Observations on the Intranasal Route of Infection in Experimental Poliomyelitis. ∗

Abstract

It is generally recognized that while experimental poliomyelitis may be induced with regularity in monkeys inoculated with a potent virus by the intracerebral route, infection results much less frequently when the virus is instilled into the nasal passages. Since the natural infection in man occurs chiefly, if not entirely, by the nasal route, it is sometimes desirable, especially in certain experimental studies, to imitate closely the natural mode of infection. To be really serviceable any method employed must produce infection with considerable regularity. While the results of different investigators with the intranasal route of inoculation have been but meagerly reported, the general experience seems to have been that while infection by the intranasal route is possible, it is seldom realized in more than one-half of the monkeys so inoculated. At times less than a third of the animals develop the disease. In exceptional instances only have somewhat better results been reported. Rhoads 1 and Weyer, Park and Banzhaf 2 have recently reported quite uniform results following 3 or more intranasal instillations of virus, administered on successive days. The total number of monkeys employed by these investigators is not specifically stated, nor do they describe in detail the procedure. The reasons for their more uniform results are therefore not apparent. Having ourselves worked with what were evidently the same strains of poliomyelitis virus, we are unable to attribute their exceptional results altogether to the employment of viruses of unusual virulence. It has become obvious to the writers that while the virulence of a virus, as well as the number of instillations, are undoubtedly of great importance in establishing infection by the intranasal route, factors other than these apparently also influence the results, including possibly such factors as the general anatomical and physiological status of the mucous membranes; the properties of the nasal secretions; the reaction (pH) of the aqueous vehicle of the virus, etc.