INFANTILE PARALYSIS (POLIOMYELITIS) in its developed form is a paralytic disease, of children chiefly, but not exclusively. It prevails during the summer-autumn period of the year. The most susceptible ages are up to the fifth, and from the fifth to the tenth years of life. One-half or more of the cases occur in children under five years of age. A small number only of adults is attacked; but the number of cases of the disease arising during epidemics is far greater than is indicated by those paralyzed. For every paralyzed person, several cases of a mild, febrile disease, poliomyelitis in nature, occur. The paralysis re sults from injury to the motor nerve cells situated in the spinal cord and brain, which control muscular motion. The injury may be slight and evanescent, when recovery may be rapid and com plete; or it may be severe and enduring, in which case some de gree of paralysis remains permanently. The fatalities vary in different epidemics, being sometimes as great as 20 per cent., or as low as 5 per cent.
History.—Infantile paralysis is an ancient disease. The lame ness of Sir Walter Scott was caused by it. Never before 1905 had epidemics become world-wide; since that year no part of the world has wholly escaped visitation.
America has, however, suffered more than any other Western country. In New York State, in 1916, some 20,000 cases were recognized, constituting the severest epidemic of poliomyelitis ever recorded.
Nature.—Infantile paralysis is both infectious and contagious ; it is caused by an invisible microbe or germ, called a virus. A characteristic of viruses is that, because of their minute size, they pass through the pores of earthenware filters. The virus gains access to the brain and spinal cord by way of the nasal passages, and probably in no other way. The organ of smell (olfac tory area) is imbedded in the nasal mucous membrane ; it is a por tion of the central nervous system, and lies freely exposed to the external air. The virus has a strong affinity for nerve tissues, and utilizes the nerve cells and fibres in the olfactory organ in or der to reach the brain, from which it spreads to the spinal cord.
The antivirus is produced irrespective of the severity of the symptoms of the disease, and it arises also in persons who har bor the virus and yet show no signs whatever of real disease. Certain devices have been discovered which mitigate the paralyz ing effects of the virus.
One such device is the mixing of virus with suitable amounts of blood serum containing antivirus, and injecting the mixture into or beneath the skin.
This method has been successfully and safely employed in monkeys, but not as yet in children. The time for the latter has not yet come, as a firmer experimental basis for the method has still to be secured. Other kinds of artificial vaccination have been proposed and some have actually been used in children. The whole subject is still so highly experimental that no conclusions are warranted.
Resort has been had to the employment of the blood serum of immune persons for the protective inoculation of children. This is a safe procedure.