Virus-like particles in winter vomiting disease.

In an outbreak of winter vomiting disease affecting both pupils and staff in a primary school, virus-like particles were found in 7 out of 8 faecal specimens examined by electron microscopy. The particles measured 26 nm in diameter and had a buoyant density of 1-38--1-40 g/cm3 in caesium chloride. They could not be cultured in tissue-culture or organ-culture. In immune electron microscopy tests the particles appeared to differ antigenically from the Norwalk and Hawaii agents. Two out of three patients examined more than one month after their illness were still excreting the particles.