Search Results (10)

This study sought to investigate the presence of anti-Rickettsia spp. antibodies in georeferenced serum samples from equids across all regions of the state of Goiás, while also presenting variables that indicate risk factors for the circulation of rickettsiae, and evaluating the presence of rickettsial DNA in ticks collected from equids and the surrounding environment in the municipalities of Uruaçu and Porangatu, located in the northern region of the state. A total of 1156 equid serum samples provided by the Goiás Agricultural Defense Agency (Agrodefesa) were analyzed for antibodies against 4 Rickettsia antigens. Additionally, 39 blood samples were collected from equids during a 3-day field expedition in January 2024, alongside 938 ticks collected from both animals and the environment. In total, 297 adult ticks were randomly selected for molecular analysis and tested by qPCR targeting the rickettsial gltA gene. Positive samples were further analyzed using cPCR to target the ompA and gltA genes. Results revealed that 9.6% (111/1156) of the serum samples were seroreactive to at least one Rickettsia antigen. Among these, 36% had antibodies against Rickettsia rickettsii, 18.9% against Rickettsia parkeri, 69.4% against Rickettsia amblyommatis, and 14.4% against Rickettsia bellii. Furthermore, the possible antigen responsible for a homologous reaction was found in 3.6% of equids for R. rickettsii, and in the same proportion for R. bellii, while 23.4% of animals showed antibodies for R. amblyommatis, and none exhibited a homologous reaction to R. parkeri. Meanwhile, 28.2% of the serum samples collected during the field expedition had antibodies against R. amblyommatis, with 72.7% identifying R. amblyommatis as the antigen involved in the homologous reaction. In the logistic regression analysis, the variables of education level, altitude below 500 m, and presence of female mules demonstrated a positive effect on seropositivity. Ticks from animals were identified as Amblyomma cajennense sensu lato, Amblyomma sculptum, Dermacentor nitens, and Rhipicephalus microplus, while environmental ticks were identified as A. cajennense s.l., A. sculptum, and Amblyomma nodosum. In the qPCR assays, two specimens of A. cajennense s.l., one of A. sculptum, and one of D. nitens amplified a fragment of the gltA gene. Of these, one A. cajennense s.l. specimen amplified a fragment of both the ompA and gltA genes, and one A. sculptum specimen amplified a fragment of the gltA gene through conventional PCR. Sequencing confirmed the detection of R. amblyommatis. These findings highlight the presence of anti-Rickettsia spp. antibodies in equid serum samples from all regions of the state of Goiás, emphasizing the important role of equids as sentinels for Rickettsia spp. To our knowledge, this study represents the largest effort to detect anti-Rickettsia spp. antibodies in equid serum samples in Brazil. Additionally, it is the first nationwide investigation of its kind conducted in collaboration with the Agricultural Defense Agency (Agrodefesa), serving as a significant example of the One Health approach. Full article

Wild boars (Sus scrofa L.) are considered among the most harmful invasive species worldwide, causing irreversible ecosystem damage, acting as zoonotic spreaders and reservoirs, threatening human and animal health, and having an important economic impact. Accordingly, the present study has assessed the rickettsial exposure, tick infestation of wild boars, and rickettsial DNA presence in ticks from infested animals from the Cerrado biome in midwestern Brazil. Anti-Rickettsia spp. antibodies were detected in serum samples of wild boars by immunofluorescence assay. Overall, 106/285 (37.2%) wild boar serum samples from 13 to 18 (72.2%) municipalities showed seroreactivity to at least one of the four Rickettsia spp. antigens tested, the largest number of wild boars serologically tested to Rickettsia spp. in this type of study. Among the 106 seroreactive animals, 34 showed possible homologous reactions between R. parkeri, R. amblyommatis, and R. bellii, with endpoint titers between 128 and 512. A sample of 45 ticks collected from four culled wild boars was identified as Amblyomma sculptum, and all tested negative for rickettsial DNA presence. In conclusion, this study has provided a reliable sampling seroprevalence and indicated high exposure of wild boars to rickettsial agents, with a potential interaction with Rickettsia spp. from the spotted fever group within the Cerrado biome from midwestern Brazil. Full article

