Tick-borne Infectious Diseases Research Articles

Evidence of zoonotic rickettsiae in ixodid ticks of domestic animals in some communal farms in the Eastern Cape Province, South Africa.

The abundance of tick populations in South Africa represents a probable risk for both animal and human health. Rickettsia spp. and Borrelia spp. are well-known agents of emerging human tick-borne infectious diseases worldwide. Nevertheless, the epidemiology of their infections has been underreported in South Africa. Therefore, this study aimed to profile zoonotic Rickettsia and Borrelia species from ticks infesting domesticated animals in the Eastern Cape, South Africa. Morphological and molecular identification techniques were conducted on 1,200 tick samples collected from domestic animals before screening for the target bacterial pathogens. The molecular identification of the tick samples was based on the amplification of the 12S rRNA mitochondrial Deoxyribonucleic acid. At the same time, those of Rickettsia and Borrelia species were carried out by amplifying fragments of gltA and ompB genes for Rickettsia and flaB gene for Borrelia spp. Thereafter, the positive amplicons for Rickettsia ompB were sequenced and further analyzed. Borrelia PCRs were negative; therefore, sequencing could not be performed. Eight species of ticks belonging to three genera; Rhipicephalus, Amblyomma, and Haemaphysalis, were identified. A total of 27% (320/1,200) samples were confirmed positive for Rickettsia, of which 23% (74/320) were positive for ompB genes. Phylogenetic analysis of ompB revealed a high homology to rickettsial reference strains from GenBank, with no positive result for Borrelia. The generated sequences showed homology with R. africae-KX227790 (100%), R. parkeri-KY113111 (99.8%), R. peacockii (99.3%), and R. slovaca-JX683122 (99.1%) representative sequences in GenBank. The findings from this study revealed that ticks harbored Rickettsia species with possible zoonotic potential.

Аналіз захворюваності на Лайм-бореліоз під час епідемії COVID-19

The global pandemic caused by the SARS-CoV-2 virus has created unprecedented health, social and economic challenges, and has led to a sharp decline in official statistical reporting of many infectious diseases, including Lyme borreliosis (LB), especially in children, due to COVID-19-related health, anti-epidemic and quarantine measures. Purpose - to assess the completeness of statistical accounting of LB in children against the background of the COVID-19 situation in the context of the epidemic in the Ternopil region of Ukraine that began in the spring of 2020. Materials and methods. A PubMed search was conducted for analytical articles on LB and COVID-19 for the period from 2020 to February 2023. Epidemiological analysis and forecasting were performed using statistical methods. The search included 300 publications. After the selection process, 25 publications were included in the review. The results of long-term epidemiologic surveillance of tick-borne infectious diseases in the Ternopil region, including data from official statistics, epidemiologic investigations, and laboratory studies, were analyzed. To predict the incidence of LB in the first half of 2023 for the age group 0-17 years, over 17 years and all age groups, increasing polynomial trends of the second order with approximation coefficients equal to 1 were used. To predict the incidence of COVID-19 in the first half of 2023 for the age group 0-17 years, an increasing linear trend with an approximation coefficient equal to 0.8 was used. To predict the incidence of COVID-19 in the first half of 2023 for the age groups 18-29 years, 30-49 years, 50-65 years, over 65 years and all age groups, we used decreasing polynomial trends of the second order with approximation coefficients equal to 1. The vast majority of the highest values of the approximation coefficients confirm the high accuracy of predicting the incidence of VL and COVID-19 in the first half of 2023 in the Ternopil region. Results and conclusions. The officially registered number of cases of pulmonary disease, including among children, during the COVID-19 epidemic in Ternopil region is likely incomplete and does not reflect the actual incidence rate. This is due to the problem of identifying patients with pulmonary disease during the COVID-19 epidemic. After a sharp decline in reported cases of LB in 2020 compared to previous years, in 2021-2023, there was an improvement in its detection and diagnosis, but at levels lower than before the COVID-19 epidemic. However, the proportion of children is decreasing. No conflict of interests was declared by the authors.

