Natural infection of questing ixodid ticks with protozoa and bacteria in Chonburi Province, Thailand

Analysis of serum proteomic profiles of endangered Siamese and Burmese Eld's deer infected with subclinical Babesia bovis in Thailand

The endangered Eld's deer is a conserved species in Thailand, where tropical parasitic infections are endemic. Although Eld's deer with babesiosis are generally asymptomatic, they can still harbor the parasite and serve as reservoirs for ticks, spreading the infection to healthy animals within the herd. The present study aimed to investigate potential serum proteome biomarkers of Eld's deer with subclinical Babesia bovis infection. A total of 67 blood samples were collected from captive Siamese and Burmese Eld's deer showing no signs of parasitic infection. The nested polymerase chain reaction (nPCR) of a conserved spherical body protein 2 (sbp-2) gene of B. bovis was utilized to classify Eld's deer groups, with 25.37 % (17/67) testing positive for B. bovis. Additionally, the application of proteomic studies showed that six B. bovis proteins, such as Obg-like ATPase 1 (OLA1) and heat shock protein 90 (HSP90), were significantly upregulated by more than a two-fold change compared with the PCR-negative samples. Of the 55 overexpressed serum proteins in the PCR-positives, alpha 2-HS glycoprotein (AHSG) and immunoglobulin lambda variable 2-8 (IGLV2-8) were notably among the top 10 proteins with the highest area under curve (AUC) values. Hence, they were proposed as potential biomarkers for subclinical B. bovis infection in Eld's deer. Analysis of the protein interaction network revealed interactions between Eld's deer AHSG and B. bovis OLA1 and HSP90, alongside associations with other proteins such as erb-b2 receptor tyrosine kinase 2 (ERBB2) and epidermal growth factor receptor (EGFR). These interactions were involved in the immune system pathway and inflammatory responses. Our findings shed light on subclinical infection of B. bovis in Eld's deer and identify potential biomarkers, contributing to the further effective detection and monitoring of B. bovis infection in this endangered species.

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.

Tick diversity and molecular detection of Anaplasma, Babesia, and Theileria from Khao Kheow open zoo, Chonburi Province, Thailand

Ticks are obligate blood-feeding ectoparasites notorious for their role as vectors for various pathogens, posing health risks to pets, livestock, wildlife, and humans. Wildlife also notably serves as reservoir hosts for tick-borne pathogens and plays a pivotal role in the maintenance and dissemination of these pathogenic agents within ecosystems. This study investigated the diversity of ticks and pathogens in wildlife and their habitat by examining ticks collected at Khao Kheow Open Zoo, Chonburi Province, Thailand. Tick samples were collected for 1 year from March 2021 to March 2022 by vegetation dragging and direct sampling from wildlife. A total of 10,436 ticks or 449 tick pools (1-50 ticks per pool) underwent screening for pathogen presence through conventional PCR and DNA sequencing. Out of the 298 samples (66.37%) where bacteria and protozoa were detected, encompassing 8,144 ticks at all stages, 114 positive samples from the PCR screenings were specifically chosen for detailed nucleotide sequencing and comprehensive analysis. Four species of ticks were conclusively identified through the application of PCR, namely, Rhipicephalus microplus, Dermacentor auratus, Haemaphysalis lagrangei, and Haemaphysalis wellingtoni. The highest infection rate recorded was for Anaplasma spp. at 55.23% (248/449), followed by Babesia spp. and Theileria spp. at 29.62% (133/449) and 16.26% (73/449), respectively. Among bacteria identified, three Anaplasma genotypes were closely related to an unidentified Anaplasma spp., A. phagocytophilum, and A. bovis. Among protozoa, only an unidentified Babesia spp. was found, whereas two Theileria genotypes found were closely related to unidentified Theileria spp. and T. equi. Significantly, our findings revealed coinfection with Anaplasma spp., Theileria spp., and Babesia spp. While blood samples from wildlife were not specifically collected to assess infection in this study, the data on the presence of various pathogens in ticks observed can serve as valuable indicators to assess the health status of wildlife populations and to monitor disease dynamics. The findings could be valuable in developing programs for the treatment, prevention, and control of tick-borne illnesses in this area. However, additional research is required to determine the ticks' ability to transmit these pathogens and enhance the current understanding of the relationship among pathogens, ticks, and hosts.

