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Abstract

Controlling ticks and tick-borne diseases by frequent applications of acaricides (e.g. dipping) is costly, and can leave treated livestock vulnerable to epizootics of tick-borne diseases should the system of applying acaricides break down. The concept of only applying acaricides on an infrequent...

Author(s)
Meltzer, M. I.; Norval, R. A. I.
Citation
Experimental & Applied Acarology, 1993, 17, 3, pp 171-185
Abstract

The disruption of the dipping of cattle in Zimbabwe for the control of tick vectors demonstrated the dangers of creating herds with little or no natural immunity to tick-borne diseases. It is known that immunity to the tick-borne diseases heartwater (caused by Cowdria ruminantium), African redwater ...

Author(s)
Norval, R. A. I.
Publisher
Tick Research Unit., Grahamstown, South Africa
Citation
Tick biology and control. Proceedings of an International Conference held from 27-29 January 1981, under the auspices of the Tick Research Unit, Rhodes University, Grahamstown, South Africa., 1981, pp 87-90
Abstract

T. p. bovis isolates were tested for their immunizing capacity under natural field challenge on Willsbridge Farm in the highveld of Zimbabwe. 15 susceptible Sussex yearlings (about 14 months old) were immunized with the Boleni stock and 15 with a mixture of 3 isolates from the farm, using...

Author(s)
Koch, H. T.; Kambeva, L.; Ocama, J. G. R.; Munatswa, F. C.; Franssen, F. F. J.; Uilenberg, G.; Dolan, T. T.; Norval, R. A. I.
Citation
Veterinary Parasitology, 1990, 37, 3-4, pp 185-196
Abstract

Repeated sensitization of Friesland × Hereford cattle resulted in reduced rates of recovery of the tick at each instar. Specific antibodies to tick salivary gland were formed, and there was an enhanced skin reaction at the site of attachment. Principal factors in the immune response were...

Author(s)
Fivaz, B. H.; Norval, R. A. I.; Brown, A.
Citation
Proceedings of the 13th World Congress on Diseases of Cattle, Durban, South Africa, 1984, 1, pp 455-460
Abstract

The history of the control of ticks and tick-borne diseases in Zimbabwe is discussed, with special reference to the development of resistance to these pests and diseases in cattle when dipping was disrupted in 1970-80, and its retention when dipping was re-introduced in 1980-81. Alternative methods ...

Author(s)
Norval, R. A. I.
Citation
Zimbabwe Science News, 1985, 19, 1/2, pp 19-20
Abstract

Studying the dynamics of tick infestations on cattle is an essential step in developing optimal strategies for tick control. Successful strategic tick control requires accurate predictions of when tick infestations will reach predetermined threshold levels. In the case of A. hebraeum, earlier work...

Author(s)
Meltzer, M. I.; Norval, R. A. I.
Citation
Experimental & Applied Acarology, 1992, 13, 4, pp 261-279
Abstract

Liveweight gains (LWGs) of 3 groups of Africander steers, maintained in the same pasture in Zimbabwe and exposed to zero, medium or high numbers of larvae, nymphs and adults of A. hebraeum, were measured. Larvae and nymphs had no significant effect on LWG but adults had a large, statistically...

Author(s)
Norval, R. A. I.; Sutherst, R. W.; Jorgensen, O. G.; Gibson, J. D.; Kerr, J. D.
Citation
Veterinary Parasitology, 1989, 33, 3-4, pp 329-341
Abstract

Serum samples were collected in 1981 and 1982 from calves less than 12 months old at 244 localities in Zimbabwe and tested by IFAT for antibodies to T. parva. Positive cases were detected at 77% of localities in communal farming areas and at 70% of localities on commercial farms, but their...

Author(s)
Norval, R. A. I.; Fivaz, B. H.; Lawrence, J. A.; Brown, A. F.
Citation
Tropical Animal Health and Production, 1985, 17, 1, pp 19-28
Abstract

It was found from examination of samples taken in the Zimbabwe National Tick Survey Collection that the most commonly occurring and economically important species of Amblyomma is A. hebraeum, which in the adult stage is parasitic on cattle and other medium-to-large ungulates, leopards and...

Author(s)
Norval, R. A. I.
Citation
Zimbabwe Veterinary Journal, 1983, 14, 1/4, pp 3, 6-18
Abstract

Arguments against intensive dipping in Southern Africa are developed, firstly, in the light of the history of tick and tick-borne disease control in Zimbabwe and South Africa and, secondly, through consideration of the economics of intensive dipping as opposed to minimum dipping and the maintenance ...

Author(s)
Norval, R. A. I.
Citation
Zimbabwe Veterinary Journal, 1983, 14, 1/4, pp 19-25

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