Coinfection With Severe Fever With Thrombocytopenia Syndrome and Scrub Typhus in Korea.

Scrub typhus and severe fever with thrombocytopenia syndrome (SFTS) are the 2 most common tick-borne infectious diseases in Korea. Every year, an increasing number of cases are reported, which is a public health concern. Therefore, we aimed to investigate the prevalence of SFTS-scrub typhus coinfection in patients with SFTS. Clinical samples were collected from 129 patients with SFTS. One-step reverse-transcription polymerase chain reaction (PCR) was performed to identify the SFTS virus (SFTSV), and real-time PCR followed by nested PCR was performed to detect the Orientia tsutsugamushi gene for scrub typhus. Phylogenetic analysis was conducted to confirm the evolutionary relationships among different species. Among 129 SFTS cases, 2 patients with SFTSV were positive for O. tsutsugamushi with a prevalence of coinfection of 1.6% (95% confidence interval, .001-.06). Phylogenetic analysis confirmed these as O. tsutsugamushi strain Boryong. Our study found that 1.6% of patients were coinfected with SFTS and scrub typhus infection. We believe that this information will add a new dimension to clinical diagnosis, which should be considered for better public health management. Further research is needed to better understand the ecological transmission dynamics and geographical distribution of SFTSV and O. tsutsugamushi in endemic countries.

Epidemiological characteristics of tick-borne infectious diseases in Hubei Province, 2016-2021

Objective: To understand the epidemiological characteristics of tick-borne infectious diseases (TBID) and the risk factors of severe illness and death in Hubei Province from 2016 to 2021. Methods: Based on the incidence data of fever with thrombocytopenia syndrome (SFTS), tsutsugamushi disease, typhus and other TBID reported during 2016-2021, the epidemiological analysis was conducted. Field investigation results of TBID in areas with high incidence in 2021, logistic regression analysis of population characteristics, epidemiological history and other factors were used to explore the risk factors of severe and fatal cases. In the field vector investigation, free ticks and surface ticks of the host animals in the cases' home and surrounding grassland were monitored and detected. Results: A total of 3 826 TBID cases were reported in Hubei from 2016 to 2021, of which 71.30% (2 728/3 826) were SFTS, 13.04% (499/3 826) were tsutsugamushi disease and 15.66% (599/3 826) were typhus. A total of 44 cases died in 6 years; the fatality rate was 1.15% (44/3 826). In the peak seasons of incidence from May to July, the cases in people engaged in agriculture related work accounted for 84.61% (3 237/3 826). The incidence rate in women was higher than that in men, and the cases aged ≥50 years accounted for 81.02% of the total (3 100/3 826), and the incidence rate increased with age (P<0.001). The TBID cases were distributed in 86 counties and districts in 16 prefectures (municipality). The incidence rates of different areas had significant differences (P<0.05), and there was a certain spatial-temporal clustering and expasion. Bovis microplus and Haemaphysalis longicornis were captured in the field, and the positive rates in host animals and grassland ticks were 10.94% (7/64) and 40.00% (2/5), respectively. Univariate logistic regression analysis results showed that age ≥50 years and leukocyte <2.0×109/L were risk factors for severe illness and death. Conclusions: The TBID reported in Hubei were mainly SFTS, tsutsugamushi disease and typhus. In order to reduce the incidence of TBID, it is necessary to strengthen the prevention and control in women aged ≥50 years and reduce field exposure and tick bites during the epidemic period.