Haemaphysalis wellingtoni (Acari: Ixodidae) from the helmeted guineafowl, Numida meleagris (Galliformes: Numididae): A new tick-host record in Peninsular Malaysia

This paper describes a new tick-host record of Haemaphysalis wellingtoni from the helmeted guineafowl (Numida meleagris) in Peninsular Malaysia. This record is also the first report of a tick infestation from N. meleagris in Asia. A checklist of the tick-guineafowl associations has been designed, resulting in 32 tick species including H. wellingtoni recorded as infesting N. meleagris worldwide. A list of pathogens harboured or transmitted by H. wellingtoni is provided. The status of H. wellingtoni as a true parasite of N. meleagris, and the health threat posed to the guineafowls are discussed in this paper.

Diversity of Anaplasma and novel Bartonella species in Lipoptena fortisetosa collected from captive Eld's deer in Thailand

Lipoptena insects are important ectoparasites of cervids and may affect humans that are incidentally bitten. The presence of zoonotic pathogen DNA, such as Anaplasma, and Bartonella, raises the importance of Lipoptena insects in veterinary and human medicine. Eld's deer (Rucervus eldii thamin), an endangered wild ruminant in Thailand, are bred and raised in the open zoo. The semi-wild zoo environment suggests ectoparasite infestation and potential risk for mechanical transmission of pathogens to visitors, zoo workers, or other animals. However, epidemiology knowledge of pathogens related to endangered wild ruminants in Thailand is limited. This study aims to determine the prevalence and diversity of Anaplasma and Bartonella in the L. fortisetosa collected from captive Eld's deer in Chon Buri, Thailand. Of the 91 Lipoptena DNA samples obtained, 42 (46.15%) and 25 (27.47%) were positive for Anaplasma and Bartonella by molecular detection, respectively. Further, 42 sequences of Anaplasma (4 nucleotide sequence types) showed 100% identity to those detected in other ruminants and blood-sucking ectoparasites. Twenty-five sequences of Bartonella (8 nucleotide sequence types) showed 97.35-99.11% identity to the novel Bartonella species from sika deer and keds in Japan. Phylogenetic trees revealed Anaplasma sequences were grouped with the clusters of A. bovis and other ruminant-related Anaplasma, while Bartonella sequences were clustered with the novel Bartonella species lineages C, D, and E, which originated from Japan. Interestingly, a new independent lineage of novel Bartonella species was found in obtained specimens. We report the first molecular detection of Anaplasma and Bartonella on L. fortisetosa, which could represent infectious status of captive Eld's deer in the zoo. Wild animals act as reservoirs for many pathogens, thus preventive measures in surrounding areas should be considered to prevent pathogen infection among animals or potential zoonotic infection among humans.

Genetic characterization of genes encoding the major surface proteins of Anaplasma marginale from cattle isolates in Thailand reveals multiple novel variants

