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Biomedical subjects

G Uilenberg

Publications and source records attributed to G Uilenberg.

At least 91 records · Page 5Linked to original sources
PubMed1980

Development of Theileria mutans (Theiler, 1906) in the gut and the haemolymph of the tick Amblyomma variegatum (Fabricius, 1794).

The development of Theileria mutans in the gut and haemolymph of its tick vector, Amblyomma variegatum, was studied by Giemsa-stained smears after the nymphal tick had completed engorgement on parasitaemic calves. Sexual stages occurred in the gut between five and seven days after repletion. The zygotes were observed in the gut from day 29 and the kinetes from day 30, i.e. three and four days after the nymphs moulted to adults. From day 34 kinetes were observed in the haemolymph. The developmental stages of T. mutans in the tick were compared with those of other Theileria spp. of cattle.

Animals↗
PubMed1980

Artificial infection of Rhipicephalus appendiculatus with Theileria parva by percutaneous injection.

Rhipicephalus appendiculatus nymphs were inoculated with fresh or cryopreserved blood containing Theileria parva piroplasms, or with cell culture grown stages of T parva. The use of fresh blood was successful. Cryopreserved blood containing dimethylsulphoxide (DMSO), killed most nymphs after inoculation: DMSO could be removed by slow dialysis, without destroying the infectivity of the blood. Attempts to infect ticks by inoculating cell culture grown stages of T parva failed, even when large numbers of merozoites were present in the inoculum.

Animals↗
PubMed1980

Cowdria ruminantium (Rickettsiales) in primary goat kidney cell cultures.

Fresh or cryopreserved kidney tissue from goats suffering from heart water (Cowdria ruminantium infection) was infective when inoculated intravenously into susceptible goats. Primary kidney cell cultures were established from 14 goats reacting to C ruminantium infection; they were tested for infectivity by intravenous injection into susceptible goats after periods varying from five to 31 days. Three cultures, five, 12 and 13 days old, induced heartwater in recipients. The other 11 cultures, varying in age from six to 31 days, did not cause any reaction and all 11 recipient goats died from heartwater on challenge. C ruminantium could not be detected microscopically in the cell cultures.

Animals↗
PubMed1979

Blood parasites of sheep in the Netherlands. I. Anaplasma mesaeterum sp.n. (Rickettsiales, Anaplasmataceae).

On two occasions an anaplasm was isolated from sheep on the Dutch island of Ameland. The organism proved to be highly pathogenic for splenectomised sheep; a non-splenectomised animal recovered spontaneously after the packed cell volume had decreased by 40%. Treatment with oxytetracycline was effective. Its pathogenicity for goats appeared to be low, and the organism was apparently not infective to splenectomised cattle. This anaplasm differs from Anaplasma ovis in that less than 30% of the organisms are marginally situated in the red cell, as against over 70% in A. ovis; cross-immunity with A. ovis was incomplete and the latter appeared to be far more pathogenic to goats than the Dutch anaplasm, for which the name Anaplasma mesaeterum sp.n. is proposed. Its ultrastructure is similar to that of A. marginale and A. ovis. The vector is either Ixodes ricinus or Haemaphysalis punctata. Its practical importance remains to be ascertained.

Anaplasma↗
PubMed1979

Theileria mutans in Nigeria.

Two strains of bovine Theileria from northern Nigeria were shown to be identical to Theileria mutans in the indirect immunofluorescent antibody test. One of the strains was transmitted by the tick Amblyomma variegatum; large macroschizonts, typical for T mutans, could be demonstrated in infected cattle. It is concluded from these experiments and from the literature that there is reliable evidence so far for the occurrence in Nigeria of only two bovine Tehileria species, T mutans and T velifera.

Animals↗
PubMed1979

On the life cycle of Theileria velifera (Uilenberg, 1964) in the gut and the haemolymph of the tick vector Amblyomma variegatum (Fabriciu, 1794).

The development of Theileria velifera in the gut and the haemolymph of the tick vector Amblyomma variegatum is described. Between days three and eight after repletion various sexual stages are present in the gut of the nymphs. Zygotes were detected in the gut on day 14, while undifferentiated kinetes first appeared on day 15. In the haemolymph, differentiated kinetes were observed from day 16 after repletion onwards. Zygotes and kinetes were also found after the moult, in the adult tick, for a prolonged period of time. The results of this study show that the developmental stages of T. velifera in the gut and haemolymph are characteristic of the genus Theileria.

Animals↗
PubMed1979

Skin nodules in East Coast fever.

A skin eruption developed in five calves with advanced experimental East Coast fever (ECF) (Theileria parva infection). In three cases the eruption was due to intradermal nodules containing numerous theilerial schizonts, in one animal the nodules contained abscesses filled with Demodex mites, and in the fifth calf both types of nodules were present. No nodules were seen in 15 other experimental cases of ECF, which generally died or were killed in an earlier stage of the disease. It is postulated that demodicosis may become apparent in healthy carriers of the mite in the course of ECF, because of immuno-depression caused by the latter disease.

Animals↗
PubMed1978

Erythrocytic forms of Theileria velifera.

The enigmatic veil associated with the cattle parasite Haematoxenus veliferus has been shown to be crystallike in ultrastructure and to stain with benzidine like haemoglobin. The ultrastructure of the organism is similar to that of other theilerial parasites. As less distinct veil-like structures are known to occur with some other Theileria species, and in one case, have also been shown to be crystalline in structure, it is proposed to sink the genus Haematoxenus as a synonym of Theileria.