Clinically differential diagnosis of human granulocytic anaplasmosis and severe fever with thrombocytopenia syndrome

This study analyzed HGA and SFTS in patients with suspected tick-borne infection by focusing on key differences that clinicians can easily recognize. A retrospective analysis was performed on confirmed patients with HGA or SFTS in 21 Korean hospitals from 2013 to 2020. A scoring system was developed by multivariate regression analysis and accuracy assessment of clinically easily discriminable parameters was performed. The multivariate logistic regression analysis revealed that sex (especially male sex) (odds ratio [OR] 11.45, P = 0.012), neutropenia (< 1500) (OR 41.64, P < 0.001), prolonged activated partial thromboplastin time (OR 80.133, P < 0.001), and normal C-reactive protein concentration (≤ 1.0 mg/dL; OR 166.855, P = 0.001) were significantly associated with SFTS but not with HGA. Each factor, such as meaningful variables, was given 1 point, and a receiver-operating characteristic curve with a cutoff value (> 1) in a 5-point scoring system (0–4 points) was analyzed to evaluate the accuracy of differentiation between HGA and SFTS. The system showed 94.5% sensitivity, 92.6% specificity, and an area under the receiver-operating characteristic curve of 0.971 (0.949–0.9). Where HGA and SFTS are endemic, the scoring system based on these four parameters such as sex, neutrophil count, activated partial thromboplastin time, and C-reactive protein concentration will facilitate the differential diagnosis of HGA and SFTS in the emergency room in patients with suspected tick-borne infectious diseases.

Co-infection of tick-borne bacterial pathogens in ticks in Inner Mongolia, China.

Tick-borne infectious diseases pose a serious health threat in certain regions of the world. Emerging infectious diseases caused by novel tick-borne pathogens have been reported that are causing particular concern. Several tick-borne diseases often coexist in the same foci, and a single vector tick can transmit two or more pathogens at the same time, which greatly increases the probability of co-infection in host animals and humans and can lead to an epidemic of tick-borne disease. The lack of epidemiological data and information on the specific clinical symptoms related to co-infection with tick-borne pathogens means that it is not currently possible to accurately and rapidly distinguish between a single pathogen infection and co-infection with multiple pathogens, which can have serious consequences. Inner Mongolia in the north of China is endemic for tick-borne infectious diseases, especially in the eastern forest region. Previous studies have found that more than 10% of co-infections were in host-seeking ticks. However, the lack of data on the specific types of co-infection with pathogens makes clinical treatment difficult. In our study, we present data on the co-infection types and the differences in co-infection among different ecological regions through genetic analysis of tick samples collected throughout Inner Mongolia. Our findings may aid clinicians in the diagnosis of concomitant tick-borne infectious diseases.

Research Priorities on One Health: A Bibliometric Analysis.

ObjectiveOne Health is an emerging research area that has received increasing attention globally. In this study, we aimed to explore the global research trend and hotspots of One Health and provide a reference for potential future research and practices.MethodsThis was a bibliometric descriptive study of publications on One Health in four directions, including zoonotic diseases, antimicrobial resistance, food safety, and vector-borne infections. Publications from 2003 to 2021 were retrieved using the Scopus database on One Health, which were screened based on the PRISMA guidelines. Keywords were analyzed and visualized using VOSviewer software.ResultsA total of 12,815 publications were included. The annual number of publications and those on each topic showed a gradual increase from 181 in 2003 to 1,647 in 2020, with an average annual growth rate of about 20.2%; the top three countries in terms of the number of publications were the United States of America (n=3,588), the United Kingdom (n=1,429) and China (n=1,233); the major research subjects were mainly in the natural sciences, with fewer social sciences subjects involved (n = 312; 1%). The main research directions within the area of zoonotic diseases included viral, bacterial, parasitic zoonotic diseases, and vector-borne diseases, with a small amount of antimicrobial resistance research. The major research interests within antimicrobial resistance were Enterobacteriaceae drug-resistant bacteria, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and antimicrobial resistance gene detection; research on food safety clustered around agronomy research, aquaculture research as well as a small amount of antimicrobial resistance research in food; and research on vector-borne diseases focused on mosquito-borne infectious diseases, tick-borne infectious diseases, and vectors.ConclusionsThe scientific literature on One Health has witnessed a rising global trend. Most research has focused on the human-animal health interface, while environmental health is often neglected. Research subjects mainly fall within natural science disciplines, with less social science research. More support needs to be given to interdisciplinary and intersectoral cooperation and research in the future.

