Molecular Detection and Identification of Babesia spp., Theileria spp., and Anaplasma spp. in Sheep From Border Regions, Northwestern China

Molecular prevalence and associated infection risk factors of tick-borne protozoan and rickettsial blood pathogens in small ruminants

BACKGROUND

Tick-borne blood pathogens cause highly pathogenic diseases, which are associated with substantial economic losses in ruminants. Despite this, epidemiological research on these pathogens remains neglected in many countries. This study initiated a regional epidemiological survey that included the detection of molecular prevalence, associated risk factors, and gene sequencing, combined with phylogenetic analysis, targeting the two main tick-borne blood protozoan and rickettsial pathogens of Babesia, Theileria, and Anaplasma that infect small ruminants. One hundred blood samples were collected from 76 sheep and 24 goats.

RESULTS

Microscopic examination of Giemsa-stained blood films revealed that 73% of the samples were infected with at least one species of the three blood pathogenic organisms. Molecular diagnosis based on the 18 S rRNA for Babesia and Theileria species and the major surface protein 4 (msp4) for Anaplasma species, revealed that 43% of the small ruminants were infected with at least one of these pathogens. The animal's sex was the most significant associated risk factor, with 49.4% of female animals infected compared with only 4% of male animals (P < 0.05). The open breeding system recorded the highest infection rate for tick-borne blood pathogens. Homology-based and phylogenetic analyses indicated that the specific isolate species were Babesia ovis (B. ovis), Theileria ovis (T. ovis), and Anaplasma ovis (A. ovis), with sequences showing significant identities with isolates from sheep, goats, and other animal species, and geographically diverse countries in Africa, Asia, and Europe, in addition to Egypt.

CONCLUSION

This was the first molecular evidence of B. ovis, T. ovis, and A. ovis infections in sheep and goat populations in the North Coast region of Egypt. More extensive studies are required to develop an epidemiological map of blood pathogenic organisms, while more effective control strategies are required to reduce the burden of tick-borne pathogens on small ruminants.

An Update of Evidence for Pathogen Transmission by Ticks of the Genus Hyalomma

Current and likely future changes in the geographic distribution of ticks belonging to the genus Hyalomma are of concern, as these ticks are believed to be vectors of many pathogens responsible for human and animal diseases. However, we have observed that for many pathogens there are no vector competence experiments, and that the level of evidence provided by the scientific literature is often not sufficient to validate the transmission of a specific pathogen by a specific Hyalomma species. We therefore carried out a bibliographical study to collate the validation evidence for the transmission of parasitic, viral, or bacterial pathogens by Hyalomma spp. ticks. Our results show that there are very few validated cases of pathogen transmission by Hyalomma tick species.

Distribution and Molecular Epidemiology of Anaplasma ovis in Melophagus ovinus and Small Ruminants in Border Regions of South Xinjiang, China

Background: Anaplasma ovis are obligate intracellular bacteria that can endanger human and animal health, and they can be transmitted by arthropod vectors, such as Melophagus ovinus and ticks. Materials and Methods: In this study, 433 specimens, including 370 M. ovinus and 63 sheep blood samples, were collected from nine districts of South Xinjiang to investigate the distribution and molecular epidemiology of A. ovis in M. ovinus and small ruminant. Results: DNA of A. ovis was detected in 109 (25.2%, 109/433) of the 433 samples using PCR and sequencing. The analysis of A. ovis msp4 sequences revealed four different genotypes, including genotype III (47.7%; 52/109), GB3 (34.0%; 37/109), AoGOv3 (15.6%; 17/109), and XJ9 (2.8%; 3/109). Conclusions: To the best of our knowledge, A. ovis genotypes GB3, AoGOv3, and XJ9 detected in this study are the first to be reported in M. ovinus, and our data indicate that XJ9 is a novel A. ovis genotype presented herein for the first time. These findings provide important references for the new understanding and prevention of A. ovis in border counties in China.

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.

Molecular detection of Anaplasma spp., Babesia spp. and Theileria spp. in yaks (Bos grunniens) and Tibetan sheep (Ovis aries) on the Qinghai-Tibetan Plateau, China

BACKGROUND

Anaplasma, Babesia and Theileria are tick-borne pathogens (TBPs) that affect livestock worldwide. However, information on these pathogens in yaks (Bos grunniens) and Tibetan sheep (Ovis aries) on the Qinghai-Tibet Plateau (QTP), China, is limited. In this study, Anaplasma spp., Babesia spp. and Theileria spp. infections were assessed in yaks and Tibetan sheep from Qinghai Province.

METHODS

A total of 734 blood samples were collected from 425 yaks and 309 Tibetan sheep at nine sampling sites. Standard or nested polymerase chain reaction was employed to screen all the blood samples using species- or genus-specific primers.

