosquitoes play an important role in circulation and transmission of multiple Rickettsia species. In this study, Rickettsia bellii was identified in four mosquito species (Culex pipiens, C. tritaeniorhynchus, Aedes albopictus, and Anopheles sinensis) collected from three Eastern China provinces during 2019-2020. Rickettsia bellii was detected in 37.50 and 26.32% of the C. pipiens pools from Beijing and Jiangsu province, respectively. In C. tritaeniorhynchus and An. sinensis from Shandong, the infection rate is 20.00 and 6.25%, respectively. Additionally, three Ae. albopictus pools (3/42, 7.14%) from Beijing were also detected positive for R. bellii. Genetic and phylogenetic analysis on 16S, gltA, and groEL genes indicates that sequences from all these strains are highly homologous and closely related to other R. bellii strains. This is the first report that Ae. albopictus and C. tritaeniorhynchus harbor R. bellii. The wide host range and high infection rate in certain areas may dramatically increase the exposure of R. bellii to human and other vertebrates. The role of mosquitoes in transmission of rickettsiosis and its potential risk to public health should be further considered.

Occurrence of tick-borne pathogens in dogs in a coastal region of the state of Ceará, northeastern Brazil

The aim of this study was to determine the occurrence of tick-borne pathogens (Ehrlichia canis, Babesia vogeli, Hepatozoon spp. and Rickettsia spp.) in dogs in Vila de Jericoacoara, coastal region of Ceará, Brazil. Blood samples were collected from 153 animals and analyzed using molecular and serological methods. Sixty animals were found to be infected or exposed to at least one of the pathogens studied. Babesia vogeli was the most prevalent pathogen (15%), followed by E. canis (13.7%) and Hepatozoon spp. (11.8%), which was identified as Hepatozoon canis through sequencing. Twenty dogs (13%) were seroreactive to Rickettsia spp. Rhipicephalus sanguineus sensu lato was observed on 11.8% of the animals. There were associations between age (< 3 years old) and positivity for B. vogeli, and between habitation (stray dogs) and positivity for H. canis. There were also associations between anemia and infection with H. canis, and between leukopenia and exposure to Rickettsia spp. No association was detected between clinical alterations and infection with or exposure to the pathogens studied. The results confirmed that pathogens of veterinary importance are circulating in northeastern Brazil and showed that dogs are exposed to Rickettsia species with zoonotic potential, thus indicating a need for vector control measures.

Detection of Rickettsia spp. in ring-tailed coatis (Nasua nasua) and ticks of the Iguaçu National Park, Brazilian Atlantic Rainforest

Wild animals are of considerable importance in the ecology of infectious agents, as they can function as hosts and even as possible vectors. In this study, DNA from Rickettsia spp. was detected on ticks and fragments of skin collected from wild coatis with synanthropic habits in the Iguaçu National Park (INP) in the state of Paraná in southern Brazil. Testing was carried out on a total of 566 ticks, comprising Amblyomma spp. larvae, nymphs of Haemaphysalis juxtakochi, Amblyomma brasiliense, Amblyomma coelebs, and adults of Amblyomma ovale. The samples were tested by polymerase chain reaction (PCR) by amplifying htrA, gltA, ompA, and ompB gene fragments to detect Rickettsia spp. A fragment of each positive sample was sequenced in both directions, submitted to Genbank for a homology search, and also used for phylogenetic analyses. Samples of A. coelebs (1.90%, 8/420), A. ovale (13%, 6/45), and ring-tailed coati skin (1%, 1/75) amplified Rickettsia spp. DNA. Through sequencing, Rickettsia bellii was observed in A. ovale, Rickettsia amblyommatis in A. coelebs, while Rickettsia rhipicephali was detected in the skin samples. Wild ring-tailed coatis with synanthropic habits in the INP and their ticks are infected by Rickettsia spp., and associations with new hosts have been described.

