British Food Journal Volume 51 Issue 10 1949

Abstract

Although a comparatively rare disease in Great Britain, cases of trichinosis have been reported from different parts of the country from time to time. Statistics show that during the present century only 59 cases were reported prior to the Wolverhampton outbreak in 1941. Trichinosis is a parasitic disease. The Trichina spiralis lives in the small intestine, the female measuring about ⅛ in. in length and the male 1/16 in. The ova emerge as minute hair‐like embryos which burrow from the intestines to the musculature of the host. Thus if man consumes pork containing live trichinæ the larvæ are freed from their capsules by the action of the gastric juices, and maturity is attained in the small intestine. The female grows rapidly and at the end of a week gives rise to a swarm of a hundred or so embryos. The burrowing process starts again, and this boring into muscles produces intense muscular pains, swelling and tenderness, high fever, and other symptoms. The effects of cooking and preserving on infected meat are described by Mr. C. R. A. Martin, who says that thorough cooking for twenty minutes at a temperature above 150° F. is sufficient to destroy all trichinæ, providing the whole of the meat is subjected to this temperature for a similar period. It is obvious, therefore, that in domestic cookery boiling would be preferable to roasting in order to kill live parasites. Only very low temperatures (0°–5° F.) applied for three weeks have any effect on the vitality of trichinæ. Dry salting will kill all trichinæ in surface layers of the meat after exposure to the salt for fourteen days, but in the case of large bacon or hams a much longer exposure of eight to twelve weeks would be necessary, together with brine pumping of the thicker parts. Pickling in brine, if the brine is sufficiently strong, is a surer method of destroying larvæ. Smoking, partly through heat and partly the resinous products of burning pine sawdust, also has a slight effect on their vitality. It has, howver, been suggested that Memo. 62/Foods issued by the Ministry of Food, which recommends that a carcase affected with trichinosis should be condemned, is out of date and that there should be no grounds for ignoring the possibility of the disease during the ordinary routine meat inspections. In this connection, the recent circular dealing with outbreaks of cysticercus bovis infestation of cattle in different parts of the country should serve as a warning. A further warning is given in a letter to the British Medical Journal in which the writer deplores the way in which corned beef is served to the public. The procedure in the majority of shops, says the writer, is to open a large tin of corned beef and place the contents on a wooden cutting board. The same knife used for cutting uncooked sausages, uncooked beef, uncooked pork, and slabs of sausage meat is used, without any attempt at cleaning it, for cutting slices of corned beef. The writer goes on to say that the corned beef is then placed on the weighing machine plate, which quite normally in a butcher's shop is covered with blood. Further contact between the uncooked meat and corned beef is made when the wrapped (and sometimes unwrapped) corned beef is placed on top of the raw meat. Should parasitic worms or cysts which have evaded the eye of the meat inspector be present in the raw meat, they will be transferred to the corned beef by knives, by butchers' hands, by scales, and by direct contact with the raw meat. Many veterinarians have pressed for the detailed examination of pig carcases for trichinosis which would necessitate the removal of suspected muscle by means of a trichinoscope, but no such instrument is in existence in the abattoirs of this country. The whole operation, which is carried out as a matter of routine inspection in many Continental abattoirs, takes only a few minutes. Should simple safeguards in feeding and inspection be adopted, it seems fairly evident that the absence of a trichinoscope need not be regarded as a serious gap in our public health services, but the rarity of outbreaks of the disease in this country must not lead to complacency or to ignoring the possibility of its presence during the normal course of meat inspection.