ABSTRACT
Viruses are a major cause of waterborne and water-related diseases. Extreme examples include the outbreak of hepatitis A and of viral gastroenteritis in Shanghai caused by shellfish harvested from a sewage-polluted estuary. Viruses predominantly associated with waterborne transmission are members of the group of enteric viruses that primarily infect cells of the gastrointestinal tract, and are excreted in the faeces of infected individuals. The viruses concerned are highly host specific, which implies that their presence in water environments is sound evidence of human faecal pollution. In some cases different strains of a viral species, or even different species of a viral genus, may infect animals. The extent of the host specificity of enteric viruses is such that it is used as a valuable tool to distinguish between faecal pollution of human and animal origin, or to identify the origin of faecal pollution. The hepatitis E virus may be the only meaningful exception to this rule, having strains that seem to infect both humans and certain animals, complying with the definition of a zoonosis. The potential risk of infection associated with respiratory viruses such as influenza and severe acute respiratory syndrome in water environments cannot be ignored. However, there is sound reason to believe that treatment and disinfection processes recommended for the acceptable control of enteric viruses will also accommodate enveloped viruses with a substantial safety margin.
ABSTRACT
Adenoviruses are of major public health importance and are associated with a variety of clinical manifestations, i.e. gastroenteritis, eye infections and respiratory infections. The importance of water in the epidemiology of adenoviruses and the potential health risks constituted by adenoviruses in water sources and supplies are widely recognised. This study was conducted to assess the incidence of human adenoviruses in raw and treated water systems. Various raw and treated water were routinely monitored for the presence of adenoviruses, over a 1-year period (July 2000-June 2001). The supplies were derived from acceptable quality surface water sources using treatment processes, which conform to international standards for the production of safe drinking water. Adenoviruses were detected by firstly amplifying the viruses in cell cultures and then amplifying the extracted nucleic acids of these viruses using molecular techniques (nested PCR). The results indicated human adenoviruses present in 13 (12.75%) of the raw and 9 (4.41%) of the treated water samples tested. The combination of cell culture and nested PCR has proved to be a quick and reliable method for the detection of adenoviruses in water environments.
