Gerald Berg

The ecology of enteroviruses in natural waters

More than 100 different enteric viruses are known to be excreted in human feces. More than 1 million viruses may be excreted per gram of feces, and concentrations as high as 500,000 infectious virus particles per liter have been detected in raw sewage. Certain enteric viruses can persist for long periods of time in the environment. Reported survival times range from 2 to 168 days in tapwater, 2 to 130 days in seawater, 25 to 125 days in soil, and up to 90 days in oysters. There are many potential routes of transmission back to man. An evaluation of the problems associated with viruses in water was prepared recently by the World Health Organization Scientific Group on Human Viruses in Water, Wastewater, and Soil which met in Geneva in October, 1978. Among its conclusions, four are pertinent to this article: (1) Viruses have been detected in the drinking water supply systems of a number of cities (including Paris and Moscow), despite the fact that those waters have received conventional water treatment cons...

A comparative study of the inactivation of viruses in water by chlorine

INTRODUCTION INFORMATION presently available concerning the inactivation of viruses in water and wastewater by chlorine and its compounds are limited. Available literature has often been equivocal because standard conditions for testing have not been used. There also occurred undefined chemical conditions in the test systems, a lack of information concerning the types of titrable chlorine actually present in the chlorinated water and the absence of adequate quantitative techniques for detection of animal virus units. Precise knowledge concerning the destruction of viruses in wastewater assumes greater importance as man turns to an ever increasing degree to the re-use of his upstream neighbors wastewater. Since sewage-contaminated water is a potential health hazard an awareness of the efficiency of applied disinfectants on human enteric pathogens has increased significance. This is particularly true with viruses which are considerably more resistant than the bacteria. Moreover, it is obvious that disinfectants need to be chosen to meet particular needs. To determine which disinfectant species is best suited to meet each specific needs situation, disinfectants must be tested under essentially identical conditions. Thus, this project is a continuing part of the cooperative comparative disinfection study coordinated by the Virology program at the National Environmental Research Center, Cincinnati.

A method for recovering viruses from sludges

Primary, activated, and anaerobic mesophilically digested sludges were salted with MgCl2 (divalent cations) or AlCl3 (trivalent cations) and acidified to bind indigenous unadsorbed virions to the sludge solids; the sludges were centrifuged, and the adsorbed virions were eluted from the solids with buffered 10% beef extract. The elution yields with this procedure were superior to those obtained from sludges that had been salted or acidified only. Homogenization of sludges prior to other treatment did not increase the numbers of virions recovered.