Bacterial invasion

Abstract

LET it be assumed that: (a) each organism invading a host has a chance λ of reaching a favourable site, and of afterwards undergoing a sequence of events which enable it to proliferate and result in the death (or infection) of the host; (b) each organism acts independently; (c) c inhaled organisms are necessary to produce the death (or infection) of 0.5 of the total of exposed animals; (d) the experimental animal population is large and homogeneous. Then the proportion S of animals remaining uninfected after the intake of n organisms each is given by: S Combining double low line (1 - λ)n, and by definition 0.5 Combining double low line (1 - λ)c, Expressing n in units of c that is, n Combining double low line fc, S Combining double low line (1 - λ)fc Combining double low line 0.5f. © 1952 Nature Publishing Group.