Botulism or Allantiasis - food, outbreaks, canned, foods and heat

BOTULISM or ALLANTIASIS. The term botulism (Lat. botulus, sausage) seems to have been first applied in the early part of the 19th century to a type of sausage poisoning observed in Wurttemberg and some other parts of Germany. A recogni zable description of this disease appeared, however, as early as 5. Although the first outbreaks studied were traced to sausage it is now known that a variety of other foods, vegetable as well as animal, may give rise to this condition, so that the name botu lism is to-day not wholly appropriate.

The symptoms of botulism are quite characteristic and, in con• tradistinction to several other forms of food poisoning, are mainly nervous rather than gastro-intestinal. They usually appear in from 18 to 24 hours after the eating of the poisonous food Marked disturbance of vision occurs, double vision being espe cially frequent drooping of the eyelids (ptosis) is common. Great difficulty in swallowing and in respiration is experienced. Muscular weakness is often extreme and may persist for a long time in those patients who recover. The mentality remains clear. There is little or no fever and the temperature may be subnormal. The case fatality is high; in the large series of outbreaks in the United States recorded by Geiger, Dickson and Meyer it was slightly over 6o%. In some group outbreaks every person partaking of the incriminated food has perished. This was the case in the famous Loch Maree outbreak in Scotland where every one of the eight persons who became ill after eating sandwiches made with a par ticular kind of potted meat died within a few days. In addition to the human outbreaks animals associated with man are some times affected and show, similarly, nervous symptoms and high fatality. Chickens that have eaten spoiled canned food—some times the same as that incriminated in a human outbreak—that has been thrown out into the chicken yard may suffer with a disease called "limberneck," in which the clinical picture is entirely analogous to that of botulism in inoculated animals. There is evidence that chickens also contract "limberneck" occasionally under natural conditions. Some investigators are of the opinion that "forage poisoning" in horses and cattle is sometimes a form of botulism, but there is not general agreement on this point.

The cause of botulism is a highly poisonous substance present in the food eaten. This poisonous substance is produced by a micro-organism, Clostridium botulinum, of which• three varieties are usually recognized—Types A, B and C. These microbes possess two significant characters : they are highly resistant to heat, and they grow only in the absence of oxygen. The fact that most of the recent cases of botulism have been due to heat preserved foods protected from the access of air in cans or jars is thus readily explained. The elimination of most other micro organisms by heat and the maintenance of conditions suitable for the development of Clostridium botulinum allow this organism to grow and produce its specific toxin. This toxin is formed when Clostridium botulinum is grown in pure cultures in the laboratory, and the symptoms and lesions produced by it in inoculated animals are entirely similar to those observed in botulism in man, and in "limberneck" in chickens. Type A produces the most, Type C the least, potent toxin. All three types are rather widely distributed in natural soils in various parts of the world and it is easy to see how they may get into all sorts of preserved foodstuffs. They are, however, particularly abundant in the soils of certain regions, the cause of the uneven distribution not being understood. In the United States most of the recorded outbreaks of botulism have occurred on the Pacific Slope or in the Rocky Mountain States— a circumstance that may be connected with the greater abundance of Type A in that region.

Knowledge of the nature and sources of botulism has aided greatly in its prevention. In the canning of foodstuffs it is possible to use sufficiently high temperatures and to insure proper heat penetration to kill even the resistant spores of the Clostridium. Methods based on exact determination of the degree of heat and the time of exposure necessary to effect complete bacterial destruc tion are now generally in use in the canning industry. It is obvious that such measures are more difficult to apply to food canned in the home, particularly in regions where the boiling point of water is lowered by the altitude, and it is perhaps significant that in recent years nearly all the outbreaks of botulism occurring in the United States have been due to home-canned food prepared in the Rocky Mountain region.

The individual consumer has some means of protecting himself against botulism. The foods that have caused botulism have in almost all the recorded instances shown signs of spoilage so that the rejection of any canned food of abnormal taste, smell or ap pearance constitutes a considerable safeguard. Fortunately, too, the toxin produced by Clostridium botulinum is itself quite read ily destroyed by heat so that thorough heating of canned foods after their removal from the can is an additional factor of safety.

Once the symptoms of botulism have developed no satisfactory method of treatment has been found. Even the specific antitoxin, although more or less potent in animal experimentation, has never been used successfully in man; further experiments are, however, desirable.

Botulism has always been a very rare disease; it is becoming still more infrequent. In the United States were recorded cases in the three-year period 192o-22, but only 85 in 1923-25 and 8 in 1926-27. The disease seems to have been practically eliminated as a hazard in the use of commercially canned foods, all the outbreaks for the past three years in the United States— where the consumption of commercially canned food is enormous —having been traced to home-canned foods.