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

16S rRNA metabarcoding for the identification of tick-borne bacteria in ticks in the Republic of Korea

Ticks are blood-sucking ectoparasites that act as vectors for transmission of various pathogens. The purpose of this study was to assess tick-borne bacteria, whether pathogenic or not, in ticks distributed in Korea using 16S rRNA metabarcoding and to confirm the results by PCR. Questing ticks were collected from four provinces in Korea in 2021 using the flagging method. After pooling the DNAs from the 61 tick pools (including 372 ticks), the bacterial 16S rRNA V3-V4 hypervariable region was amplified and sequenced using the MiSeq platform. Rickettsia, Ehrlichia, and the endosymbiont Wolbachia were confirmed by conventional PCR and molecular analysis. In total, 6907 ticks (534 pools) were collected and identified as belonging to five species (Haemaphysalis spp., H. longicornis, H. flava, I. nipponensis, and A. testudinarium). Through 16S rRNA metabarcoding, 240 amplicon sequence variants were identified. The dominant taxa were Rickettsiella and Coxiella. Additionally, pathogenic bacteria such as Rickettsia and Ehrlichia, endosymbiotic bacteria such as Wolbachia and Spiroplasma were identified. Polymerase chain reaction (PCR) was performed to confirm the presence of Rickettsia, Ehrlichia, Bartonella, and Wolbachia in individual ticks. Overall, 352 (65.92%) of 534 pools tested positive for at least one of the screened tick-borne bacteria. Rickettsia was the most prevalent (61.42%), followed by Wolbachia (5.05%). Ehrlichia was detected in 4.86% of tested samples, whereas Bartonella was not detected. In this study, 16S rRNA metabarcoding revealed the presence of Rickettsia, Wolbachia, and Ehrlichia, in that order of abundance, while showing absence of Bartonella. These results were confirmed to exhibit the same trend as that of the conventional PCR. Therefore, large-scale screening studies based on pooling, as applied in this study, will be useful for examining novel or rare pathogens present in various hosts and vectors.

Prevalence and genetic diversity of Anaplasma and Ehrlichia in ticks and domesticated animals in Suizhou County, Hubei Province, China

Anaplasma and Ehrlichia are tick-borne bacterial pathogens that cause anaplasmoses and ehrlichioses in humans and animals. In this study, we examined the prevalence of Anaplasma and Ehrlichia species in ticks and domesticated animals in Suizhou County, Hubei Province in the central China. We used PCR amplification and DNA sequencing of the 16S rRNA, groEL, and gltA genes to analyze. We collected 1900 ticks, including 1981 Haemaphysalis longicornis and 9 Rhipicephalus microplus, 159 blood samples of goats (n = 152), cattle (n = 4), and dogs (n = 3) from May to August of 2023. PCR products demonstrated that Anaplasma bovis, Anaplasma capra, and an Ehrlichia species were detected in the H. longicornis with the minimum infection rates (MIR) of 1.11%, 1.32%, and 0.05%, respectively; A. bovis, A. capra, and unnamed Anaplasma sp. were detected in goats with an infection rate of 26.31%, 1.31% and 1.97%, respectively. Anaplasma and Ehrlichia species were not detected from cattle, dogs and R. microplus ticks. The genetic differences in the groEL gene sequences of the Anaplasma in the current study were large, whereas the 16S rRNA and gltA gene sequences were less disparate. This study shows that ticks and goats in Suizhou County, Hubei Province carry multiple Anaplasma species and an Ehrlichia species, with relatively higher infection rate of A. bovis in goats. Our study indicates that multiple Anaplasma and Ehrlichia species exist in ticks and goats in the central China with potential to cause human infection.

Tick Diversity and Pathogen Transmission in Daejeon, Korea: Implications from Companion Animals and Walking Trails

With the ongoing global warming-induced climate change, there has been a surge in vector-borne diseases, particularly tick-borne diseases (TBDs). As the population of companion animals grows, there is growing concern from a One Health perspective about the potential for these animals to spread TBDs. In this study, ticks were collected from companion animals and the surrounding environment in Daejeon Metropolitan City, Korea, using flagging and dragging, and CO2 trap methods. These ticks were then subjected to conventional (nested) PCR for severe fever with thrombocytopenia syndrome virus (SFTSV), Anaplasma spp., Ehrlichia spp., and Borrelia spp. We identified a total of 29,176 ticks, consisting of three genera and four species: H. longicornis, H. flava, I. nipponensis, and A. testudinarium. Notably, H. longicornis was the predominant species. The presence of A. testudinarium suggested that the species traditionally found in southern regions are migrating northward, likely as a result of climate change. Our PCR results confirmed the presence of all four pathogens in both companion animals and the surrounding environment, underscoring the potential for the indirect transmission of tick-borne pathogens to humans through companion animals. These findings emphasize the importance of the ongoing surveillance of companion animals in the management and control of TBDs.