Serological evidence of infection of Anaplasma and Ehrlichia in domestic animals in Xinjiang Uygur Autonomous Region area, China

Genetic diversity of tick (Acari: Ixodidae) populations and molecular detection of Anaplasma and Ehrlichia infesting beef cattle from upper-northeastern Thailand

Genetic diversity, genetic structure and demographic history of the ticks infesting beef cattle in Thailand were examined based on mitochondrial cytochrome c oxidase I (cox1) sequences. Tick samples were collected in 12 provinces in upper-northeastern Thailand. Three species were found; Rhipicephalus microplus, R. sanguineus, and Haemaphysalis bispinosa. Of these, R. microplus was by far the most abundant species in beef cattle and was widely distributed throughout the area. No cox1 sequence variation was found in the R. sanguineus or H. bispinosa specimens collected. Low nucleotide diversity but high haplotype diversity was observed in R. microplus. All collected R. microplus specimens belonged to lineage A. Mismatch-distribution analysis, as well as Tajima's D and Fu's Fs tests, provided evidence of recent demographic expansion. A subsample of tick specimens was investigated for presence of Anaplasma and Ehrlichia using a fragment of the 16S rRNA gene. Three species of Anaplasma were detected from R. microplus; Anaplasma marginale (19.08%), Anaplasma platys (1.97%) and unidentified Anaplasma strain (0.66%). The infection rate of Ehrlichia was 7.24% (two ticks were infected with E. minasensis (1.97%) and eight with an unidentified Ehrlichia strain (5.26%). No infections were found in R. sanguineus or H. bispinosa. This is the first report of A. platys and E. minasensis in cattle ticks in Thailand, providing information for future epidemiological surveys and control strategies in this region.

Molecular Detection of Zoonotic and Veterinary Pathogenic Bacteria in Pet Dogs and Their Parasitizing Ticks in Junggar Basin, North-Western China

Despite the recognized epidemiological importance of ticks as vectors for pathogens that cause numerous zoonotic and veterinary diseases, data regarding the pathogens of pet dogs and their parasitic ticks in the Junggar Basin are scarce. In this study, a total of 178 blood samples and 436 parasitic ticks were collected from pet dogs in Junggar Basin, Xinjiang Uygur Autonomous Region (XUAR), north-western China. All ticks were identified as Rhipicephalus turanicus sensu stricto (s.s.) according to morphological and molecular characteristics. Rh. turanicus s.s. ticks were collected from pet dogs in China for the first time. Seven tick-borne pathogens, such as Ehrlichia chaffeensis, Anaplasma phagocytophilum, Rickettsia massiliae, Candidatus R. barbariae, Brucella spp., Rickettsia sibirica, and Anaplasma ovis, were detected from ticks, whereas the first five bacteria were detected from blood samples of dogs. Brucella spp. was the most predominant pathogen in both blood samples and ticks of pet dogs, with the detection rates of 16.29 and 16.74%, respectively. Moreover, 17 ticks and 1 blood sample were co-infected with two pathogens, and 1 tick was co-infected with three pathogens. This study provided molecular evidence for the occurrence of Anaplasma spp., Ehrlichia spp., Rickettsia spp., and Brucella spp. circulating in pet dogs and their parasitic ticks in Junggar Basin, north-western China. These findings extend our knowledge of the tick-borne pathogens in pet dogs and their parasitic ticks in Central Asia; therefore, further research on these pathogens and their role in human and animal diseases is required.

Ehrlichia chaffeensis and Four Anaplasma Species With Veterinary and Public Health Significance Identified in Tibetan Sheep (Ovis aries) and Yaks (Bos grunniens) in Qinghai, China

Tick-borne diseases (TBDs) can cause serious economic losses and are very important to animal and public health. To date, research on TBDs has been limited in Qinghai-Tibet Plateau, China. This epidemiological investigation was conducted to evaluate the distribution and risk factors of Anaplasma spp. and Ehrlichia chaffeensis in livestock in Qinghai. A total of 566 blood samples, including 330 yaks (Bos grunniens) and 236 Tibetan sheep (Ovis aries) were screened. Results showed that A. bovis (33.3%, 110/330) and A. phagocytophilum (29.4%, 97/330) were most prevalent in yaks, followed by A. ovis (1.2%, 4/330), A. capra (0.6%, 2/330), and E. chaffeensis (0.6%, 2/330). While A. ovis (80.9%, 191/236) and A. bovis (5.1%, 12/236) infection was identified in Tibetan sheep. To our knowledge, it is the first time that A. capra and E. chaffeensis have been detected in yaks in China. Apart from that, we also found that co-infection of A. bovis and A. phagocytophilum is common in yaks (28.2%, 93/330). For triple co-infection, two yaks were infected with A. bovis, A. phagocytophilum, and A. capra, and two yaks were infected with A. bovis, A. phagocytophilum, and E. chaffeensis. Risk analysis shows that infection with A. bovis, A. phagocytophilum, and A. ovis was related to region and altitude. This study provides new data on the prevalence of Anaplasma spp. and E. chaffeensis in Qinghai, China, which may help to develop new strategies for active responding to these pathogens.

