In (2) the symptoms are those of acute gastro-enteritis—violent vomiting, purging, prostration, cramps in the legs, and collapse; the temperature is generally subnormal, but may be elevated. The post-mortem appearances are those produced by gastro-enteritis, with hæmorrhages into the intestinal mucous membrane; the spleen is frequently enlarged, and Peyer‘s patches may be infiltrated.
Meat poisoning has usually been most frequently associated with the ingestion of pork, veal, beef, meat pies, potted meat, tinned meat, sausages, and brawn. The more finely divided the meat, the more easily and completely it may become infected and poisonous. Cases of poisoning from the ingestion of canned meats are not uncommon. In some instances they may be due to metallic poisoning, in the great majority they are due to putrefactive changes having taken place in the meat. Ungefug reports a case confirmed by the celebrated chemist Heinrich Rose, in which sulphate of zinc had been used as a preservative instead of saltpetre. In some the canning may have been imperfect, and putrefaction taken place before reaching the consumer; in others decomposition may have begun after opening the can. The meat may have been taken from diseased animals, or decomposed prior to canning.
Poisoning by tinned provisions with the metal used for tinning is more likely to occur with fruits than meat. The malic acid of the juice probably dissolves the solder and forms a malate of tin. Cherries, apples, pineapples, and tomatoes are the most likely to do this.
In 1890 Luff investigated four cases of tin poisoning due to the consumption of tinned cherries. Some of the material left was analysed, and the juice contained malate of tin in solution equivalent to two grains of the higher oxide of tin per fluid ounce. It was estimated that the symptoms were produced by doses of two to four grains of malate of tin. Two of the patients nearly died from the diarrhœa and collapse.
Sulphate of copper is used to give a full green colour to peas, olives, and pickles, or it may contaminate preserved fruits if they be left in copper vessels. The copper combines with the phyllocyanic acid of the chlorophyll, and although insoluble in the surrounding liquor, is set free and absorbed by the process of digestion.
Fish Poisoning
(Ichthyotoxismus)
Fish may cause poisoning in two ways: in one the poison is a physiological product of certain glands of the animal, and is quite independent of bacteria; the other is due to the poisonous products of bacterial growth. The fish that are inherently poisonous as a rule occupy tropical waters: several of them exist in Japanese waters. Mackerel, carp, barbel, and herrings may become poisonous at times; some of these, especially mackerel, may rapidly become unfit for food after they are dead. Caviare and the roe of herrings have caused poisoning. Shell-fish, especially mussels, also may prove poisonous.
The symptoms of fish and shell-fish poisoning are variable. In some cases disturbance of the nervous system predominates, with delirium, convulsions, and paralysis. There may be dryness and constriction of the throat, dyspnœa, disturbed vision, vertigo, jerky speech or aphonia, rapid pulse, loss of co-ordination, numbness, formication, coldness of the limbs, dilated pupils, paralysis, and collapse, followed by death in a few hours. Other cases exhibit symptoms of severe gastro-intestinal irritation, with nausea, vomiting, pain, tenesmus, mucous and bloody stools; in the most dangerous cases the bowels are constipated. Cases exhibiting the nervous type of symptoms resemble poisoning by atropine, and an alkaloid—ptomatropine—is regarded as the cause. It has never been obtained in the pure state, and nothing is known of its composition. It must not be mistaken, in toxicological examination, for atropine; its presence can only be recognised by its action on the pupil.
Many cases of fish poisoning are accompanied by erythema, urticaria, and severe itching of the skin. In probably all cases there is an elevation of the body temperature.
Tinned fish has caused poisoning on many occasions. In one case of tinned salmon poisoning, which proved fatal, parts of the stomach and intestines were almost gangrenous from the intensity of the inflammation.