§ Mr. de Freitasasked the Minister of Agriculture, Fisheries and Food whether he is aware that the 1,000 pigs which died or were slaughtered at Risby, Scunthorpe, Lincolnshire, after an outbreak of swine fever, had all been vaccinated with crystal violet; and whether he will make a statement on the use of this method of vaccination.
Mr. Vane:Swine fever was confirmed on two farms in the same ownership at Low Risby, near Scunthorpe, on 24th January. With the exception of most of the breeding stock, which are at present still apparently healthy, all the pigs on the two farms were sent to slaughterhouses and bacon factories or died or were destroyed on the premises Crystal violet vaccine had been used regularly on both farms as soon as the pigs were considered old enough to be vaccinated.
Crystal violet vaccine normally confers a reasonable degree of protection against natural infection from swine fever for about twelve months but, as with vaccines generally, there are limitations.
184WThe vaccination of pigs may not be fully effective if before, or during the fortnight after, vaccination, they are exposed to infection. Similarly, if pigs are harbouring some other infection when vaccinated, they may not develop sufficient immunity to protect them against swine fever.