Crimean-Congo hemorrhagic fever: a growing threat to Europe

Tick-borne infectious diseases are increasing, driven by geographic expansion of ticks. Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus of the family Nairoviridae that poses serious threat to public health. CCHFV can cause severe forms of hemorrhagic fever with high case fatality rates (CFR) (10-40%) and can be transmitted from human to human. Until a few years ago, no cases of CCHF had been reported in western Europe. However, high seropositivity rates in wildlife and detection of multiple strains of CCHFV in ticks in Spain suggest that CCHFV enzootic cycle has been established in some areas of southwestern Europe. As far as CCHFV-associated morbidity and mortality are concerned, there are no approved therapeutic options or US/EU licensed vaccines for treatment. Here we discuss some eco-epidemiological aspects as well as public health and socio-economic impacts associated with CCHFV circulation and outbreaks. We also emphasize that it has become essential to identify key inter-species transmission processes of this group of pathogens, to understand basic molecular mechanisms of their replication, and to define their pathogenic potentials.

MRNA vaccination induces tick resistance and prevents transmission of the Lyme disease agent.

Ixodes scapularis ticks transmit many pathogens that cause human disease, including Borrelia burgdorferi. Acquired resistance to I. scapularis due to repeated tick exposure has the potential to prevent tick-borne infectious diseases, and salivary proteins have been postulated to contribute to this process. We examined the ability of lipid nanoparticle–containing nucleoside-modified mRNAs encoding 19 I. scapularis salivary proteins (19ISP) to enhance the recognition of a tick bite and diminish I. scapularis engorgement on a host and thereby prevent B. burgdorferi infection. Guinea pigs were immunized with a 19ISP mRNA vaccine and subsequently challenged with I. scapularis. Animals administered 19ISP developed erythema at the bite site shortly after ticks began to attach, and these ticks fed poorly, marked by early detachment and decreased engorgement weights. 19ISP immunization also impeded B. burgdorferi transmission in the guinea pigs. The effective induction of local redness early after I. scapularis attachment and the inability of the ticks to take a normal blood meal suggest that 19ISP may be used either alone or in conjunction with traditional pathogen-based vaccines for the prevention of Lyme disease, and potentially other tick-borne infections.

Severe chronic idiopathic suppurative lymphoplasmacytic rhinitis in a dog

AbstractA 5‐year‐old, intact male, Border collie dog was evaluated because of a 10‐day history of right epistaxis. On physical examination, there was no evidence of nasal discharge. A mild depigmentation of the right nasal planum was observed. The infectious panel was negative for Leishmania infantum, Dirofilaria immitis, Angiostrongylus vasorum and tickborne infectious diseases. CT scan of the head, rhinoscopy, histopathologic examination of the right nasal mucosa, fungal culture and PCR sequencing were performed at initial diagnostic workup and follow‐up. A severe and diffuse chronic idiopathic suppurative lymphoplasmacytic rhinitis was diagnosed, along with isolation of Trichosporon ashaii. Because of the unsatisfactory clinical response to marbofloxacin, piroxicam, itraconazole and clotrimazole, oral prednisone was administered. After the initial 2 weeks, prednisone was progressively reduced and discontinued 9 months later. The dog showed complete disappearance of clinical signs, without recurrence after therapy discontinuation.

The Impact of Tick-Borne Diseases on the Bone.

