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Ticks and Tick-borne Diseases Jul 2023Ticks are vectors for several pathogens, including bacteria belonging to the Rickettsia genus, such as Rickettsia rickettsii and Rickettsia parkeri, the causative agents...
Ticks are vectors for several pathogens, including bacteria belonging to the Rickettsia genus, such as Rickettsia rickettsii and Rickettsia parkeri, the causative agents of spotted fever. The aim of the present study was to investigate the tick species richness and rickettsial agents associated with wild birds captured in the Humaita Forest Reserve, Acre, in the Western Amazon region. Wild birds were captured with ornithological nets for visual inspection with the purpose of collecting ticks, which were identified through morphological analyses and molecular tests for several genes (12S rDNA, 16S rDNA, gltA, ompA, and sca4). A total of 607 wild birds were captured, 12% of which were parasitized by 268 ticks of the Amblyomma genus, with new host-parasite associations reported for Amblyomma calcaratum, Amblyomma geayi, Amblyomma longirostre, Amblyomma naponense, Amblyomma nodosum, and Amblyomma varium. Of the total ticks collected, 113 were tested for the presence of rickettsial DNA fragments, with 19 testing positive for R. parkeri in A. geayi, Rickettsia tamurae-like in Amblyomma sp., and Rickettsia amblyommatis in A. geayi, A. longirostre, and Amblyomma sp. We detected R. tamurae-like in Amblyomma larvae for the first time in the Western Brazilian Amazon biome, and registered spotted fever group rickettsiae, although the relevance of the detected species in a public health context should be further explored in South America, as well as new host-parasite interactions in this underexplored region.
Topics: Animals; Ticks; Ixodidae; Brazil; Tick Infestations; Rickettsia; Animals, Wild; Spotted Fever Group Rickettsiosis; Amblyomma; Birds; DNA, Ribosomal
PubMed: 37100028
DOI: 10.1016/j.ttbdis.2023.102182 -
Acta Tropica Jun 2023Neglected bacterial zoonoses are a group of Neglected Tropical Diseases (NTDs) that are commonly underdiagnosed and underreported due to their undifferentiated febrile...
Neglected bacterial zoonoses are a group of Neglected Tropical Diseases (NTDs) that are commonly underdiagnosed and underreported due to their undifferentiated febrile illness symptomology. Spotted fever group rickettsioses (SFGR), a subset of tick-borne bacterial zoonoses, belong in this group. There is a dichotomy in the reporting and recognition of these pathogens in Central America: countries with reduced human development scores-like El Salvador-have little to no research or surveillance dedicated to these pathogens and the diseases they cause. This was the third-ever tick survey in El Salvador, highlighting the knowledge gap in this country. A total of 253 ticks were collected from 11 animals at two farm sites and one veterinary office. Standard and quantitative PCR were used to detect presence of SFGR, Ehrlichia, and Anaplasma sp. pathogens in ticks. Ehrlichia sp. were detected in 2.4% of all collected ticks and Anaplasma sp. were detected in 5.5% of all ticks. Rickettsia rickettsii was amplified in 18.2% of ticks, and amplicons similar to R. parkeri, and R. felis were found in 0.8% and 0.4%, of collected ticks, respectively. This is the first report of these pathogenic bacterial species in El Salvador. This study emphasizes the need for further surveillance and research including incorporating additional human seroprevalence and testing to understand the public health burden in this country.
Topics: Animals; Humans; Rickettsia; Ehrlichia; Ticks; Anaplasma; Bacterial Zoonoses; El Salvador; Seroepidemiologic Studies; Tick-Borne Diseases
PubMed: 37030489
DOI: 10.1016/j.actatropica.2023.106909 -
Journal of Medical Entomology May 2023Ticks and tick-borne diseases are increasing in the United States, including New Hampshire (NH). We report on the findings of an ongoing free crowdsourcing program...
