Sanitation on ships: compendium of outbreaks of foodborne and waterborne disease and Legionnaires's disease associated with ships, 1970-2000
The shipping industry has grown dramatically in recent years with substantial increases in size and passenger capacity. The WHO Guide to Ship Sanitation is the global reference on health requirements for ship construction and operation. It was first published in 1967 and is directly referenced in the International Health Regulations (1981). However, the document was produced over 30 years ago and is in urgent need of updating. Revising the current International Health Regulations provides an opportunity to update the WHO Guide to Ship Sanitation.
A number of outbreaks and incidents of infectious diseases, particularly gastrointestinal disease and Legionnaires’ disease, have occurred on ships. The aim of this compendium is to review all outbreaks of food and waterborne diseases and Legionnaires’ disease associated with passenger ships, general cargo ships, fishing vessels and naval vessels. Evidence from this review will assist in updating the revised WHO Guide to Ship Sanitation.
A search was carried out on scientific databases to find articles reporting an outbreak or incident of infection associated with a ship, since 1970. The results show that over 100 outbreaks of food and waterborne diseases have been associated with ships. A wide range of pathogens affected passengers and crew during ship associated outbreaks. Over one third of the outbreaks were foodborne and one fifth waterborne. Pathogens included Salmonella typhi, Vibrio cholerae, Vibrio parahaemolyticus, Salmonella spp, Enterotoxigenic E coli, Shigella spp, Norwalk like virus (NLV), Cryptosporidium sp, Giardia lamblia and Cyclospora sp. Norwalk like virus is the most common viral gastroenteritis associated with ships and Salmonella spp the most common bacterial pathogen.
Most of the gastrointestinal disease outbreaks were linked to food or water consumed onboard the ship. Few outbreaks were associated with offshore excursions. Factors contributing to the foodborne outbreaks included deficiencies in food hygiene and infected food handlers. Factors contributing to the waterborne outbreaks included contaminated bunkered water, cross connections between potable and non-potable water, improper loading procedures, poor design and construction of potable water storage tanks and inadequate disinfection.
Almost 200 cases of Legionnaires’ disease were associated with ships. Most incidents affected one or two people. The majority were associated with passenger ships. Very little information is available on the incidence of Legionnaires’disease among seafarers on general cargo vessels. However, serologic surveys of seafarers have suggested that one third have antibodies to Legionella pneumophila. Surveys have also shown that drinking water and air conditioning systems on general cargo ships have been contaminated with Legionella pneumophila.