Browsing by Author "Young, A.S."

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Attempted Transmission of Theileria gorgonis, Brocklesby & Vidler 1961, from Blue Wildebeest (Connochaetes taurinus) to Cattle
(Tropenmed Parasitol, 1973) Purnell, R.E.; Schiemann, B.; Brown, C.G.; Irvin, A.D.; Ledger, M.A.; Payne, R.C.; Radley, D.E.; Young, A.S.; Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research Organisation, Muguga
Four blue wildebeest (Connochaetes taurinus), two from the Serengeti National Park in Tanzania and two from the Athi/Kapiti Plains m Kenya, were splenectomied. Of the two wildebeest from Tanzania, one which had previously had detectable intra-erythrocytic piroplasms of Theileria gorgonis, had an increase in parasitaemia to a peak of 7%, the other, which had previously had no detectable parasites, developed a low-level parasitaemia. The two wildebeest from Kenya had severely exacerbated T. gorgonis infections all in one case a concomitant Anaplasma marginale infection They died of severe anaemia after febrile responses and theilenal parasitaemias in excess of 70%. Attempts to transmit T. gorgonis to spienectomised calves by blood passage and to steer~ via Rhipicephalus appendiculatus ticks failed despite the establishment of the parasite in the ticks. A. marginale, on the other hand, was blood-passaged to two of the splenectomised calves, which were inoculated with blood from the infected wildebeest.
Attempted Transmission of Theileria Gorgonis, Brocklesby & Vidler 1961, From Blue Wildebeest (Connochaetes Taurinus) to Cattle
(1973) Purnell, R.E.; Schiemann, B.; Brown, C.G.D.; Irvin, A.D.; Ledger, M.A.; Payne, R.C.; Young, A.S.; East African Veterinary Research Organization, Muguga, Kenya
Two blue wildebeest (Connochaetes taurinus) from the Serengeti National Park in Tanzania and two from Kenya were splenectomised. Of the two from Tanzania, one that had previously had detectable intra-erythrocytic piroplasms of Theileria gorgonis showed an increase in parasitaemia (percentage of erythrocytes infected) to 7%, and the other, which had had no detectable parasites, developed a low-level parasitaemia. The two animals from Kenya had severely exacerbated infections with T. gorgonis and in one case a concomitant infection with Anaplasma marginale. They developed Theileria parasitaemias of more than 70% and died. Attempts to transmit T. gorgonis to steers by means of adults of Rhipicephalus appendiculatus Neum. that had fed as nymphs on infected wildebeest were unsuccessful, although it was shown that the parasite became established in the ticks. Some 500 ticks were used on each steer.
Comparative Infectivity for Cattle of Stabilates of Theileria Lawrencei (Serengeti) Derived from Adult and Nymphal Ticks
(1974) Purnell, R.E.; Young, A.S.; Brown, C.G.D.; Burridge, M.J.; Payne, R.C. ; East African Veterinary Research Organization P.O Box 32, Kikuyu Kenya
Larval and nymphal Rhipicephalus appendiculatus ticks were fed simultaneously on steers reacting to the inoculation of an infective stabilate of cattle-passaged Theileria lawrencei (Serengeti). The larvae and nymphs dropped engorged from the steers when their intra-erythrocytic piroplasm parasitaemias were in excess of 14 per cent.: after the ticks had moulted, they were fed on rabbits and removed after 3 and 5 days respectively. Some of the ticks were processed for histological examination of their salivary glands whilst others were ground and stabilates were prepared from them. Examination of the salivary glands indicated that there was a higher infection rate in the nymphs than in the adults although this was not statistically significant: subsequent inoculation into susceptible cattle of titrated aliquots of the stabilates, however, showed that aliquots from a certain number of adult ticks were more infective than those from the equivalent number of nymphal ticks. The duration of the prepatent period in the susceptible cattle could be correlated with the infective dose. The possibility of obtaining stabilates of nymphal material by feeding larval ticks all over the body of an infected animal is discussed, since such stabilates may be more concentrated and more easily prepared than adult tick stabilates.
