Contamination of food and water by human pathogenic viruses

Food and water contamination by human viruses is a great health problem. Th ese viruses are shed in stools. Norwalk-like viruses, hepatitis E virus, po liovirus, echovirus, hepatitis A virus, rotavirus, astrovirus, enteric aden ovirus and parvovirus B19 have been described. The most important ones are Norwalk-like viruses, rotavirus and hepatitis A virus as reported in epidem iological surveys. The most frequently implicated foods are shellfish (biva lve mollusks) harvested from waters contaminated with human sewage, as well as water itself. The other source of infection is the handling of food in poor hygienic conditions. In this case contaminated foods are vegetables, s andwiches, fruits, pastries that are soiled. The detection of viruses in foods is difficult for several reasons: Virus-f ood interactions make difficult the concentration and the purification of v iruses, several virus species are difficult or unable to grow in cell cultu re, furthermore viruses are present in the sample in very low amounts. Molecular techniques are therefore the methods of choice for detecting thes e viruses, especially the polymerase chain reaction which is often describe d. Another possibility consists in a fecal viral indicator. Bacteriophages seem to be the most promising in this respect.