Molecular and Phylogenetic Analysis of Tick-Borne Pathogens in Ticks Parasitizing Native Korean Goats (Capra hircus coreanae) in South Korea

Hard Tick Species Parasitism Levels in Domestic Ruminants with Their Distribution and Role as Vectors: A Detailed Global Meta-analysis and Systematic Review

PURPOSE

This comprehensive global meta-analysis reviews the parasitism levels of tick genera and species, life stages, seasonality, attachment sites, the global mean ranks of tick species parasitism rates and records, and their distribution and role as vectors.

METHODS

From the 418 papers identified, 390 papers were selected to become part of the study.

RESULTS

The genera recorded as infesting domestic ruminants were Rhipicephalus (42 species), Haemaphysalis (32 species), Hyalomma (19 species), Amblyomma (18 species), Ixodes (10 species), Dermacentor (8 species), Margaropus and Nosomma (1 species). Globally, domestic ruminants are more infested by adult females and males than by the nymphal and larval stages of the tick species. The global tick species parasitism levels at the attachment sites of domestic ruminants were, in order, tail and anal region, neck and dewlap, scrotum or udder, ear region, thigh and abdomen, and dorsal surface.

CONCLUSIONS

Among 131 species of eight genera of hard ticks recorded infesting domestic ruminants, 42 species had mean ranks of tick species parasitism rates up to 10%, and 37 species had mean ranks of tick species parasitism up to 10 records. Briefly, the higher the indexes of tick species parasitism rates and records, the more important their role as vectors. In addition, the majority of them are found among tick species-infested humans with nearly high ranks of tick species parasitism rates and records that double their medical, veterinary, and zoonotic importance to be the most common vectors and reservoirs of bacterial, protozoan, and viral pathogenic microorganisms, causing severe infectious diseases, and as a result, can be more dangerous to humans and domestic ruminants.

Molecular analysis of Rickettsia spp. and related tick-borne pathogens detected in dogs in Korea

Ticks are widespread in nature and serve as primary vectors for several tick-borne pathogens (TBPs). Ticks and TBPs cause considerable harm to humans and animals and have emerged as a major global public health concern. Domestic dogs are the major reservoirs of zoonotic agents owing to their constant interaction with humans. This study aimed to assess the prevalence and risk factors of canine TBPs, such as Rickettsiales, Coxiella burnetii, hepatozoa, and Borrelia spp., using molecular analyses. A total of 906 dogs were examined and 4 TBPs were identified: Anaplasma phagocytophilum (5; 0.6%), Hepatozoon canis (9; 1.0%), Candidatus Rickettsia longicornii (2; 0.2%), and Rickettsia tamurae (1; 0.1%). Ehrlichia spp., C. burnetii, and Borrelia spp. were not detected. To the best of our knowledge, this is the first study to perform a phylogenetic analysis of Candidatus R. longicornii and R. tamurae in dogs. These findings can help determine the potential public health risks by enhancing our understanding of the geographical and vector distributions of TBPs in Korea.

Molecular Detection of Toxoplasma gondii in Blood Samples of Domestic Livestock in the Republic of Korea

Toxoplasma gondii, a major zoonotic pathogen distributed worldwide, causes severe infections in humans, animals, and birds. However, limited information is available regarding T. gondii infection in livestock in the Republic of Korea (ROK). Herein, we determined the prevalence of T. gondii infection in livestock in the ROK and identified animal species that can potentially transmit T. gondii to humans. B1 gene-targeting nested polymerase chain reaction detected T. gondii DNA in 3.3% (2/61), 2.9% (3/105), 14.1% (11/78), and 15.4% (14/91) of dairy cattle, beef cattle, Boer goats, and Korean native goats, respectively. The prevalence of T. gondii was significantly higher (p = 0.002) in goats than in cattle. The risk of contracting T. gondii infection was significantly higher by 6.18-fold in Korean native goats (95% confidence interval [CI]: 1.72–22.27%, p = 0.005) and by 5.58-fold in Boer goats (95% CI: 1.50–20.76%, p = 0.010) than in beef cattle. Our T. gondii DNA sequences exhibited 97.1–100% homology with those obtained from various hosts in other countries. To the best of our knowledge, this is the first study to report T. gondii infection using the blood samples of domestic ruminants in the ROK. The results revealed that the prevalence of T. gondii infection is higher in goats than in cattle as determined by molecular detection. Thus, these findings suggest that T. gondii can be transmitted from ruminants to humans via meat consumption.