Comparative Infectivity for Cattle of Stabilates of Theileria Lawrencei (Serengeti) Derived from Adult and Nymphal Ticks
(1974) Purnell, R.E.; Young, A.S.; Brown, C.G.D.; Burridge, M.J.; Payne, R.C.; East African Veterinary Research Organization, P.O. Box 32, Kikuyu, Kenya
Larval and nymphal Rhipicephalus appendiculatus ticks were fed simultaneously on steers reacting to the inoculation of an infective stabilate of cattle-passaged Theileria lawrencei (Serengeti). The larvae and nymphs dropped engorged from the steers when their intra-erythrocytic piroplasm parasitaemias were in excess of 14 per cent.: after the ticks had moulted, they were fed on rabbits and removed after 3 and 5 days respectively. Some of the ticks were processed for histological examination of their salivary glands whilst others were ground and stabilates were prepared from them. Examination of the salivary glands indicated that there was a higher infection rate in the nymphs than in the adults although this was not statistically significant: subsequent inoculation into susceptible cattle of titrated aliquots of the stabilates, however, showed that aliquots from a certain number of adult ticks were more infective than those from the equivalent number of nymphal ticks. The duration of the prepatent period in the susceptible cattle could be correlated with the infective dose. The possibility of obtaining stabilates of nymphal material by feeding larval ticks all over the body of an infected animal is discussed, since such stabilates may be more concentrated and more easily prepared than adult tick stabilates.
Detection of Antibody to Theileria Parva Schizonts and Cell Surface Membrane Antigens of Infected
(Elsevier, 1984) Cowan, K.M.; Dolan, T.T.; Teale, A.J.; Young, A.S.; Stagg, D.D.; Groocock, C.M.;
Peroxidase-labeled antibody procedures were described for detecting bovine anti-bodies reactive with intracellular Theileria parva schizonts and cell surfacesmembrane antigens of infected lymphoblastoid cells. Indirect tests were performed where the reacting bovine antibodies were localized with affinity purified rabbit-anti-bovine IgG coupled to horseradish peroxidase. A 4- to 8-fold increase in sensitivity for detecting bovine anti-bodies was obtained with unlabeled rabbit-anti-bovine IgG which in turn was detected with peroxidase labeled goat-anti-rabbit IgG. The T. parva infected cells used as antigen were attached to poly-l-lysine treated glass slides and all reaction steps were performed on the slides. The intracellular schizonts and cell surface staining reactions were dependent upon the status of the cells; acetone-fixed cells were required for schizont reactions and viable unfixed cells for cell surface membrane reactions. Sera from cattle stimulated in various ways with T. parva were examined by the techniques. Cattle infected by stabilate inoculation or inoculated with infected autologous lymphoblastoid cells developed relatively high levels of antibody to schizonts, but no detectable antibody to cell surface membrane antigens. This would indicate that parasite antigens do not occur on the surface of infected lymphoblasts. Cattle inoculated with infected allogeneic lymphoblasts developed low-levels of antibody to schizonts and readily demonstrable antibody to cell surface antigens. The immunoperoxidase procedures have certain advantages over immunofluorescence in that light microscopy is used; therefore, the reactions do not fade which permits a more detailed examination and provides a relatively permanent record, the preparations can be counterstained, and the reagents may be used for immunoelectron-microscopy. The procedures could provide suitable alternatives to immunofluorescence methods for East Coast fever investigations and other systems having intracellular and/or cell surface membrane antigens.