Cases of rocky mountain spotted fever (RMSF) are increasingly reported every year in Long Island, New York. In clinical practice, an uncommonly high number of referrals with a positive RMSF IgG test result have been seen in our tick-borne disease clinic. The aim of this study is to describe the clinical–epidemiological characteristics and outcomes of hospitalized patients with positive serologies for RMSF in our academic center in Long Island, NY. We found that out of twenty-four patients with a positive serology for RMSF, only one case met the case definition per CDC criteria, two had suspected RMSF, and the other twenty-one did not have a clinical picture consistent with RMSF. A high number of false-positive RMSF serology may be due to other spotted fever rickettsioses in Long Island. Further studies are needed to investigate the presence of another Rickettsia spp. (such as Rickettsia amblyommatis) in this area that may affect humans. Full article

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. Full article

Of the documented tick-borne diseases infecting humans in México, Rocky Mountain spotted fever (RMSF), caused by the Gram-negative bacterium Rickettsia rickettsii, is responsible for most fatalities. Given recent evidence of brown dog tick, Rhipicephalus sanguineus s.l., as an emerging vector of human RMSF, we aimed to evaluate dogs and their ticks for rickettsiae infections as an initial step in assessing the establishment of this pathosystem in a poorly studied region of northeastern México while evaluating the use of dogs as sentinels for transmission/human disease risk. We sampled owned dogs living in six disadvantaged neighborhoods of Reynosa, northeastern México to collect whole blood and ticks. Of 168 dogs assessed, tick infestation prevalence was 53%, composed of exclusively Rh. sanguineus s. l. (n = 2170 ticks). Using PCR and sequencing, we identified an overall rickettsiae infection prevalence of 4.1% (n = 12/292) in ticks, in which eight dogs harbored at least one infected tick. Rickettsiae infections included Rickettsia amblyommatis and Rickettsia parkeri, both of which are emerging human pathogens, as well as Candidatus Rickettsia andeanae. This is the first documentation of pathogenic Rickettsia species in Rh. sanguineus s.l. collected from dogs from northeastern México. Domestic dog infestation with Rickettsia-infected ticks indicates ongoing transmission; thus, humans are at risk for exposure, and this underscores the importance of public and veterinary health surveillance for these pathogens. Full article

Spotted Fever Rickettsiosis (SFR) is caused by spotted fever group Rickettsia spp. (SFGR), and is associated with symptoms common to other illnesses, making it challenging to diagnose before detecting SFGR-specific antibodies. The guinea pig is a valuable biomedical model for studying Spotted Fever Rickettsiosis (SFR); its immune system is more like the human immune system than that of the murine model, and guinea pigs develop characteristic clinical signs. Thus, we have a compelling interest in developing, expanding, and optimizing tools for use in our guinea pig-Amblyomma-Rickettsia system for understanding host-tick-pathogen interactions. With the design and optimization of the three multiplex TaqMan^® qPCR assays described here, we can detect the two SFGR, their respective primary Amblyomma sp. vectors, and the guinea pig model as part of controlled experimental studies using tick-transmission of SFGR to guinea pigs. We developed qPCR assays that reliably detect each specific target down to 10 copies by producing plasmid standards for each assay target, optimizing the individual primer-probe sets, and optimizing the final multiplex reactions in a methodical, stepwise fashion. We anticipate that these assays, currently designed for in vivo studies, will serve as a foundation for optimal SFGR detection in other systems, including fieldwork. Full article

Tick-borne diseases are a major threat to both humans and their pets; therefore, it is important to evaluate the prevalence of pathogens carried by ticks on companion animals. In this study, attached and unattached Ixodid ticks were removed from companion animals by a veterinary practice in Hall County, Georgia. DNA was extracted from unengorged adult ticks and each was screened for the presence of Rickettsia spp. by polymerase chain reaction (PCR) and sequenced to determine the species present. Two hundred and four adult hard-bodied ticks were identified to species and Rickettsia spp. were found in 19.6% (n = 38) of the 194 analyzed DNA extracts. Rickettsia montanensis was found in Dermacentor variablis (14.7%; n = 25), Amblyomma maculatum (33.3%; n = 2), and Rhipicephalus sanguineus s.l. ticks (25%; n = 4). One Amblyomma americanum tick contained Rickettsia amblyommatis, while Rickettsia felis was found in one Dermacentor variablis tick, serving as the first report of Rickettsia felis in a tick in this region and within this tick vector. This study suggests that there is a risk of companion animals contracting a species of Rickettsia from a tick bite in northeastern Georgia, indicating a need for more investigation and highlighting the importance of tick prevention on pets. Full article

