ENTEROVIRUSES IN ALASKA 



publications of the Robert A. Taft Sanitary Ei^ineering Center, 

 illustrate this conserving effect of low temperatures on entero- 

 virus viability. They showthatviability is enhanced further by gross 

 organic pollution. Type 1 poliovirus and ECHO Type 7 persist two to 

 three times longer at 4° C than at 28° C in relatively unpolluted 

 water, but in sewage poliovirus persisted seven times and ECHO- 7 

 four and a half times longer at the lower temperature. The pre- 

 serving effect of cold storage was not nearly so marked with Cox- 

 sackie A-9 and ECHC)-12 as with the firsttwo agents. 



A few laboratory studies have given some information on persis- 

 tence of viability of enterovirus cultures at various temperatures. In 

 one investigation of viability of viruses in tissue culture held at 

 37° C,thefollowinghalf-lifeswereobserved:Poliovirus-l,47 hours; 

 ECHO-1, 24 hours; ECHO-4,18 hours;ECHO-6,40 hours;ECHO-9,19 

 hours; and ECHO-20,2,5hours(Lehmann-GrubeandSyverton, 19 59), 

 In another study, ECHO- 20, which was quite short- lived at 37° C, re- 

 mained fully viable for a year when stored at -20° C (Rosen et al,, 

 19 58a), Data kindly provided by Dr, H.G. Cramblett (1962) showed 

 that certain enteroviruses would survive six to eleven times longer 

 at 20° C, and twenty to sixty times longer at 5° C than they did at 

 37° C. The presence of cells and organic debris enhance viability. 

 Although freezing is a common means of long-term preservation of 

 viruses in laboratory procedures, little is known of a definitive na- 

 ure of the effects of successive freezing and thawing, Generally,it is 

 considered deleterious to virus viability but definitive information on 

 this point gained in controlled experiments would be desirable. 



In general, the experimental evidence shows that low ambient 

 temperatures, high organic content, and low biological activity favor 

 the long-term persistence of enteroviruses in aquatic menstruum. 

 These favorable conditions could be provided by the haphazard human 

 waste disposal methods of many small arctic communities. 



Limited experiments have shown that soil absorbed large quanti- 

 ties of poliovirus; it remained viable for three weeks in natural 

 soil and for six weeks in previously sterilized soil (Murphy et al., 

 19 58). These experiments were carried out at 30° C, but one could 

 expect much longer survival of enteroviruses in soils at lower en- 

 vironmental temperatures. The information available is sketchy, 



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