Ticks and tick-borne diseases are increasing in the United States, including New Hampshire (NH). We report on the findings of an ongoing free crowdsourcing program spanning four years within NH. The date of tick's submission was recorded along with species, sex, stage, location they were collected (translated into latitude and longitude), the activity the individual was doing when the tick was found, and host species. A total of 14,252 ticks belonging to subclass Acari, family Ixodidae and genera Ixodes, Dermacentor, Amblyomma, and Haemaphysalis was recorded from the period 2018-2021 throughout NH. A total of 2,787 Ixodes scapularis and 1,041 Dermacentor variabilis, were tested for the presence of Borrelia sp. (Spirochaetales: Spirochaetaceae), B. burgdorferi sensu lato, B. miyamotoi, B. mayonii, Babesia microti (Piroplasmida: Babesiidae), Anaplasma phagocytophilum (Rickettsiales: Anaplasmataceae), Francisella tularensis (Thiotrichales: Francisellaceae), and Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) by PCR. For the I. scapularis ticks tested, the pathogen prevalence was 37% B. burgdorferi s.l. 1% B. miyamotoi, 6% A. phagocytophilum, and 5% Ba. microti. Only one D. variabilis resulted positive to F. tularensis. We created state-wide maps informing the differences of ticks as detailed by administrative divisions. Dermacentor variabilis peaked in June and I. scapularis peaked in May and October. The most reported activity by people with tick encounters was while walking/hiking, and the least was biking. Using the reported distribution of both species of ticks, we modeled their climate suitability in the target territory. In NH, I. scapularis and D. variabilis have distinct patterns of emergence, abundance, and distribution. Tick prevention is important especially during April-August when both tick species are abundant and active.
Topics: Animals; New Hampshire; Ixodes; Ixodidae; Borrelia; Borrelia burgdorferi
PubMed: 37030013
DOI: 10.1093/jme/tjad030 -
Veterinary Parasitology May 2023As the main vector for the bacterium Rickettsia rickettsii in Brazil, the tick Amblyomma sculptum is a parasite of great public health importance in this country....
As the main vector for the bacterium Rickettsia rickettsii in Brazil, the tick Amblyomma sculptum is a parasite of great public health importance in this country. Wolbachia is an endosymbiont bacterium highly widespread among invertebrates and because of its impact on its hosts' biology, form a powerful alternative for pests and disease control. The aim of this study was to investigate the occurrence of this bacterium in A. sculptum. For this, 187 adult ticks collected in two municipalities in the interior of the state of São Paulo, Brazil, were analyzed using molecular techniques and bioinformatics tools. A total of 15 ticks were positive for the presence of Wolbachia. Phylogenetic analysis on the 16S rRNA gene indicated that the Wolbachia DNA sequences obtained in this investigation belonged to different clades, probably in supergroups B and F. This was the first study to report the occurrence of Wolbachia in A. sculptum and it enriches knowledge about the susceptibility of ticks to this bacterium. Now that we know that Wolbachia can be found in A. sculptum, the objective for a next study must be to investigate Wolbachia's possible origin in this tick.
Topics: Animals; Ixodidae; Rocky Mountain Spotted Fever; Amblyomma; Wolbachia; Phylogeny; RNA, Ribosomal, 16S; Brazil; Ticks; Rickettsia
PubMed: 37001324
DOI: 10.1016/j.vetpar.2023.109907 -
Ticks and Tick-borne Diseases Jul 2023Amblyomma is an important tick genus for animal and human health, with some species being the vectors of zoonotic pathogens, such as Rickettsia rickettsii, in the...
Amblyomma is an important tick genus for animal and human health, with some species being the vectors of zoonotic pathogens, such as Rickettsia rickettsii, in the Neotropical region. Knowing their hosts may help to understand the distribution of these agents and decrease the occurrence of clinical cases. Primates are intelligent and adaptable animals that can get close to humans in the search for food. So, they may be an important epidemiological link for the spread of these ticks. Beyond that, primates also suffer from these infections, serving as sentinels for different diseases. Thus, the present study aims to report the parasitism by Amblyomma spp. on six species of Neotropical primates from different locations in Brazil. The 337 collected ticks were morphologically identified using stereomicroscopes and taxonomic keys, and six distinct species of ticks were identified. We report here the first record of nymphs of the tick species Amblyomma cajennense sensu stricto on Alouatta belzebul, a male of Amblyomma fuscum on Alouatta guariba clamitans, nymphs of Amblyomma sculptum on Leontopithecus chrysopygus and Callithrix aurita, as well as nymphs of Amblyomma geayi on Saimiri collinsi. Of the 337 tick specimens collected, 256 (75,96%) were nymphs. The importance of primates in the life cycle of these species remains to be elucidated.
Topics: Animals; Male; Humans; Ticks; Amblyomma; Ixodidae; Brazil; Primates; Rickettsia
PubMed: 36966542
DOI: 10.1016/j.ttbdis.2023.102169 -
Scientific Reports Mar 2023Rocky Mountain spotted fever (RMSF) is a rapidly progressive and often fatal tick-borne disease caused by Rickettsia rickettsii. Its discovery and characterization by...
