What is serum?

Serum - is the part of the blood in which the antibodies or antitoxins which the body uses to fight off infection are carried. For every disease carrying toxin there is another, called an antitoxin which cancels it out. The blood normally carries the antitoxins to combat the common infections which attack the body. But there are many diseases and infections for which we do not carry the right antibodies. A cure or prevention is provided by injections of extra serum to which the correct antitoxin has been added. It takes many years of scientific experiments to work out which antitoxin will fight a particular disease. But once it is known, the antitoxin can be introduced into animals whose serum is then used to inject human beings. Sometimes, as for snake bites, the serum injection is given only after the infection has set in. Often the antitoxin works only if given quickly. People going on long expeditions far away from hospitals take serum with them, so that they can inject themselves. However, serums for some diseases can be given, as a precaution, before the infection appears. The tetanus injection which you can given if you cut yourself is one example. The diphtheria injection given to a baby is another.