Browsing by Author "Payne, R.C."
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Item 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, MugugaFour 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.Item 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, KenyaTwo 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.Item 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 KenyaLarval 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.Item 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, KenyaLarval 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.Item Correlation between the morphology and infectivity of Theileria lawrencei developing in the tick Rhipicephalus appendiculatus(1975) Purnell, R.E.; Kimber, C.D.; Payne, R.C.; Immunological Research on Tick-borne Cattle Diseases and Tick Control Project; East African Veterinary Research OrganizationAdult Rhipicephalus appendiculatus ticks, infected as nymphs by feeding them on an African buffalo harbouring Theileria lawrencei, were applied to the ears of rabbits. Equal numbers of the feeding ticks were removed daily from rabbits and either dissected and processed so that parasites in their salivary glands could be examined morphologically and classified, or ground in Eagle's Minimal Essential Medium, to harvest parasites from the ticks in the resultant supernatant fluid. The infectivity of the supernatant fluid was tested by inoculation of aliquots into groups of susceptible cattle. It was found that supernatant fluids produced from day 0 to day 2 fed ticks were uninfected to cattle but those produced from 3 to 9 days were infective. The most infective supernatant fluid was produced from 6 day fed ticks. The reactions resulting in cattle were correlated with the number and morphology of parasites in sections of salivary glands and it was found that mature parasites coincided with infectivity of the supernatant fluid to cattle. From the reactions in cattle inoculated with supernatant fluids from 5- and 6-day fed ticks it was concluded that this method of harvesting parasites was efficient. Examination of the salivary glands of a representative sample of a T. lawrencei infected tick batch is a potential means of screening material for T. lawrencei stabilates.Item 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 OrganizationA 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.Item 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.Item East Coast Fever: 60Co-Irradiation of Theileria Parva in Its Tick Vector, Rhipicephalus Appendiculatus(1974) Purnell, R.E.; Brown, C.G.D.; Burridge, M.J.; Cunningham, M.P.; Emu, H.; Irvin, A.D.; Ledger, M.A.; Njuguna, L.M.; Payne, R.C.; Radley, D.E.; East African Veterinary Research Organization, Muguga P.O. Box 32, Kikuyu, KenyaThree experiments were carried out in which Theileria parva was irradiated in its tick vector, Rhipicephalus appendiculatus. In the first experiment, infected unfed adult ticks were irradiated at doubling doses from 4 to 32 krad. Some of the ticks were then fed for 4, 5, 6, 7 and 8 days on rabbits, and the parasites in their salivary glands examined. Five male and 5 female ticks from each irradiation dose were put onto each of a pair of susceptible cattle, whose reactions were recorded. Increasing doses of irradiation resulted in progressive destruction of the parasites. All cattle receiving ticks irradiated at doses up to and including 16 krad died of East Coast fever (ECF), and one of the cattle receiving ticks irradiated at 32 krad died.Item East Coast Fever: Further Laboratory Investigations on the Use of Rabbits as Vehicles for Infecting Ticks with Theilerial Piroplasms(1974) Purnell, R.E.; Irvin, A.D.; Kimber, C.D.; Omwoyo, P.L.; Payne, R.C.; East African Veterinary Research Organisation, Muguga, KenyaA series of experiments was carried out in which attempts were made to achieve maximum survival of Theileria parva-infected bovine erythrocytes in inoculated rabbits. By varying the treatment of the rabbits and of the erythrocytes and by altering the route of inoculation, it was finally shown that the best and most consistent results could be obtained by the intravenous inoculation of 20 ml of infected bovine blood into splenectomised rabbits. When nymphal Rhipicephalus appendiculatus ticks were fed on such rabbits, the resultant adult ticks showed high Theileria parva infection rates in their salivary