Non-specific immunization against bovine tropical theileriosis (Theileria annulata) using killed Corynebacterium parvum

Killed Corynebacterium parvum was used as an adjuvant for the production of non-specific resistance against Theileria annulata in cattle. Groups of cross-bred (Bos indicus X Bos taurus) calves were administered C. parvum adjuvant subcutaneously and were then challenged with T. annulata-infected ticks on 45, 60 or 90 days later. The challenge caused mild reactions in the protected calves. None of the 10 immunized calves died due to theileriosis, whereas all three paris of susceptible control calves died due to theileriosis. It appears from this pilot study that cattle can be protected non-specifically with C parvum adjuvant against T. annulata.     

In vivo comparison of susceptibility between Bos indicus and Bos taurus cattle types to Theileria parva infection

The objective of this study was to determine whether Bos taurus cattle differ form Bos indicus in their susceptibility to infection with the Muguga stabilate of Theileria parva and in their resistance to the resultant disease. Ten Friesians (B. taurus), ten improved Borans (B. indicus), ten unimproved Borans (B. indicus) and ten Zebus (B. indicus) born to dams from an East Coast fever (ECF) endemic area were inoculated with an infective dose50 dilution of T. parva Muguga stabilate 147. All the animals except one Friesian and one Zebu developed schizont parasitosis. All the improved Borans, nine of the Friesians, eight of the unimproved Borans and six of the Zebus developed a febrile response. Four of the improved Borans, four of the Friesians and three of the unimproved Borans died of theileriosis. No significant difference (P > 0.05) in the prepatent period occurred between the groups, but the Zebus had a significantly shorter duration of schizont parasitosis (P > 0.05) and took a significantly shorter time to recover (P > 0.05) than the other three groups. There was no significant difference in the two parameters between the other three groups. The study showed that three B. indicus breds and a B. taurus breed are equally susceptible to T. parva infection. However, Zebus born to dams from an ECF endemic area showed a better ability to control the course of disease than cattle from ECF free areas.     

Immunization of cattle with a Theileria parva bovis stock from Zimbabwe protects against challenge with virulent T.p. parva and T.p. lawrencei stocks from Kenya

Following inoculation of 34 Bos indicus (Boran) cattle with a Theileria parva bovis (Boleni) stock from Zimbabwe, 18 animals underwent mild theilerial reactions, 12 underwent moderate reactions, three suffered severe reactions and one died. When these animals were subsequently challenged with different virulent stocks of either T.p. parva (Muguga, Marikebuni or Mariakani) or T.p. lawrencei (Ngong 1 or Nanyuki) from Kenya, all except two animals resisted challenge. The two reactors were part of the group challenged with the T.p. parva (Mariakani) stock. All 12 susceptible control animals underwent severe reactions and 11 died. The results of these experiments suggest that T.p. bovis (Boleni) may be used in some situations to immunize cattle against East Coast fever without the need to provide concomitant chemotherapy as in the infection and treatment method of immunization.     

Effect of timing and intensity of challenge following immunization against East Coast fever

When groups of Theileria parva parva Muguga-immunized cattle were given a homologous lethal challenge at different times after immunization, it was found that 4/6, 5/6, 6/6 and 6/6 animals survived when challenged on Days 5, 10, 20 and 30, respectively, post-immunization. With a heterologous challenge (T.p.parva Marikebuni), 2/6, 5/6, 4/6, 4/6 and 5/6 cattle survived when challenged on Days 5, 10, 20 and 30, respectively, after immunization. All controls, except one, died of East Coast fever (ECF). The survivor underwent severe ECF and recovered after a prolonged convalescence. When two T.p.parva Muguga-immunized animals were each given homologous challenge by application of 1000 infected ticks (infection rate of 20 infected acini (i.a.) per tick), both survived a mild ECF reaction. When groups of T.p.parva Muguga- or T.p.parva Muguga/Marikebuni-immunized cattle were challenged with different doses of T.p.parva Muguga sporozoites (equivalent of 140, 1400 and 14,000 i.a. per animal), 28/29 cattle survived. All controls died of ECF. It was concluded that cattle could be safely exposed to tick challenge 1 week after immunization by infection and treatment using appropriate immunizing stock(s). Massive homologous challenge did not break through the immunity induced by the immunization procedure.     

