Epidemiology and genetic diversity of Theileria equi and Babesia caballi in Mongolian horses

Equine piroplasmosis is a tick-borne disease caused by Theileria equi and Babesia caballi in horses. Because of its impact on horse industry, control of this disease is crucial for endemic countries. The control of equine piroplasmosis may be influenced by the genotypic diversity of T. equi and B. caballi. Mongolia, a country with a thriving livestock industry, is endemic for T. equi and B. caballi. However, nationwide epidemiological surveys have not been conducted to determine the current status of infections and genetic diversity of these two parasite species. Therefore, the objective of this research was to investigate the infection rates and genotypes of T. equi and B. caballi in horses across Mongolia. Blood samples were collected from 1353 horses in 15 of Mongolia's 21 provinces, and their DNAs were analyzed with T. equi- and B. caballi-specific PCR assays. Additionally, blood smears were prepared from 251 horses, stained with Giemsa, and examined under a light microscope to identify T. equi and B. caballi. The microscopy revealed that 30 (11.9%) and 4 (1.6%) of the 251 horses were positive for T. equi and B. caballi, respectively. By contrast, PCR assays detected the T. equi and B. caballi in 1058 (78.2%) and 62 (4.6%) horses, respectively. Phylogenetic analysis of 18S rRNA sequences from 42 randomly selected T. equi-positive DNA samples detected the genotypes A and E. On the other hand, the rap-1 sequences from 19 randomly selected B. caballi-positive DNA samples occurred in clades representing the genotypes A and B1, as well as in a distinct clade closely related to the genotype A. Our findings confirm the widespread occurrence of T. equi and B. caballi infections in Mongolian horses, highlighting the need for a comprehensive control approach.

Molecular survey of bovine Babesia species in Bactrian camels (Camelus bactrianus) in Mongolia

Bovine babesiosis, which is caused by species of genus Babesia, is a leading cause of considerable economic losses to the cattle industry each year. Bovine Babesia species have frequently been detected in non-cattle hosts, such as water buffalo (Bubalus bubalis), from which the parasites can be transmitted by ticks to cattle. Therefore, Babesia infections should be minimized not only in cattle but also in non-cattle carriers. In the present study, we surveyed the Bactrian camels (Camelus bactrianus) in Mongolia for three clinically significant bovine Babesia species, including Babesia bovis, B. bigemina, and Babesia sp. Mymensingh, which had been detected previously in Mongolian cattle. We screened blood DNA samples from 305 Bactrian camels in six Mongolian provinces for these species, using parasite-specific PCR assays. Our findings showed that the Bactrian camels in Mongolia were infected with all three Babesia species surveyed. The overall positive rates of B. bovis, B. bigemina, and Babesia sp. Mymensingh were 32.1%, 21.6%, and 24.3%, respectively, whereas 52.5% of the surveyed animals were infected with at least one parasite species. We also found that the female Bactrian camels and the Mongolian native camel breed had significantly higher Babesia positive rates than the male Bactrian camels and the Hos Zogdort breed. In Mongolia, cattle and Bactrian camels usually share common pasture lands for grazing; furthermore, tick species infesting cattle also infest Bactrian camels. Our findings, together with these observations, suggest that the tick transmission of bovine Babesia species might be possible between cattle and Bactrian camels. Therefore, strategies for the control of bovine babesiosis in Mongolia should include methods to minimize bovine Babesia species infections in Bactrian camels.

Nationwide serological surveillance of non-tsetse-transmitted horse trypanosomoses in Mongolia

