THE INACTIVATION OF HEPATITIS A VIRUS AND OTHER MODEL VIRUSES BY UV IRRADIATION

Ultraviolet light is an attractive alternative to chemical disinfection of water, but little is known about its ability to inactivate important waterborne pathogens such as hepatitis A virus. Therefore, the sensitivity of HAV strain HM-175, coxsackievirus type B-5, rotavirus strain SA-11, and bacteriophages MS2 and phiX174 to ultraviolet radiation of 254 nm wavelength in phosphate buffered water was determined. Purified stocks of the viruses were combined and exposed to collimated UV radiation in a stirred reactor for a total dose of up to 40 mW sec/cm 2 . Virus survival kinetics were determined from samples removed at dose intervals. The 4 log10 (99.99%) inactivation doses for HAV, CB5, SA-11 and phiX174 were 16, 29, 42 and 9 mW sec/cm2, respectively. MS2 exhibited the greatest resistance in buffered water with less than a 1 log10 reduction observed after exposure to 25 mW sec/CM2. A 15 mW sec/cm2 exposure induced a 7 log10 reduction of phiX174, while inactivation of HAV, CB5 and SA11 was intermediate, with at least 3 log10 reductions occurring after a 20 mW sec/cm2 exposure. The results of these experiments indicate that UV radiation can effectively inactivate viruses of public health concern in drinking water.