Rocky Mountain spotted fever (RMSF) is a rapidly progressive and often fatal tick-borne disease caused by Rickettsia rickettsii. Its discovery and characterization by Howard Ricketts has been hailed as a remarkable historical example of detection and control of an emerging infectious disease, and subsequently led to the establishment of the Rocky Mountain Laboratories (RML). Here, we examined an unopened bottle of a vaccine, labeled as containing RMSF inactivated by phenol-formalin of infected ticks, developed prior to 1944 at RML by DNA analysis using Illumina high throughput sequencing technology. We found that it contains DNA from the Rocky Mountain wood tick (Dermacentor andersoni), the vector of RMSF, the complete genome of Rickettsia rickettsii, the pathogen of RMSF, as well as the complete genome of Coxiella burnetii, the pathogen of Q-fever. In addition to genomic reads of Rickettsia rickettsii and Coxiella burnetii, smaller percentages of the reads are from Rickettsia rhipicephali and Arsenophonus nasoniae, suggesting that the infected ticks used to prepare the vaccine carried more than one pathogen. Together, these findings suggest that this early vaccine was likely a bivalent vaccine for RMSF and Q-fever. This study is the among the first molecular level examinations of an historically important vaccine.
Topics: Animals; Rocky Mountain Spotted Fever; Rickettsia rickettsii; Ticks; Coxiella burnetii; Vaccines
PubMed: 36949107
DOI: 10.1038/s41598-023-31894-0 -
Parasites & Vectors Mar 2023The tick Amblyomma sculptum is the major vector of Rickettsia rickettsii, the causative agent of the highly lethal Brazilian spotted fever. It has been shown that R....
BACKGROUND
The tick Amblyomma sculptum is the major vector of Rickettsia rickettsii, the causative agent of the highly lethal Brazilian spotted fever. It has been shown that R. rickettsii inhibits apoptosis in both human endothelial cells and tick cells. Apoptosis is regulated by different factors, among which inhibitors of apoptosis proteins (IAPs) play a central role. In the study reported here, we selected an IAP of A. sculptum that has not yet been characterized to assess its role in cell death and to determine the effects of its gene silencing on tick fitness and R. rickettsii infection.
METHODS
An A. sculptum cell line (IBU/ASE-16) was treated with specific double-stranded RNA (dsRNA) for either IAP (dsIAP) or green fluorescent protein (dsGFP; as a control). The activity of caspase-3 and the exposure of phosphatidylserine were determined in both groups. In addition, unfed adult ticks, infected or not infected with R. rickettsii, were treated with either dsIAP or dsGFP and allowed to feed on noninfected rabbits. In parallel, noninfected ticks were allowed to feed on an R. rickettsii-infected rabbit. Ticks (infected or not with R. rickettsii) that remained unfed were used as a control.
RESULTS
Caspase-3 activity and the externalization of phosphatidylserine were significantly higher in IBU/ASE-16 cells treated with dsIAP than in those treated with dsGFP. The mortality rates of ticks in the dsIAP group were much higher than those in the dsGFP group when they were allowed to feed on rabbits, independent of the presence of R. rickettsii. Conversely, lower mortality rates were recorded in unfed ticks.
CONCLUSIONS
Our results show that IAP negatively regulates apoptosis in A. sculptum cells. Moreover, IAP-silenced ticks experienced higher mortality rates following the acquisition of a blood meal, suggesting that feeding may trigger the activation of apoptosis in the absence of this physiological regulator. These findings indicate that IAP is a potential antigen for an anti-tick vaccine.
Topics: Animals; Humans; Rabbits; Ticks; Amblyomma; Caspase 3; Ixodidae; Inhibitor of Apoptosis Proteins; Endothelial Cells; Phosphatidylserines; Rickettsia rickettsii; Rocky Mountain Spotted Fever; Brazil
PubMed: 36899435
DOI: 10.1186/s13071-023-05701-8 -
Microorganisms Jan 2023The Soprano pipistrelle bat, , is a common species in large parts of Sweden. Many of its natural habitats are near human habitations. This creates opportunities for...
The Soprano pipistrelle bat, , is a common species in large parts of Sweden. Many of its natural habitats are near human habitations. This creates opportunities for ticks infesting these bats to encounter humans and possibly transmit zoonotic pathogens by tick bites. The bats are often infested with , a tick species that, in addition to bats, has been recorded to bite humans on occasion. This study aimed to investigate if acts as a reservoir for , , Tick-borne encephalitis virus, and species of and and to improve currently used conventional PCR protocols for molecular species determination of spp. Ninety-two ticks were collected from underneath a bat-box harbouring . Pathogen-specific PCR assays showed that 58.4% were positive for spp. and negative for the other pathogens analysed. Phylogenetic analyses indicate that the species belong to , , , subsp. , , and a hitherto uncultured sp. Several of these species are considered pathogenic to humans. Given the ecology and behaviour of , it may be a vector of these rickettsiae among bats and occasionally humans. To determine the species with certainty, and to determine if may be a reservoir and vector of the spp., further studies are needed.
