Even if you take no precautions, the chances of your child catching diphtheria are less than a hundredth of what they would have been in 1890.
For the very good reason that there is less diphtheria to catch. And that is due to the fact that other parents have taken precautions to prevent the disease in their children.
What are these precautions? The use of an immunizing substance diphtheria toxoidwhich will create a condition in the child’s body by which it will immediately throw off diphtheria if exposed.
To understand this we must go back a little ways. The germs which causes diphtheria, the diphtheria bacillus, can be grown on bouillon broth in a glass flask. The broth is very much like ordinary beef tea, or bouillon soup. The bacillus usually grows in a sort of scum on the surface of the broth. In the clear broth below there forms as a product of the growth of the bacilli, a poison, the toxin of diphtheria. The culture can be passed through a filter, which strains the bacilli off, leaving the pure toxin.
Much the same conditions obtain in the body affected by diphtheria. The germs grow in a membrane in the throat and produce this same toxin which, absorbed in the blood stream, is the agent which does the damage.
It is this toxin alsonot the germs themselveswhich is injected into horses to obtain antitoxin. Diphtheria is one of the few diseases in which the immunity is absolutely anti-toxicin which recovery takes place by means of the formation of an antidote by the body cells.
Several years ago a method was perfected by which is is possible to tell whether a person is susceptible to diphtheria or not. It consists in scratching a small amount of toxin into the skin. If the person will catch diphtheria when exposed a red spot appears (in 24 to 48 hours) at the site of inoculation of the toxin. This is called the Schick test.
If this test shows that the person is susceptible it is possible to immunize him so he will not catch diphtheria if exposed.
This was done at first with a toxin-antitoxin mixturea combination of the two so as to neutralize the toxin. This had to be given in three doses and, human nature being what it is, and people getting tired of taking shots, it sometimes was ineffective.
Now we use a preparation called toxoid. It is toxin which has been chilled so as to reduce its toxicity. This can be given in one (sometimes two) doses.
All children as soon as they get to be one year old should have this preventive treatment.
We can look forward to the day when every child will be so treated and diphtheria will be as rare as smallpox.
The proof of its effectiveness can be seen in the drop in the number of cases of diphtheria. In New York, where the largest number of treatments have been given, the number of cases of diphtheria reported in 1919 was 14,014. In 1923 four years after the wholesale immunization of school children was begunthe number was 8,050nearly cut in half.