On the connection between supersaturation in the upper airways and «humid-rainy» and «cold-dry» seasonal patterns of influenza

We have originally shown for the first time the two different climatic patterns of seasonality of influenza and common colds have an only one common “link”. It is the effect of supersaturation and condensational growth in the upper airways which occurs under specific environmental conditions when flu seasons take place in the tropical/subtropical and temperate regions.

We have found that under climatic conditions which are peculiar to the seasonal patterns of influenza and common colds (“humid-rainy” and “cold-dry”) the effect of supersaturation and condensational growth may be additional factor/reason leading to the next:

- dramatic rise of deposition rate of infectious agents from inhaled air in the upper airways;

- additional acidification of epithelial lining fluid in the local areas of the respiratory tract, and, as a result, may lead to destructive impacts on host cells and weakening of the defense mechanisms of the airways;

- additional affecting on the critical local cooling and reducing (as a consequence) the antiviral immune response of the airway epithelial cells.

Thus, the effect of supersaturation and condensational growth in the upper airways can act as a common trigger for influenza, common colds and other respiratory infection in both mid-latitudes and in the tropics/subtropics.