# 1148
This week's Journal of Emerging Infectious Diseases has a study by the US Environmental Protection Agency, Cincinnati, Ohio into the effectiveness of chlorination for inactivating HPAI H5N1.
The good news is, it apparently works.
Over the past few years there has been speculation that the levels of chlorine normally found in water treatment facilities wasn't sufficient to inactivate the Highly pathogenic H5N1 virus. This study appears to contradict those earlier assumptions.
Here are the highlights, reformated for easier reading.
Volume 13, Number 10–October 2007
Chlorine Inactivation of Highly Pathogenic Avian Influenza Virus (H5N1)
Eugene W. Rice,*
Noreen J. Adcock,* Mano Sivaganesan,* Justin D. Brown,† David E. Stallknecht,† and David E. Swayne‡
*US Environmental Protection Agency, Cincinnati, Ohio, USA; †University of Georgia, Athens, Georgia, USA; and ‡US Department of Agriculture, Athens, Georgia, USASuggested citation for this article
Abstract
To determine resistance of highly pathogenic avian influenza (H5N1) virus to chlorination, we exposed allantoic fluid containing 2 virus strains to chlorinated buffer at pH 7 and 8, at 5°C. Free chlorine concentrations typically used in drinking water treatment are sufficient to inactivate the virus by >3 orders of magnitude.
<snip>
Conclusions
The results of this study confirm that avian influenza (H5N1) is readily inactivated by chlorination. Although the viral inoculum exerted a considerable initial chlorine demand, the maintenance of a free chlorine residual (0.52–1.08 mg/L) was sufficient to inactivate the virus by >3 orders of magnitude within an exposure time of 1 minute.
Chlorine demand would also be anticipated when the virus is associated with fecal material. These findings indicate that the ability to compensate for an initial chlorine demand followed by exposure to a relatively low level of free chlorine for a short time is sufficient to inactivate the virus by chlorination.
For drinking water disinfection at conditions similar to those used in this study, the US Environmental Protection Agency specifies free chlorine Ct values of 6 and 8 mg-min/L to achieve enteric virus inactivation of 3 and 4 orders of magnitude, respectively (14).
According to our results, these Ct values would be more than sufficient to inactivate HPAI (H5N1) in the water environment. The information on chlorine disinfection presented here should be helpful for developing risk management procedures regarding the role of water in the transmission of the virus to humans and poultry.
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