Tick Populations and Molecular Analysis of Anaplasma Species in Ticks from the Republic of Korea

The present study was performed to survey the dominant tick populations and molecularly determine the pathogenic agents of anaplasmosis in ticks from Gyeongsang, Republic of Korea. A total of 3825 questing ticks were collected by the flagging method from 12 sites near animal farms in Gyeongsang from March to October 2021. A molecular genomic study was performed with ticks stored in 70% ethanol to detect Anaplasma genes by the previously described method. The monthly incidence of ticks varied by developmental stages, i.e., nymphs, adults, and larvae, and each of their populations peaked in May, March, and October, respectively. The predominant tick species were Haemaphysalis longicornis, Haemaphysalis sp., Haemaphysalis flava, Ixodes nipponensis, and Amblyomma testudinarium in order. To determine the Anaplasma infection rate, collected ticks were pooled into 395 groups. The minimum infection rate (MIR) of Anaplasma was 0.7% (27 pools). That of A. phagocytophilum was highest (23 pools, MIR 0.6%), followed by A. phagocytophilum-like Anaplasma spp. clade B (2 pools, MIR 0.1%), A. bovis (1 pool, MIR 0.1%), and A. capra (1 pool, MIR 0.1%), respectively. In this study, five species of ticks, including unidentified Haemaphysalis species, were collected in 12 survey sites in Gyeongsang, but their prevalence was somewhat different according to the tick species and survey sites. Further, the incidence rate (6.8%) of 4 Anaplasma spp. was not as high in tick pools. However, the results of this study may offer a basis for future epidemiological research and risk assessment of tick-borne diseases.

Molecular epidemiology of Theileria species in ticks and its potential threat to livestock in the Republic of Korea

The purpose of this study was to investigate molecular epidemiology of Theileria spp. in ticks in Korea and assess their potential threat from wildlife animals to domestic animals. A total of 21152 hard ticks were collected from Chungcheong and Jeolla provinces of Korea from March to October 2021. Tick species were identified by microscopy and Theileria spp. were screened by nested PCR targeting 18S rRNA. Haemaphysalis spp. were the most abundant tick species, followed by H. longicornis, H. flava, Amblyomma testudinarium, and Ixodes nipponensis. Of the collected ticks, 6914 ticks (541 pools) were screened, and PCR showed 211 positive pools (39.0%; MIR: 3.05). The PCR and phylogenetic analysis identified two Theileria species, T. luwenshuni and Theileria sp., with T. luwenshuni (162/211, 76.78%; MIR: 2.34) being more abundant than Theileria sp. (36/211, 17.06%; MIR: 0.52); co-infection of the two species were noted (13/211, 6.16%; MIR: 0.19). Among the tick species, H. longicornis, especially nymphs, showed the highest prevalence. Regarding season, the highest prevalence was observed in May. Considering the tick and Theileria species identified in this study, H. longicornis nymph and cervine play a critical role in maintaining Theileria spp. in Korea and could be a potential threat to domestic animals, including deer and goats. In addition, there are significant correlations among tick distribution, region, season, and prevalence of Theileria.

High prevalence of Rickettsia spp. in ticks from wild hedgehogs rather than domestic bovine in Jiangsu province, Eastern China

Background

Spotted fever group Rickettsia (SFGR), containing various pathogenic Rickettsia spp., poses remarkable negative influences to public health by causing various severe or mild diseases. Information regarding prevalence of SFGR in ticks in Jiangsu province, Eastern China, is still limited and needs urgent investigations.

Methods

Hedgehog- and bovine-attached ticks were collected from Jiangsu province, Eastern China. DNA of individual ticks was extracted for nested polymerase chain reaction amplifications targeting gltA, 16S ribosomal RNA (rrs), ompA, ompB, and sca4 genes following with sequencing. SFGR-specific IgG antibodies in sera of local donators were evaluated using ELISA.