Tick infestation on birds in an urban Atlantic Forest fragment in north-eastern Brazil

Birds are important hosts for various tick species, playing a significant role in their biological life cycle and dispersion. In this study, we investigated tick infestations on birds trapped in an urban remnant of Atlantic Forest in Pernambuco state, Brazil. From February 2015 to March 2017, 541 birds belonging to 52 species were trapped with mist nets and examined for ectoparasites. Birds trapped in the late successional forest were significantly more infested than birds trapped in the early successional forest. In the same way, ectoparasite infestation varied significantly according to bird weight and collection plot. Overall, 198 birds (36.6%) belonging to 27 species were parasitized by ectoparasites (i.e., ticks, lice and/or mites). Ectoparasites were effectively collected from 111 birds, of which 99 belonging to 20 species were infested by ticks (n = 261), namely, Amblyomma longirostre (13 nymphs), Amblyomma nodosum (21 nymphs), Amblyomma varium (one nymph), and Amblyomma spp. (five nymphs and 221 larvae). Most of the ticks (> 90%) were collected from Passeriformes. This study provides the second record of A. varium in Pernambuco state and confirms that birds, especially Passeriformes, are important hosts for larvae and nymphs of Amblyomma spp. in the Atlantic Forest biome of Pernambuco.

Microbiome analysis of the midguts of different developmental stages of Argas persicus in China

Argas persicus is an ectoparasite of poultry. The bacterial community structure and the pathogenic bacteria associated with different developmental stages of A. persicus have implications for control. Argas persicus were collected from chickens in the city of Jiuquan in Gansu, China. Bacterial DNA was extracted from the midgut contents of blood engorged larvae, nymphs and adult females. The V3-V4 hypervariable regions of 16S rRNA genes were sequenced using the IonS5™XL platform. Identification of Rickettsia spp. and detection of Coxiella burnetii were performed using PCR on target genes. The bacterial diversity within larvae was the highest and the bacterial diversity within nymphs was greater than that of adults. At different classification levels, seven bacterial phyla were common phyla, 27 genera were common genera, and 18 species were common species in the three samples. At the phylum level, Proteobacteria showed a marked predominance in all samples. Rickettsia, Stenotrophomonas, Spiroplasma, and Coxiella were the dominant bacteria at the genus level. The Rickettsia species in A. persicus was identified as Rickettsia hoogstraalii and the Coxiella species was identified as a Coxiella-like endosymbiont. Additionally, some bacterial species such as Pseudomonas geniculata, Sphingomonas koreensis, and Acinetobacter haemolyticus were reported here for the first time in A. persicus.

Ixodes tropicalis (Acari: Ixodidae) infesting a human and molecular detection of Rickettsia bellii, Colombia

INTRODUCTION

Ixodes tropicalis is a little-known tick species reported parasitizing wild rodents only in Colombia and Perú.

OBJECTIVE

To report a case of I. tropicalis infesting a human in the south of the metropolitan area of the Valle de Aburrá, Antioquia, Colombia, and to report the molecular detection of Rickettsia bellii in this species.

MATERIALS AND METHODS

The tick was identified using a morphological key and sequencing of tick mitochondrial 16S rRNA. Additionally, bacterial and protozoa pathogens were evaluated using PCR for the detection of Rickettsia spp., family Anaplasmataceae, Borrelia spp., and piroplasmid.

RESULTS

We identified the tick as an I. tropicalis female according to Kohls, 1956, description and to partial 16S rRNA sequences showing a minimum of 5% divergencies compared to Ixodes sequences. We also detected the gltA gene of R. bellii in the tick with 99.87% of identity.

CONCLUSION

This is the first report in Colombia of a species of the Ixodes genus parasitizing a human and the first report of the detection of R. bellii in this tick species.

Frequency and factors associated of potential zoonotic pathogens (Borrelia spp., Rickettsia spp., Leishmania spp., and Anaplasma phagocytophilum) in equids in the state of Bahia, Brazil

BACKGROUND

Currently, various zoonotic diseases are classified as emerging or reemerging. Because equids have a direct relationship with various vectors, they are possibly more frequently exposed to zoonotic agents than are humans. The undeniable importance of diseases such as human granulocytic anaplasmosis, spotted fever, and leishmaniasis for both public and animal health, as well as the possibility of equids acting as sources, reservoirs, or even sentinels for these pathogens, justifies the detection of their frequency and factors associated with infection in equids from northeastern Brazil.

