Given the immense disease burden of viral agents of gastroenteritis, our research must be directed toward prevention and control of the resulting disease. For the endemic agents of children, vaccines provide the most likely approach toward prevention. Rotavirus represents the most important virus in this group, and vaccines against rotavirus have already been under development and testing for 15 years (Bresee et al 1999). The enteric adenoviruses and astrovirus pose another challenge, since the disease they cause is less common than rotavirus diarrhoea, and most studies indicate that gastroenteritis associated with astrovirus is less severe than that caused by rotavirus (Pang et al 2000). Consequently, efforts to push for a vaccine would require more data documenting that there was enough severe or fatal disease or hospital or health care costs to justify the massive investment required.
For the epidemic diseases, other challenges remain. The caliciviruses pose the greatest epidemic threats, and investigation often identifies a breach of sanitation with faecal contamination of water or food (either at its source or by a food-handler) that can be corrected. At the same time, the virus can be transmitted by person-to-person contact or perhaps by aerosols, and therefore much disease is not easily prevented (Becker et al 2000). Control of calicivirus disease outbreaks is currently directed at halting those outbreaks where problems of contamination of food or water can be easily corrected. This approach leaves many outbreaks to run their course despite the best public health interventions and intent. Efforts to develop vaccines against the caliciviruses are being pursued with the hope that even mimicking the short-term natural immunity of infection would be a useful preventive measure for travellers and soldiers, provided that the vaccine contained the proper broad mix of antigens or induced immunity to a common immune determinant of many strains (Estes et al 2000).
We know little about the prospects of control of the other novel viruses of epidemic gastroenteritis. Group B rotaviruses that were epidemic in China, affected people of all ages, and were believed to be transmitted by contaminated water have only recently been identified outside of China in India, where they did not cause epidemics (Hung et al 1984). This experience warns us to be on the alert for new viruses that may emerge and spread by novel means and have an impact on health that cannot be assessed in advance.
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