The Severity of Poliomyelitis in Multiple-Case Households

D TIRI-NG the 1953 poliomyelitis season an attempt was made oni a niational scale to assess the value of gnamma, globulin as a propllylactic agent in modifying the severity of illness wlhen administered to subsequent cases ainong hlousehold contacts of a diagnosed case of poliomnyelitis.One difficuity ill such ian eval- uiation mav arise from tlhe occurrence of subsequent cases wlhiclh are clinically less severe thani the case initially recognized in multiple- case lhouselholds.Moore and Kessell (1) have found that, in monkeys inoculated intracereb- rally with poliomyelitis virus, decreasing con- centrations of the virus produce longer incuba- tion periods.They have also found that as the incubation period is lengthened, illness is less severe.Gard (2), workinig with Theiler's mouse enceplhalomyelitis virus, obtained similar results.Accordingly, it was decided to exam- ine the relative severity of initial and subsequent cases of poliomyelitis occurring in house- holds during a period when gamma globulin was not available as a prophylactic agent.