METHODS

Blood samples were collected from 569 equids (528 horses, 33 donkeys, and 8 mules), 516 from a rural area and 53 from an urban area. Pathogen detection was carried out as follows: Borrelia spp. and Rickettsia spp., serological analysis; Leishmania spp., serological analysis and polymerase chain reaction (PCR); Anaplasma phagocytophilum, PCR. Determination of associated factors was carried out through generalized linear models.

RESULTS

The frequencies of positivity for the pathogens observed in equids were as follows: Borrelia spp., 13.9% (79/569); Leishmania spp., 3.5% (20/569); Rickettsia spp. 33.4% (190/569). Regarding factors associated with infection, male sex was associated with protection against Borrelia spp.; donkeys and mules were associated with protection against Rickettsia spp., while a younger age was a risk factor. The infection of A. phagocytophilum was not detected in the sampled population. Co-infection was detected in 5.1% (29/569) of the animals.

CONCLUSIONS

Most of the studied pathogenic agents are present in the prospected area, indicating a possible risk for both human and animal health. This demonstrates that equids can be considered important sentinels in the assessment of pathogens with zoonotic potential in the region.

Diversity of ticks and detection of Rickettsia amblyommatis infecting ticks on wild birds in anthropogenic landscapes in Bahia state, northeast Brazil

Birds are important hosts in the maintenance and spread of ticks worldwide, including several species of Amblyomma which harbor rickettsial agents as members of the spotted fever group (SFG). The current survey shows the diversity of tick and rickettsial agents infecting ticks on wild birds from an Atlantic rainforest in the state of Bahia, Brazil. A total of 365 birds were captured, representing two orders, 22 families and 51 species, among which 68 specimens (18.6%) were parasitized. Overall, 132 immature ticks (81 larvae and 51 nymphs) were identified to species level, representing six recognized species of the genus Amblyomma: Amblyomma longirostre (n = 45), Amblyomma nodosum (n = 40), Amblyomma varium (n = 5), Amblyomma parkeri (n = 2), Amblyomma coelebs (n = 3) and Amblyomma calcaratum (n = 1). Amplification by PCR and sequencing of rickettsial genes (gltA and ompA), detected the presence of Rickettsia DNA in 12 (9.1%) of the ticks. Rickettsia amblyommatis was the only agent detected in nine larvae and two nymphs of A. longirostre and one nymph of A. varium with 99-100% similarity.

Rickettsia amblyommatis isolated from Amblyomma mixtum (Acari: Ixodida) from two sites in Panama

Rickettsia amblyommatis is widely distributed in the Americas, and has been reported to infect different species of ticks within its distribution. In Panama, R. amblyommatis is the most common Rickettsia and its presence was molecularly detected in nine species of ticks and one flea species. This work described the isolation of R. amblyommatis in Vero cells by shell vial technique, from Amblyomma mixtum ticks collected from a captive tapir from Gamboa (Colon province), and a horse from El Valle de Antón (Cocle province). These represent the first isolations of R. amblyommatis in Panama.

Characterization of the complete mitochondrial genome of Amblyomma ovale, comparative analyses and phylogenetic considerations

In this study, we sequenced two complete mitochondrial genomes of Amblyomma ovale, a tick of public health importance. Sequencing two distinct individuals, the resulting mitochondrial genomes were 14,756 and 14,760 bp in length and maintained the same gene order previously reported in Amblyomma. These were combined with RNA-seq derived mitochondrial sequences from three additional species, Amblyomma aureolatum, Amblyomma maculatum, and Amblyomma moreliae, to carry out mitogenome comparative and evolutionary analyses against all previously published tick mitochondrial genomes. We described a derivative genome rearrangement that isolates Ixodes from the remaining Ixodidae and consists of both a reverse translocation as well as an event of Tandem Duplication Random Loss. Genetic distance analyses indicated that cox2, nd1, nd5, and 16S are good candidates for future population studies in A. ovale. The phylogenetic analyses corroborated the utility of complete mitochondrial genomes as phylogenetic markers within the group. This study further supplements the genome information available for Amblyomma and facilitates future evolutionary and population genetic studies within the genus.

