Browsing by Author "East African Veterinary Research Organization, Muguga, P.O. Kabete, Kenya"
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Item Attempts to Grow Tissue Culture Cells, Infected with Theileria Parva, in Laboratory Animals(1972) Irvin, A.D.; Brown, C.G.D.; Crawford, J.G.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaTransformed bovine lymphoid cells infected with macroschizonts of Theileria parva were inoculated into normal mice and newborn mice by the subcutaneous route and also into hamster cheek pouches and the anterior chamber of rabbits' eyes. There was no evidence of growth or persistence of parasitized cells in any of the systems, nor were tumour-like masses formed. This contrasts with previous work when inoculation of similar material into whole-body irradiated mice resulted in persistence of parasitized cells and the formation of tumour-like masses.Item The developmental Periods of the Ixodid Tick Rhipicephalus Appendiculatus Neum. under Laboratory Conditions(1973) Branagan, D.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaA study, begun in 1966 at Edinburgh University, and completed during the ensuing 30 months at Muguga, Kenya, of the developmental periods of Rhipicephalus appendiculatus Neum. under controlled temperature and humidity was carried out to provide basic background information for an intensified FAO/EAVRO programme of East Coast fever research. Quantitative data are given on the preoviposition, pre-eclosion and, for larvae and nymphs, premoulting periods at three constant temperatures, 25, 21 and 18°C. The rate of development at all stages was accelerated by raising the temperature and retarded by lowering it. A “pre-immobilization period” which precedes the entry of engorged larvae and nymphs to the true moulting process also appeared to be temperature dependent. Development became very prolonged as temperatures fell below 18°C, being negligible at 15°C and having apparently ceased altogether at 9°C. Continuous exposure for more than two or three days to temperatures of 4°C and below were lethal to all engorged instars. Humidity (controlled at levels between 18 and 87% r.h.) had no influence on the rate of development. It is concluded that within limits of tolerable aridity, developmental periods would be completed within the times dictated by temperature regardless of the level of humidity or changes in the level of humidity. No suggestion of any diapause mechanism was discerned.Item Duration of Serological Response to the Indirect Fluorescent Antibody Test of Cattle Recovered from Thcilcria Parva Infection(1973) Burridge, M.J.; Kimber, C.D.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaUsing the indirect fluorescent antibody test, a significant antibody titre to Thcilcria parva cell culture schizont antigen was demonstrated until 12–73 weeks (mean 29·7 weeks) after infection in the sera of 35 cattle recovered from experimental East Coast fever. In the same animals a significant titre to T. parva piroplasm antigen was only detected until 7–25 weeks (mean 13·5 weeks) after infection. It is recommended, therefore, that the schizont antigen should be preferred to the piroplasm antigen when the indirect fluorescent antibody test is used in epizootiological studies of East Coast fever.Item East Coast Fever: The Infectivity for Cattle of Infective Particles of Theileria Parva Harvested in Various Substrates(1973) Cunningham, M.P.; Brown, C.G.D.; Burridge, M.J.; Joyner, L.P.; Purnel, R.E.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaFemale Rhipicephalus appendiculatus ticks infected with Theileria parva were pre-fed on rabbits for 4 days before being removed and restrained on ‘plasticine’. They were then fed for 2-h periods on capillary tubes containing various substrates, the contents of which were subsequently inoculated into East Coast fever-susceptible cattle. Using this technique, precolostral calf serum and Eagle's Minimum Essential Medium, with the addition of Bovine Albumin Powder, were selected as substrates suitable for further laboratory investigation on East Coast fever as they were acceptable to the ticks and supported the viability of the parasites.Item The Indirect Fluorescent Antibody Test for Experimental East Coast Fever (Theileria Parva Infection of Cattle). Evaluation of Dried Blood Samples as a Source of Antibody(1972) Kimber, C.D.; Burridge, M.J.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaEluatesfrom blood collected and dried on filter paper were a reliable alternative to sera for use in the indirect fluorescent antibody test for experimental East Coast fever, since the paiten of antibody response was similar to that detected wi.h serum samples. The collection of blood on filter paper greatly simplified the procedure for the routine serological screening of cattle and it is suggested that this technique may have considerable application in epizootiological studies on East Coast fever.Item Investigations of Allerton-type Herpes Virus Infection in East African Game Animals and Cattle(1971) Plowright, W.; Jessett, D.M.