RESULTS

The results showed that 14.1% (60/425) of yaks and 79.9% (247/309) of Tibetan sheep were infected with at least one pathogen. Anaplasma ovis, Anaplasma bovis, Anaplasma capra, Anaplasma phagocytophilum, Babesia bovis and Theileria spp. were detected in this study, with total infection rates for all the assessed animals of 22.1% (162/734), 16.3% (120/734), 23.6% (173/734), 8.2% (60/734), 2.7% (20/734) and 19.3% (142/734), respectively. For yaks, the infection rate of A. bovis was 6.4% (27/425), that of B. bovis was 4.7% (20/425) and that of Theileria spp. was 3.3% (14/425). Moreover, 52.4% (162/309) of the Tibetan sheep samples were infected with A. ovis, 30.1% (93/309) with A. bovis, 56.0% (173/309) with A. capra, 19.4% (60/309) with A. phagocytophilum and 41.4% (128/309) with Theileria spp.

CONCLUSIONS

This study revealed the prevalence of Anaplasma spp., Babesia spp. and Theileria spp. in yaks and Tibetan sheep in Qinghai Province, China, and provides new data for a better understanding of the epidemiology of TBPs in these animals in this area of the QTP, China.

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.

Infection by haemopathogens and tick infestation of sheep during summer season in Constantine region, Northeast Algeria

A study on tick infestation of 43 sheep with clinical symptoms of piroplasmosis and anaplasmosis was carried out during summer seasons of 2016 and 2017 in 34 sheep flocks from Beni Hamidene locality, district of Constantine, Northeast Algeria. Only animals with clinical symptoms of piroplasmosis and/or anaplasmosis were checked for tick infestation. Among the 43 examined sheep, 58 ± 15% were infested by ticks. A total of 185 adult ticks (100 males and 85 females) were collected from the 25 sheep. Two tick genera, Rhipicephalus and Hyalomma consisting of four species were collected, Rhipicephalus bursa was the most frequent tick (164/185; 88.6 ± 4.6%), followed by Rhipicephalus sanguineus sensu lato (16/185; 8.6 ± 4%), Rhipicephalus (Boophilus) annulatus (4/185; 2.2 ± 2.1%) and Hyalomma scupense (1/185; 0.5 ± 1%). Mean overall tick infestation intensity was 7.4. Mixed infestations with two tick species were found in 10 sheep (23.3 ± 12.6%). All farmers (34/34) used ivermectin, and only 11% of them used acaricide to control ticks. The majority of R. bursa ticks (87/185; 45 ± 7%) were located on the ears 37/185; 20 ± 6%) and the testicles (50/185; 27 ± 6%). Giemsa-stained blood smears examination showed the presence of three haemopathogens: Anaplasma spp. (19/43; 44 ± 15%); Babesia spp. (6/43; 14 ± 10%) and Theileria spp. (1/43; 2 ± 4%). These results showed the presence of several low infestation burdens by ticks transmitting three haemopathogens.

Molecular survey on prevalence and risk factors of Anaplasma spp. infection in cattle and sheep in West of Iran

Tick-borne pathogens (TBPs) in general and Anaplasma spp. in particular are known as economically important agents of diseases of domestic ruminants worldwide. Little information exists regarding the prevalence and the role of various factors affecting the occurrence of anaplasmosis in the west of Iran. The present study was carried out to determine the prevalence and risk factors associated with Anaplasma pathogens in Kurdistan province, west of Iran. During spring and summer 2016, blood samples were collected from a total of 401 livestock animals from different farms distributed in the Kurdistan province. Furthermore, data on general husbandry traits and management practices were recorded. PCR examination showed an overall prevalence of 37.3 and 10% in cattle and sheep, respectively. Cattle were infected with A. phagocytophilum (23.8%), A. bovis (15.4%), and A. marginale (13.9%) while sheep were infected with A. ovis (10%) and A. phagocytophilum (3.5%). The occurrence of anaplasmosis was considerably higher in cattle compared to sheep (P < 0.0001). Based on results of logistic regression models, risk of Anaplasma infection was significantly higher in crossbreeds (odds ratio (OR) = 1.93, 95% confidence interval (CI) = 1.025-3.65, P = 0.042) compared with local cattle breeds. Furthermore, being older than 1 year was associated with increased risk of Anaplasma infection in cattle (OR = 2.18, 95%, CI = 1.022-4.68, P = 0.044) and sheep (OR = 2.86, 95%, CI = 1.006-8.22, P = 0.049) compared to younger individuals. No difference was observed between the counties. Identifying potential risk factors and potential vectors and reservoirs contribute to the successful control and prevention of tick-borne diseases.