Immunisation of cattle against theileriosis in Coast Province, Kenya: laboratory evaluation of a Theileria parva parva stabilate for use in 'infection and treatment' immunisation in the field

Theileria parva parva Marikebuni stock, previously shown to give good protection to immunised cattle in Kilifi District, Coast Province of Kenya, was chosen for large scale immunisation in the district. A large sporozoite stabilate was prepared and evaluated for efficacy and safety in the 'infection and treatment' method, using a long or short acting formulation of oxytetracycline. Susceptible cattle were infected with selected doses of stabilate (10(0), 10(-1), 10(-1.7) and left either as untreated controls, or treated with one of the two oxytetracycline formulations. It was concluded that stabilate dilution at 10(-0.7) or 10(-1) in combination with either formulation of oxytetracycline would effect satisfactory immunisation. The short acting oxytetracycline treatment was judged to be the most efficacious in protecting cattle against homologous challenge. On heterologous challenge it was found that T p parva Marikebuni immune cattle were protected against seven T p parva stocks from Kilifi District and also against four stocks of T p parva from other areas of Kenya. In addition, the Marikebuni stock provided partial protection against challenge by T p lawrencei stocks. Furthermore, cattle immune to T p parva and T p lawrencei were protected against lethal challenge of T p parva Marikebuni stock. Thus, it appears that large scale immunisation of cattle against theileriosis in Kilifi District could be undertaken using the Marikebuni stock. With continued assessment, this stock could provide a master theilerial stock for immunisation against cattle theileriosis in areas free of buffaloes elsewhere in Kenya.     

Immunization against East Coast fever: the use of selected stocks of Theileria parva for immunization of cattle exposed to field challenge

Two antigenically different stocks of Theileria parva parva (Kilifi and Marikebuni), previously characterized as belonging to groups A and C respectively on monoclonal antibody (MAb) profiles, were selected for immunization of different breeds of cattle against East Coast fever (ECF) by the infection and treatment method. A total of 52 immunized cattle and 33 susceptible controls of different group sizes were exposed to field challenge by ticks for periods of 42-90 days at three field sites where ECF is endemic on the Kenyan coast. All immunized cattle survived ECF challenge, but 87% of the controls died of the disease. The cattle exposed at one site had been immunized 1 year earlier and maintained tick-free in the intervening period. The level of immunity in these cattle was similar to that of cattle which had been immunized 1 or 2 months prior to exposure. Thus, immunity had not waned over the 1-year period. A study at another site showed that acaricidal treatment of immunized cattle could be safely extended from twice a week to once every three weeks, whereas in susceptible cattle even twice weekly spraying did not control ECF. The isolates made from infected controls during the trials indicated the presence of three T. p. parva stocks as defined by MAb profiles. Of the two stocks used for immunization, T. p. parva Marikebuni induced broader protection. In view of the apparent limited antigenic diversity of T. p. parva strains within the Coast Province it is suggested that the Marikebuni stock might represent a key stock for vaccination in this area.     

Some preliminary observations on the susceptibility and resistance of different cattle breeds to Theileria parva infection

Theileria parva-na?ve Friesian (Bos taurus), Boran (Bos indicus) and Maasai Zebu steers (B. indicus) were infected with a T. parva sporozoite stabilate dose which had previously been shown to induce an estimated 50% mortality rate in Boran cattle. All the cattle developed patent infections with no significant differences in the length of the prepatent period to development of macroschizonts (P > 0.05) between the three groups. Clinical theileriosis occurred in all eight the Friesians (100%), five out of nine Borans (55.6%) and two out of five Zebus (40%). Three of the Friesians (37.5%), and two of the Borans (22.2%) died of theileriosis. The different cattle types were equally susceptible to the infective dose used as indicated by the length of the prepatent periods, but there was a marked difference in their development of clinical theileriosis. The gradation in resistance to disease confirms the findings of earlier less critical studies and identifies these cattle breeds as suitable for investigations into the mechanisms of resistance to theileriosis.     

Chemoimmunoprophylaxis against bovine tropical theileriosis in young calves: a comparison between buparvaquone and long-acting oxytetracycline

Eighteen seven to 21-day-old crossbred (Bos taurus cross Bos indicus) calves were allocated to four groups (A to D). Groups A and B each consisted of six calves and groups C and D three calves each. Each calf in groups A, B and C was inoculated with ground-up tick supernate (GUTS) equivalent to two infected acini prepared from Theileria annulata-infected Hyalomma anatolicum anatolicum. Each calf in group A was also given a single intramuscular injection of buparvaquone, 2.5 mg kg-1 bodyweight simultaneously with GUTS, whereas each calf in group B was given a single intramuscular injection of long-acting oxytetracycline, 20 mg kg-1 bodyweight following inoculation of GUTS. In calves of group A clinicopathological reactions were negligible, whereas in calves of group B mild to severe reactions were observed resulting in the death of three of the six calves. All the calves of group C (infected, untreated controls) died of acute theileriosis. All the surviving calves of groups A and B withstood a lethal homologous challenge given on day 30 after immunisation, indicating no difference in the immune status of the surviving calves of the two groups. Group D, challenge control, all calves died of theileriosis within 18 days of challenge.     