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.

Ticks and Associated Pathogens From Rescued Wild Animals in Rainforest Fragments of Northeastern Brazil

The Ixodidae family comprises ticks that are hematophagous ectoparasites and are considered vectors of several hemoparasites from the Anaplasmataceae family and the genus Hepatozoon, Babesia, and Rickettsia. These ectoparasites parasitize domestic and wild animals belonging to several vertebrate groups. Ticks are highly adapted to different biomes and thus possess a wide geographical distribution. In the Brazilian state of Bahia, localized in the Northeast region, there are large rainforest fragments. Studies have rarely been carried out on ticks, and their hemoparasites, that parasitize wild animals in this region. Thus, this study aimed to identify the tick species parasitizing wild animals rescued in rainforest fragments of Bahia and investigate the presence of hemoparasites in tick tissues. During a 2-year period, 238 ticks were collected from 41 wild mammalians, reptiles, and amphibians. These ectoparasites were taxonomically classified according to their morphological characteristics. The ticks identified belonged to five different species from the Ixodidae family: Amblyomma varium, Amblyomma rotundatum, Amblyomma nodosum, Ixodes loricatus, and Rhipicephalus sanguineus. For the first time, an A. rotundatum parasitizing the Mesoclemmys tuberculata turtle was described. PCR assays using DNA extracted from salivary glands or midgut of the ticks were performed to detect specific DNA fragments of hemoparasites from the genus Rickettsia, Ehrlichia, Babesia, Hepatozoon, and from the Anaplasmataceae family. The results showed positive detection of the Rickettsia genus (7.9%), Anaplasmataceae family (15.8%), and Hepatozoon genus (15.8%). Specific DNA from the Ehrlichia and Babesia genera were not detected in these samples. Specific DNA from members of the Anaplasmataceae family was detected in A. varium for the first time. The present work showed that amphibians, reptiles, and mammals from Bahia's Atlantic Forest areparasitized by different tick species, and that these ectoparasites present pathogens in their tissues that impact both humans and animals due to their zoonotic potential.

Novel Rickettsia genotypes in ticks in French Guiana, South America

Rickettsia are obligate intracellular bacteria often associated with ticks and best known for causing human diseases (rickettsiosis), including typhus fever and sporadic cases of serious infection. In this study, we conducted a large survey of ticks in French Guiana to understand the overall diversity of Rickettsia in this remote area largely covered by dense rainforests. Out of 819 individuals (22 tick species in six genera), 252 (30.8%) samples were positive for Rickettsia infection. Multilocus typing and phylogenetic analysis identified 19 Rickettsia genotypes, but none was 100% identical to already known Rickettsia species or strains. Among these 19 genotypes, we identified two validated Rickettsia species, Rickettsia amblyommatis (spotted fever group) and Rickettsia bellii (bellii group), and characterized a novel and divergent Rickettsia phylogenetic group, the guiana group. While some tick hosts of these Rickettsia genotypes are among the most common ticks to bite humans in French Guiana, their potential pathogenicity remains entirely unknown. However, we found a strong association between Rickettsia genotypes and their host tick species, suggesting that most of these Rickettsia genotypes may be nonpathogenic forms maintained through transovarial transmission.

Tick-borne pathogens in ticks collected from dogs, Latvia, 2011-2016

BACKGROUND

Different tick species are able to transmit different pathogens, and tick-borne diseases are of substantial concern worldwide for both humans and animals. Environmental changes and changes in the range of tick species, including Dermacentor reticulatus in Europe, can affect the spread of zoonotic pathogens. The aim of this study was to investigate the prevalence of the tick-borne pathogens in ticks removed from dogs in Latvia, and to explore possible changes between years 2011 and 2016.