PubMed: 36838322
DOI: 10.3390/microorganisms11020357 -
Experimental & Applied Acarology Feb 2023Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever, which is an important tick-borne zoonosis and, in Brazil, it causes Brazilian spotted...
Evaluation of a mimotope of the Rickettsia outer membrane protein A (OmpA) as an antigen in enzyme-linked immunosorbent assay to detect rickettsiosis in capybaras (Hydrochoerus hydrochaeris), horses (Equus caballus), and opossums (Didelphis sp.).
Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever, which is an important tick-borne zoonosis and, in Brazil, it causes Brazilian spotted fever, which has high lethality rate. This study aimed to evaluate a synthetic peptide corresponding to a segment of the outer membrane protein A (OmpA) as an antigen in a serological test for the diagnosis of rickettsial infections. The amino acid sequence of the peptide was selected by predicting B cell epitopes using B Cell Epitope Prediction (Immune Epitope Database and Analysis Resource) and Epitopia and OmpA sequences of Rickettsia rickettsii strain 'Brazil' and Rickettsia parkeri strains 'Maculatum 20' and 'Portsmouth'. A peptide with amino acid sequence common to both Rickettsia species was synthesized and arbitrarily named OmpA-pLMC. To evaluate this peptide in enzyme-linked immunosorbent assay (ELISA), serum samples of capybara (Hydrochoerus hydrochaeris), horse (Equus caballus), and opossum (Didelphis albiventris) that had been previously tested by indirect immunofluorescence assay (IFA) for rickettsial infection were separated into IFA-positive and IFA-negative groups and used in the assay. There were no significant differences in ELISA optical density (OD) values between IFA-positive and IFA-negative groups with horse samples. The mean OD values were significantly higher in the IFA-positive capybara serum samples (IFA-pos vs. IFA-neg = 2.389 ± 0.761 vs. 1.760 ± 0.840). However, receiver operating characteristic (ROC) curve analysis did not show significant diagnostic parameters. On the other hand, 12 out of 14 (85.7%) opossum samples of the IFA-positive group showed reactivity in ELISA, and this was significantly higher than of the IFA-negative group (0.7196 ± 0.440 vs. 0.2318 ± 0.098, respectively; 85.7% sensitivity, 100% specificity). Therefore, our results show that OmpA-pLMC has a potential to be used in immunodiagnostic assays to detect spotted fever group rickettsial infections.
Topics: Horses; Animals; Rodentia; Didelphis; Rickettsia; Rickettsia Infections; Rocky Mountain Spotted Fever; Rickettsia rickettsii; Enzyme-Linked Immunosorbent Assay; Horse Diseases; Rodent Diseases
PubMed: 36795267
DOI: 10.1007/s10493-023-00776-5 -
Ticks and Tick-borne Diseases Mar 2023Two well characterized tick-borne rickettsioses occur in Brazil. Rickettsia rickettsii caused spotted-fever, transmitted by Amblyomma sculptum and Amblyomma aureolatum,... (Review)
Review
Two well characterized tick-borne rickettsioses occur in Brazil. Rickettsia rickettsii caused spotted-fever, transmitted by Amblyomma sculptum and Amblyomma aureolatum, is a severe disease with a high case-fatality rate in the southeastern region of the country. Rickettsia parkeri strain Atlantic rainforest infections transmitted by adult Amblyomma ovale ticks cause a milder non-lethal febrile disease with an eschar (necrosis) at the tick bite site. Clinical diagnosis of rickettsiosis is challenging, particularly during the early stages of the illness when signs and symptoms are non-specific. Since eschar at the tick bite site has emerged as the main clinical feature of mild R. parkeri infections and used to differentiate it from severe R. rickettsii infection, its proper recognition, distinction from other tick bite lesions, and boundaries as a clinical tool must be highlighted. Of importance, eschars induced by Rickettsia must be differentiated from dermatoses caused by other tick-borne skin infections as well from lesions caused by the tick bite itself. We herein highlight information on eschar in rickettsial diseases in Brazil and discuss the need for further research on its clinical relevance and application in the diagnosis of spotted fever caused by R. parkeri strain Atlantic rainforest. In particular, we draw attention to diagnosis of other febrile diseases in the presence of concomitant tick bites.
Topics: Animals; Adult; Humans; Tick Bites; Brazil; Ixodidae; Rickettsia; Rickettsia Infections; Spotted Fever Group Rickettsiosis; Amblyomma; Tick-Borne Diseases; Skin Diseases
PubMed: 36693294
DOI: 10.1016/j.ttbdis.2023.102127