Tick-borne infectious diseases can affect many tissues and organs including bone, one of the most multifunctional structures in the human body. There is a scarcity of data regarding the impact of tick-borne pathogens on bone. The aim of this review was to survey existing research literature on this topic. The search was performed using PubMed and Google Scholar search engines. From our search, we were able to find evidence of eight tick-borne diseases (Anaplasmosis, Ehrlichiosis, Babesiosis, Lyme disease, Bourbon virus disease, Colorado tick fever disease, Tick-borne encephalitis, and Crimean–Congo hemorrhagic fever) affecting the bone. Pathological bone effects most commonly associated with tick-borne infections were disruption of bone marrow function and bone loss. Most research to date on the effects of tick-borne pathogen infections on bone has been quite preliminary. Further investigation of this topic is warranted.

A cross‐sectional study of hard ticks (acari: ixodidae) on horse farms to assess the risk factors associated with tick‐borne diseases

Zoonotic diseases are significant public health issues. There is an urgent need to focus our efforts on the development of strategies that prevent and control potential arthropod vector-borne pathogens. Hard ticks transmit a variety of viral, bacterial and protozoan pathogens to their vertebrate hosts. This is becoming of more concern, as anthropogenic alterations of the environment may unleash the spread of tick-borne diseases throughout the world. Developing countries that are highly dependent on the livestock economy are a hot spot for tick-borne infectious diseases. In this work, through a cross-sectional approach that included a bibliographic survey, field collection and epidemiological questionnaire, we identified five tick species that were found to parasitize equines and transmit tick-borne pathogens. Our data revealed a gap in fundamental knowledge of ticks and tick-borne infectious diseases among equine breeders and owners. This article highlights the relevant risk factors that were found and the urgent actions that are needed to prevent the wide spread of hard ticks and their associated zoonotic diseases.

Molecular Evidence of Novel Spotted Fever Group Rickettsia Species in Amblyomma albolimbatum Ticks from the Shingleback Skink (Tiliqua rugosa) in Southern Western Australia.

Tick-borne infectious diseases caused by obligate intracellular bacteria of the genus Rickettsia are a growing global problem to human and animal health. Surveillance of these pathogens at the wildlife interface is critical to informing public health strategies to limit their impact. In Australia, reptile-associated ticks such as Bothriocroton hydrosauri are the reservoirs for Rickettsia honei, the causative agent of Flinders Island spotted fever. In an effort to gain further insight into the potential for reptile-associated ticks to act as reservoirs for rickettsial infection, Rickettsia-specific PCR screening was performed on 64 Ambylomma albolimbatum ticks taken from shingleback skinks (Tiliqua rugosa) located in southern Western Australia. PCR screening revealed 92% positivity for rickettsial DNA. PCR amplification and sequencing of phylogenetically informative rickettsial genes (ompA, ompB, gltA, sca4, and 17kda) suggested that the single rickettsial genotype detected represented a novel rickettsial species, genetically distinct from but closely related to Rickettsia gravesii and within the rickettsia spotted fever group (SFG). On the basis of this study and previous investigations, it would appear that Rickettsia spp. are endemic to reptile-associated tick species in Australia, with geographically distinct populations of the same tick species harboring genetically distinct SFG Rickettsia species. Further molecular epidemiology studies are required to understand the relationship between these diverse Rickettsiae and their tick hosts and the risk that they may pose to human and animal health.

Asymptomatic-anaplasmosis confirmation using genetic and serological tests and possible coinfection with spotted fever group Rickettsia: a case report

BackgroundAnaplasmosis is an emerging acute febrile disease that is caused by a bite of an Anaplasma phagocytophilum–infected hard tick. As for healthy patients, reports on asymptomatic anaplasmosis resulting from such tick bites are rare.Case presentationA 55-year-old female patient visited the hospital with a tick bite in the right infraclavicular region. The tick was suspected to have been on the patient for more than 10 days. PCR and an indirect immunofluorescence assay (IFA) were performed to identify tick-borne infectious diseases. The blood sample collected at admission yielded a positive result in nested PCR targeting Ehrlichia- or Anaplasma-specific genes groEL and ankA. Subsequent sequencing confirmed the presence of A. phagocytophilum, and seroconversion was confirmed by the IFA involving an A. phagocytophilum antigen slide. PCR detected no Rickettsia-specific genes [outer membrane protein A (ompA) or surface cell antigen 1 (sca1)], but seroconversion of spotted fever group (SFG) rickettsiosis was confirmed by an IFA.ConclusionsThis study genetically and serologically confirmed an asymptomatic A. phagocytophilum infection. Although SFG rickettsiosis was not detected genetically, it was detected serologically. These findings indicate the possibility of an asymptomatic coinfection: anaplasmosis plus SFG rickettsiosis. It is, therefore, crucial for clinicians to be aware of potential asymptomatic anaplasmosis following a tick bite.

