PubMed · 7402149
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R L Doherty. 1980-06-14. Q for query.. https://doi.org/10.5694/j.1326-5377.1980.tb135149.x
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The study was designed to determine the effect on bovine spongiform encephalopathy (BSE) and scrapie agents of the solvent extraction processes used in the past by British renderers. The raw material was mouse spleen infected with either the 22A strain of scrapie agent or the 301V strain of BSE agent. Samples were exposed to hexane, heptane, petroleum spirit or perchlorethylene at the relevant temperatures for the appropriate times. Control samples were exposed to the same range of temperatures for the same range of times in saline. Other samples were exposed to the hot solvents, followed by treatment with dry heat at 100 degrees C for 30 minutes and steam at 100 degrees C for 30 minutes. Further samples were exposed only to the dry heat and steam cycles. No single complete process was significantly more effective than any of the others, and they all produced only slight inactivation, less than one log on average for both strains of agent. The average degree of inactivation produced by exposure to hot saline was generally comparable to that produced by exposure to the hot solvents. This was also true for the samples exposed only to dry heat and steam compared with those exposed to hot solvent before treatment with dry heat and steam, and suggests that the slight inactivation was caused by the heat rather than by the solvents. It is concluded that the solvent extraction processes used by renderers in Britain had little capacity to inactivate BSE and scrapie agents.
Contagious bovine pleuropneumonia (CBPP) caused by Mycoplasma mycoides subspecies mycoides small colony (M. mycoides) has been endemic in many parts of Africa for the greater part of this century. Because of an international vaccination campaign the disease was almost eliminated from the continent. With the deteriorating economic situation of many countries, vaccination programs have been allowed to slip; drought conditions have resulted in great movements of livestock and the disease has spread rapidly to the east and south. For Government Veterinary Departments, the implications of this resurgence of CBPP, are serious. The costs threaten to overwhelm completely under-funded government, services. Where cost-recovery measures are introduced, the charging for vaccines may damage rapport with communities and erode the credibility of the government services. Farmers may find the loss of cattle and the costs of vaccine severe burdens which threaten their livelihoods and social well-being (Zambia) and even, in extreme cases, their survival (Botswana). Controlling the disease today presents new possibilities which include increased cross-border collaboration (Malawi/Tanzania), increased emphasis on monitoring (N. Zambia) and the greater involvement of communities in disease control (W. Zambia).
A study was made to evaluate the use of a marker organism for assessing whether hygienic slaughter practices were being followed at red meat abattoirs. The organism, a nonpathogenic strain of Escherichia coli K12 that was resistant to nalidixic acid, was detected and counted on a highly specific isolation medium. With beef carcases, the practice of bagging the excised anus reduced, but did not prevent the spread of the organism from an inoculum applied in the anal region before the hide was removed. The carcases of sheep that were processed at a low-throughput abattoir, were contaminated with the marker after the fleece had been inoculated at a single site. The contamination was significantly reduced (P<0.001) when the operative responsible for flaying had cleaned his hands, arms and apron before and during the handling of each carcase, and used a knife which was freshly pasteurised on several occasions. However, the subsequent washing of carcases had little or no effect on the levels of the marker organism. It was concluded that the marker may be of value in assessing hygiene control, improving present practices, and training abattoir staff.