Efficiency of viral depuration was a function of water temp within the range 

 (5 to 20°C) tested. Reduction of salinity to 50-60% of the original level 

 stopped the process completely, but 25% reduction had no significant effect. 

 Depuration in a large tank was equally as efficient as that in small 

 experimental tanks under the conditions of the experiment. In some European 

 countries which depurate shellfish, no obvious hepatitis outbreaks associated 

 with shellfish have occurred in 4 yrs, which inspires confidence in 

 commercial application of the method. More information is needed before the 

 process can be adopted with complete confidence in the United States. - J.L.M. 



1092 



Liu, Oscar C, Helen R. Seraichekas, and Bert L. Murphy. 1967. 



Viral pollution and self-cleansing mechanism of hard clams. In Transmission 

 of Viruses by the Water Route. Gerald Berg (edj . Interscience Publishers 

 Div., John Wiley & Sons, New York: 419-437. 



Cites unpublished data of Feng and Haskin, who showed that maximal uptake of 

 virus occurred within 2 to 3 hr in oysters and Meroenar-ia m&Taenaria polluted 

 with large quantities of staphylococcal phage in seawater. In clean sea- 

 water, initial reduction in viral content was considerable, but complete 

 elimination was not achieved after several transfers to clean seawater over 

 more than 100 hr. Viral elimination was much faster at 15° than at 5°C. In 

 recirculated seawater (Atwood et al.-also unpublished) quahaugs accumulated 

 coxsackievirus B5 rapidly during the 1st 2 days in contaminated water. Then 

 viral content declined as viral content of the water declined, but more slowly 

 in clams than in water. The authors of this paper experimented with M. mer- 

 cenaria exposed to LSc 2ab strain of poliovirus 1. In polluted waters viral 

 pollution of clams occurred rapidly and maximum pollution of various organic 

 systems was reached in a few hrs . High level of pollution was retained as 

 long as sufficient virus was present in the water. As viral content of sea- 

 water was reduced, viral content of clams decreased correspondingly. These 

 results agreed with those of some workers, but not with others. Reduction of 

 viral content of shellfish was not slower in this study than reduction in 

 surrounding seawater. It was not clear whether the discrepancy was caused 

 by use of different species, e.g. oysters vs clams, or by differences in 

 experimental conditions. When shellfish were held in stationary polluted 

 seawater most virus was distributed equally in digestive diverticulum and 

 in drained fluids, which presumably contained most of the shell liquor and 

 some hemolymph. In polluted running seawater, uptake of virus was 

 considerably higher in diverticulum and much reduced in fluid portions. This 

 suggested that naturally polluted shellfish should accumulate most virus in 

 the digestive system, but this was not investigated. The authors concluded 

 that the self -cleansing mechanism appears uniformly efficient, provided that 

 shellfishes are held under conditions that favor activity. Contrary results 

 of others were attributed to poor aquarium systems. Running water systems, 

 not standing or recycling, appear to be essential. Depuration in clean 

 flow-through water for 48 to 96 hrs reduced virus concentrations to non- 

 detectable levels in meats and shell liquor. Some problems remain to be 

 solved before predictable commercial application is possible. - J.L.M. 



1093 



Liu, 0. C, H. R. Seraichekas, D. A. Brashear, W. P. Hef f ernan, and V. J. 

 Cabelli. 1968. 



The occurrence of human enteric viruses in estuaries and shellfish. Bact. 

 Proc. 1968: 151 (abstract V42). 



In an estuary in Rhode Island, approximate viral isolation rates were: raw 

 sewage from a nearby sewage treatment plant 100%; seawater 28%; quahaugs 

 33%; and oysters 55%. This confirmed a previous report that in estuaries 

 shown by bacterial examination to have various levels of fecal pollution, 

 human enteric viruses can be isolated from water and shellfishes, including 

 Uercenaria mevcenavia . - J.L.M. 



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