First description of Coxiella burnetii and Rickettsia spp. infection and molecular detection of piroplasma co-infecting horses in Xinjiang Uygur Autonomous Region, China

Q fever, spotted fever rickettsioses and equine piroplasmosis, are some of the most serious equine tick-borne diseases caused by Coxiella burnetii, Rickettsia spp., Babesia caballi and/or Theileria equi. This study surveyed and molecularly characterized these pathogens infecting horses in ten ranches from XUAR, China using molecular technology. Among 200 horse blood samples, 163 (81.5%) were infected with at least one of the pathogens. Rickettsia spp. was the most prevalent pathogen (n = 114, 57.0%), followed by C. burnetii (n = 79, 39.5%), T. equi (n = 79, 39.5%) and B. caballi (n = 49, 24.5%). Co-infections were observed in 61.3% of positive samples in this study. Statistically significant differences were observed between the sampling regions for C. burnetii, B. caballi and T. equi, and also in different age group for C. burnetii and T. equi. The genotype analysis indicated that C. burnetii htpB, Rickettsia spp. ompA, B. caballi rap-1, B. caballi 18S rRNA, T. equi EMA-1 and T. equi 18S rRNA gene sequences from horses in XUAR were variable. To the best of our knowledge, this study is the first report of C. burnetii and Rickettsia spp. infection and co-infected with piroplasma in horses in China. Overall, this study revealed the high infection rate of the pathogens in horses in XUAR, China. The current findings are expected to provide a basis for better tick-borne disease control in the region.

Molecular survey and characterization of Theileria annulata and Ehrlichia ruminantium in cattle from Northwest China

Theileriosis and ehrlichiosis are two important tick-borne diseases affecting cattle farming in China. However, limited information is available regarding prevalence and molecular characterization of Theileria annulata and Ehrlichia ruminantium in cattle in Xinjiang Uygur Autonomous Region (XUAR), northwestern China. In this study, a total of 176 blood samples of cattle from three rural areas of XUAR were collected in June 2017 and were tested by nested-PCR. A total of 34 (19.3%) samples were found to be infected with one or two pathogens. The overall prevalence rates of T. annulata and E. ruminantium were 18.2% and 1.7%, respectively. Phylogenetic analyses revealed that the E. ruminantium isolates from XUAR were located in the same clade but diverged from the isolates from African countries using pCS20 gene while T. annulata isolates from XUAR revealed differences in the genotypes using Tams1 sequences. To our knowledge, this is the first report of E. ruminantium infection in cattle in China. It also provides the first genetic characterization of T. annulata in cattle in XUAR. The current findings are important for understanding the distribution of agents of theileriosis and ehrlichiosis and in designing measures for the prevention and control of tick-borne diseases in cattle, other animals, and humans.

Anaplasma phagocytophilum in sheep and goats in central and southeastern China

BACKGROUND

Anaplasma phagocytophilum is wide spread throughout the world and impacts both human and animal health. Several distinct ecological clusters and ecotypes of the agent have been established on the basis of various genetic loci. However, information on the genetic variability of A. phagocytophilum isolates in China represents a gap in knowledge. The objective of this study was to determine the prevalence and genetic characterization of A. phagocytophilum in small ruminants in central and southeastern China.

METHODS

The presence of A. phagocytophilum was determined in 421 blood samples collected from small ruminants by PCR. Positive samples were genetically characterized based on 16S rRNA and groEL genes. Statistical analyses were conducted to identify ecotypes of A. phagocytophilum strains, to assess their host range and zoonotic potential.

RESULTS

Out of 421 sampled small ruminants, 106 (25.2%) were positive for A. phagocytophilum. The positive rate was higher in sheep (35.1%, 40/114) than in goats (26.4%, 66/307) (P < 0.05). Sequence analyses revealed that the isolates identified in this study were placed on two separate clades, indicating that two 16S rRNA variants of A. phagocytophilum were circulating in small ruminants in China. However, analysis using obtained groEL sequences in this study formed one cluster, which was separate from other known ecotypes reported in Europe. In addition, a novel Anaplasma sp. was identified and closely related to an isolate previously reported in Hyalomma asiaticum, which clustered independently from all recognized Anaplasma species.