RESULTS

In 2011, only Ixodes ticks (221 Ixodes ricinus and 22 Ixodes persulcatus) were collected from dogs, while in 2016 tick samples belonged to Ixodes ricinus (360), Ixodes persulcatus (2) and Dermacentor reticulatus (27) species. In total, 35.8 and 40.0% of adult ticks were pathogen-positive in 2011 and 2016, respectively; the difference was not statistically significant (P > 0.05). The molecular analysis indicated the presence of 13 tick-borne microorganisms; the most prevalent pathogen was Rickettsia, followed by Borrelia burgdorferi sensu lato group spirochetes, Anaplasma phagocytophilum and Babesia species. Borrelia miyamotoi was also present. A co-infection with two and three tick-borne pathogens was detected in 7.9 and 7.4% of Ixodes ricinus and Dermacentor reticulatus, respectively. The results of this study confirmed that the spread of novel vectors could bring additional risk of exposure to novel emerging pathogens to pets and their owners, as both Babesia canis and Rickettsia raoultii were shown to be highly associated with Dermacentor reticulatus ticks in Latvia.

CONCLUSIONS

This study demonstrates the potential danger from the inadvertent introduction of novel disease pathogens and vectors. Awareness of co-infections and Dermacentor reticulatus-related pathogens needs to be increased.

Two for the price of one: Co-infection with Rickettsia bellii and spotted fever group Rickettsia in Amblyomma (Acari: Ixodidae) ticks recovered from wild birds in Brazil

The bacterium Rickettsia bellii has been detected in 25 species of ticks in the American continents, but its pathogenic potential is considered as undetermined. A possible role for this species in the phenomenon of transovarial exclusion of pathogenic members of the spotted fever group (SFG) of Rickettsia has been suggested and co-infections with pathogenic species have been reported infrequently in both North and South America. Traditional methods for the molecular detection of rickettsial agents in ticks focus largely on the identification of sequences found in SFG Rickettsia, an approach that may overlook the presence of co-infections with R. bellii. Two novel, species-specific polymerase chain reaction (PCR) assays, targeting the genes encoding the surface cell antigen (Sca), autotransporter proteins sca9 and sca14, were developed and validated for the detection of R. bellii using 150 Amblyomma ticks collected from wild birds in Brazil. Co-infection of R. bellii infected ticks was evaluated using a novel PCR assay targeting the ompA sequence characteristic of SFG Rickettsia. Preliminary species-level identification was achieved by restriction fragment length polymorphism (RFLP) analysis and subsequently confirmed by sequencing of amplicons. Nine out of seventy-three Amblyomma longirostre and one of two Amblyomma calcaratum ticks were shown to be co-infected with R. bellii and Rickettsia amblyommatis, while two out of sixty-seven Amblyomma sp. haplotype Nazaré ticks were recorded as co-infected with R. bellii and the Rickettsia parkeri-like bacterium, strain ApPR. Interestingly, our data represent the first records of R. bellii in association with A. calcaratum and Amblyomma sp. haplotype Nazaré. The novel PCR-RFLP systems reported herein, provide an alternative, rapid and cost-efficient (relative to strategies based on sequencing or real-time PCR), approach to evaluate rickettsial co-infection of ticks, a potentially significant phenomenon that has most likely been underestimated to date.

Diversity of Rickettsia species in border regions of northwestern China

Background

Rickettsia species belonging to the spotted fever group (SFG) cause infections in humans, domestic animals and wildlife. At least ten SFG Rickettsia species are known to occur in China. However, the distribution of rickettsiae in ticks and fleas in the border region of northwestern China have not been systematically studied to date.

Results

A total of 982 ticks (Rhipicephalus turanicus, Dermacentor marginatus, D. nuttalli and Haemaphysalis punctata) and 5052 fleas (18 flea species from 14 species of wild mammals) were collected in ten and five counties, respectively, of Xinjiang Uygur Autonomous Region (northwestern China). Tick and flea species were identified according to morphological and molecular characteristics. Seven sets of primers for amplifying the 17-kDa antigen gene (17-kDa), citrate synthase gene (gltA), 16S rRNA gene (rrs), outer membrane protein A and B genes (ompA, ompB), surface cell antigen 1 gene (sca1) and PS120-protein encoding gene (gene D) were used to identify the species of rickettsiae. Nine Rickettsia species have been detected, seven of them in ticks: R. aeschlimannii, R. conorii, R. raoultii, Rickettsia sibirica, R. slovaca, R. massiliae and “Candidatus R. barbariae”. In addition, R. bellii and two genotypes of a rickettsia endosymbiont (phylogenetically in an ancestral position to R. bellii) have been detected from flea pools.

