Recovery, survival and dissemination of human enteric viruses in ocean waters receiving sewage in Hawaii

Abstract

A commercial model of a portable virus concentrator operating on the principle of the membrane virus adsorption-elution technique was used to examine the recovery and distribution of human enteropathogenic viruses in Hawaiian waters receiving sewage wastes. Although operating at an efficiency of 20%, a variety of human enteric viruses was isolated, including polioviruses, Coxsackievirus and Echoviruses. Positive virus isolations were consistently made and at high concentrations at sampling stations closest to the sewage outfall. The frequency of virus isolations decreased with increasing distance from the discharge site. viruses were recovered in all directions from the outfall and even as far as 3.2 km east but not 6.4 km away from the discharge site.

Tidal conditions to some degree were found to influence the dissemination of viruses. However, since sampling was generally performed at the surface of the water (0.3 to 0.6 m depth), the influence of winds and surface currents was more difficult to assess. Although a positive correlation was found between the presence of high concentrations of indicator coliforms and viruses in waters closest to the discharge site, this relationship was not seen at sampling stations farther away. At these latter stations, positive virus isolations with corresponding low to negligible coliform counts were made which reaffirmed previous published observations that human enteric viruses are relatively more stable in ocean water than coliform bacteria. Furthermore, the instability of the coliform bacteria consequently affected the fecal coliform/fecal streptococci ratios which thus invalidated the use of such ratios to indicate contamination by human wastes.