Animals↗
PubMed1978

Is Mukherjeella caprae Bandaranayake and Neitz, 1961 (Rickettsiales) a microorganism?

Longitudinal structures in red cells in Giemsa-stained blood smears of goats in the Netherlands were in distinguishable from what has been described as Mukherjeella caprae Bandaranayake and Neitz, 1961 (Rickettsiales). Electron microscopic studies and animal experiments showed, however, that these structures are not parasitic in nature, but are fibres consisting of bundles of microfilaments embedded in the erythrocytic cytoplasm, apparently identical with the longitudinal fibres in goat erythrocytes which are considered to be a haemoglobin abnormality. The condition appears to be genetic. M caprae should be considered as a nomen dubium.

Alphaproteobacteria↗
PubMed1977

Biological differences between African Theileria mutans (Theiler 1906) and two benign species of Theileria of cattle in Australia and Britain.

Serological and morphological comparisons between the theilerias found in Australian and British cattle and of these with African Theileria mutans (Theiler 1906) showed that the Australian and British parasites were similar to each other but different from T. mutans. Further investigations are required to determine taxonomic affinities between the Australian and British theilerias and T. sergenti, a similar parasite found in eastern Asia.

Animals↗
PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania. VI. Second field trial on immunization against cattle theileriosis.

Nine cattle, immunized by an infection and treatment method with 3 strains of Theileria parva (Muguga, Kiambu 5 and Serengeti transformed) and nine controls, were exposed to natural tick infestation in Tanzania. All controls contracted fatal East Coast Fever within 2 months of exposure. All immunized animals survived the period of exposure (over 2 months), but later one died of ECF, one of heart-water, one of an undetermined cause (not a theileriosis), and one disappeared from the herd. The 5 remaining animals survived for over 3 months after exposure ended. It is thought that this method of immunization is of value in protecting valuable animals at risk. An attempt to immunize against pathogenic Theilereia mutans, by injecting blood containing an apathogenic strain of this parasite, gave inconclusive results as no pathogenic strains were encountered during the trial.

Animals↗
PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania. VIII. Experiments with African buffalo (Syncerus caffer).

It has been found that African buffalo may remain infective carriers of Theileria parva lawrencei for at least 5 years. This infection is now known to exist in buffalo in 3 sites in northern Tanzania. It was shown that buffalo can be infected with Haematoxenus veliferus and Theileria mutans of cattle and retransmission of these parasites from buffalo to cattle was successful. The species of Haematoxemus reported in wild buffalo in central and East Africa is likely to be H. veliferus, while the possibility that Theileria barnetti of buffalo is identical with T. mutans should be considered. African buffalo can also be infected with Babesia bigemina and Anaplasma marginale of cattle and although the infections are latent, their blood may remain infective for at least several months.

Animals↗
PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania IX. Unidentified bovine Theileriae.

Two strains of nonpathogenic Theileriae, designated as Theileria sp. (Idobogo) and Theileria sp. (Mwanza), were isolated from cattle in southern and northern Tanzania respectively. They were similar to each other, producing low numbers of T. parva-like macroschizonts and of small piroplasms. Both were readily transmitted by Rhipicephalus appendiculatus. No serological relationship with T. mutans was found, while serum of some of the recovered animals gave fleeting, low titres in the indirect fluorescent antibody test to T. parva schizont antigen. Recovered animals were fully susceptible to T. parva challenge. The possibility that these strains may be similar to Theilleria sp. (Githunguri) of Kenya is suggested.

Animals↗
PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania. X. A large-scale field trial on immunization against cattle Theileriosis.

50 cattle immunized by an infection and treatment method with 3 strains of Theileria parva (Mugaga, Kiambu 5 and Serengeti transformed), together with 19 controls, were exposed to natural tick infestation in Tanzania, in a site where a continuous influx of infected ticks from different regions of the country may be expected to occur. Exposure lasted for 2 months, monitoring continued for 3 more weeks after exposure ended. All 19 controls contracted East Coast Fever and died. 40 of the 50 immunized animals survived the whole period of monitoring; the other 10 died of accidents (2), heartwater (3) and unidentified causes (5); none died of ECF. It is recommended that this method of immunization be routinely applied to protect valuable animals at risk. An attempt to immunize against pathogenic Theileria mutans, by injecting blood containing piroplasms of a strain of low pathogenicity, showed that this method may protect against high parasitaemias caused by natural tick-borne infections and may be useful in eliminating the confusing factor of T. mutans in future trials on East Coast Fever.

Animals↗
PubMed1976

Studies on Theileriidae (Sporozoa) in Tanzania. V. Preliminary experiments on a new method for infecting ticks with Theileria parva and Theileria mutans.

Bovine blood with a high parasitaemia of Theileria mutans was injected through the cuticle into fully engorged nymphs of Amblyomma variegatum which had recently detached from a rabbit. After moulting, they transmitted this parasite to a susceptible calf. Rhipicephalus appendiculatus transmitted Theileria parva in the same way, but results were negative with A. variegatum and T. parva. This method of infecting ticks appears promising for the isolation of Theileria strains from the field, and might be useful in research on theilerioses.

Animals↗