MALE-SPECIFIC RNA COLIPHAGES ARE RELIABLE MARKERS OF SEWAGE (POINT SOURCE) CONTAMINATION

Male-specific RNA (FRNA) coliphages are viruses which infect piliated enteric bacteria and have the same shape, size, genetic content and stability as pathogenic human enteric viruses. Moreover, the method for their enumeration is relatively simple and efficient. Since human enteric viruses have been reported to be the major cause of water-borne diseases and to be more resistant to disinfection than traditional fecal indicator bacteria (fecal coliform, Escherichia coli, enterococci), monitoring environmental waters for sewage pollution using alternative fecal microorganisms such as FRNA coliphages and Clostridium perfringens has been proposed. The objective of this study was to evaluate the feasibility of monitoring streams in Hawaii for FRNA coliphages as reliable indicators or markers of sewage contamination. The impetus of this study was our previous findings that traditional fecal indicator bacteria, which are used to establish recreational water quality standards, are naturally present in high concentrations in streams of Hawaii and are not useful in determining when streams are contaminated with sewage. The design of this study was to monitor sewage, stream waters, soil, human feces and animal feces for comparative concentrations of traditional fecal indicator bacteria (fecal coliform, E. coli, enterococci) and alternative fecal indicators (C. perfringens, FRNA coliphages). The results of this study showed that sewage treatment and disinfection can drastically reduce the concentrations of traditional fecal indicator bacteria but not that of alternative fecal indicators, especially FRNA coliphages, which are still present in significant concentrations in these treated sewage. These results indicate that monitoring sewage effluents and environmental waters for only traditional fecal indicator bacteria may not be adequately protective of human health effects. The results of this study showed that ambient concentrations of FRNA coliphages and C. perfringens in soil and streams of Hawaii are consistently low. As a result, elevated concentrations of these two alternative fecal indicators in streams are reliable indicators or markers of sewage contamination. Since FRNA coliphages are consistently present in human sewage but not in human feces and are found in few animal feces, these coliphages are reliable indicators of sewage contamination but may not be reliable indicators of direct fecal contamination. The results clearly indicate the superiority of monitoring streams of Hawaii for FRNA coliphages as compared to traditional fecal indicator bacteria. However, more information is required to determine the source of the high concentrations of FRNA coliphages in sewage and to determine the predictive health effects related to levels of these coliphages in streams, so that appropriate water quality standards can be developed.