Abortive poliomyelitis or minor illness as a clue to genetic susceptibility.

The model of genetic susceptibility to poliomyelitis has been used to examine minor illness caused by poliovirus infection. It is suggested that persons who are genetically susceptible but who have not converted to phenotypic susceptibility are those who develop minor illness. The overall rates of the sum of paralytic and minor illness are close to the predicted 26%. For families with a case of illness, the prediction that 58%--71% of the children become ill has been examined. The rates of illness in children of different ages in the same families should be similar. Data from a number of epidemics is shown to be consistent with the predictions of the model.