CONCLUSIONS

A molecular survey of A. phagocytophilum was conducted in sheep and goats from ten provinces in central and southeastern China. Two 16S rRNA variants and a new ecotype of A. phagocytophilum were identified in small ruminants in China. Moreover, a potential novel Anaplasma species was reported in goats. Our findings provide additional information on the complexity of A. phagocytophilum in terms of genetic diversity in China.

Molecular detection and characterization of Anaplasma spp. in sheep and cattle from Xinjiang, northwest China

BACKGROUND

Anaplasmosis is caused by obligate intracellular bacteria in the genus Anaplasma. These bacterial pathogens are transmitted by ticks and impact both human and animal health. This study was conducted to determine the prevalence and molecular characterization of Anaplasma spp. in ruminants sampled in Xinjiang, northwest China.

METHODS

A survey was performed in August 2012 in rural areas of six counties in Xinjiang province. A total of 250 blood samples from ruminants were collected and tested for the presence of Anaplasma spp. by PCR. Positive samples were genetically characterized based on the 16S rRNA and msp4 genes.

RESULTS

The results showed a high prevalence of Anaplasma spp. in ruminants, with at least three different Anaplasma species detected (A. phagocytophilum, A. bovis and A. ovis). The mean prevalence of single infection with each species was 17.6% (A. phagocytophilum), 4.8% (A. bovis) and 40.5% (A. ovis). Coinfection occurred in 20 (8.0%) animals. Phylogenetic analysis of the 16S rRNA gene of A. bovis and A. phagocytophilum revealed a higher degree of genetic diversity for the latter. The results for A. ovis showed genotypic variation among geographic regions in China. In addition, a closely related isolate to the canine pathogen A. platys was identified in ruminants.

CONCLUSIONS

This survey revealed a high prevalence of Anaplasma sp. infections in sheep and cattle in the northwestern border regions of China, indicating the potential risk of transboundary disease.

Extensive diversity of Rickettsiales bacteria in two species of ticks from China and the evolution of the Rickettsiales

Background

Bacteria of the order Rickettsiales (Alphaproteobacteria) are obligate intracellular parasites that infect species from virtually every major eukaryotic lineage. Several rickettsial genera harbor species that are significant emerging and re-emerging pathogens of humans. As species of Rickettsiales are associated with an extremely diverse host range, a better understanding of the historical associations between these bacteria and their hosts will provide important information on their evolutionary trajectories and, particularly, their potential emergence as pathogens.

Results

Nine species of Rickettsiales (two in the genus Rickettsia, three in the genus Anaplasma, and four in the genus Ehrlichia) were identified in two species of hard ticks (Dermacentor nuttalli and Hyalomma asiaticum) from two geographic regions in Xinjiang through genetic analyses of 16S rRNA, gltA, and groEL gene sequences. Notably, two lineages of Ehrlichia and one lineage of Anaplasma were distinct from any known Rickettsiales, suggesting the presence of potentially novel species in ticks in Xinjiang. Our phylogenetic analyses revealed some topological differences between the phylogenies of the bacteria and their vectors, which led us to marginally reject a model of exclusive bacteria-vector co-divergence.

Conclusions

Ticks are an important natural reservoir of many diverse species of Rickettsiales. In this work, we identified a single tick species that harbors multiple species of Rickettsiales, and uncovered extensive genetic diversity of these bacteria in two tick species from Xinjiang. Both bacteria-vector co-divergence and cross-species transmission appear to have played important roles in Rickettsiales evolution.

Anaplasma phagocytophilum in horses and ticks in Tunisia

Background

Anaplasma phagocytophilum , the causative agent of granulocytic anaplasmosis, affects several species of wild and domesticated mammals, including horses. We used direct and indirect methods to compare and evaluate exposure to A. phagocytophilum in horses in northern Tunisia.

Methods

Serum from 60 horses was tested by IFA for antibodies to A. phagocytophilum , and whole blood was tested for A. phagocytophilum 16S rRNA gene using a nested-PCR. To examine the risk of A. phagocytophilum transmission, 154 ticks that had been collected from horses were examined for the presence of A. phagocytophilum by nested-PCR targeting 16S rRNA gene.

Results

This is the first time that A. phagocytophilum has been detected in horses in Tunisia, with an overall seroprevalence of 40/60 (67%). Six of the seroreactive samples (10%) had an IFA titer of 1:80, 14 (23%) of 1:160, 8 (13%) of 1:320 and 12 (20%) a titer 1 ≥ 640. The seroprevalence revealed no significant regional and sex differences. In contrast, a significant difference was observed between breeds. Eight (13%) of the horses were positive for A. phagocytophilum in the PCR, with no significant breed and age differences. Hyalomma marginatum was a predominant tick species (130/154), and 3 were infected by A. phagocytophilum (a prevalence of 2.3%). The concordance rate of A. phagocytophilum detection between IFA and PCR had a k value of −0.07.

