title: Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine.
abstract: It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, Mail Stop D-66, Atlanta, GA, 30329, USA. akahler@cdc.gov.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Kahler
authors.affiliation: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Atlanta, USA.
authors.forename: Theresa L
authors.initials: TL
authors.lastname: Cromeans
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, Mail Stop D-66, Atlanta, GA, 30329, USA.
authors.forename: Maureen G
authors.initials: MG
authors.lastname: Metcalfe
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, Mail Stop D-66, Atlanta, GA, 30329, USA.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Humphrey
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, Mail Stop D-66, Atlanta, GA, 30329, USA.
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Hill
mesh_terms: D000260:Adenoviruses, Human / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D002713:Chlorine / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000295:instrumentation / Q000379:methods*; D005618:Fresh Water / Q000737:chemistry / Q000821:virology*; D006863:Hydrogen-Ion Concentration; D038301:Virus Inactivation / Q000187:drug effects
chemical_list: D004202:Disinfectants; D002713:Chlorine
keywords: Adenovirus; Aggregation; Chlorine disinfection; Water