Experimental Infection by Waterborne Enteroviruses.

This study concerned infections caused by minimal quantities of waterborne enteroviruses. The model system comprised young weanling swine and their homologous enteroviruses; the porcine digestive tract and its enteroviruses are like those of man, and the system affords greater reproducibility and safety than those employing humans or other primates. Subjects swallowed known numbers of viral plaque-forming units (pfu) in 5 ml of drinking water. The body was about 1000 times (600 to 750 for one virus and 1800 to 2500 for another) less likely than a tissue culture to be infected by a given quantity of enterovirus. Doses given after eating, or in four daily portions, produced similar results. No infected animal became ill, despite the reported virulence of the viruses. Chlorination reduced viral infectivity greatly, but short of total extinction, in a single trial. Two newborns were not infected by 20 pfu administered by gavage.