Immunisation against Theileria parva in eastern Zambia: influence of maternal antibodies and demonstration of the carrier status

Immunisation of calves by the infection and treatment method (I & T) has been extensively used in the eastern province of Zambia to control East Coast fever (ECF), a protozoan tick-borne disease. This paper presents the results of a field longitudinal study, which included a total of 148 Angoni calves. After immunisation against ECF, they were monitored for a full rainy season, coinciding with the main peak of activity of the vector of Theileria parva, the tick Rhipicephalus appendiculatus. Dysimmunisation (acute reaction generated by I & T immunisation), seroconversion and mortality are among the parameters recorded. The effect of maternal antibodies on these parameters was analysed and also studied in experimental conditions on two calves. Before immunisation, young calves had a higher seroprevalence than older animals (maternal antibodies) but their post-immunisation seroprevalence was lower. There was no evidence that their immunoprotection was weaker but this indicates that the post-immunisation seroconversion is probably not a reliable tool to monitor the efficacy of calf immunisation. The carrier state of cattle after immunisation was investigated in experimental conditions on three bovines whereas in the field, the infection prevalence in the ticks was estimated using the relation between the tick burden and the T. parva contacts with the calves. The ability of larval and nymphal R. appendiculatus ticks to pick-up T. parva from carriers and to transmit it to na?ve animals after moulting was assessed. It was found that both instars are able to transmit clinical and lethal ECF but that the prevalence of T. parva infection in nymphs is much lower than in adults, confirming the primary role of adults in the transmission of ECF in endemic conditions. Similar results were obtained from the field whereby the ECF peak corresponds with the peak of adult R. appendiculatus activity. The infection prevalence in the ticks was however much lower in the field than in experimental conditions indicating that an important proportion of them feed on alternative hosts. Old ticks seemed to have lost part of their infectivity.     

Seroprevalences of vector-transmitted infections of small-holder dairy cattle in coastal Kenya

A cross-sectional study was carried out from July to September 1989 in Kaloleni Division, Coast Province, Kenya to estimate the prevalence of vector-transmitted diseases in small-holder dairy cattle and to identify the risk factors associated with different management systems. One hundred and thirty of the 157 herds with dairy cattle in Kaloleni Division were surveyed. These were from three agro-ecological zones (coconut-cassava, cashew nut-cassava and livestock-millet), comprised two management systems (stall-feeding and herded grazing) and were herds with either dairy cattle only or with Zebu and dairy cattle. A formal questionnaire sought answers to questions on cattle health and management practices. A total of 734 dairy and 205 Zebu cattle in 78 dairy and 52 mixed (dairy and Zebu) herds were sampled and screened for haemoparasites (Trypanosoma, Anaplasma, Babesia, and Theileria infections). Sera were tested for antibodies to Theileria parva, using the schizonts-antigen indirect fluorescent-antibody (IFA) test and to antibodies for Babesia bigemina and antigens to Anaplasma marginale by enzyme-linked immunosorbent assay (ELISA). Packed-cell volume (PCV) also was measured. Tick-control measures were practised by all except three of the farmers. Despite this, overall seroprevalence to T. parva was >70%--suggesting either that control practices were not strictly implemented or they were ineffective. The seroprevalence of T. parva in adult cattle kept in stall-feeding systems in the coconut-cassava zone was significantly lower (57+/-8% (S.E.)) than in herded-grazing systems (79+/-3%) and there was no association between antibody prevalence and age of cattle in this zone. Antibody prevalences in cattle in the cashew nut-cassava and the drier livestock-millet zone increased with age. Cattle in herded-grazing systems had an overall lower seroprevalence of T. parva infection in the livestock-millet zone (45+/-6%) than in the other two zones.Analysis was confined to the coconut-cassava zone for B. bigemina and to the coconut-cassava and cashew nut-cassava zones for A. marginale. Mean prevalences of B. bigemina were 40.9+/-9 and 73+/-6% for dairy cattle under stall-feeding and herded-grazing systems, respectively, and increased with age. Antigen prevalences of A. marginale were over 80% in all age groups of cattle in the coconut-cassava and cashew nut-cassava zones. Overall trypanosome prevalence in cattle was <1%. Trypanocidal treatment was uncommon. The variations in antibody prevalence associated with risk factors such as feeding system, agro-ecological zone and age of animal suggest that management system influenced exposure to tick-borne infection (particularly, T. parva infections) in small-holder dairy cattle in coastal Kenya.     

