Food is commonly a carrier of pathogenic matter. Parasites, such as intestinal worms and trichinae, are introduced into the human system by infected meat. Such parasitism is entirely preventable, first, by proper civic or state inspection of meat that is used as food, and, secondly, by thoroughly cooking all meat before it is eaten, for these parasites are destroyed by cooking. Trichiniasis is caused by eating raw pork, usually by eating raw ham, or sausages. Intestinal worms are transmitted to man in a larval state in beef and pork that is eaten raw or imperfectly cooked.

Micro-organisms are also not infrequently introduced into the human system by food. The danger of transmitting tuberculosis, typhoid fever, cholera, scarlet fever, and diphtheria by milk has been dwelt upon (p. 71). Tuberculosis may also be conveyed by raw meat that has been infected. Disease caused in these ways can be prevented by vigilant inspection by trained experts of the raw foods sold in markets. The flesh of animals that have been slaughtered and examined according to the laws of the Jewish rabbis ('Kosher' meat) is free from infection. Cooking will destroy most parasites. Cleanliness in the preparation and serving of foods is also necessary to prevent its becoming a carrier of disease. It has been demonstrated in recent cholera epidemics in Europe and in typhoid epidemics among the soldiers of the United States in the Spanish-American War, that flies, because of their filthy habits, carry disease germs from the excrements of the sick to the food of the healthy. Infection has also been caused by eating raw vegetables, improperly washed, that, while growing, had been sprayed with liquid and contaminated manure. The utmost pains must be taken to have all food perfectly clean and in a wholesome state of preservation.

Certain individuals who have had typhoid fever harbor the living virulent germs of the disease and when employed as cooks or in dairies as milkers or handlers of milk not infrequently unwittingly contaminate food and cause typhoid fever wherever they live.

Not only living parasites, but also deleterious chemical compounds, are transmitted to man by food. These may be pto-mains, the result of the growth of certain microbes in the foods, such as tyrotoxicon in milk and milk products, and similar poisons in shell-fish, crab meat, fish, meat, and game that is too 'high,' or too long preserved. Oysters and clams are sometimes the conveyors of living typhoid and cholera germs because they are grown near sewers, or at the mouth of rivers made foul by the sewage of cities. The meat of animals and birds has been known to be unwholesome because they had eaten poisonous plants - as, for instance, stramonium seeds. Cereals may carry poisons and produce such diseases as ergotism, lathyrism, and possibly pellagra.