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PubMed1977

The serological relationship of a British Theileria with other Theileria species using the indirect fluorescent antibody test.

Antisera and antigens of a Theileria species isolated from British cattle were compared with those of six strains of Theileria mutans from geographically separated areas in East and South Africa, using the indirect fluorescent antibody (IFA) test. It was found that the British Theileria species did not react in the IFA test with these strains of T mutans. The British Theileria species was also compared with a variety of other Theileria species using the IFA test and no reactions were detected. It was concluded that the British Theileria species, which has been designated T mutans Essex, could be distinct from African T mutans.

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PubMed1977

Biological differences between African Theileria mutans (Theiler 1906) and two benign species of Theileria of cattle in Australia and Britain.

Serological and morphological comparisons between the theilerias found in Australian and British cattle and of these with African Theileria mutans (Theiler 1906) showed that the Australian and British parasites were similar to each other but different from T. mutans. Further investigations are required to determine taxonomic affinities between the Australian and British theilerias and T. sergenti, a similar parasite found in eastern Asia.

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PubMed1977

Isolation of a Theileria species from Eland (Taurotragus oryx) infective for cattle.

Theileria infections were induced in cattle by feeding ticks on them from 3 sources: (a) adult rhipicephalid ticks obtained from the vegetation in a paddock containing an eland EAO at the Animal Orphanage, Nairobi National Park, Kenya, (b) Rhipicephalus appendiculatus adults fed as nymphs on the same eland, (c) R. pulchellus adults fed as nymphs on an eland W 68 captured in the Machakos district of Kenya. Both eland were harbouring Theileria parasites at the time nymphal ticks were fed. Mild infections were produced when adult ticks from these 3 batches were applied to cattle associated with low numbers of schizonts and piroplasms. The indirect fluorescent antibody test demonstrated that cattle recovered from infections resulting from the above 3 tick batches from eland W 68 and EAO produced antibodies which reacted with schizont antigen of the Theileria species (eland) and Theileria species (Githunguri) which had been isolated from cattle and not to antigens of other Theileria species used. The cattle recovered from the Theileria species (eland) were fully susceptible to a lethal challenge of a T. parva (Muguga) stabilate. It was concluded that the Theileria species (eland) and Theileria species (Githunguri) may be closely related and could represent a new species of Theileria infective to cattle.

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PubMed1979

The differential diagnosis of the bovine theilerias of Southern Africa.

It is currently thought that the following species or sub-species of Theileria occur in cattle in southern Africa: Theileria parva parva (East Coast fever), Theileria parva lawrencei (Corridor disease), Theileria parva bovie (Rhodesian theileriosis), Theileria mutans proper (transmitted by Amblyomma species), so-called Theileria mutans (a non-pathogenic species transmitted by Rhipicephalus appendiculatus, possibly identical with Theileria taurotragi) and Theileria velifera. The parasites can be differentiated on serological, morphological and epidemiological grounds. The four true species are serologically distinct. T. mutans proper and T. velifera show morphological differences from the other two species in some stages of their development. The T. parva group are the only parasites that are commonly pathogenic. Differentiation of the three members of this group is based on differences in the numbers of schizonts and piroplasms present and on differences in the epidemiology of the diseases they cause.

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PubMed2026

Prevalence of Theileria luwenshuni in goats (Capra hircus) on Tarama Island, Okinawa, Japan.

Caprine theileriosis is an economically important tick-borne disease caused by various Theileria species, particularly Theileria lestoquardi, Theileria luwenshuni, and Theileria uilenbergi, in goats (Capra hircus). Goat farming plays an economically and culturally important role on Tarama Island, Okinawa, Japan. Because goats on the island are mainly managed under an extensive grazing system, tick infestation is common. However, Theileria infections have not previously been investigated in goats on Tarama Island. To address this, archived DNA samples prepared from blood collected from 44 goats on Tarama Island were screened using a universal PCR assay targeting 18S rRNA sequences of Theileria and Babesia species. Two DNA samples were positive, and sequencing analysis of the amplicons identified T. luwenshuni. To further investigate the epidemiology of T. luwenshuni on Tarama Island, blood samples were subsequently collected from 96 goats across 19 farms. From each blood sample, a thin blood smear was prepared and genomic DNA was extracted. Microscopic examination of Diff-Quik-stained smears detected intraerythrocytic Theileria-like organisms in 35 (36.5%) goats. In addition, screening of DNA samples using a newly developed T. luwenshuni-specific PCR assay detected 77 (80.2%) positive goats, and the subsequent sequencing analysis confirmed the PCR results. Given that T. luwenshuni can cause severe disease in small ruminants, our findings highlight the importance of managing T. luwenshuni infection in goats on Tarama Island.

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PubMed1979

Cell-mediated immunity to Theileria-transformed cell lines.

