A rare but very serious form of food poisoning caused by the bacterium Clostridium botulinum, which may grow in canned or bottled food which have been inadequately sterilized. This bacterium, normally present in small numbers in soil, flourishes without oxygen (hence in full, closed containers) to produce a powerful toxin which poisons the nervous system to cause difficulty in swallowing, speaking and breathing, and extreme muscular weakness. Botulism is often fatal. Instruction for adequate sterilization should be followed strictly for all home preserving, and preserved food should never be eaten from any container which bulges or from which gas under pressure escapes on opening.
Slowing of the heartbeat to a rate of less than 60 per minute. In health, a slow heart rate at rest is often found in fit athletes, where it is an index of the heart’s capacity to respond to the need for increased effort during strenuous physical activity. Bradycardia is a health problem only when the heart rate is too slow to maintain the blood pressure and adequate circulation. This happens briefly in fainting and permanently in disorders of the cardiac pacemaker or of the heart’s conducting system.