Based on limited serological studies, at least 10% of the US population has been exposed to spotted fever group Rickettsia (SFGR) species. The immunofluorescence antibody assay (IFA) has been the gold standard for the serodiagnosis of rickettsial infections such as spotted fever rickettsiosis (SFR). However, the IFA is semi-quantitative and subjective, requiring a high level of expertise to interpret it correctly. Here, we developed an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Rickettsia parkeri infection in the guinea pig. Our ELISA is an objective, quantitative, and high-throughput assay that shows greater sensitivity and resolution in observed titers than the IFA. We methodically optimized relevant parameters in sequence for optimal signal-to-noise ratio and low coefficient of variation% values. We used a guinea pig model as it is a part of our overall research efforts to understand the immunological and clinical response to SFGR species after tick transmission. Guinea pigs are a useful model to study SFR and show clinical signs of SFR, such as fever and eschars. We anticipate that this assay will be easily adapted to other hosts, including humans and other SFGR species. Full article

Cases of tick-borne diseases, including spotted fever rickettsioses, borreliosis, babesiosis, anaplasmosis and ehrlichiosis, in the United States and territories have more than doubled from 2004 to 2016 and account for 77% of all vector-borne disease reports. In an effort to inform control efforts, the presence of tick-borne pathogens and their vectors was assessed in a recreational park in Walker County, Texas. Here we report data from questing ticks collected on three dates from June 2017 to June 2018. The majority of ticks collected were Amblyomma americanum (96.69%) followed by three additional tick species: Dermacentor variabilis (2.59%), Ixodes scapularis (0.52%), and A. maculatum (0.21%). Ticks were pooled and tested for molecular evidence of bacterial and viral pathogens, respectively. All of the 68 pools of A. americanum had molecular evidence of the spotted fever group rickettsia, Rickettsia amblyommatis. Additionally, six (8.82%) of the A. americanum pools contained sequences matching Ehrlichia chaffeensis, the pathogen responsible for human monocytotropic ehrlichiosis, and 11 (16.18%) for E. ewingii. Three of the A. americanum pools demonstrated evidence of Borrelia lonestari. The presence of etiologic agents of known human disease in this study merits the continued surveillance efforts of ticks and their pathogens in areas where they could pose risks to public health. Full article

Within the past three decades, new bacterial etiological agents of tick-borne disease have been discovered in the southeastern U.S., and the number of reported tick-borne pathogen infections has increased. In Florida, few systematic studies have been conducted to determine the presence of tick-borne bacterial pathogens. This investigation examined the distribution and presence of tick-borne bacterial pathogens in Florida. Ticks were collected by flagging at 41 field sites, spanning the climatic regions of mainland Florida. DNA was extracted individually from 1608 ticks and screened for Anaplasma, Borrelia, Ehrlichia and Rickettsia using conventional PCR and primers that amplified multiple species for each genus. PCR positive samples were Sanger sequenced. Four species of ticks were collected: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. Within these ticks, six bacterial species were identified: Borrelia burgdorferi, Borrelia lonestari, Ehrlichia ewingii, Rickettsia amblyommatis, Rickettsia andeanae, Rickettsia parkeri, and Rickettsia endosymbionts. Pathogenic Borrelia, Ehrlichia, and Rickettsia species were all detected in the North and North-Central Florida counties; however, we found only moderate concordance between the distribution of ticks infected with pathogenic bacteria and human cases of tick-borne diseases in Florida. Given the diversity and numerous bacterial species detected in ticks in Florida, further investigations should be conducted to identify regional hotspots of tick-borne pathogens. Full article