Biomedical subjects
Publications and source records attributed to G Uilenberg.
Theileria sp. (Bwengwa) of low virulence was isolated by feeding R. appendiculatus ticks collected from the field on a susceptible calf and subsequently transmitted between cattle by R. appendiculatus ticks- Theileria sp. (Bwengwa) was shown to be T. taurotragi on parasitological, clinical and serological grounds. T. taurotragi is the fourth Theileria sp. shown to be present in Zambia.
An outbreak of bovine theileriosis in Burundi was investigated and the occurrence of Theileria orientalis in Central Africa was confirmed for the first time. Its identity was established on morphological and serological grounds. The parasite was associated with clinical signs and further complicates the disease picture of bovine theileriosis in Africa. Amblyomma variegatum is suspected as being the local vector.
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Starting from a stabilate of caprine blood infected with the Kwanyanga stock of Cowdria ruminantium, eight serial passages were made in groups of mice, and eight parallel serial passages in goats. Cross-immunity tests in goats and mice failed to demonstrate any difference between stabilates made after the eighth passage. The Kwanyanga stock was of exceptionally low virulence for Dutch goats.
For the first time cases of babesiosis have been diagnosed in dogs that had not been abroad. Three cases were seen in the province of Gelderland (Bennekom, Elspeet), two in North-Holland (Koog aan de Zaan). A female Dermacentor reticulatus tick, the main vector of the disease in Europe, was found on one of the dogs at Koog; previously specimens of this tick species had only occasionally been seen on dogs returning from abroad. Serological evidence was obtained that in at least four of the cases European Babesia canis, transmitted by Dermacentor ticks, was involved.
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Serological and morphological comparison of Theileria orientalis stocks from Australia, Britain, Iran, Japan and the USA with a more pathogenic stock from Korea, corresponding to T sergenti of Russian literature, showed that they all belong to one species, for which the name T orientalis is recommended. T orientalis is now known to occur on all continents. Macroschizonts and microschizonts, found in some of the calves infected with the Korean stock, are described and illustrated. Infections with the Korean stock were associated with early hyperthermia during the period schizonts are found, and commonly with high parasitaemias and anaemia even in unsplenectomised calves. The higher pathogenicity of this stock may be related to a faster rate of division. T orientalis may cause latent infection in sheep. With the exception of the stock from the USA, all stocks could be transstadially transmitted by Haemaphysalis longicornis and, or, H punctata.
A benign species of Theileria of cattle in northern Iran proved to be indistinguishable from T. orientalis in the indirect fluorescent antibody test as well as in the morphology of its piroplasms. It was transmissible transstadially by Haemaphysalis punctata.
Microschizonts and free merozoites developed in bovine lymphoblastoid cell cultures containing macroschizonts of 6 different strains of Theileria parva. Clean bovine red cells were added to the cultures, which were incubated in various ways. No penetration of red cells by merozoites was observed, not even when cultures in diffusion chambers were introduced into the peritoneal cavity of non-infected cattle.
Blood from calves with a parasitaemia of Theileria mutans was cultivated in vitro in various ways. No significant increase in the percentage of infected red cells was observed, but the percentage of dividing forms of the parasite rose sharply during the first two days of incubation. The conditions of the cultures were apparently unsuitable for the invasion of erythrocytes.
Rhipicephalus zambeziensis was shown experimentally to transmit Theileria parva parva in cattle from nymph to adult and Theileria parva lawrencei, Theileria parva bovis and Theileria taurotragi from larva to nymph and nymph to adult. In a single trial the tick failed to transmit Theileria mutans. The tick is believed to be a vector of T. parva lawrencei in the field in Zimbabwe.
Cross immunity tests with strains of Cowdria ruminantium from South Africa, the Sudan, São Tomé and Nigeria failed to demonstrate antigenic differences. The antibiotic ampicillin showed no activity against heartwater.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
One pathogenic and 4 mild bovine Theileria strains from southern Africa, all transmitted by Rhipicephalus appendiculatus, were compared amongst themselves as well as to bovine and buffalo strains of the T. parva complex from eastern and southern Africa and to bovine strains of T. taurotragi from Tanzania considered to be derived from eland antelope. Criteria used were parasitological, clinical, serological and cross-immunity characters. The mild strains are similar to bovine T. taurotragi. Serological evidence suggested that T. taurotragi is also infective to sheep. The pathogenic strain belongs to the T. parva complex; the latter consists of a series of types with different behaviour ranging from the lawrencei-type (of buffalo) causing Corridor disease, through the bovis-type causing Rhodesian malignant theileriosis to the parva-type causing classical East Coat fever. Seven cattle-tick passages of a bovis-type strain did not result in transformation into a parva-type. Four species of bovine Theileriae are now known to occur in southern Africa: T. parva (lawrencei- and bovis-types) and T. taurotragi, both transmitted by R. appendiculatus, and T. mutans and T. velifera both with Amblyomma spp. as vectors.
Theileria parva infected lymphoblastoid bovine cells were grown in a medium based on HEPES-buffered RPMI 1640 with glutamine and antibiotics, supplemented with bovine serum. There were no significant differences in growth rate, viability, and percentage of infected cells when the substrate contained 10 or 20 per cent of either commercially available newborn calf serum of serum prepared from adult non-infected Friesian cattle or of serum prepared from a Friesian calf immunised against East Coast fever and having a high titre of antibodies to T. parva antigen in the indirect fluorescent antibody test. If studies showing that newborn calf serum gives results in the establishment and maintenance of T. parva cell culture similar to those of foetal calf serum are confirmed, this finding could mean an appreciable saving in the cost of in vitro work on this parasite.