In East and Central Africa the protozoan parasite Theileria parva causes a disease of cattle called East Coast fever (ECF). In Kenya alone between 60,000 and 85,000 cattle die from ECF every year. Infected animals can recover from ECF either naturally or after treatment with tetracyclines or menoctone and are subsequently able to resist challenge with the homologous strain of parasite. That this acquired resistance is due to cell-mediated rather than humoral immunity has been suspected but never decisively shown. A major difficulty in studying immunity to ECF has been the lack of inbred animals for studying Theileria-specific immunity in the absence of allogeneic histocompatibility barriers. We have avoided this problem by measuring cell-mediated immune responses in a syngeneic system in vitro. Unidirectional mixed lymphocyte cultures (MLC) were set up using bovine peripheral blood lymphocytes (PBL) as responder cells and autologous cell lines transformed in vitro by T. parva as stimulator cells. In these cultures, DNA synthesis was induced in PBL from both normal and Theileria-immune animals. However, cytotoxic lymphocytes were induced only in cultures containing responder lymphocytes from Theileria-immune cattle. The results show that Theileria-transformed cells express antigens which are recognized by effector cells and provide evidence that cell-mediated cytotoxic mechanisms function in immunity to ECF.

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PubMed1977

Serological studies on strains of Theileria mutans isolated in East Africa using the indirect fluorescent antibody technique.

The serological response of cattle infected with Theileria mutans (Aitong) by cyclical and mechanical transmission was studied using the indirect fluorescent antibody technique with T. mutans piroplasm and schizont antigens. Cattle infected by either method show high antibody titres against piroplasm antigens which persist for periods of over one year. Only cattle with tick-induced infections had an antibody response to schizont antigen. The serological cross-reactions of T. mutans (Ationg) with other strains of T. mutans isolated in East and South Africa sere investigated as were the serological cross-reaction of T, mutans (Aitong) and other species of Theileria. It was concluded that isolated of Theileria in East Africa which behaved like T. mutans were serologically indistinguishable using the IFA technique while other species of Theileria were easily distinguishable from T. mutans.

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PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania IX. Unidentified bovine Theileriae.

Two strains of nonpathogenic Theileriae, designated as Theileria sp. (Idobogo) and Theileria sp. (Mwanza), were isolated from cattle in southern and northern Tanzania respectively. They were similar to each other, producing low numbers of T. parva-like macroschizonts and of small piroplasms. Both were readily transmitted by Rhipicephalus appendiculatus. No serological relationship with T. mutans was found, while serum of some of the recovered animals gave fleeting, low titres in the indirect fluorescent antibody test to T. parva schizont antigen. Recovered animals were fully susceptible to T. parva challenge. The possibility that these strains may be similar to Theilleria sp. (Githunguri) of Kenya is suggested.

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PubMed1978

In vitro studies on the action of menoctone and other compounds on Theileria parva and T. annulata.

Bovine lymphoblastoid cell cultures permanently infected with Theileria parva and T. annulata were used in an in vitro screen to test a wide range of compounds for chemotherapeutic activity against these parasites. Only two compounds, menoctone and methotrexate, showed significant activity, which has subsequently been confirmed by tests in infected cattle. Menoctone was about 100 times more active than methotrexate. Mixtures of menoctone and various other other compounds were tested, but showed no potentiation. The activity of menoctone was antagonized by cycloguanil and methotrexate. The in vitro test represents a rapid, cheap, and apparently reliable method of screening compounds for activity against Theileria.

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PubMed1979

Theileria mutans in Nigeria.

Two strains of bovine Theileria from northern Nigeria were shown to be identical to Theileria mutans in the indirect immunofluorescent antibody test. One of the strains was transmitted by the tick Amblyomma variegatum; large macroschizonts, typical for T mutans, could be demonstrated in infected cattle. It is concluded from these experiments and from the literature that there is reliable evidence so far for the occurrence in Nigeria of only two bovine Tehileria species, T mutans and T velifera.

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PubMed1979

On the life cycle of Theileria velifera (Uilenberg, 1964) in the gut and the haemolymph of the tick vector Amblyomma variegatum (Fabriciu, 1794).

The development of Theileria velifera in the gut and the haemolymph of the tick vector Amblyomma variegatum is described. Between days three and eight after repletion various sexual stages are present in the gut of the nymphs. Zygotes were detected in the gut on day 14, while undifferentiated kinetes first appeared on day 15. In the haemolymph, differentiated kinetes were observed from day 16 after repletion onwards. Zygotes and kinetes were also found after the moult, in the adult tick, for a prolonged period of time. The results of this study show that the developmental stages of T. velifera in the gut and haemolymph are characteristic of the genus Theileria.

Animals↗

PubMed1978

East Coast fever: cultivation in vitro of cell-free schizonts and merozoites of Theileria parva and their immunogenicity in cattle.

Cell-free schizonts and merozoites of Theileria parva and Theileria lawrencei, derived from parasitized lymphoid cell lines, were propagated in vitro using enriched medium. Use of radioisotopic markers showed that the bovine cell-independent parasites passed through a limited but marked replication by day 4. If normal bovine RBC were inoculated in vitro with the cell-free merozoites, development of piroplasms in the RBC occurred. Electron microscopic studies of the merozoites and piroplasms revealed their structure to be similar to previous descriptions. Cattle inoculated with T parva merozoites and schizonts and later challenge exposed with homologous stabilate developed leukopenia, showed low macroschizont index, and survived longer than unvaccinated controls.

