Theileria orientalis: a review

Theileria orientalis (also known historically as T. sergenti and T. buffeli) is responsible for benign or non-transforming theileriosis, and exerts its major effect through erythrocyte destruction. The life cycle of T. orientalis is essentially similar to that of other Theileria species, except that the schizonts do not induce transformation and fatal lymphoproliferation. The pathogenesis of anaemia as a result of infection is not clearly established and may be multifaceted. Clinical signs of weakness, reluctance to walk and abortion are early but non-specific indications of disease, particularly if accompanied by a history of cattle being moved. Physical examination may reveal pallor (pale eyes, vaginal mucosa), pyrexia, and elevated heart and respiratory rates. T. orientalis is an economically important parasite of cattle in New Zealand, Australia and Japan, especially where naïve animals are introduced into an endemic area or in animals under stress. Increased awareness of the risks posed by the parasite is required to enable management practices to be implemented to minimise its impact.     

Theileria orientalis in Iran

A benign species of Theileria of cattle in northern Iran proved to be indistinguishable from T. orientalis in the indirect fluorescent antibody test as well as in the morphology of its piroplasms. It was transmissible transstadially by Haemaphysalis punctata.     

Theileria orientalis occurs in Central Africa

An outbreak of bovine theileriosis in Burundi was investigated and the occurrence of Theileria orientalis in Central Africa was confirmed for the first time. Its identity was established on morphological and serological grounds. The parasite was associated with clinical signs and further complicates the disease picture of bovine theileriosis in Africa. Amblyomma variegatum is suspected as being the local vector.     

Cloning and characterization of cDNA encoding a prohibitin-like protein from Theileria orientalis

A cDNA clone encoding a prohibitin-like protein (Toprh) was isolated from a piroplasm cDNA library of Theileria orientalis and its nucleotide sequence was determined. An open reading frame, encoding a polypeptide of 278 amino acid residues, was found in Toprh cDNA sequence. An intron of 89 bp was identified when this cDNA clone was compared with the Toprh gene in the genome of T. orientalis. The deduced amino acid sequence of Toprh shares 93.8, 93.1 and 69.1% identities with the prohibitins of T. parva (from chromosome 1), T. annulata (from chromosome 1), and Plasmodium falciparum, (from chromosome 10), respectively. By Western blot analysis, Toprh was found to be expressed in the piroplasm stage of the parasites.     

Theileria orientalis, a cosmopolitan blood parasite of cattle: demonstration of the schizont stage

Serological and morphological comparison of Theileria orientalis stocks from Australia, Britain, Iran, Japan and the USA with a more pathogenic stock from Korea, corresponding to T sergenti of Russian literature, showed that they all belong to one species, for which the name T orientalis is recommended. T orientalis is now known to occur on all continents. Macroschizonts and microschizonts, found in some of the calves infected with the Korean stock, are described and illustrated. Infections with the Korean stock were associated with early hyperthermia during the period schizonts are found, and commonly with high parasitaemias and anaemia even in unsplenectomised calves. The higher pathogenicity of this stock may be related to a faster rate of division. T orientalis may cause latent infection in sheep. With the exception of the stock from the USA, all stocks could be transstadially transmitted by Haemaphysalis longicornis and, or, H punctata.     

Genetic diversity of Theileria orientalis from cattle in Turkey

Theileria orientalis is usually a benign parasite but some genotypes cause infection and economic losses to the cattle industry. This study was carried out to determine T. orientalis genotypes in cattle. T. orientalis positive 63 sample were analyzed by amplifying the MPSP gene region by PCR. As a result of the SSCP analysis, samples with different band profiles were sent to the sequence analysis and genotypes were determined. T. orientalis genotype-specific PCR was performed to determine the mix genotypes. Type 1 (chitose), type 3 and type 1-type 3 mix were found positive 11.1%, 46%, and 17.5% respectively. In addition, phylogenetic analysis was performed to separate the chitose genotypes, and two samples were found in chitose A, one sample was found in chitose B. Although chitose A genotype is suggested to be more pathogenic than chitose B, but there is little evidence for this. As a result of this study, we showed the presence of pathogenic genotype T. orientalis in Turkey. Therefore, extensive epidemiological studies are required to understand the geographic distribution, different genotypes and clinical pathologies of T. orientalis.     

The first survey of Theileria orientalis infection in Mongolian cattle

In the present study, we have surveyed the presence of a bovine Theileria protozoan, Theileria orientalis, in Mongolian cattle and engorging tick populations from selected provinces and districts in Mongolia. The percentages of infection in the cattle and ticks ranged from 8.8 to 66.6 and from 3.7 to 73.3, respectively, on a per district basis. The genetic diversity of T. orientalis isolates was also studied, based on the protozoan gene encoding a major piroplasm surface protein (MPSP). At least five genotypes (types 1, 3, 5, 7, and N-3) of T. orientalis were found to be circulating among the Mongolian cattle and tick populations. In particular, types 3 and N-3 were common in most of the districts examined, while a strong geographical relationship among the genotypes was not detected in the present study. This is the first epidemiological report describing the presence of T. orientalis infection in Mongolian cattle.     