Results

Overall, 144 (83.2%) of the 173 ticks from hedgehogs and 2 (1.2%) of the 168 ticks from bovine were positive for one of the three identified Rickettsia spp., with significant difference between the two groups (P = 3.6e-52). Candidatus Rickettsia principis (9; 5.2%) and R. heilongjiangensis (135; 78.0%) were detected in Haemaphysalis flava rather than in H. longicornis ticks from hedgehogs. R. heilongjiangensis (1; 0.6%) and Candidatus R. jingxinensis (or Candidatus R. longicornii) (1; 0.6%) were identified in H. longicornis and Rhipicephalus microplus ticks from bovine, respectively. Phylogenetic analysis indicated Candidatus R. jingxinensis belonged to R. japonica subgroup, whereas Candidatus R. principis belonged to a novel subgroup. Higher serological prevalence of spotted fever and SFGR-specific IgG antibody level in humans were observed around the investigated area than in urban areas, without significant difference.

Conclusion

Candidatus R. principis and Candidatus R. jingxinensis were identified in Jiangsu province, Eastern China, and fully genetically characterized for the first time. The higher prevalence of SFGR in hedgehog-attached ticks as well as the higher SFGR-specific IgG antibody level and seropositive rate in humans around the investigated area suggested that more attention should be paid to SFGR. This pathogen is usually transmitted or harbored by wild animals and ticks. This study provides important epidemiological data for both physicians and public health officers in developing early prevention and control strategies against potential Rickettsia infections and in the preparation of suitable testing and treatment needs for rickettsiosis in the endemic areas.

Molecular Detection and Genetic Diversity of Tick-Borne Pathogens in Goats from the Southern Part of Thailand

Tick-borne hemoprotozoan and rickettsial diseases affect the health and productivity of small ruminants in tropical and subtropical regions. Despite the large population of goats in the southern part of Thailand, there is limited information on the prevalence of tick-borne pathogens. In this study, polymerase chain reaction was used to detect the presence of Theileria spp., T. ovis, T. orientalis, Babesia ovis, Anaplasma ovis, and A. marginale in 262 goats from three provinces in the southern part of Thailand. In this investigation, Theileria spp. and A. ovis were detected while T. ovis, B. ovis, and A. marginale were not detected. Overall infection rates of Theileria spp. and A. ovis were 10.3% and 1.5%, respectively. The co-infections of two parasites was observed in 1.5% of goats. Sequence analysis showed the presence of T. luwenshuni and T. orientalis in the goat samples. This study is the first to use the molecular detection of T. orientalis in Thai goats, and presents genetic characterization using the major piroplasm surface protein (MPSP) gene. In the phylogenetic analysis, the T. orientalis MPSP sequence was classified as type 7. The A. ovis major surface protein 4 (MSP4) gene sequences shared high identities and similarity with each other and clustered with isolates from other regions. This study provides information about the prevalence and genetic diversity of tick-borne pathogens in goats in the study area, and is expected to be valuable for the development of effective control measures to prevent disease in animals in Thailand.

Diversity of Anaplasma species and importance of mixed infections in roe deer from Spain

Although wildlife can act as reservoirs of some Anaplasma species, studies on the presence and distribution of Anaplasma spp. in wild cervids are mainly limited and focused on zoonotic species. In order to identify the Anaplasma species in roe deer from Spain and to detect co-infections, 224 spleen samples were tested for Anaplasma spp. using a commercial qPCR; positive samples were further characterized using generic 16S rRNA primers and species-specific primers targeting the msp2 and groEL genes. Anaplasma DNA was detected in the 50.9% of samples, and four Anaplasma species were identified. Anaplasma phagocytophilum (43.8%) was predominant, followed by Anaplasma bovis (13.8%), Anaplasma capra (5.8%) and Anaplasma ovis (2.2%). In addition, strains similar to Anaplasma platys were found in nine animals. Most positive roe deer (71.9%) were infected with a single Anaplasma species, whereas co-infections with two (19.3%) or three (8.8%) Anaplasma species were also found. This study confirms the widespread occurrence of Anaplasma spp. in roe deer from Spain, being the first report of A. platys-like strains and A. capra in this cervid; it is also the first report of A. capra in Spain. The detection of Anaplasma species pathogenic for humans and/or domestic animals in roe deer suggests that this cervid may play a role in the sylvatic cycle of these bacteria contributing to the appearance of clinical anaplasmosis cases. In addition, co-infections are common in roe deer revealing that Anaplasma species specific PCR assays are essential for a reliable identification as well as for determining their real prevalence.

