Recovery of Poliomyelitis Virus From the Throat During the Incubation Period

Recovery of poliomyelitis virus from pharyngeal washings, tissues, and swabs of patients has been described repeatedly. 1 Virus has also been recovered from similar sources in healthy carriers. 2 The early reports of this nature formed a basis for the hypothesis that the upper respiratory tract is the site of entrance and egress of virus. Studies in monkeys supported, by analogy, the theory that virus reached the central nervous system from the nasopharynx via the olfactory nerve. 3 When histologic studies 4 failed to supply evidence for passage of virus through the human olfactory bulb and newer methods allowed the ready demonstration of virus in stools, 5 increased attention was directed to the alimentary canal. Although it became easier to demonstrate virus in stools than in nasopharyngeal washings, it was realized 6 that the difference could be accounted for by longer persistence of virus in the stool (to the seventh