Bovine anaplasmosis is a serious tick-borne disease that is responsible for economic loss worldwide. The major surface proteins (MSPs), encoded by msp1 to msp5 genes of Anaplasma marginale, play an important role in host-pathogen and tick-pathogen interactions. These markers have been used for genetic characterization and phylogenetic studies. Despite domestic reports concerning suspected outbreaks of anaplasmosis in Thailand, genetic analysis of A. marginale in the country remains largely limited. Therefore, we aim to investigate the infection rate of the rickettsia organism in the Anaplasmataceae family throughout five regions of Thailand and to further characterize the key genetic markers: msp1a, msp2, and msp5 of A. marginale. From 2016 to 2021, we collected a total of 384 cattle blood samples across 18 provinces. Overall, the infection rate of the rickettsia organism in the Anaplasmataceae family was 46.1%. Over 65% of the positive samples were confirmed as A. marginale. We successfully obtained a total of 138 A. marginale msp1a (38), msp2 (79), and msp5 (21) sequences from all regions of the country. The msp1a and msp2 genes exhibit a high degree of genetic diversity, while the msp5 gene is highly conserved among the Thai isolates. Our findings regarding msp1a corroborated the genetic heterogeneity of A. marginale strains in endemic regions worldwide. Additionally, we found multiple novel variants for the first time in the current nationwide survey. We found 45 tandem repeat characters of the msp1a sequence. Among them, 24 characters were not shared with other countries. Collectively, we expanded the extent of genetic diversity in key markers; msp1a and msp2 genes, and further confirmed the previous finding that msp5 was highly conserved. The msp1a and msp2 genes could be useful for the surveillance of newly introduced strains. The current data may also be useful in designing a vaccine containing potential epitopes of different antigens in the future.

The specificity of Babesia-tick vector interactions: recent advances and pitfalls in molecular and field studies

Background

Babesia spp. are protozoan parasites of great medical and veterinary importance, especially in the northern Hemisphere. Ticks are known vectors of Babesia spp., although some Babesia-tick interactions have not been fully elucidated.

Methods

The present review was performed to investigate the specificity of Babesia-tick species interactions that have been identified using molecular techniques in studies conducted in the last 20 years under field conditions. We aimed to indicate the main vectors of important Babesia species based on published research papers (n = 129) and molecular data derived from the GenBank database.

Results

Repeated observations of certain Babesia species in specific species and genera of ticks in numerous independent studies, carried out in different areas and years, have been considered epidemiological evidence of established Babesia-tick interactions. The best studied species of ticks are Ixodes ricinus, Dermacentor reticulatus and Ixodes scapularis (103 reports, i.e. 80% of total reports). Eco-epidemiological studies have confirmed a specific relationship between Babesia microti and Ixodes ricinus, Ixodes persulcatus, and Ixodes scapularis and also between Babesia canis and D. reticulatus. Additionally, four Babesia species (and one genotype), which have different deer species as reservoir hosts, displayed specificity to the I. ricinus complex. Eco-epidemiological studies do not support interactions between a high number of Babesia spp. and I. ricinus or D. reticulatus. Interestingly, pioneering studies on other species and genera of ticks have revealed the existence of likely new Babesia species, which need more scientific attention. Finally, we discuss the detection of Babesia spp. in feeding ticks and critically evaluate the data on the role of the latter as vectors.

Conclusions

Epidemiological data have confirmed the specificity of certain Babesia-tick vector interactions. The massive amount of data that has been thus far collected for the most common tick species needs to be complemented by more intensive studies on Babesia infections in underrepresented tick species.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05019-3.

Molecular detection of tick-borne pathogens in infected dogs associated with Rhipicephalus sanguineus tick infestation in Thailand

Background and Aim:

Tick-borne pathogens (TBPs) are of great concern having the potential to threaten canine health. Dogs infected with Ehrlichia canis, Anaplasma platys, Babesia canis, and Hepatozoon canis are commonly found in Thailand; Rhipicephalus sanguineus tick is the most common vector of diseases. This study aimed to determine the prevalence of common TBPs in dogs and their ticks in Thailand using polymerase chain reaction (PCR) and DNA sequencing methods.

Materials and Methods:

Forty-four blood samples were positively diagnosed with TBPs infection by microscopy. Samples were from animal hospitals in Maha Sarakham, Amnat Charoen, Nakhon Ratchasima, and Bangkok, Thailand, during January-June 2020. Five to six ticks were also taken from infected dogs, and then, both blood and tick were analyzed using PCR and DNA sequencing.