Diversity and genotypic analysis of tick-borne pathogens carried by ticks infesting horses in Korea

Ticks account for an extensive range of health and welfare issues in horses. In addition, tick-borne pathogens (TBPs) limit global animal trading and equine sporting events. Here, we assess the prevalence, co-infectivity and risk factors of TBPs in horse ticks in Korea. A total of 245 hard ticks, including 103 male and 142 female adults, were obtained from horses on Jeju Island during the spring to autumn seasons of 2013-2019. All collected ticks were identified as adult Haemaphysalis longicornis. We screened and analyzed each tick for the presence of several TBPs by polymerase chain reaction (PCR) analysis. Among the 245 ticks, we detected genes for three TBPs, Candidatus Rickettsia longicornii (22.9%), Ehrlichia canis (0.4%) and Theileria luwenshuni (0.4%), while Anaplasma spp. was not detected. TBPs were most prevalent in ticks harvested during the autumn season, and more abundant in the female than male adults. This is the first report of the genera Ehrlichia, Rickettsia and Theileria in horse ticks in Korea. TBPs in horse ticks are likely a reservoir for zoonotic transmission to other animals, including humans. Our findings demonstrate the need for further understanding of the prevalence and epidemiology of TBPs in wild and domestic animals.

Co-Infection with Anaplasma Species and Novel Genetic Variants Detected in Cattle and Goats in the Republic of Korea

Anaplasmosis, a tick-borne disease with multiple reservoirs, has been evolving in its pathogenesis, increasing domestic ruminants susceptibility to simultaneous infections with multiple pathogens. However, there is limited information regarding anaplasmosis in domestic ruminants in the Republic of Korea (ROK). We aimed to evaluate the role of Korean cattle and goats in Anaplasma infection maintenance. Polymerase chain reaction was performed to investigate the prevalence and genetic diversity of Anaplasma spp. from 686 whole blood samples collected from different ROK provinces. Anaplasma infection was mostly caused by A. phagocytophilum (21.1%) in cattle, and A. bovis (7.3%) in goats. Co-infection cases were found in cattle: A. bovis and A. phagocytophilum (16.7%), and in goats: A. bovis and A. capra (1.0%). Notably, a triple co-infection with A. bovis, A. phagocytophilum, and A. capra was found in one cow. Phylogenetic analysis revealed novel variants of the A. phagocytophilum 16S rRNA and A. capra gltA genes. This research contributes to the ratification of cattle as a potential reservoir of A. capra and demonstrates Anaplasma co-infection types in Korean domestic ruminants. As anaplasmosis is a zoonotic disease, our study could be crucial in making important decisions for public health.

Genotypic Analysis of Piroplasms and Associated Pathogens from Ticks Infesting Cattle in Korea

Tick-borne pathogens (TBPs) impose an important limitation to livestock production worldwide, especially in subtropical and tropical areas. Earlier studies in Korea have examined TBPs residing in ticks and animals; however, information on multiple TBPs in ticks infesting cattle is lacking. This study assessed the prevalence of TBPs in ticks parasitizing cattle. A total of 576 ticks, including 340 adults and 236 nymphs, were collected from cattle in Korea between 2014 and 2018. All ticks collected were identified as Haemaphysalis longicornis based on their morphological and molecular characteristics. Among piroplasms and other tick-associated pathogens, seven TBP genes, namely Theileria orientalis (5.0%), Anaplasma bovis (2.3%), Anaplasma capra (4.7%), Anaplasma phagocytophilum-like Anaplasma spp. (APL) clades A (1.9%) and B (0.5%), Ehrlichia canis (1.6%), and Candidatus Rickettsia longicornii (17.5%), were detected. Bartonella spp. and severe fever with thrombocytopenia syndrome virus were not found. To our knowledge, this is the first study to report the presence of the pathogens T. orientalis major piroplasm surface protein genotypes 3 and 7, A. capra, and APL in ticks from Korea. Cattle ticks may be maintenance hosts for many TBPs, and veterinary and medical clinicians should be aware of their high probability of infection and clinical complexity in humans.

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.