Edited transcript of an oral presentation Looking at the survival of viruses on environmental surfaces, most data have come from laboratory studies, from data obtained from outbreaks and from hygiene intervention studies, collected over several years. Consider what happens if we place an object contaminated by a virus in the environment, how quickly will that virus circulate? One recent study looked at this problem. 1 Viruses spread in childcare facilities were studied using modified cauliflower virus DNA as an environmental marker. The viral DNA, introduced through treated toy balls, spread within a few hours of handling. Although the marker treated balls were removed after 1 day, the viral DNA continued circulating in the facilities for up to 2 weeks. The markers could also be detected in the children’s homes, on the hands of family members, and on environmental surfaces within those homes, including toys – this shows the potential for the environment to spread viruses. Many studies have been carried out to determine the level of environmental contamination in the course of rotavirus infections, in childcare centres, paediatric wards and so on. 2–4 Up to 10 12 virus particles, per ml of faeces, are shed when someone has rotavirus diarrhoea, so if we consider splashing effects in toilets, changing nappies and handling young children who are not toilet trained, there is great potential for the virus to spread. In such studies rotavirus was found to be widely disseminated on refrigerator handles, door handles, toilet handles, telephone receivers, toys and in play areas, moist surfaces such as sinks, water play at tables, and so on. Work by Ward et al. 5 examined the role of the environment in the acquisition of rotavirus more critically. The authors looked at surfaces that had been contaminated with rotavirus seeded in non-fat milk and dried onto a surface. They worked with volunteers, males aged 18–45 years, and in a controlled experiment they had the volunteers drink a virus-seeded salt solution, after which increases in the level of viral shedding and antibodies were measured, and found that seven out of eight volunteers became infected. They also looked at how the virus could be transmitted by licking the surface – normally we would not lick surfaces but we do use knives and forks, cups and so on. Eight volunteers became infected from directly licking a contaminated surface. When a surface was wiped with a finger and transferred to the mouth five out of eight volunteers became infected. These adults had no clinical symptoms but became shedders of the virus. Adults do not normally show symptoms; it is only in children and the elderly that rotavirus can become a serious problem. These workers also showed that spraying rotavirus-contaminated surfaces with a disinfectant (79% ethyl alcohol and 0.1% phenylphenol) prevented infection. Volunteers touching the disinfected surfaces with their fingers and then their mouths did not acquire infection. Let us consider environmental contamination with the Norwalk-like viruses (NLVs – also known as small roundstructured viruses) and the use of the reverse-transcriptase polymerase chain reaction (RT-PCR) assay for detection. As NLV cannot be grown in tissue culture RT-PCR has become an important assay for detection. RT-PCR can be used to determine whether viral nucleic acid is present in the environment. However, the assay does not indicate whether an intact, infectious virus particle is present in the sample, it only detects the nucleic acid component. Nevertheless, RT-PCR is the only way we have of looking for NLV in the environment.