Development of Theileria Mutans (Aitong) in the Tick Amblyomma Variegatum Compared to That of T. Parva (Muguga) in Rhipicephalus Appendiculatus
(1975) Purnell, R.E.; Young, A.S.; Payne, R.C.; Mwangi, J.M.; East African Veterinary Research Organization
A comparison was made between the development of Theileria mutans (Aitong) in adult Amblyomma variegatum ticks and the development of T. parca (Muguga) in adult Rhipicephalus appendiculatus ticks. Both batches of ticks dropped as engorged nymphs from cattle whose intraerythrocytic parasitemias were approximately 40%, and it was thus possible to make a direct comparison of the infection rates produced in their tick hosts in this experiment by the 2 species of Theileria. Ticks of the 2 batches were fed in ear bags on rabbits, and equal numbers of male and female ticks were removed daily for 5 days. The salivary glands were dissected out from these ticks, and from infed ones in each batch, processed, and examined for Theileria parasites, which were categorized according to their morphological maturity. The A. variegatum ticks had a lower rate of infection with Theileria. Fewer parasites were observed in the ticks, and they took longer to mahue. When the development of the 2 species of Theileria was compared, the major difference appeared to be that T. mutans had large Babesialike infective particles.
East Coast Fever the Significance of Host Ace in Infection or Immunization of Cattle with Theileria Parva
(1979) Irvin, A.D.; Dobbelaere, D.A.E.; Morzaria, S.P.; Spooner, P.R.; Dolan, T.T.; Young, A.S.; Gettinby, G.; International Laboratory for Research on Animal Diseases, Nairobi, Kenya; Kenya Agricultural Research Institute, Muguga, Kenya; University of Strathclyde, Glasgow, UK
T a number of tick-borne diseases of cattle, young animals show a significant resistance to infection which is independent of maternally transferred or acquired immunity. Such resistance has been detected in babesiosis (Riek 1968, Zwart and Brocklesby, 1979) an: lasmosis (Ristic, 1968; 1981) and heartwater (Uilenberg, 1983), but,10 evidence for an age-related innate resistance has been described in theileriosis apart from the rather equivocal data reported by Adler and Ellenbogen (1935) for calves infected with Theileria annulata.
East Coast Fever: 3. Chemoprophylactic Immunization of Cattle using Oxytetracycline and a Combination of Theilerial Strains
(1975) Radley, D.E.; Brown, C.G.D.; Cunningham, M.P.; Kimber, C.D.; Musisi, F.L.; Payne, R.C.; Purnell, R.E.; Stagg, S.M.; Young, A.S.; East African Veterinary Research Organization, Kikuyu Kenya,
In the first of two experiments performed, 29 animals were immunized by chemoprophylaxis against either a combination of three theilerial strains, Theileria parva (Muguga), T. parva (Kiambu 5) and T. lawrencei (Serengeti transformed), or against one or two elements of the combination separately, and then challenged with either T. parva (Kiambu 1) or T. lawrencei (Solio KB1), both of which were known to be heterologous to T. parva (Muguga). The animals immunized against the combination had mild or inapparent reactions to challenge, whilst the susceptible control cattle and many of those immunized against one or two strains either had severe reactions of died. In the second experiment, 17 cattle immunized by chemoprophylaxis against the combination were challenged with lethal doses of three theilerial strains, T. parva (Entebbe 1), T. parva (Entebbe 2) and T. parva (Ukunda), recently isolated from two widely separated areas of East Africa. They had mild or inapparent reactions whilst 13 of 15 susceptible control cattle died. Chemoprophylaxis using a combination of theilerial strains and a limited oxytetracycline regimen was shown to be an effective means of immunizing cattle against East African theilerioses. The use of this technique as a method of immunizing cattle before exposure in the field is proposed.
The Effect of High and Low Dose Theileria Parva Infection on the Reproductive Function of Boran/Friesian Heifers
(1993) Young, A.S.; Rowland, A.C.; Watson. E.D.; National Veterinary Research Centre; International Laboratory for Research in Animal Diseases; University of Edinburgh, Veterinary Field Station
Two separate experiments were carried out to find the effect of infection with low and high doses of Theileria parva sporozoites on the cyclical status of Boran/Friesian cross heifers. In each experiment, ten heifers were infected, and another four heifers acted as controls. Routine monitoring of estrous behavior, determination of serum progesterone concentrations and palpat10n of the ovar1es per rectum were used to assess the cyclical status of each animal. Two and eight animals died in the T. parva low (TpL) and h1gh (TpH) dose experiments, respectively. Five of e1ght recovered an1mals 1n the TpL group cycled regularly postinfection, while three others had extended periods of ovarian dysfunct10n postinfection. Both infected and recovered animals in the TpH-group similarly had extended periods of ovarian dysfunction postinfect1on. All controls in both experiments cycled regularly throughout the study period.
