An outbreak of norovirus infection has been reported from a cruise liner owned by a British cruise operator, P&O Cruises. The liner departed from Southampton on England’s south coast for a cruise of the Mediterranean on 20 October 2003 with a complement of nearly 1800 passengers and over 800 crew. The first cases of gastroenteritis among passengers occurred on day 2 of the cruise. A sharp increase in illness was reported to the ship’s medical team on day 6. Over 500 people have been affected since the start of the outbreak, and symptoms include projectile vomiting and diarrhoea, with 86% of patients reporting vomiting. Most of the patients recovered after two days of illness. This epidemiological and clinical pattern is typical of norovirus outbreaks in semi-closed settings such as cruise ships, hotels, schools and healthcare institutions. Norovirus was identified in patient specimens by the medical team on the ship using a commercial enzyme linked immunosorbent assay (ELISA).

P&O Cruises have been working with the Health Protection Unit in Southampton on the implementation of control measures. As the home port for the vessel, Southampton Port Health Services have been kept fully informed of the progress of the outbreak and the control measures employed. The primary responsibility of the Port Health Service is to protect the public health and Port Health and medical officers will board the vessel when she docks to verify that procedures and policies have been correctly implemented in response to the outbreak.

Each year a small number of norovirus outbreaks on cruise ships, particularly ships sailing in the Mediterranean and Caribbean, are reported to health authorities around the world. Norovirus is the commonest cause of gastroenteritis in the developed world, and it has been estimated from population studies in England and the Netherlands that 1-3% of the population will be affected each year (2,3).