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PubMed1978

Erythrocytic forms of Theileria velifera.

The enigmatic veil associated with the cattle parasite Haematoxenus veliferus has been shown to be crystallike in ultrastructure and to stain with benzidine like haemoglobin. The ultrastructure of the organism is similar to that of other theilerial parasites. As less distinct veil-like structures are known to occur with some other Theileria species, and in one case, have also been shown to be crystalline in structure, it is proposed to sink the genus Haematoxenus as a synonym of Theileria.

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PubMed2026

Can host genetics transform the sustainable control of tropical theileriosis? Insights from the Tick-Theileria interface.

Tropical theileriosis, caused by the tick-transmitted apicomplexan parasite Theileria annulata, remains a major constraint on cattle production across North Africa, the Mediterranean basin, the Middle East and South Asia. Current control depends on acaricides, the theilericidal drug buparvaquone and live attenuated schizont vaccines, but acaricide resistance, buparvaquone-resistance mutations and the logistical demands of vaccination are eroding the sustainability of these tools. Host genetics offers a complementary and durable alternative. Indigenous Bos indicus breeds are consistently more resistant to ticks and tolerate T. annulata infection better than exotic Bos taurus cattle, and this advantage has a measurable heritable component. Unlike previous reviews, which treat tick resistance, T. annulata immunobiology and livestock genomic selection as separate subjects, we integrate all three and assess host genetics specifically against the failure modes of current control. We review the tick, parasite and host interface, the evidence for natural resistance, and the genetic and immunological mechanisms involved, including signal-regulatory protein, bovine major histocompatibility complex class II and inflammatory pathway genes. We then assess whether genomic selection, multi-omics, machine learning and gene editing can translate these mechanisms into resistant cattle, and we weigh the biological, economic and infrastructural barriers to implementation. The evidence indicates that host genetics will not replace existing control but could reduce reliance on acaricides and chemotherapy. That contribution remains prospective rather than demonstrated: no resistance marker for T. annulata has yet been validated, prediction accuracies are moderate and transfer poorly between breeds, and no endemic production system has implemented selection for resistance.

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PubMed2004

Bovine leukocyte antigen major histocompatibility complex class II DRB32703 and DRB31501 alleles are associated with variation in levels of protection against Theileria parva challenge following immunization with the sporozoite p67 antigen.

Initial laboratory trials of an experimental subunit vaccine against Theileria parva based on the 67-kDa major sporozoite surface antigen revealed a range of responses to challenge. We have analyzed convergence in seven sets of monozygotic twins which suggests that genetic factors may have an influence in determining the degree of protection provided by p67 immunization. In addition, we have examined whether allelic diversity at major histocompatibility complex class II loci influences protection. Analysis of bovine leukocyte antigen DRB3 diversity in 201 animals identified significant associations with vaccine success (DRB3*2703; P = 0.027) and vaccine failure (DRB3*1501; P = 0.013). Furthermore, DRB3*2703 was associated with the likelihood of immunized animals showing little to no clinical signs of disease following challenge. We discuss the acquired and innate immune mechanisms that may be behind the associations described here.

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PubMed1979

Rapid quantitative assessment of Theileria infection in ticks.

A simplified method for methyl green pyronin staining is described for Theileria parva and T. annulata in whole salivary glands of Rhipicephalus appendiculatus and Hyalomma anatolicum subspecies respectively. The stain gives results comparable with Feulgen staining and can be used after the ticks have been in cold storage for 3 days. There is considerable variability in the rate and intensity of infection of these ticks with theilerial parasites and it is concluded that the method permits large samples (60 ticks per person per day) to be examined to overcome this variability when assessing infection quantitatively.

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PubMed1979

The production of nymphs of Hyalomma anatolicum anatolicum for experimental infection with Theileria annulata.

Methods are described for the production of nymphs of Hyalomma anatolicum anatolicum for later use in transmission experiments with Theileria annulata where the timing of the application of nymphs to infected cattle needs to be accurately controlled. Larvae are fed on the torsos of rabbits where approximately 98% undergo a two-host feeding cycle. This cycle is interrupted 2 days after the first larvae moult into nymphs by killing the rabbits and the nymphs are then collected with a suction pump. Nymphs produced by the interrupted larval feeding method feed well on cattle, in regard to timing of detachment and weight, compared with nymphs produced by interrupted feeding on rabbits.

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PubMed1978

Development of infectivity in Hyalomma detritum (Schulze, 1919) ticks infected with Theileria annulata (Dchunkowsky and Luhs, 1904).

The time-course for the development of infectivity was studied in Hyalomma detritum ticks fed as pre-imagoes on calves infected with Theileria annulata. Unfed adults derived from infected nymphs were non-infectious when inoculated into susceptible calves, whereas ticks of both sexes that had fed for 2-3 days or longer on calves or rabbits were always infectious. Some adults fed for only 1-2 days were infectious, whereas others were not. As few as 2 ticks were capable of infecting susceptible calves.

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