The Effect of Immunization against Theileriosis on the Reproductive Function of Boran/Friesian Cross Heifers Preliminary Study
(1994) Rumberia, R.M.; Watson, E.D.; Young, A.S.; National veterinary Research Centre; Kenya Agricultural Research Institute; University of Edinburgh; Veterinary Field Station; International Laboratory for Research in Animal Diseases.
Bovine theileriosis, caused by Theileria parua is the most important disease of livestock in East and Central Africa. T parva infection is associated with high morbidity and mortality rates (Brocklesby et at., 1961). To date, the only method of immunization against T parua is by infection with sporozoite stabilates and treatment with oxytetracyclines (Purnell, 1977; Radley, 1978, 1981). This method has been adopted and is being used in several countries in the region where theileriosis is endemic. Currently, long-term programmes have been formulated in these countries with the aim of protecting a larger proportion of animals at risk. However, T parva infected animals have been shown to suffer from loss of reproductive function (Rumberia et at., 1993). In view of these findings and anecdotal reports linking theileriosis with abortions and long anoestrous periods (Oteng, 1977), this study was undertaken to determine if immunization has any adverse effect on reproductive function in cattle.
Further Studies on the Immunization of Cattle against Theileria La Wrencei by Infection and Chemoprophylaxis
(Elsevier, 1979) Radley, D.E.; Young, A.S.; Grootenhuis, J.G.; Cunningham, M.P.; Dolan, T.T.; Morzaria, S.P.; Veterinary Research Department, Kenya Agricultural Research Institute, Muguga; Veterinary Laboratories, Kabete (Kenya); International Centre for Insect Physiology and Ecology, Kenya; MAFF Central Veterinary Laboratories, Great Britain.
Three experiments were carried out to ascertain the feasibility of immunization of cattle against Theileria lawrencei using infection and chemoprophylaxis. In the first two experiments, cattle were immunized with a combination of three theilerial strains (‘cocktail’) and simultaneous treatment with an experimental formulation of oxytetracycline. When groups of these immunized cattle were challenged with stabilates of T. lawrencei isolated from African buffalo captured in Kenya and Tanzania, many of the immunized cattle had severe reactions and 3 out of 20 died, as did 18 of the 20 controls. A paddock containing carrier buffalo which maintained a population of Rhipicephalus appendiculatus continuously infected with T. lawrencei, was used in a second and third experiments. Cocktail immunized and control cattle were exposed to this tick challenge, and 55% of the immunized animals and 91% of the controls died. The protection provided by cocktail immunization was compared with immunization using different isolates of T. lawrencei from the buffalo paddock, but little difference in the degree of protection was detected. However, a high degree of immunity was observed when cocktail immunized cattle which had undergone a T. lawrencei stabilate challenge were exposed in the paddock. Only mild reactions were seen and no deaths occurred. Field immunization of cattle against T. lawrencei may be difficult due to immunovariants of this parasite emanating from the buffalo populations.
Haematoxenus Species from Ugandan Buffalo Syncerus caffer
(1973) Young, A.S.; Woodford, M.J.; Irvin, A.D.; FAO Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research Organization; and Nuffield Institute of Comparative Medicine, Zoological Society of London; East African Veterinary Research Organization; Institute for Research on Animal Diseases, Compton; Nuffield Unit of Tropical Animal Ecology; E.A.V.R.O.,
Blood parasites, Haematoxenus and Theilenia, were found to be common in African buffalo sampled in Queen Elizabeth Park, Uganda. These parasites are described and compared with similar forms from cattle.
Immunization of Cattle against Theileriosis Using Varying Doses of Theileria Par VA Lawrencei and T. Par VA Par VA Sporozoites and Ox tetracycline Treatments
(1988) Ndungu, S.G.; Young, A.S.; Stagg, D.A.; Mutugi, J.J.; Maritim, A.C.