Comparative Thickness of the Medulla of Bos taurus and Bos indicus Kidneys

Twenty kidneys of 4 years old Bos taurus cattle and 26 kidneys of 2—4 years old Bos indicus (Zebu cattle) of East African Shorthorn breen were examined lobe by lobe after fixation. The cortex and medulla with subunits were measured and compared in the two sub-species. The width of the cortex was about the same in both. The outer and inner stripes of the outer medullary zone were significantly broader in Bos taurus whereas outer inner zone was significantly broader in Bos indicus. The width of the entire medulla was greater in Bos taurus.     

Vaccine potential of recombinant antigens of Theileria annulata and Hyalomma anatolicum anatolicum against vector and parasite

In an attempt to develop vaccine against Hyalomma anatolicum anatolicum and Theileria annulata, three antigens were expressed in prokaryotic expression system and protective potentiality of the antigens was evaluated in cross bred calves. Two groups (grs. 1 and 4) of male cross-bred (Bos indicus × Bos taurus) calves were immunized with rHaa86, a Bm86 ortholog of H. a. anatolicum, while one group of calves (gr. 2) were immunized with cocktails of two antigens viz., surface antigens of T. annulata (rSPAG1, rTaSP). One group each was kept as negative controls (grs. 3 and 5). The animals of groups 1, 2 and 3 were challenged with T. annulata infected H. a. anatolicum adults while the animals of groups 1, 3, 4 and 5 were challenged with uninfected adult ticks. A significantly high (p<0.05) antibody responses to all the three antigens were detected in immunized calves, but the immune response was comparatively higher with rHaa86 followed by rTaSP and rSPAG1. Upon challenge with T. annulata infected ticks, animals of all groups showed symptoms of the disease but there was 50% survival of calves of group 1 while all non immunized control calves (group 3) and rSPAG1+rTaSP immunized calves died. The rHaa86 antigen was found efficacious to protect calves against more than 71.4-75.5% of the challenge infestation. The experiment has given a significant clue towards the development of rHaa86 based vaccine against both H. a. anatolicum and T. annulata.     

Immunisation of cattle against theileriosis in Nakuru District of Kenya by infection and treatment and the introduction of unconventional tick control.

One hundred and one cross European-Boran cattle (50 cows and 51 calves), on a farm in Nakuru District, Kenya, were immunised against theileriosis using Theileria parva lawrencei and Theileria parva parva stocks from another district of Kenya. The stabilates used were T.p.lawrencei (Mara III) used at 10(-1.7) dilution and T.p.parva (Kilae) used at 10(-1.0) dilution. The stabilates were combined and inoculated simultaneously with a short-acting formulation of oxytetracycline hydrochloride given intramuscularly at 10 mg kg-1 body weight and was repeated on Day 4 after inoculation of the stabilate. Most of the theileriosis challenge on the farm was thought to be derived directly from the African buffalo (Syncerus caffer). Nine percent of the cattle had significant indirect fluorescent antibody (IFA) titres before the immunisation and 99% after immunisation. The immunised cattle were exposed to tick-borne disease challenge on the farm by withdrawal of acaricide cover. The immunised cattle were divided into five groups plus two susceptible control cows and two calves for each group. Cattle in four of the groups had acaricidal ear tags, each group having a different type, applied to both ears and the fifth group remained untagged. The animals remained without conventional acaricide application for 134 days. Ten out of 20 (50%) non-immunised control cattle became T.p.lawrencei reactors which only one out of 97 (1%) of the immunised cattle reacted. A frequent complication noted was mild infections due to unidentified Theileria sp. which required expert differentiation from T.parva infections. An additional group of ten steers whose tick load was removed by hand at weekly intervals was introduced 79 days after exposure; these had no tick control and four became T.p.lawrencei reactors. Of 12 calves born during the exposure period and without tick control, four became theilerial reactors and one died. The application of acaricidal tags however, reduced tick infestation levels considerably compared with untagged controls but did not prevent transmission of theileriosis with the possible exception of tags on Group 4. A number of transient low grade fevers were noted and attributed to Theileria sp., Ehrlichia bovis, Ehrlichia (Cytoecetes) ondiri and Borrelia theileri infections, none of which were fatal. One immunised animal died of acute dual infection of Babesia bigemina and Borrelia theileri after acaricide control by spraying was re-introduced but no Anaplasma infections were detected. An analysis of the economic effects of immunisation was made.     