In Mongolia, horses play important roles, not only in livestock production, but also in terms of culture, tradition, and Mongolian beliefs. Although the presence of non-tsetse-transmitted horse trypanosomoses, which are caused by infections with Trypanosoma evansi (surra) and T. equiperdum (dourine), has been reported in the country, whether there is a nationwide epidemic of these infectious diseases is unknown. In the present study, a nationwide surveillance of horse trypanosomoses was performed. The sample sizes for each province, the whole country, and male and female horses were, respectively, 96, 2,400, and 316 and 306. In total, 3,641 samples of horse sera were collected by simple random sampling. The rTeGM6-4r-based ELISA, which was applied for surra against cattle and water buffalo and dourine against horse, revealed that the overall sero-prevalence of the diseases in Mongolia was 4.8%. Among them, high sero-prevalences were observed in the central provinces (5.2–11.0%, p < 0.05) of the country. The sero-prevalence was significantly higher in females than in males (6.0% and 4.0%, p < 0.05, respectively) and in non-castrated males (8.4%, p < 0.01) compared with castrated males (3.0%). These results suggested that currently, horse trypanosomoses are a nationwide endemic problem in Mongolia. Knowledge of the nationwide endemic status of non-tsetse-transmitted horse trypanosomoses in Mongolia will be useful to prevent these diseases.

Molecular epidemiological survey of Babesia bovis, Babesia bigemina, and Babesia sp. Mymensingh infections in Mongolian cattle

Bovine babesiosis caused by Babesia species is an economically significant disease of cattle. Severe clinical babesiosis in cattle is caused by Babesia bovis, B. bigemina, and the recently discovered Babesia sp. Mymensingh. Mongolia is an agricultural country with a large cattle inventory. Although previous studies have detected active infections of B. bovis and B. bigemina in Mongolian cattle, only a few provinces were surveyed. Additionally, the endemicity of Babesia sp. Mymensingh in Mongolia remains unknown. We screened blood DNA samples from 725 cattle reared in 16 of the 21 Mongolian provinces using B. bovis-, B. bigemina-, and Babesia. sp. Mymensingh-specific PCR assays. The overall positive rates of B. bovis, B. bigemina, and Babesia sp. Mymensingh were 27.9% (n = 202), 23.6% (n = 171), and 5.4% (n = 39), respectively. B. bovis and B. bigemina were detected in cattle in all surveyed provinces; whereas Babesia sp. Mymensingh was detected in 11 of the 16 surveyed provinces. On a per province basis, the B. bovis- B. bigemina-, and Babesia sp. Mymensingh-positive rates were 5.9-52.0%, 9.1-76.3%, and 0-35.7%, respectively. In conclusion, this is the first report of Babesia sp. Mymensingh in Mongolia. In addition, we found that species of Babesia that are capable of causing bovine clinical babesiosis, including B. bovis, B. bigemina, and Babesia sp. Mymensingh, are widespread throughout the country.

A Seroepidemiological Survey of Theileria equi and Babesia caballi in Horses in Mongolia

Equine piroplasmosis caused by Theileria equi and Babesia caballi is an economically important disease with a worldwide distribution. The objective of the present study was to investigate the seroepidemiology of T. equi and B. caballi in horses reared in various Mongolian provinces. Serum samples prepared from blood collected from horses in 19 Mongolian provinces were screened for antibodies specific to T. equi and B. caballi using enzyme-linked immunosorbent assays based on recombinant forms of T. equi merozoite antigen-2 and the B. caballi 48-kDa merozoite rhoptry protein, respectively. Of 1,282 horses analyzed, 423 (33%) and 182 (14.2%) were sero-positive for T. equi and B. caballi, respectively. Additionally, 518 (40.4%) were positive for at least 1 parasite species, of which 87 (16.8%) were co-infected with both parasites. Both T. equi and B. caballi were detected in all surveyed provinces, and on a per province basis the positive rates ranged from 19.0 to 74.2% and 4.5 to 39.8%, respectively. Theileria equi- and B. caballi-positive rates were comparable between male horses (31.9 and 14.1%, respectively) and female horses (34.5 and 14.3%, respectively). However, the positive rates were higher in the >3-yr-old age group (37.7 and 15.6%, respectively) compared with the 1-3-yr-old age group (19.4 and 10.0%, respectively). These findings confirmed that T. equi and B. caballi infections are widespread among horses all over Mongolia, and that horse age is a risk factor for infection in this country. Our results will be useful for designing appropriate control measures to minimize T. equi and B. caballi infections among Mongolian horses.