Immunization of cattle against theileriosis using varying doses of Theilera parva lawrencei and T parva parva sporozOtes and oxytetracycline treatments. International Journal for Parasitology 18: 453-461. Theileria parva lawrencel and T parva parva parasites, from three sources (two from African buffalo, SWlcerus caifer, and one from indigenous cattle, Bos indicus) iwlated from two areas of Kenya, were chosen for invetigations mto immunization of cattle agaimt thellenonsis. Varying concentration of stabllates were used to Infect cattle singly in one experiment and In combination in another experiment, wIth one or two treatments with either long- or short-acting formulations of oxytetracyclines, respectively. It was found that high concentrations with T parva lawrencei stabilates (10°) were not controlled satisfactonly by oxytetracyclines but with concentration of stabilate at 10- 1 or particularly 1O-~ It was possible to Induce sub-climcal theileriosis with the development of antibodies to T pan'a. Both short- and long-acting formulatIOns of oxytetracyclines appeared to be equally effective. Some chrome effects were seen after immumzation but these were not usually detected when lower concentratlom of stabilate were given. Cattle Immunized by this procedure were shown to be immune to homologow. and heterologous challenge and some were demomtrated to become T parva carriers.
An Improved Method of Handling Ticks Collected from the Field
(1973) Young, A.S.; Newson, R.M.
Batches of Adult Rhipicephalid Ticks, mainly Rhipicephalus Appendiculatus, were collected Ir0111 the vegetation at 2 sites Ill Kenya Alld were maintained either at the ambient temperature or at 4 DC Beior,' application to Rabbits or caule. Significantly Liiore oi the ticks maintained at the cooler temperature attached and fed. It ss Suggested that cooled ticks were superior material or attempts to isolate parasites pathogenic to Cattle
The Incidence of Theilerial Parasites in East African Buffalo (Syncerus caffer)
(1978) Young, A.S.; Brown, C.G.D.; Burridge, M.J.; Grootenhuis, G.K.; Kanhau, G.K.; Purnell, R.E.; Stagg, D. A.; Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research Organization
245 buffalo from 13 areas of East Africa were examined for theilerial infections, The vast majority of buffalo (97,1%) examined had piroplasms in their erythrocytes. Theileria lawrencei was isolated from the buffalo by tick feeding and cell culture and was found to be common in most of these buffalo populations. Also over 50% of the buffalo had indirect fluorescent antibody (IF A) titres to T. lawrencei. T. mutans was only isolated from 3 buffalo populations but is probably common.
The incidence of Theilerial Parasites in East African Buffalo (Syncerus caffer).
(1978) Young, A.S.; Brown, C.G.; Burridge, M.J.; Grootenhuis, J.G.; Kanhai, G.K.; Purnell, R.E.; Stagg, D.A.; Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research Organisation, Muguga
245 buffalo from 13 areas of East Africa were examined for theilerial infections. The vast majority of buffalo (97.1%) examined had piroplasms in their erythrocytes. Theileria lawrencei was isolated from the buffalo by tick feeding and cell culture and was found to be common in most of these buffalo populations. Also over 50% of the buffalo had indirect fluorescent antibody (IFA) titres to T. lawrencei. T. mutans was only isolated from 3 buffalo populations but is probably common. Haematoxenus sp. was detected in the blood of 56% of the buffalo sampled. In the light of these results the role of buffalo as a reservoir of cattle pathogenic theilerioses in East Africa is discussed.
