Armstrong – Table of Contents

to be confined to the warm months of the year as one proceeds either north or south from
the equator. Spread of polio is by contact, through the fecal-oral route, with the throat
serving as a primary entry and exit point of virus in addition to initial infection in the
lower gastrointestinal tract. The nose was generally abandoned in the 1940s as the
primary point of virus entry following the demonstration of the intestine as a site of major
viral multiplication, and subsequent dissemination or development of immunity (see the
chapter on Poliomyelitis). However, the observation of others that poliomyelitis often
occurred after tonsillectomies and that the virus could be recovered from the throat both
before and after an attack of poliomyelitis, led Armstrong to theorize that local conditions
in the upper airways occurred that favored the entrance of poliovirus through the throat
epithelium. This might depend on the presence or absence of excess mucus in the
nasopharynx to provide a protective mechanism to prevent viral attachment. Armstrong
set up some laboratory models using mice and other viruses mixed with commercial
mucus to determine the protective effect of mucus against herpes and rabies in mice. He
further postulated that there was a change in the relative humidity in the upper respiratory
passages that kept the inhaled air at a relative humidity of about 90 per cent when
warmed to 90F. The relative humidity of ambient temperature air was much lower.
Armstrong, consulting with the local weather bureaus in a variety of locations, obtained
interval recordings of average monthly atmospheric temperatures and average monthly
relative humidity at 7AM, and atmospheric relative humidity adjusted to a temperature of
88F. He correlated these figures with the incidence of poliomyelitis in various locations.
These locations were Washington, DC, in 1949, New York City in 1949, combined
District of Columbia and Arlington, Virginia in 1950, and Denver, Colorado in 1950 and