glands.Item Infection and Transformation of Bovine Lymphoid Cells In Vitro by Infective Particles of Theileria Parva(1973) Brown, C.G.D.; Stagg, D.A.; Purnell, R.E.; Kanhai, G.K.; Payne, R.C.; East African Veterinary Research Organization Muguga, PO Box 32, KikuyuTechniques recently developed in this laboratory can be used to infect cattle reproducibly with East Coast fever with infective particles of Theileria parva collected from the tick vector, Rhipicephalus appendiculatus. Infective particles can be collected either as in vitro tick feed material by inducing prefed, infected ticks to salivate into capillary tubes containing foetal calf serum1, or as ground tick supernatant obtained by grinding the ticks in Eagle's minimum essential medium with Earle's salts (MEM) supplemented with bovine plasma albumin (Fraction V from bovine plasma) (BPA) and collecting the supernatant2.Item Preliminary Studies on an Atypical Strain of Bovine Theileria Isolated in Kenya(1974) Burridge, M.J.; Brown, C.G.D.; Crawford, J.G.; Kirimi, I.M.; Morzaria, S.P.; Payne, R.C.; East African Veterinary Research Organization, PO Box 32, Kikuyu, Kenya FAO/UNDP Project KEN 22, Veterinary Research Laboratory, PO Kabete, KenyaA theilerial parasite infective for cattle, Theileria sp. (Githunguri), was isolated from the Kiambu District of Kenya through Rhipicephalus appendiculatus ticks. Eight cattle were experimentally infected with Theileria sp. (Githunguri); their reactions were characterized by the production of low numbers of macroschizonts, no microschizonts, few or no piroplasms, and a transient febrile response. All these cattle recovered from clinically mild reactions to infection, but were fully susceptible to subsequent Theileria parva (Muguga) challenge. A cell culture isolate of Theileria sp. (Githunguri) was made from injected lymphoid cells of a reacting animal and, from the resultant in vitro culture suspension, a schizont antigen of the parasite was prepared for the indirect fluorescent antibody test. Serological studies on Theileria sp. (Githunguri), using this test, indicated that it was antigenically distinct from T. parva, T. lawrencei and T. mutans, but had some antigens in common with T. parva and T. lawrencei.Item Specific Problems of Semi-Arid Environments(1965) Payne, R.C.; E. A. A. F. R. 0.A precise definition of what constitutes a semi-arid environment is difficult, but it is generally agreed that the fundamental cause of aridity is climatic. While the major climatic factor involved is the total amount of rainfall per annum, its effectiveness depends on monthly distribution, the potential evaporation rate, the soil moisture infiltration rate and the vegetative cover. Pragmatically, a semi-arid environment can be defined as one in which the effective precipitation is too small for the successful practice of continuous crop production without irrigation water, but sufficient for the seasonal growth of forage and for limited animal production.Item Theileria Parva: Variation in the Infection Rate of the Vector Tick, Rhipicephalus Appendiculatus(1974) Purnell, R.E.; Ledger, M.A.; Omwoyo, P.L.; Payne, R.C.; Peirce, M.A.; East African Veterinary Research Organization, P,O, Box 32, Kikuyu, KenyaThe variation in Theileria parva infection rates of experimental batches of adult Rhipicephalus appendiculatus ticks, used during the course of several years, was examined. It was found that considerable variation occurred, but that this could not always be correlated with the piroplasm parasitaemia in the cattle on which the ticks engorged as nymphs. Statistical analysis showed that the infection rate of ticks fed on cattle with a parasitaemia of 41–50 per cent was significantly higher than that of ticks fed on cattle with lower parasitaemias. A number of experiments were then carried out in which one or several factors of this aspect of the host-parasite relationship remained constant whilst others were altered. None of these factors was seen to play a major part in the variation. Finally, randomly selected groups of 10 ticks which had dropped engorged as nymphs from the same animal on the same day were examined. The variation observed even in these groups was so great that it was concluded that the infection rate could depend on a factor such as the juxtaposition of possibly-infected gut epithelial cells and developing salivary glands during the nymphal moult.