Infection of African Buffalo and Cattle with Theileria Parva Lawrencei after Serial Passage in Cattle
(1987) Grootenhuis, J. G.; Young, A.S.; Stagg, D.A.; Leitch, B.L.; Dolan, T.T.; Conrad, P.A.; Veterinary Research Laboratory, Kabete; Kenya Agricultural Research Institute; International Laboratory for Research on Animal Diseases
The infectivity of a Theileria parva lawrencei stabilate, from a stock derived from an African buffalo (Syncerus caffer) in the Serengeti National Park, Tanzania, was investigated. In the first experiment a buffalo and three cattle were inoculated with a stabilate from a stock passaged three times in cattle. All cattle developed fatal theilerial infections. Isolations from the buffalo by tick feeding and cell culture isolation showed that it was infected with T p lawrencei at the time of inoculation, but the second isolation made 19 days after inoculation behaved like T p parva in cattle, developing a high parasitosis, while the third isolation made three months later behaved like T p lawrencei with low parasitosis. It was concluded that two biological types of T parva could exist in a buffalo at one time, but it was not shown that the buffalo had become a carrier of T p lawrencei adapted to cattle. In the second experiment two buffaloes and three cattle were inoculated with T p lawrencei (Serengeti) stabilate which had been passaged six times through cattle and ticks. The two buffaloes had mild theilerial infections and developed serological titres in the indirect fluorescent antibody test, but the cattle had fatal infections. Tick and cell culture isolations of T parva were possible during the clinical reactions of the buffaloes, but no carrier state was demonstrated. Theileria-infected cell lines were established from the buffaloes and the cattle and were examined using monoclonal antibodies against T parva schizonts. The macroschizonts in the cell lines isolated from the buffaloes and cattle had different staining profiles with the monoclonals, indicating either antigenic change of the parasite after inoculation into the buffalo or the presence of different antigenic types in the stabilate.
Infection of Mammalian Cells with Theileria Species
(1983) Stagg, D.A.; Young, A.S.; Leitch, B.L.; Grootenhuis, J.G.; Dolan, T.T.; Veterinary Research Department, Kenya Agricultural Research Institute, Muguga, P.O. Box 32, Kikuyu, Kenya
Experiments were carried out to determine the susceptibility of mammalian cells to infection with different species of Theileria in vitro. Sporozoites of Theileria parva (parva), Theileria parva (lawrencei) and Theileria taurotragi were isolated from Rhipicephalus appendiculatus ticks by grinding infected ticks in medium, filtering the suspension and concentrating by centrifugation. The sporozoites were used in attempts to infect in vitro peripheral blood leucocytes harvested from 16 different mammalian species which included 12 species of Bovidae from 6 different sub-families. The technique was shown to be both sensitive and reproducible. The sporozoites of T. parva (parva) infected and transformed cells from 2 species of the sub-family Bovinae, the two cattle types and African buffalo. Theileria parva (lawrencei) infected and transformed cells from the two cattle types, African buffalo and Defassa waterbuck. Theileria taurotragi sporozoites infected in vitro cells from 11 different species of Bovidae which were members of 6 sub-families; Bovinae, Tragelaphinae, Reduncinae, Alcelaphinae, Antilopinae and Caprinae. Transformed lymphoblastoid cell lines were established from 7 of the species infected. Sporozoite attachment and infection was not observed with non-susceptible bovid host cells, nor were any of the non-bovid leucocytes infected by the parasites. The host range observed in this study corresponded to the known host range in vivo.
Isolation of a Theileria Species from Eland (Taurotragus Oryx) Infective for Cattle
(1977) Young, A.S.; Grootenhuis, J.G.; Kimber, C.D.; Kanhai, G.K.; East African Veterinary Research Organisation, Muguga, Kikuyu, Kenya
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.
Observations on Babesia Equi in the Salivary Glands of Rhipicephalus Evertsi
(1973) Young, A.S.; Purnell, R.E.; East African Veterinary Research Organization, Muguga, Kenya
Forty out of 56 zebra sampled in the Loliondo division, Tanzania, were found to have patent infections of B. equi. Nymphal ticks engorged on infected zebra were collected, allowed to moult and identified as R. evertsi. The adult ticks were applied to rabbits' ears and were removed four days after attachment. Acini of three out of eight tick salivary glands showed developing parasites, which were thought to be stages of B. equi. Twenty-one out of 23 infected acini showed mature parasites; the other two showed intermediate stages of development.

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