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaNeutralization tests with a strain (BA) of Allerton-type herpes virus, derived from a buffalo (Syncenis caffer) were carried out on 924 sera from 17 species of E. African game animals and on cattle sera from Tanzania (2001), Kenya (792) and Uganda (410). Buffalo populations throughout E. Africa showed a very high rate of infection, with all animals over 2 years of age serologically positive. Antibody was present in some giraffe, waterbuck and hippopotamus sera and, less frequently, in impala, eland, bushbuck and oryx. Data are provided on the titres of positive samples; the mean titre of buffalo sera increased with age. Cattle in many localities of N. Tanzania and S. Kenya showed a very high rate of infection, 85–95% of sera from animals more than 2-years old containing antibody; the titres recorded were lower than those in buffaloes. Very high infection rates were also found in Karamoja and Teso (Uganda) and also in some other areas of Kenya, whilst a considerably lower incidence of infection was detected in W. Nile Province of Uganda and in central Tanzania. Differences in infection rates may have been related to herd size and husbandry practices. It was shown that a wave of infection was probably spreading through cattle in N. Tanzania at about the same time as an outbreak of disease occurred in buffaloes and it is suggested that virus transmission may have been by biting flies. No clinical signs attributable to the virus were reported in cattle but mouth lesions similar to those recorded in buffaloes, or nasal lesions, could have passed undetected. Allerton-type virus probably produces a range of clinical syndromes in cattle, closely resembling those associated with some herpes viruses in primates but infection is seldom related in the field to either pseudo-lumpy skin disease, mammillitis or stomatitis.Item Preliminary Observations on a Theilerial Species Pathogenic to Cattle Isolated from Buffalo (Syncerus Caffer) in Tanzania(1973) Young, A.S.; Branagan, D.; Brown, C.G.D.; Burridge, M.J.; Cunningham, M.P.; Purnell, R.E.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaA theilerial species, pathogenic to cattle, and resembling Theileria lawrencei, was isolated from two buffalo captured in the Serengeti National Park, Tanzania. When nymphal Rhicephalus appendiculatus ticks were fed on the buffalo, on four out of six occasions the resultant adults were shown to be capable of causing highly pathogenic T. lawrencei-type infections in cattle. Aspects of the life cycle of the parasite in both ticks and cattle were studied. Its development in the tick was apparently similar to that of T. parva, and, in cattle, only differed from T. parva by causing the host’s death when relatively few lymphocytes were infected with macroschizonts and when neither microschizonts nor piroplasms were detectable. The parasite was designated T. lawrencei (Serengeti).Item Response of Whole-body Irradiated Mice to Inoculation of Theileria Parva Infected Bovine Lymphoid Cells(1974) Irvin, A.D.; Brown, C.G.D.; Kanhai, G.K.; Kimber, C.D.; Crawford, J.G.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaTheileria parva-infected bovine lymphoid cells produced tumour-like masses at the site of subcutaneous inoculation in whole-body irradiated Swiss mice. The optimal dose range for irradiation was 800 to 900 rad. Intact parasitized cells were detected in these masses up to about d. 17 after inoculation and were then gradually rejected as the host's defence mechanisms recovered. The masses appeared to be produced by the continued growth of tissue culture in the immuno-suppressed host. There was no evidence that mouse cells became parasitized.Item Theileria Parva: Comparative Infection Rates of Adult and Nymphal Rhipicephalus Appendiculatus(1971) Purnell, R.E.; Boarer, C.D.H.; Peirce, M.A.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaThe tick Rhipicephalus appendiculatus is the usual vector of Theileria parva, the causative organism of East Coast fever (ECF) of cattle. When immature ticks engorge on parasitaemic cattle, they imbibe red cells containing T. parva piroplasms. The parasite subsequently undergoes a cycle of development in the body of the tick resulting in the production of a stage infective for cattle in the tick's next instar. It is generally accepted that adult ticks, which have engorged as nymphs on infected cattle, are largely responsible for the maintenance of the disease in the field (Theiler, 1905). However, Reichenow (1940) has suggested that if larval and nymphal ticks are fed on animals with the same level of infection, more parasite groups will be present in the salivary glands of the resultant nymphs than in those of the resultant adults. Reichenow also suggested that a group of nymphs, unlike a group of adult ticks, will begin to feed synchronously when applied to a host, and that the maturation of the parasite can be completed after 72 h feeding instead of 108 h as in adult female ticks.Item The use of Fluorescent Antibody Techniques to Detect Theileria Parva in the Salivary Glands of the Tick Rhipicephalus Appendiculatus(1973) Kimber, C.D.; Purnell, R.E.; Sellwood, S.A.; East African Veterinary Research Organization, Muguga, P.O. Kabete, KenyaNymphal Rhipicephalus appendiculatus ticks were experimentally infected with Theileria parva. Developing stages of the parasite were subsequently detected in the salivary glands of the resultant adult ticks using direct and indirect fluorescent antibody techniques. It was found that the indirect method used was more sensitive than the direct methods, probably because of difficulties in preparing a direct conjugate of sufficient activity against the tick stages of the parasite.