Immunization of cattle against East Coast fever using Theileria parva (Marikebuni) and relaxation of tick control in North Rift, Kenya.

A total of 90 animals was immunized against East Coast fever (ECF) using Theileria parva (Marikebuni) stock on three large-scale farms in Kiminini Division, Trans-Nzoia District, North Rift, Kenya. Another 90 cattle served as non-immunized controls. Following immunization the number of cattle with significant indirect fluorescent antibody (IFA) titres increased from 43.9% to 84.4% and 6.7% of the cattle developed clinical ECF reactions. Two months after immunization, the immunized and non-immunized cattle were divided into two groups one of which was dipped every 3 weeks and the other dipped when total full body tick counts reached 100. All the animals were monitored for 51 weeks for incidences of ECF and other tick-borne diseases. Twenty-four cases of ECF were diagnosed among the non-immunized cattle compared to four cases among the immunized cattle; a difference that was significant (P > 0.05). There was no significant difference in the incidences of babesiosis and anaplasmosis between the immunized and non-immunized cattle.     

A Cytogenetic Investigation of Madura Cattle

Contents: " Madura cattle," the variety found on the Indonesian island of Madura, is most often referred to as a cross between Bos javanicus and Bos indicus, based largely on phenotypic appearance. The karyotypic patterns of Madura cattle resemble those of Bos taurus, with the exception of the Y chromosome, which is of Bos indicus type. Based on what is known of Bos javanicus, it is concluded that Madura cattle could be the result of a cross between a Bos taurus or Bos javanicus cow and a Bos indicus bull .
Inhalt: Eine cytogenetische Untersuchung über das Madura-Rind
Das Madura-Rind, eine Varietät der indonesischen Insel Madura, wird wegen seines Aussehens oft als Kreuzung zwischen Bos javanicus ( Banteng) und Bos indicus ( Zebu) angesehen. Das karyotypische Bild des Madura-Rindes gleicht jenem von Bos taurus mit Ausnahme des Y-Chromosoms, welches dem Bos indicus- Typ entspricht. Nachdem, was über Bos javanicus bekannt ist, muβ man folgern, daβ das Madura-Rind ein Kreu-zungsprodukt zwischen einer Bos taurus- oder Bos javanicus-Kuh und einem Bos indi- cusBullen sein könnte .     

Histopathology of attachment sites of Amblyomma variegatum and Rhipicephalus appendiculatus on zebu cattle of varying resistance to ticks.

Mature, unimproved East African Zebu cattle (Bos indicus) naturally exposed to ticks from birth were ranked for resistance to ticks by repeated whole-body counts of infesting ticks. Four cattle of high resistance, four of low resistance and two of intermediate resistance were artificially infested with nymphs of Amblyomma variegatum and Rhipicephalus appendiculatus. Two Friesian cattle (Bos taurus) with less exposure to ticks were similarly infested. Biopsies of tick attachment sites were examined histologically. All attachment sites showed acute inflammatory lesions, and sites of both tick species on high resistance cattle showed delayed hypersensitive reactions with intra-epidermal pustulation and significant increases in the numbers of granulocytes. The predominant cells infiltrating attachment sites on high resistance cattle were eosinophils with A. variegatum and neutrophils with R. appendiculatus. Such differences need to be taken into account in developing immunological tests for selecting cattle for resistance but there are sufficient common features of reactions to the two infesting tick species to justify dermal hypersensitivity tests.     

