The Effect of Gamma Globulin on Subclinical Infection in Familial Associates of Poliomyelitis Cases

Summary In the summer and fall of 1953, family associates of reported cases of poliomyelitis were inoculated with gamma globulin as a possible prophylactic measure. Fecal specimens were collected at three weekly intervals from 135 individuals in 29 families, most of whom had received twice the amount (0.28 ml/lb) of gamma globulin. Four of 64 individuals (6%) in families of questionable cases from whom no virus could be isolated were found to be positive for virus. In contrast, 29 of 70 persons (41%) in families of confirmed poliomyelitic cases were undergoing subclinical infection. The quantity of fecal virus was determined by direct titration in Hela cell type tissue cultures. The specimens of some individuals were infective in dilutions as high as 10-6. Virus was found to persist during the period of study in essentially the same titer in most individuals. Nine persons with low titered virus became negative, but five who were originally negative for virus developed subclinical infection with high titered virus although the gamma globulin had been administered over a week before. From these data it would appear that subclinical infections, when present at the time of inoculation, were usually not affected by gamma globulin nor were they necessarily prevented from developing during the week after its administration. The significance of these data and their possible applications to the phenomenon of passiveactive immunization against poliomyelitis are discussed.