Understanding risk perception from traditional knowledge of Mayan farmers on Rickettsioses

ABSTRACT Rickettsioses are a group of tick-borne infectious diseases. The clinical presentation is characterised by unspecified manifestations seen in illnesses such as dengue, zika, and chikungunya, so identification is complicated. The greatest impact occurs among the world’s poorest populations. Rickettsioses have hardly been studied from a qualitative perspective to show the cultural horizon of the people affected. We aimed to describe the perception of Mayan indigenous farmers about their risk perception for disease transmission. We used the ethnographic method and built life stories. From the perspective of people interviewed, their relationship with the reservoirs for vectors did not represent a high risk, did not consider that blisters and other skin lesions are caused by tick bites. Contributions as this article show the thinking logic underlying the perception of risk of these impoverished populations. To produce synergy with prevention efforts, it is necessary to know the cultural perspectives of targeted groups.

Tick-Borne Viruses of North America

The global incidence of tick-borne infectious diseases has increased since the beginning of the 21st century. The expansion of tick populations into new geographic locations and a variety of anthropogenic and natural factors are all drivers of the increase. In addition to the establishment of known tick-borne pathogens in new areas, several novel agents, including many viruses, have also emerged. At present in North America, there are five tick-borne viruses that are known to cause human disease: deer tick virus, Powassan virus, Colorado tick fever virus, Heartland virus, and Bourbon virus. Although uncommon causes of disease, these viruses pose formidable threats to the health of individuals residing in regions of endemicity, especially since there are currently no medical countermeasures available to combat them. This review focuses on the basic biology, ecology, epidemiology, transmission, clinical presentation, diagnosis, treatment, and prevention of these North American tick-borne arboviruses.

Molecular Identification of Borrelia afzelii from Ticks Parasitizing Domestic and Wild Animals in South Korea.

Lyme borreliosis is one of the most prevalent tick-borne infectious zoonotic diseases caused by spirochetes of the Borrelia burgdorferi sensu lato group. The present study assessed the risk factors and prevalence of Lyme borreliosis in ticks parasitizing domestic and wild animals. A total of 589 ticks (329 tick pools) collected from animals were identified as Haemaphysalis longicornis, (85.7%), H. flava (10.0%), and Ixodes nipponensis (4.3%) using morphological and molecular methods in South Korea. In this study, the 5S–23S gene sequences of B. afzelii (6/329, 1.8%) were detected in ticks taken from mammals, including ticks from horses (2/147 pools, 1.4%), wild boar (1/19 pools, 5.3%), native Korean goats (NKG, 2/34 pools, 5.9%), and Korean water deer (1/129 pools, 0.8%). Unfortunately, ospA, pyrG, and flagellin genes were not able to be amplified in the present study. To our knowledge, our results are the first inclusive data available for B. afzelii circulation in several tick species taken from NKG, horses, and wild boar in South Korea. We believe that the current findings extend our knowledge of the distribution and possible vector spectrum of Borrelia spp. We recommend continuous evaluation of the potential public health threat posed by Borrelia infected ticks.

Emerging Tick-Borne Diseases.

