Monday, September 24, 2007

Good news - Chlorine kills H5N1

From Emerging Infectious Diseases (

With waterfowl being significant carriers of H5N1, there are definite concerns about H5N1 being transmitted to other poultry and humans through water.

A recent study published in EID demonstrated that Chlorination, the most common form of water treatment, does indeed kill H5N1

"The results of this study confirm that avian influenza (H5N1) is readily inactivated 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."

1 comment:

Dipl.-Ing. Wilfried Soddemann said...
Rice EW, Adcock NJ, Sivaganesan M, Brown JD, Stallknecht DE, Swayne DE.
Chlorine inactivation of highly pathogenic avian influenza virus (H5N1).
Emerg Infect Dis. 2007 Oct; [Epub ahead of print]:

“… Briefly, virus-infected allantoic fluid was diluted (1:1,000) into continuously stirred, chlorinated, chlorine demand–free phosphate buffer (0.05 M, pH 7.0 and 8.0). … To slow the rate of inactivation, experiments were conducted at 5 °C. …“

“Ct (Ct value is the chlorine concentration, C [mg/L], multiplied by the exposure time, t [min]) apply to microorganisms in suspension, not embedded in particles.” [GUIDELINES FOR DRINKING-WATER QUALITY, 7. MICROBIAL ASPECTS, 7.3.2 Treatment, Table 7.6, footnote].

In (drinking-) water H5N1 viruses are embedded in particles and drinking-water may be colder than 5 °C and the pH often is > 8.0, perhaps 9.5 …

Inactivates chlorination in practice and under all conditions avian flu strains, flu viruses embedded in particles, water pH 9.5, water temperature at 3 °C…?

True reassuring news?

Dipl.-Ing. Wilfried Soddemann