To the Editor:—In the July 1950 issue of the American Journal of Diseases of Children, page 10, Baskin, Soule and Mills reported a case of proved poliomyelitis in a newborn infant with onset 3½ days after birth. In support of the possibility of intrauterine infection they cite "the fairly well established fact that the minimal incubation period of clinical poliomyelitis is five days." This "fact" is based on the papers of Aycock and Luther in 1929 and Casey in 1942. Unfortunately, they have overlooked the more recent paper by Horstmann and Paul (J. A. M. A. 135:11 [Sept. 6] 1947) in which it is stated that "the interval between apparent exposure and the onset of clinical symptoms and signs has been observed to be as short as three and as long as thirty-five days, with many cases developing after a four to ten day period."
In case 1 of