PROPERTIES OP SERUM 689 



from animal experimentation. Monkeys which have passed 

 through an attack of the disease are insusceptible to fresh 

 inoculation, but definite disease manifestations are apparently 

 essential to the establishment of immunity, as animals which 

 have at first yielded negative results are usually susceptible to 

 a second inoculation. Both in man and in the monkey the 

 serum of a recovered case contains substances capable of neutral- 

 ising the virus, for if such serum be mixed with virus and 

 incubated for a time at 37° C. the mixture becomes inopera- 

 tive on intracerebral injection into monkeys. The antibodies 

 persist in the serum in man for many years after an acute 

 attack, and they possess this further significance, that they may 

 be found in the so-called abortive cases where a transient illness 

 with little or no involvement of the nervous system occurs. The 

 only evidence, in fact, that such a condition is due to the virus 

 of poliomyelitis lies in the fact that subsequently the serum has 

 the capacity of neutralising the virus. Not only has the 

 immune serum neutralising properties in vitro, but it has been 

 shown experimentally to have a certain effect in vivo when 

 introduced intrathecally into monkeys previous to intravenous 

 inoculation. Here it probably neutralises the virus as the latter 

 is passing through the cerebro-spinal fluid. Further, the serum 

 of recently recovered human cases when injected into patients 

 suffering from poliomyelitis (especially during the first forty-eight 

 hours) has a capacity of arresting paralysis. The amount of 

 serum given has been from 35 to 120 c.c, administered both 

 intrathecally and intravenously. It is stated by Kraus that if 

 the virus which has been killed by exposure to phenol is injected 

 into monkeys they develop resistance, but such a prophylactic 

 vaccine treatment requires further investigation. 



The fact that poliomyelitis appears under a variety of clinical 

 types makes the diagnosis difficult in many cases, especially of 

 mild illness. This is specially true of the meningitic type, which 

 may be difficult to distinguish from epidemic cerebro-spinal 

 meningitis, especially as the characters of lumbar puncture fluid 

 in the two diseases are very similar, and, as is known, it may 

 often be difficult to isolate the meningococcus where it is actually 

 the causal organism. It may be stated that cases have occurred 

 where the diagnosis lay between poliomyelitis and the paralytic 

 type of rabies, and in the present stage of knowledge the sus- 

 ceptibility of the rabbit to the latter disease would constitute 

 the only means by which the diagnosis could be arrived at. 



Rb'mer has described a paralytic disease in guinea-pigs closely 

 resembling human poliomyelitis. 



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