Conclusions

This study provides molecular evidence for the occurrence of several SFG rickettsiae in Rhipicephalus turanicus, Dermacentor nuttalli and D. marginatus. Furthermore, R. bellii and two ancestral rickettsia endosymbionts are present in fleas infesting wild rodents in the border regions of northwestern China. These data extend our knowledge on the diversity of rickettsiae in Central Asia.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3233-6) contains supplementary material, which is available to authorized users.

Detection of Rickettsia spp. in ticks associated to wild mammals in Northeastern Brazil, with notes on an undetermined Ornithodoros sp. collected from marsupials

We report tick infestations and rickettsial detection in ticks infesting free-living wild mammals (Monodelphis domestica, Tolypeutes tricinctus, Thrichomys inermis and Kerodon rupestris) captured in the Caatinga ecoregion of Bahia state, northeastern Brazil, during September to December 2016. Overall, 117 ticks (61 larvae, 25 nymphs, 25 males, 6 females) belonging to two genera, and at least three species were collected: Amblyomma auricularium, Amblyomma parvum, Amblyomma sp., Ornithodoros rietcorreai and an unidentified Ornithodoros sp. We provide new host records to the rodent T. inermis parasitized by larva and nymphs of A. auricularium and to the marsupial M. domestica infested by larvae of A. auricularium. Furthermore, we describe new tick-host association for larvae of O. rietcorreai on the rodents K. rupestris and T. inermis. Concerning tick-Rickettsia associations, we detected Rickettsia amblyommatis and an uncharacterized species of Rickettsia belonging to the spotted fever group (SFG) in both A. auricularium and A. parvum. Additionally, 'Candidatus Rickettsia andeanae' was detected in A. parvum as well.

Diversity of rickettsiae and potential vectors of spotted fever in an area of epidemiological interest in the Cerrado biome, midwestern Brazil

The Brazilian state of Goiás, untouched by spotted fever (SF) until 2012, has subsequently reported cases of the disease in several regions. This study aimed to survey the diversity of potential vectors and rickettsia in areas of Goiás under environmental surveillance or case investigation for SF. Collected specimens were assayed with molecular biology technology using DNA extraction, amplification and sequencing of fragments of the genes gltA, ompA, ompB and sca4 to detect rickettsia in ticks and fleas. Amplification of cytochrome oxidase subunit II and 16S rRNA was performed to assist tick identification. Rickettsia felis (Rickettsiales: Rickettsiaceae) was found in Ctenocephalides felis (Bouché, 1835) (Siphonaptera: Pulicidae). Rickettsia bellii was found in Amblyomma rotundatum Koch, 1844 (Ixodida: Ixodidae) and in Amblyomma cajennense sensu lato. Rickettsia sp. strain NOD was found in Amblyomma nodosum Neumann, 1899. Of the Amblyomma cajennense complex, Amblyomma sculptum Berlese, 1888 was confirmed in the northern, northeast, midwest and southeast regions of Goiás, whereas Amblyomma cajennense sensu stricto (Fabricius, 1787) was found only in the northern region of the state. Amblyomma dubitatum Neumann, 1899 associated with a species of the A. cajennense complex was the most common epidemiological finding, although Rickettsia rickettsii was not detected. This is the first report of Rickettsia sp. strain NOD in Goiás.

