Adenovirus Type 3 Epidemic Associated with Intermittent Chlorination of a Swimming Pool

et al. 2005

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Inactivation of Enteric Adenovirus and Feline Calicivirus by Chlorine Dioxide

et al. 2005

“…Although no waterborne outbreaks have been reported for the enteric adenoviruses, increased environmental stability compared to those of other enteric viruses and their presence in sewage and surface waters have been reported (8,25,29). Outbreaks from waterborne viruses contracted by swimming have been reported for the non-enteric adenoviruses (7,22).…”

mentioning

confidence: 99%

Inactivation of Feline Calicivirus and Adenovirus Type 40 by UV Radiation

et al. 2003

238

221

Little information regarding the effectiveness of UV radiation on the inactivation of caliciviruses and enteric adenoviruses is available. Analysis of human calicivirus resistance to disinfectants is hampered by the lack of animal or cell culture methods that can determine the viruses' infectivity. The inactivation kinetics of enteric adenovirus type 40 (AD40), coliphage MS-2, and feline calicivirus (FCV), closely related to the human caliciviruses based on nucleic acid organization and capsid architecture, were determined after exposure to low-pressure UV radiation in buffered demand-free (BDF) water at room temperature. In addition, UV disinfection experiments were also carried out in treated groundwater with FCV and AD40. AD40 was more resistant than either FCV or coliphage MS-2 in both BDF water and groundwater. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in BDF water were 109, 55, and 16 mJ/cm 2 , respectively. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in groundwater were slightly lower than those in BDF water. FCV was inactivated by 99% by 13 mJ/cm 2 in treated groundwater. A dose of 103 mJ/cm 2 was required for 99% inactivation of AD40 in treated groundwater. The results of this study indicate that if FCV is an adequate surrogate for human caliciviruses, then their inactivation by UV radiation is similar to those of other single-stranded RNA enteric viruses, such as poliovirus. In addition, AD40 appears to be more resistant to UV disinfection than previously reported.

“…Enteric adenoviruses have greater environmental stability than other enteric viruses (10), and their presence in sewage and surface water makes them likely contaminants in public water supplies (24,25). Moreover, enteric adenoviruses and NLVs were identified as two of the etiological agents causing acute gastroenteritis in a waterborne outbreak in Finland (30), and waterborne outbreaks of pharyngoconjuctivitis from swimming have been reported for nonenteric adenoviruses (15,35).…”

mentioning

confidence: 99%

Chlorine Inactivation of Adenovirus Type 40 and Feline Calicivirus

et al. 2003

166

135

Ct values, the concentration of free chlorine multiplied by time of contact with virus, were determined for free-chlorine inactivation experiments carried out with chloroform-extracted (dispersed) and non-chloroformextracted (aggregated) feline calicivirus (FCV), adenovirus type 40 (AD40), and polio virus type 1 (PV-1). Experiments were carried out with high and low pH and temperature conditions. Ct values were calculated directly from bench-scale free-chlorine inactivation experiments and from application of the efficiency factor Hom model. For each experimental condition, Ct values were higher at pH 8 than at pH 6, higher at 5°C than at 15°C, and higher for dispersed AD40 (dAD40) than for dispersed FCV (dFCV). dFCV and dAD40 were more sensitive to free chlorine than dispersed PV-1 (dPV-1). Cts for 2 log inactivation of aggregated FCV (aFCV) and aggregated PV-1 (aPV-1) were 31.0 and 2.8 orders of magnitude higher than those calculated from experiments carried out with dispersed virus. Cts for 2 log inactivation of dFCV and dAD40 in treated groundwater at 15°C were 1.2 and 13.7 times greater than in buffered-demand-free (BDF) water experiments at 5°C. Ct values listed in the U.S. Environmental Protection Agency (EPA) Guidance Manual were close to, or lower than, Ct values generated for experiments conducted with dispersed and aggregated viruses suspended in BDF water and for dispersed viruses suspended in treated groundwater. Since the state of viruses in water is most likely to be aggregated and associated with organic or inorganic matter, reevaluation of the EPA Guidance Manual Ct values is necessary, since they would not be useful for ensuring inactivation of viruses in these states. Under the tested conditions, dAD40, dFCV, aFCV, dPV-1, and aPV-1 particles would be inactivated by commonly used free chlorine concentrations (1 mg/liter) and contact times (60 to 237 min) applied for drinking water treatment in the United States.