Abstract
Many pathogenic micro-organisms are likely to attack passengers of cruise ships and other vessels or travel between continents as a peculiar type of a “stowaway”. The epidemiological tests conducted since 1987 with regard to watercraft led to the coining of a term known as the Sick Boat Syndrome (SBS). The main illnesses encountered on watercraft include gastrointestinal diseases (foodborne) and Legionellosis. Additionally, the ventilation and airconditioning systems of old commercial ships (the so-called Tramps) constitute a real technical challenge. Conditioned air (with removed undesired odour and micro-organisms) should constitute ca. 25% of circulating air. In practice this situation is not typical for vessels of this class. Unclean air poses a real hazard for the crew.