Browsing by Author "Purnell, R.E."

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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.
Blood Parasites of the Impala (Aepyceros Melampus) in the Serengeti National Park
(1973) Irvin, A.D.; Omwoyo, P.; Purnell, R.E.; Peirce, M.A.; Schiemann, B.; East African Veterinary Research Organisation, Muguga, P.O. Kabete, Kenya. Serengeti Research Institute, Tanzania National Parks, P.O. Box 3144, Arusha, Tanzania
The incidence of parasites was: Theileria 44.7%, Trypanozoon 5.8%, Haematoxenus 2.3% and Borrelia 1.2%. There was no evidence that these parasites were pathogenic to their hosts. Rhipicephalus evertsi ticks collected from these animals showed a salivary gland infection rate of 5.4%. Haematoxenus has not been described previously from impala.
Carnivores as Vehicles for Ticks Carrying Disease Agents: A Possible Role of the Large-Spotted Genet, Genetta Tigrina, In the Epizootiology of East Coast Fever
(1970) Purnell, R.E.; Peirce, M.A.; Musoke, A.; FAO Tick-borne Disease Project: East African Veterinary Research Organization
Captive genets were offered the ears of steers which had died of East Coast fever (E.c.F.), and on which nymphal Rhipicephalus appendiculatus were feeding. The genets fed on the ears and the ticks re-attached to the genets and completed their engorgement. After moulting, the resultant adult ticks were applied to a steer which had a typical fatal E.C.P. reaction.
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.
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 Organization
Adult 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.
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 of Cattle: 60 Co Irradiation of Infective Particles of Theileria Parva
(1973) Purnell, R.E.; Brown, C.G.D.; Cunningham, M.P.; Burridge, M.J.; Musoke, A.J.; Dargie, J.D.; East African Veterinary Research Organization, Muguga, P. O. Kabete, Kenya. Faculty of Veterinary Science, University of Nairobi, Nairobi, Kenya
Infective particles (IPs) of Theileria parva, the causative organism of East Coast Fever of cattle, were harvested from the tick vector, Rhipicephalus appendiculatus, using an in vitro feeding technic. In a ranging experiment, pairs of cattle were inoculated with aliquots of suspensions of IPs irradiated at doses of 4–137.6 krad. Doses of irradiation in excess of 8 krad appeared to destroy the parasite. In the 2nd and 3rd experiments, groups of 5 cattle were inoculated with aliquots of suspensions containing low and high concentrations of IPs respectively, irradiated at doses of 4–32 krad. In the 2nd experiment, doses of irradiation in excess of 10 krad appeared to destroy the parasite. In the 3rd experiment, at least 1 animal became infected when inoculated with an aliquot of a suspension irradiated at 16 krad. In all experiments, it appeared that increasing doses of irradiation destroyed increasing numbers of IPs. There was no conclusive evidence that IPs which survived irradiation were attenuated, and it appears that vaccination of cattle against ECF is unlikely to be achieved by inoculation of irradiated IPs using the methods described.
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.
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, Kenya
Three 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.
East Coast Fever: Challenge if Immunised Cattle by Prolonged Exposure to Infected Ticks
(1975) Radley, D.E.; Brown, C.G.D.; Cunnigham, M.P.; Kimber, C.D.; Musisi, F.L.; Purnell, R.E.; Stagg, S.M.; East African Veterinary Research Organization, Muguga, PO Box 32, Kikuyu, Kenya
Bos taurus steers, previously treated with acaricide but washed before the trial commenced, were introduced sequentially to a paddock with a high level of T. parva infected ticks. The 12 animals exhibited macroschizonts in lymph nodes at 7-12 days, a febrile response at 9-13 days, and died at 14-21 days. Tick counts were highest on ears (the maximum level was 330), and the build-up of tick attachment correlated with time to death. Four steers immunized three months previously with tick-derived T. parva stabilate material plus Terramycin ECF were kept in the paddock throughout the experiment (60 days). Prepatent period was 10-15 days, but despite high levels of tick attachment (peaks of 500 on ears), there were minimal symptoms and only a slight transient rise in antibody titre on day 40. A few macroschizonts were detected in lymph nodes during the first week of infection and they reappeared from days 34-38. A few piroplasms were seen intermittently in blood smears.
East Coast fever: correlation between the morphology and infectivity of Theileria parva developing in its tick vector
(1973) Purnell, R.E.; Brown, C.G.D.; Cunningham, M.P.; Burridge, M.J.; Kirimi, L.M.; Ledger, M.A.
Rhipicephalus appendiculatus ticks, infected with Theileria parva, were fed on rabbits and removed at daily intervals for 9 days. Half of the ticks removed were dissected and their salivary glands processed and examined for parasites. The remaining ticks which had been removed were ground up and aliquots of the supernatant fluid thus obtained were injected into East Coast fever susceptible cattle. Cattle injected with supernatant fluids from ticks fed for 4-9 days became infected, and this could be correlated with the histological detection of mature parasites in the corresponding ticks. The most highly ineffective supernatant fluids were prepared from 5-day-fed ticks. In a second experiment it was shown that female ticks of a variety of weights contained ineffective particles of T.parva.
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, Kenya
A 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.
The feeding behavior on rabbits and in vitro of the Ixodidtick Rhipicephalus appendiculatus Neumann, 1901
(1968) Joyner, L.P.; Purnell, R.E.
The tick, Rhipicephalus appendiculatus, has been the object of considerable interest in Africa, because it is the vector of several protozoal and viral infections of cattle, sheep, goats and man. Its major importance is as the principal vector of Theileria parva, the causal agent of East Coast Fever of cattle.
Host-parasite relationships in schistosomiasis
(1966) Purnell, R.E. ; East African Institute for Medical Research, Mwanza, Tanzania
In the first paper of this series (Purnell, 1966) the effect was examined of temperature at the time of contact on the infection of snails by miracidia and of mice by cercariae of Schistosoma mallsoni. Before the actual contact, the larvae had been maintained at ambient room temperature, and the influence of the various temperatures at contact was therefore considered as an isolated effect. This clearly may not be strictly related to field results, since the temperature at which the larvae had been kept before contact, coupled with their age, would also be expected to influence their vitality. In the present paper the effect is examined of the maintenance of the larvae at different temperatures for varying times before contact with the potential host.
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 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, Kikuyu
Techniques 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.
Infection of the Tick Rhipicephalus Appendiculatus with Theileria Parva Using an Artificial Feeding Technique
(1970) Purnell, R.E.; East African Veterinary Research Organization
R. appendiculatus nymphs were fed through capillary tubes containing blood with a 21-35% parasitaemia from cattle infected with T. parva, or containing washed red cells from similar samples suspended in serum. Nymphs which first partially engorged on a rabbit, then completed engorgement on infective blood from capillary tubes, produced adults infective for cattle. Nymphs which initially fed from capillary tubes and completed engorgement on a normal rabbit were not infective for cattle. -DWT

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Browsing by Author "Purnell, R.E."

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