Treatment of experimentally induced Theileria annulata infection in cross-bred calves with buparvaquone

Twenty cross-bred (Bos taurus X Bos indicus) calves, 7-21 days old, were infected by a ground-up tick supernate of Hyalomma anatolicum anatolicum infected with the Hisar isolate of Theileria annulata. Six calves acted as untreated controls and they all died of theileriosis within 17 days of infection. The remaining 14 calves were divided into Group A and B, each consisting of seven calves. All the calves of Groups A and B were treated intramuscularly with buparvaquone (BW 720C) on Day 11 post-infection, when clinical signs of theileriosis were apparent. Each calf received 2.5 mg BW 720 C kg-1 body weight as a single injection. In addition, each calf of Group B was given proprietary haematinics by intramuscular injection, daily for 12 days. In Group A, two calves died of cerebral theileriosis and five were clinically cured. However, four of these five calves later died of anaemia. In Group B, all the calves were clinically cured and none died during the observation period of 1 month. The parasitaemia declined to less than 1% within a fortnight of treatment. The initial declines in haemoglobin concentration and packed cell volume were halted and preinfection values were soon restored. No toxic signs attributable to treatment with buparvaquone were observed.     

The effect of East Coast fever immunisation and different acaricidal treatments on the productivity of beef cattle

A trial was performed on a farm in the Coast Province of Kenya to study the effects of East Coast fever immunisation and different acaricidal treatments on the productivity of immunised and unimmunised beef cattle. Eighty cattle were immunised against Theileria parva parva (Marikebuni) by the infection and treatment method and a similar group was left as an unimmunised control. Immunisation had no deleterious effect on the cattle. After immunisation, the immunised and control groups were each subdivided into four groups of 20 and each subgroup was managed under a different tick control regimen. The tick control regimen were, acaricidal spraying twice a week or once every three weeks, the application of acaricide-impregnated ear-tags, and no tick control. During a nine-month exposure period there were 18 cases of East Coast fever among the 80 immunised cattle, three which were severe and the others mild. Among the 80 unimmunised cattle there were 57 cases of East Coast fever, 50 of which were severe. The highest morbidity and mortality occurred in the groups under limited tick control or without tick control. Overall weight gain in the immunised cattle, irrespective of the tick control regimen, was better than the weight gain in the unimmunised groups. Within the immunised groups, the weight gain of the cattle sprayed twice weekly was comparable to the weight gain of the animals with acaricidal ear-tags and was significantly higher than the weight gains in the groups sprayed once every three weeks or with tick control. Preliminary cost/benefit analysis showed that it was uneconomical to maintain unimmunised cattle under limited or no tick control.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunization of neonatal bovines against Theileria annulata by an infection and treatment method

Sixty three cross-bred (Bos taurus X Bos indicus) 4-5-day-old calves were divided into 16 groups (A-P). Each calf in Groups A and B was given ground-up-tick supernate prepared from Theileria annulata-infected or non-infected Hyalomma anatolicum anatolicum (GUTS) equivalent to 5 ticks (50 infected acini). Groups D and E received infected GUTS equivalent to 2 ticks (20 infected acini) and Groups G and H were given infected GUTS equivalent to 1 tick (10 infected acini). Each calf in Groups J, K and L received infected GUTS equivalent to 5 infected acini (0.035 tick), and Group O was inoculated with non-infected GUTS equivalent to 5 ticks. Each calf in Groups A, D, G, J, K and O was also given a single intramuscular injection of long acting oxytetracycline, 20 mg kg-1 body weight just after inoculation of GUTS. Severe reactions resulted in the death of five of eight, three of eight, five of six, one of five and one of five calves in Groups A, D, G, J and K respectively and all of the calves in Groups B, E, H, and L. The surviving calves of Groups A, D, G, J, K and O were challenged on Day 45 post-immunization along with freshly introduced susceptible control calves of Groups C, F, I, M, N and P. All the calves of Groups A, G, J and K withstood the challenge dose; in Group D four of five and in Groups C, F, I, M, N, O, and P all the calves died of theileriosis. It is concluded that though the infection and treatment method of immunization may be used for neonatal bovines, the dose of immunogen should be based on actual counts of infected salivary acini of ticks instead of the number of ticks.     

Immunoprophylaxis against Theileria annulata with protein from plasma membrane of infected lymphoblasts

Cross-bred (Bos taurus male x Bos indicus female) calves were protected against the homologous sporozoite-induced challenge of Theileria annulata when immunised with protein from the plasma membrane of macroschizont-infected lymphoblasts of allogeneic origin. However, such protection was parasite-strain specific with the plasma membrane originating from lymphoblasts infected and transformed by the same isolate of T. annulata sporozoites. No protection ensued when the infected lymphoblasts and sporozoites were from immunologically different isolates of T. annulata. There was enhanced proliferation of cells and evidence for lymphokine, originating from antigen-sensitised lymphocytes, demonstrable as macrophage migration inhibition factor in peripheral blood lymphocytes of the calves immunised by plasma membrane protein and challenged by sporozoites of homologous origin.