Chlorine inactivation of highly pathogenic avian influenza (H5N1...

To determine resistance of highly pathogenic avian influenza (H5N1) virus to chlorination, Rice et al. exposed allantoic fluid containing 2 virus strains to chlorinated buffer at pH 7 and 8, at 5°C. Rice et al. concluded that free chlorine concentrations typically used in drinking water treatment are sufficient to inactivate the virus by >3 orders of magnitude. However, drinking-water may be colder than 5°C as 3°C. The pH value often is >8.0 as 9.5. In the cold and at high pH values virus inactivation by chlorine is rather poor. Rice et al. used the maximum US chlorination level with 2.0 mg/L free chlorine. Just 0.1-0.3 mg/L free chlorine are tolerated e.g. in Germany. Virus inactivation performances of water treatment units are valid under the precondition that microorganisms in water are in suspension, not embedded in particles. In water secreted influenza viruses always are embedded in particles. Hence the proved orders of magnitude of avian flu virus inactivation in allantoic fluid diluted into buffer are not consistent with the real conditions. Moreover the WHO requires virus inactivation/filtration rates from 6 (surface water) to 4 (ground water) orders of magnitude. Rice et al. just proved 3 orders of magnitude. Hence we can’t be convinced that chlorinated water is safe. Real worst case conditions are cold drinking-water at 3°C, pH value at 9.5, lower chlorination than 2 mg/L (or no chlorination but filtration), perhaps 0,2 mg/L like in Germany, influenza viruses embedded in particles, required virus inactivation/filtration performance from 6 (surface water) to 4 (ground water) orders of magnitude.