Genotypic Characterization of Rickettsia bellii Reveals Distinct Lineages in the United States and South America

The bacterium Rickettsia bellii belongs to a basal group of rickettsiae that diverged prior to the pathogenic spotted fever group and typhus group Rickettsia species. Despite a diverse representation of R. bellii across more than 25 species of hard and soft ticks in the American continent, phylogeographical relationships among strains of this basal group-Rickettsia species are unknown; the work described here explores these relationships. DNA was extracted from 30 R. bellii tick isolates: 15 from the United States, 14 from Brazil, and 1 from Argentina. A total of 2,269 aligned nucleotide sites of 3 protein coding genes (gltA, atpA, and coxA) and 2 intergenic regions (rpmE-tRNA^fmet and RC1027-xthA2) were concatenated and subjected to phylogenetic analysis by Bayesian methods. Results showed a separation of almost all isolates between North and South Americas, suggesting that they have radiated within their respective continents. Phylogenetic positions of the 30 isolates could be a result of not only their geographical origin but also the tick hosts they have coevolved with. Whether R. bellii originated with ticks in North or South America remains obscure, as our analyses did not show evidence for greater genetic divergence of R. bellii in either continent.

Prevalence of different Rickettsia spp. in Ixodes ricinus and Dermacentor reticulatus ticks (Acari: Ixodidae) in north-eastern Poland

In two surveys conducted in April and May 2013, a total of 1148 unfed ticks belonging to two species, Ixodes ricinus and Dermacentor reticulatus, were collected by flagging lower vegetation in 15 different localities throughout the Białowieża Primeval Forest (Podlaskie voivodship; north-eastern Poland) and in its buffer zone. In order to establish their infection rate with Rickettsia spp. individual adult ticks and pooled nymphs were tested by real-time PCR targeting the gltA gene. For the further identification of rickettsial species, positive samples were subjected for nested and semi-nested PCR targeting ompA and 16S rRNA genes, respectively, followed by sequencing analysis. Rickettsial DNA was detected in at least 279 ticks (minimum infection rate [MIR], 23.9%), including 52 nymphal and adult I. ricinus (MIR 8.6%) and 222 adult D. reticulatus (41%). Three species of SFG rickettsiae were identified: Rickettsia helvetica and 'Candidatus R. mendelii' in I. ricinus and R. raoultii in D. reticulatus and I. ricinus. Moreover, unidentified Rickettsia spp. which showed 99.4% identity, among others, with the uncultured Rickettsia sp. isolated from Cicadella viridis leafhopper, Rickettsia endosymbiont of Lasioglossum semilucens bee and R. bellii, were detected in I. ricinus, while Rickettsia sp. 98.3-98.4% homologous to Rickettsia secondary endosymbionts of Curculio spp. weevils was found in D. reticulatus. These results confirm the diversity of rickettsiae occurring in Poland. Further studies are needed to expand the knowledge on the species spectrum, prevalence and epidemiology of SFG rickettsiae in the country.

Experimental infection of Rickettsia parkeri in the Rhipicephalus microplus tick

This study aimed to evaluate, by means of artificial feeding, the interaction between a pathogenic rickettsia and the hard tick R. microplus. We used partially engorged females fed on calves free of Rickettsia spp. Group 1 (G1), containing 20 ticks, was fed bovine blood only. Group 2 (G2), containing 20 ticks, was fed blood containing uninfected VERO cells, and group 3 (G3), containing 40 ticks, was fed blood containing VERO cells infected with Rickettsia parkeri. Biological parameters of the non-parasitic phase and a possible bacterial transmission to the tick eggs and to guinea pigs were evaluated. At the end of oviposition, all G3 females were PCR-positive for genes specific for the genus Rickettsia. Although no guinea pigs were infected, the experimental infection of R. microplus by R. parkeri caused a deleterious effect on the oviposition and provided the first report of transovarian transmission of rickettsia in this tick.

First report of Rickettsia raoultii and R. slovaca in Melophagus ovinus, the sheep ked

BACKGROUND

Melophagus ovinus (Diptera: Hippoboscidae), a hematophagous ectoparasite, is mainly found in Europe, Northwestern Africa, and Asia. This wingless fly infests sheep, rabbits, and red foxes, and causes inflammation, wool loss and skin damage. Furthermore, this parasite has been shown to transmit diseases, and plays a role as a vector. Herein, we investigated the presence of various Rickettsia species in M. ovinus.

