The Bridgeport evening farmer., 1916-07-25

corresponds to the onset. rise and then the fall in number and severity or cases as observed in the course of cpl demics of infantile paralysis and other epidemic diseases. Hence either new active specimen of the virus may be- introduced from without which, after. a certain number of passages from person to person, acquires a high potency; or a specimen of virus al- ready present and left over from previous epidemic afte resting per- iod and similar passages again be- comes active, and reaches an infective power which equals or even exceeds that originally possessed. Another but more indefinite factor relates to the degree of susceptibility among children and others affected, which at one period may be greater or less than at another.
 Varying Individual Susceptibilities. Not all children and relatively few adults are susceptible to infantile paralysis Young children are more susceptible. generally speaking, than older ones; but no age can be said to be absolutely insusceptible. When several children exist in a family or in a group, one or more may be ar- fected, while the others escape or seem to escape. The closer the family or other groups are studied by phy- sicians the more numerous it now appears are the number of cases among them. This means that the term "infantile paralysis Is misno- mer, since the disease arises without causing any paralysis whatever. or such slight and fleeting paralysis as to be difficult of detection. The light for abortive cases. as they are called indicate a greater general susceptibil- tty than has always been recognized. and their discovery promises to have far reaching consequences in respect to the means employed to limit the spread or eradicate foci of the dis ease.
 Period of Incubation.--Lke all other infectious diseases, infantile paralysis does not, arise at once after exposure, but only after an interven- ing lapse; of time called the period of incubation. This period is subject to wide limits of fluctuation; in cer- tain instances 1t has been as short as two days; in others 1t has been two weeks or possibly even longer. But the usual period does not exceed about eight days.
 Period of the period at which the danger of com munication is greatest is during the very early and acute stage of the dis ease This statement must be made tentatively since it depends on infer ence, based on general knowledge of infection. rather than on demonstra- ton. Judging from experiments on animals, the virus tends not to per- sist In the body longer than four or five weeks, except in those exceAtion- al instances in which chronic carriage is developed. Hence cases of infan- tile paralysis which have been kept under supervision for period of six weeks from the onset of the symptoms may be regarded as practically free from danger.
 Protection by Previous Attack Infantile paralysis is one of the infec- tious diseases in which insusceptibility is conferred by one attack. The evil dence derived from experiments on monkeys Is conclusive in showing that an infection which ends in recovery gives protection from a subsequent inoculation. Observations on human beings have brought out the same fact, which appears to be generally true, and to include all the, forms of infantile paralysis, namely, the para lytic, meningea1 or abortive, which all confer immunity.
 Basis of the Immunity.-The blood of normal persons and monkeys is not capable of destroying or neutralizins the effect of the virus of infantile paralysis. The blood of persons or monkeys who have recovered from the disease is capable of destroying or neutralizing the effect of the virus The insuscepttbility or immunity tc subsequent infection. whether occur. ring in human beings after exposure or monkeys after inoculation, rests on the presence of the destroying sub. stances, the so-called immunity bod ies which arise in the internal organs and are yielded to the blood. So long as these Immunity bodies persist ir the body, protection is afforded: and their presence has been detected twenty years or even longer after re. Ncovery from infantile paralysis. Elk. periments have seem to show that the immunity bodies appear in the blood III tuo COuI5e Ol 0Vcu tHS LIlluSSI dt' tack of the disease, which fact ex. plains why protection is afforded ir. respective of the severity of the case Active ImmunizatioE.-Pro Protection has been afforded monkeys agains inoculation with effective quantitiel of the virus of infantile paralysis by previously subjecting them to inocula. tion. with subeffective quantities 0, doses of the virus By this mean. and without any evident illness or ef feet of the protective inoculation complete immunity has been achiev ed. But the method is not perfect since in certain instances not only wa. immunity not obtained, but unexpect ed paralysis intervened. Tn the in stances in which protection was ac complained, the immunity bodies ap peared in the blood.
 Passive Protection.-By transfer ring the blood of immune monkeys t, normal or untreated ones they car 1 be rendered insusceptible or immune and the immunity will endure for {
 relatively short period during whicl the passively transferred immunit.
 bodies persist. The accomplishment
 of passive immunization is somewha
 uncertain. and its brief duration ren
 ders it useless for, purposes of protec
 tive immunization.
 Serum Treatment.-On the othe hand, a measure of success has beel
 achieved in the experimental serum
 treatment of inoculated monkeys. Flo
 this purpose blood serum derived eith