Reduction of Norwalk virus, poliovirus 1 and coliphage MS2 by monochloramine disinfection of water

Abstract

The reduction of Norwalk virus (NV) by a 2 mg/L dose of pre-formed monochloramine was determined at pH 8 and 5°C in bench-scale, batch disinfection experiments using quantitative RT-PCR for NV assays. Two other enteric viruses, poliovirus 1 (PV1) and coliphage MS2, were included for comparison and assayed by infectivity as well as RT-PCR. After 3h, reductions of PV1 and MS2 by infectivity assays were about 1 log10 but there were no reductions of these viruses by RT-PCR assays. Hence, RT-PCR underestimated virus inactivation by monochloramine. However, NV reduction by monochloramine was about 1 log10 by RT-PCR assay, suggesting that it is more susceptible to monochloramine than the other two viruses tested. Based on RT-PCR titre reduction, the CT99 value for NV was about 775 mg-min/L. If the reduction of NV infectivity by monochloramine is ever greater than the reduction of RT-PCR signals, the CT99 value would be smaller. However, the results of this study indicate that NV and the other enteric viruses tested are not rapidly and extensively reduced by disinfection with pre-formed monochloramine.

Particle-Associated Viruses in Water: Impacts on Disinfection Processes

“…Shin and Sobsey 1998;Thurston-Enriquez et al 2003). However, several studies have concluded that viral particle-association has an adverse effect on chemical disinfection.…”

Inactivation of Enteric Adenovirus and Feline Calicivirus by Chlorine Dioxide

“…Their ability to withstand current drinking water disinfection practices is largely unknown, since there are no known animal or mammalian cell culture systems that determine NV infectivity. Due to these difficulties, two alternative studies, a human feeding study and a PCRbased study, were carried out previously (30,41). However, conflicting results between these studies made conclusions regarding NV chlorine resistance difficult.…”

Chlorine Inactivation of Adenovirus Type 40 and Feline Calicivirus

“…Chlorine inactivation studies have demonstrated the susceptibilities of important enteric viruses that have threatened or caused waterborne outbreaks, such as polio virus (5,38,40) and hepatitis A virus (HAV) (17,43). Based on previous viral disinfection studies, the EPA published the Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Sources (EPA Guidance Manual) (45).…”

“…Their ability to withstand current drinking water disinfection practices is largely unknown, since there are no known animal or mammalian cell culture systems that determine NLV infectivity. Due to these difficulties, two studies, a human feeding study and a PCRbased study, have been carried out previously (29,40). Conflicting results, however, between these studies make conclusions regarding NLV chlorine resistance difficult.…”

“…Inactivation of PV-1 by chlorine was carried out in order to compare Ct values generated by this study to previously reported PV-1 inactivation experiments. Extensive information regarding poliovirus inactivation by chlorine is available in the literature (5,9,14,21,(38)(39)(40); and, therefore, it has been used as a model virus for investigations involving disinfection (2,17,33,40). In order to determine Ct values for each virus and experimental condition, the efficiency factor Hom (EFH) model was applied to the observed bench-scale results in order to determine Ct values for 2-, 3-and 4-log inactivation.…”