Results:

PCR results showed that R. sanguineus was the only tick species detected in this study. The appearance of single infection with E. canis was the most common infection found in dogs and ticks (64% and 82%, respectively). Correlation of pathogen infection in hosts and their vector was performed by similarity detection of pathogens between blood and tick samples based on PCR analysis in 29 samples (66%) but there was no significant differentiation.

Conclusion:

E. canis appears as the most common canine tick-borne pathogen in Thailand, which was detected in both healthy and sick dogs as well as in R. sanguineus. The findings show the relationships among host dogs, pathogens, and ticks. Veterinarians should be proactive in educating pet owners about the risks associated with ticks and their important pathogens and plan effective control strategies.

Global Distribution of Babesia Species in Questing Ticks: A Systematic Review and Meta-Analysis Based on Published Literature

Babesiosis caused by the Babesia species is a parasitic tick-borne disease. It threatens many mammalian species and is transmitted through infected ixodid ticks. To date, the global occurrence and distribution are poorly understood in questing ticks. Therefore, we performed a meta-analysis to estimate the distribution of the pathogen. A deep search for four electronic databases of the published literature investigating the prevalence of Babesia spp. in questing ticks was undertaken and obtained data analyzed. Our results indicate that in 104 eligible studies dating from 1985 to 2020, altogether 137,364 ticks were screened with 3069 positives with an estimated global pooled prevalence estimates (PPE) of 2.10%. In total, 19 different Babesia species of both human and veterinary importance were detected in 23 tick species, with Babesia microti and Ixodesricinus being the most widely reported Babesia and tick species, respectively. Regardless of species, adult ticks with 2.60% had the highest infection rates, while larvae had the least with 0.60%. Similarly, female ticks with 4.90% were infected compared to males with 3.80%. Nested-polymerase chain reaction (PCR) 2.80% had the highest prevalence among the molecular techniques employed. In conclusion, results obtained indicate that Babesia species are present in diverse questing tick species at a low prevalence, of which some are competent vectors.

Molecular detection and genetic characterization of Anaplasma marginale and Anaplasma platys-like (Rickettsiales: Anaplasmataceae) in water buffalo from eight provinces of Thailand

Background

Anaplasmosis, an animal disease caused by rickettsial bacteria in the genus Anaplasma, is of considerable economic importance in livestock animals in many countries worldwide. The objectives of this study were to determine the identity, prevalence, and geographic distribution of Ehrlichia and Anaplasma in naturally infected water buffalo in Thailand using PCR amplification and sequencing of the 16S ribosomal RNA and heat shock protein groEL genes. A total of 456 buffalo blood samples from Thailand were investigated. Species identification and genetic differentiation of intra-population and inter-population with the global isolates were conducted based on nucleotide sequences. Interplay between the infection and host factors was also assessed.

Results

Overall, 41% of water buffalo were found to be infected with rickettsial organisms in the family Anaplasmataceae, but Ehrlichia spp., Neorickettsia spp., and Wolbachia spp. were not found in any of the sequenced samples in this study. Female buffalo were more frequently infected with bacteria in the family Anaplasmataceae than males [71 out of 176 females (40.3%) versus 11 out of 47 males (23.4%)]. The Odds Ratio value indicated that the risk of infection for female buffalo was 2.2-fold higher than that for males (p < 0.05). We detected three haplotypes of A. marginale 16S rRNA gene and they were placed in a clade that was closely related to the A. marginale in buffalo in China; and cattle in Thailand, Uganda, and China. Homology searching of groEL sequences against the GenBank™ database using the BLASTn algorithm revealed that the obtained sequences had a high percentage similarity (98.36–99.62%) to A. platys sequences. The groEL sequences of three A. platys-like isolates were clustered in the same clade as the A. platys from the tick Rhipicephalus microplus in China.

Conclusions

Our data showed that the apparently healthy buffalo were naturally infected by bacteria in the family Anaplasmataceae at a relatively high prevalence. We also report the finding of A. platys-like infections in water buffalo in Thailand for the first time. Water buffalo serving as the reservoir host of anaplasmosis is of concern for managing the disease control and prevention in ruminants.