Theileria orientalis, a blood parasite of cattle. First report in New Zealand

A Theileria sp. piroplasm has been found in cattle from 10 Northland herds. Transmission studies, involving two splenectomized calves, led to its identification as T. orientalis, which has not been previously found in New Zealand. This piroplasm is relatively benign hut can cause severe anaemia in heavily parasitized animals. The cattle tick Haemaphysalis longicornis is considered to be the likely vector.     

Theileria orientalis,a blood parasite of cattle. first report in New Zealand

A Theileria sp. piroplasm has been found in cattle from 10 Northland herds. Transmission studies, involving two splenectomized calves, led to its identification as T. orientalis, which has not been previously found in New Zealand. This piroplasm is relatively benign, but can cause severe anaemia in heavily parasitized animals. The cattle tick Haemaphysalis longicornis is considered to be the likely vector.     

Assessment of criteria for improvement in Theileria orientalis sergenti infection tolerance

We examined the relationships between calf productivity, anemia and Theileria orientalis sergenti infection from records of 109 Japanese shorthorn calves during a grazing period and we quantified the relative importance of the T. orientalis sergenti infection‐resistance criteria used. A decrease in average parasitemia (AvePara) and an increase in average packed cell volume (AvePCV) would cause a decrease in the number of drug treatments. An increase in AvePCV would decrease the number of drug treatments more efficiently than a decrease in AvePara. An increase in AvePCV would cause an increase in dairy gain, while a decrease in AvePara would cause a decrease in dairy gain. Therefore, an improvement in the capacity to control anemia development would improve T. orientalis sergenti infection resistance more efficiently than an improvement in the capacity to control parasitemia development.     

Molecular epidemiological survey of Theileria orientalis in Thua Thien Hue Province, Vietnam

Theileria orientalis is a benign bovine protozoan parasite that occasionally causes serious economic loss in the livestock industry. We report the findings of a molecular epidemiological survey of T. orientalis in 94 Vietnamese yellow cattle, 43 water buffaloes, 21 sheep, 21 goats and 85 blood-sucking ticks of cattle in the Thua Thien Hue province of Vietnam. The major piroplasm surface protein (MPSP) gene of T. orientalis was detected using polymerase chain reaction from 13 cattle (13.8%), 11 water buffaloes (25.6%), 1 sheep (4.8%) and 9 ticks (10.6%). Phylogenetic analysis using MPSP gene sequences showed the presence of seven genotypes, four previously categorized genotypes (Types 1, 3, 5 and 7) and three new genotypes (Types N-1, N-2 and N-3).     

吉林省牛东方泰勒虫与嗜吞噬细胞无形体的流行病学调查

为了进一步了解吉林省牛东方泰勒虫和嗜吞噬细胞无形体的流行情况,对采自吉林省洮南,松原,珲春3个地区的103份牛血液样本,采用PCR和巢式PCR方法分别东方泰勒虫与嗜吞噬细胞无形体进行检测。结果显示,东方泰勒虫在洮南、松原和珲春地区的感染率分别为8.7%,12.5%和92.5%,嗜吞噬细胞无形体在洮南、松原和珲春地区的感染率分别为0,7.5%和12.5%。本研究首次在吉林省洮南地区和松原地区牛体内检测到东方泰勒虫,首次在松原地区和珲春地区牛体内检测到嗜吞噬细胞无形体。本研究结果为吉林省控制和预防牛东方泰勒虫病与嗜吞噬细胞无形体病提供了有效的流行病学依据。     

Observations on the development of tick-transmitted Theileria buffeli (syn T orientalis?) in cattle

The development and morphology of Australian Theileria buffeli in cattle were studied after infection had been experimentally transmitted by the tick, Haemophysalis humerosa. Macroschizonts of T buffeli were demonstrated in Giemsa's stained lymph node preparations for between six and 20 days following tick infestation. The presence of schizonts was confirmed by immunofluorescence with sera from known infected animals. Microschizonts were seen infrequently. The schizonts and piroplasms of T buffeli are morphologically similar to those of T orientalis.     

Genotypic diversity of Theileria orientalis detected from cattle grazing in Kumamoto and Okinawa prefectures of Japan

Theileria orientalis is a benign protozoan species that is widely distributed in Japan, yet sometimes causes serious economic losses in the livestock industry. In this study, we conducted a molecular survey based on genes encoding the major piroplasm surface protein (MPSP) and p23 for T. orientalis detected in cattle grazing in southern areas of Japan, consisting of 2 farms in Kumamoto prefecture (Aso and Kuma districts) and 3 farms in Okinawa prefecture (Ishigaki, Iriomote, and Yonaguni Islands). High prevalence rates of T. orientalis infection were shown in all the cattle populations using the diagnostic MPSP- and p23-PCR assays. Phylogenetic analyses revealed 4 MPSP genotypes and 3 p23 genotypes. Furthermore, MPSP genotype-specific PCR methods were developed in this study and wide distributions of 5-district genotypes of T. orientalis were observed for the examined farms. Our results indicate that at least 5 types of T. orientalis exist in Kumamoto and Okinawa prefectures of Japan and that genotype-specific PCR assays are highly applicable for the quarantine of transported cattle and for epidemiological surveys of bovine theileriosis in Japan.