Conclusions

The results presented in this study suggest that horses infested by ticks in Tunisia are exposed to A. phagocytophilum.

Molecular detection of Anaplasma phagocytophilum in Ixodid ticks in Hebei Province, China

A total of 3696 Ixodid ticks, collected from Hebei Province, China, were examined by a nested polymerase chain reaction for the presence of Anaplasma phagocytophilum. Forty-three (15.4%) of 280 pools tested, including 39 (14.6%) of 267 Haemaphysalis longicornis and four (30.8%) of 13 Dermacentor nuttalli, were positive, but no significant difference was found between D. nuttalli and H. longicornis (p>0.05). Sequence and phylogenetic analyses of 16S rRNA gene indicated that A. phagocytophilum in China is genetically diverse. To our knowledge, this is the first evidence of A. phagocytophilum in ticks from Hebei Province, China, and the first documentation of Anaplasma infection in D. nuttalli.

Predominance of Ehrlichia chaffeensis in Rhipicephalus sanguineus ticks from kennel-confined dogs in Limbe, Cameroon

Rhipicephalus sanguineus ticks (n = 63) collected from five dogs (two adults and three puppies) housed in a kennel were screened for Ehrlichial agents (Ehrlichia canis, E. chaffeensis, and E. ewingii) using a species-specific multicolor real-time TaqMan PCR amplification of the disulphide bond formation protein (dsb) gene. Ehrlichia chaffeensis DNA was detected in 33 (56%) ticks, E. canis DNA was detected in four (6%) ticks, and one tick was coinfected. The E. chaffeensis and E. canis nucleotide sequences of the amplified dsb gene (374 bp) obtained from the Cameroonian R. sanguineus ticks were identical to the North American genotypes.

Natural history of Ehrlichia chaffeensis: vertebrate hosts and tick vectors from the United States and evidence for endemic transmission in other countries

Ehrlichia chaffeensis, an intracellular gram-negative zoonotic bacterium, is the causative agent of human monocytotropic ehrlichiosis (HME). In humans, the disease can range from a mild, non-specific illness with few to no clinical signs to a moderately severe to fatal disease, especially those with compromised immune systems. E. chaffeensis is maintained in a complex cycle involving white-tailed deer (WTD; Odocoileus virginianus) as a primary reservoir and the lone star tick (LST; Amblyomma americanum) as a primary vector. Numerous other species are naturally exposed to E. chaffeensis and disease has been documented in some domestic animals and wildlife including domestic dogs and ring-tailed lemurs. The organism has been found throughout the natural range of the LST and as the tick continues to expand its range, the geographic range of risk for E. chaffeensis infections will likely continue to expand. Recent data have indicated that E. chaffeensis, or a closely related organism, has been found in many species of ticks and vertebrate hosts in numerous countries.

Ehrlichia species in Rhipicephalus sanguineus ticks in Cameroon

Ehrlichia and Anaplasma species are tick-transmitted obligately intracellular bacteria that commonly cause disease in dogs worldwide. In addition to causing disease in canines, Ehrlichia chaffeensis, Ehrlichia ewingii, and Anaplasma phagocytophilum are responsible for emerging and life-threatening human zoonoses in the United States. We previously reported a high prevalence of E. canis infection in Cameroonian dogs based on serologic and molecular evidence. This study was undertaken to determine the Ehrlichia species (E. canis, E. chaffeensis, E. ewingii) present in Rhipicephalus sanguineus ticks (n = 92) collected from those dogs (n = 51). Ehrlichial DNA was detected by real-time polymerase chain reaction (PCR) in 28 (30%) unengorged R. sanguineus ticks attached to dogs. E. canis, the causative agent of canine monocytic ehrlichiosis, was detected in 19 (21%) ticks from 15 dogs, E. ewingii was detected in six (6%) ticks from 6 dogs, and E. chaffeensis, the etiologic agent of human monocytotropic ehrlichiosis, was detected in 4 (4%) ticks. Notably, 2 ticks were coinfected with E. chaffeensis and E. canis, one tick with E. canis and E. ewingii, and one tick with E. chaffeensis and E. ewingii. These findings further support our previous conclusion that multiple Ehrlichia species are present in Cameroon and identify R. sanguineus ticks primarily infected with E. canis, but suggest that they may be infected with and transmit other ehrlichial agents in Cameroon, potentially to humans.