[CHAPTER IV.]
DISEASES DUE TO FOOD.
Diseases may arise from the noxious character or from deficiency or excess of some particular food, or of the food as a whole.
Diseases from Unwholesome Food.—I. The Meat of Diseased Animals.
(1) The flesh of animals which have not been slaughtered should be prohibited from sale, whether death has resulted from accident or disease. The meat from diseased animals is also generally dangerous, sometimes owing to the drugs with which the animals have been dosed before death, e.g. tartar emetic, or opium.
(2) Meat may be unwholesome from the presence of parasites. Of these the most common is—
(a) The cysticercus cellulosæ, which is the undeveloped embryo of the tape-worm; that from the pig becomes the tænia mediocanellata. The cysticercus of the pig is the most common; it forms a cyst about the size of a hemp-seed, commonest on the under surface of the tongue. In hams oval holes are found or opaque white specks, which are the remains of the cysts converted into calcareous matter. When meat containing the cysticercus alive (as in under-cooked or raw meat) is swallowed, it develops into the tape-worm, which consists of a number of flat segments, each capable of producing numerous ova of new cysticerci, with a minute head at the narrow end surrounded by hooklets. A temperature of 174° F. kills the cysticercus. Another kind of tape-worm common on the continent, called bothriocephalus latus, is derived from the cysticercus of fish.
Fig. 2.
Cysticercus (“Measles”) in Pork.
(Natural Size.)
(b) The trichina spiralis is not a solid worm like the tænia, but possesses an intestine. In pork it forms a minute white speck, just visible to the naked eye, which forms a nest, and in this one or two coiled up worms can be seen by a magnifying glass in active movement. They are effectually killed by the temperature of boiling water; but no form of drying, salting, or even smoking at a low temperature is sufficient for this purpose. Boiling or roasting does not suffice to destroy all the trichinæ unless the joint is completely cooked in its interior. When trichinous pork is swallowed, the eggs develop in the alimentary canal in about a week into complete worms, and in three or four days more each female produces over a hundred young ones. These burrow into every part of the body, producing great irritation and inflammation. In one case after death upwards of 50,000 worms were estimated to exist in a square inch of muscle. Most of the cases of trichinosis have occurred in Germany, from eating imperfectly cooked sausages. The pig becomes trichinous by eating offal, and man is infected by eating pork. This disease is rare in England.