Increases in tick-borne disease prevalence and transmission are important public health issues. Efforts to control these emerging diseases are frustrated by the struggle to control tick populations and to detect and treat infections caused by the pathogens that they transmit. This review covers tick-borne infectious diseases of nonrickettsial bacterial, parasitic, and viral origins. While tick surveillance and tracking inform our understanding of the importance of the spread and ecology of ticks and help identify areas of risk for disease transmission, the vectors are not the focus of this document. Here, we emphasize the most significant pathogens that infect humans as well as the epidemiology, clinical features, diagnosis, and treatment of diseases that they cause. Although detection via molecular or immunological methods has improved, tick-borne diseases continue to remain underdiagnosed, making the scope of the problem difficult to assess. Our current understanding of the incidence of tick-borne diseases is discussed in this review. An awareness of the diseases that can be transmitted by ticks in specific locations is key to detection and selection of appropriate treatment. As tick-transmitted pathogens are discovered and emerge in new geographic regions, our ability to detect, describe, and understand the growing public health threat must also grow to meet the challenge.

Differentiation of endemic areas by incidence rates of tick-borne infectious diseases as the basis for choosing prevention strategy and tactics

Research objective. Differentiation of natural focal areas of Western Siberia by integral incidence rates of tick-borne infectious diseases for determination of the strategy and tactics of their comprehensive prevention. Materials and methods. A retrospective analysis of official statistics for the period 2002-2018 for eight sub-federal units in the context of administrative territories was carried out. The criteria of differentiation were determined by means of three evaluation scales, including long-term mean rates of tick-borne encephalitis, tick-borne borreliosis, and Siberian tick-borne typhus. As a scale gradation tool, we used the number of sample elements between the confidence boundaries of the median. The integral assessment was carried out by the sum of points corresponding to the incidence rates for each of the analyzed infections. Results. The areas of low, medium, above average, high and very high risk of tick-borne infectious diseases were determined. Recommendations on the choice of prevention strategy and tactics were given. In areas of very high and high incidence rates, a combination of population-based and individual prevention strategies is preferable while in other areas a combination of high-risk and individual strategies is recommended. Discussion. Epidemiologic zoning should be the basis of a risk-based approach to determining optimal volumes and directions of preventive measures against natural focal infections. It is necessary to improve the means and methods of determining the individual risk of getting infected and developing tick-borne infectious diseases in case of bites, in view of mixed infection of vectors, as well as methods of post-exposure disease prevention (preventive therapy).

Molecular detection of spotted fever group rickettsiae in hard ticks, northern China.

Spotted fever group (SFG) rickettsiae are important causative agents of (re)emerging tick-borne infectious diseases in humans, and ticks play a key role in their maintenance and transmission. In this study, hard ticks were collected from five sampling sites in North China in 2017 and 2018. Of them, Haemaphysalis longicornis, Rhipicephalus microplus and Dermacentor nuttalli were collected from livestock (sheep and goats) and the vegetation, Hyalomma asiaticum from sheep, goats and camels, and Hyalomma marginatum from sheep and goats. The SFG rickettsiae were identified in these ticks by amplifying the partial rrs and complete 17-kDa genes, with an overall infection rate of 52.9%. In addition, the nearly full-length rrs and gltA and partial ompA genes were recovered to classify the species of SFG rickettsiae further. Phylogenetic analysis revealed the presence of three human pathogenic species in Hy. asiaticum, Hy. marginatum, Ha. longicornis and De. nuttalli, including two cultured ones (Rickettsia raoultii and Rickettsia aeschlimannii) and one uncultured (Candidatus R. jingxinensis). Furthermore, partial groEL gene was also obtained, and phylogenetic trees were also reconstructed to better understand the genetic relationship with known sequences in each SFG rickettsiae species detected in the current study. Notably, the R. aeschlimannii sequences described in this study were closely related to those from abroad rather than from another part of China, indicating their different origin. However, the R. raoultii and Ca. R. jingxinensis sequences presented close relationship with variants from other parts of China. In sum, our data revealed SFG rickettsiae species in northern China, highlighting the need for surveillance of their infection in local humans.