METHODS

In this study, a total of 95 sheep keds were collected in Kuqa County and Alaer City southern region of Xinjiang Uygur Autonomous Region, northwestern China. First, collected sheep keds were identified on the species level using morphological keys and molecular methods based on a fragment of the 18S ribosomal DNA gene (18S rDNA). Thereafter, to assess the presence of rickettsial DNA in sheep keds, the DNA of individual samples was screened by PCR based on six Rickettsia-specific gene fragments originating from six genes: the 17-kilodalton antigen gene (17-kDa), 16S rRNA gene (rrs), surface cell antigen 4 gene (sca4), citrate synthase gene (gltA), and outer membrane protein A and B genes (ompA and ompB). The amplified products were confirmed by sequencing and BLAST analysis ( https://blast.ncbi.nlm.nih.gov/Blast.cgi?PROGRAM=blastn&PAGE_TYPE=BlastSearch&LINK_LOC=blasthome ).

RESULTS

According to its morphology and results of molecular analysis, the species was identified as Melophagus ovinus, with 100% identity to M. ovinus from St. Kilda, Australia (FN666411). DNA of Rickettsia spp. were found in 12 M. ovinus samples (12.63%, 12/95). Rickettsia raoultii and R. slovaca were confirmed based on phylogenetic analysis, although the genetic markers of these two rickettsial agents amplified in this study showed molecular diversity.

CONCLUSIONS

This is the first report of R. raoultii and R. slovaca DNA in M. ovinus. Rickettsia slovaca was found for the first time around the Taklimakan Desert located in China. This finding extends the geographical range of spotted fever group rickettsiae.

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.

Molecular detection of Rickettsia rhipicephali and other spotted fever group Rickettsia species in Amblyomma ticks infesting wild birds in the state of Minas Gerais, Brazil

The current study evaluated parasitism of wild birds by ticks in a fragment of Atlantic Forest in the state of Minas Gerais, Brazil, and examined the ticks for rickettsial agents. Birds were captured during 2014 and 2015 and ticks were identified by sequencing fragments of the 16S and 12S ribosomal DNA. Among 260 birds representing 19 families and 52 species, a total of 69 (26.5%) were found to be infested by larvae (LL) and/or nymphs (NN) of Amblyomma longirostre (Koch, 1844) (45 LL, 4 NN), Amblyomma calcaratum Neumann, 1899 (9 LL, 15 NN), Amblyomma nodosum Neumann, 1899 (2 NN), Amblyomma parkeri Fonseca and Aragão, 1952 (21 LL), Amblyomma sp. haplotype Nazaré (77 LL), and Haemaphysalis leporispalustris (Packard, 1869) (17 LL, 1 NN). The use of PCR and sequencing of the rickettsial genes gltA, htrA, ompA and ompB, revealed the presence of "Candidatus Rickettsia amblyommii" in A. longirostre (13/49; 26%) and Rickettsia parkeri (strain ApPR) in both A. parkeri (1/21; 5%) and haplotype Nazaré (42/77; 55%) ticks. In addition, we detected Rickettsia rhipicephali in 31 (40%) of the 77 haplotype Nazaré ticks. This is the first record of this rickettsial agent in a species of the genus Amblyomma. The pathogenic potential of this bacterium is undetermined, but the unprecedented association with Amblyomma ticks may represent a cause for concern for public and/or animal health.

First report of "Candidatus Rickettsia amblyommii" in west coast of Mexico

We report the first case of "Candidatus Rickettsia amblyommii" detected in Amblyomma mixtum ticks on humans on the west coast of Mexico. This is the most western record of "Ca. R. amblyommii" in the Western Hemisphere, representing the first record for the western coast of the Americas. Even if the record is far from the previously known locations for the species it does not represent a new record regarding temperature, precipitation and topographic parameters. Since "Ca. R. amblyommii" antibodies have been detected in patients suspected of Rocky Mountain spotted fever, and the tick A. mixtum has been associated with humans, it is important to consider "Ca. R. amblyommii" as a potential risk for the human population that has not been considered at risk before.