Summary of the first international workshop on human caliciviruses.

The First International Workshop on Human Caliciviruses was held from 29 to 31 March 1999 at the Centers for Disease Control and Prevention in Atlanta. The attendance of over 100 scientists specializing in diverse fields (including civilian and military clinical medicine, basic research, epidemiology, public health, food and water safety, environmental protection, and veterinary medicine) from 18 countries underscored the increasing interest in these diarrheal pathogens. The prototype human calicivirus strain (Norwalk virus) was discovered in 1972. In the nearly 3 decades since then, enteric caliciviruses have been linked to sporadic cases and epidemic outbreaks of gastroenteritis in humans. However, the magnitude of the medical importance of Norwalk virus and an increasing number of related caliciviruses (known collectively as the “human caliciviruses”) has been recognized only recently. In part, this delayed recognition has been attributed to the extraordinary technical difficulties in working with these viruses, which, even now, cannot be grown in cell culture. The cloning of the Norwalk virus genome in 1990 and the development of molecular biologic methods were an important advance that enabled rapid progress in nearly all areas of human calicivirus research in the past decade. The purpose of the First International Workshop on Human Caliciviruses was to provide a forum in which this progress could be reviewed in order to evaluate what is currently known about the role of human caliciviruses in diarrheal disease and to consider future directions of research. A predominant theme in the workshop was the remarkably high frequency with which human caliciviruses are associated with acute gastroenteritis worldwide. New data collected from several large-scale epidemiologic studies (one involving an entire country, The Netherlands), community studies, and gastroenteritis outbreak investigations confirmed that calicivirus infection and disease are common. Environmental surveys found that caliciviruses are ubiquitous and apparently stable in the environment, providing a ready source of virus for potential infection. It is now estimated that as many as 95% of nonbacterial gastroenteritis outbreaks, many of which are associated