Historically, ships have played a significant role in the global transmission of infectious disease. Some of the earliest recorded evidence of attempts to control human disease transmission via ships dates to the 14th century, when ports denied access to ships suspected of carrying the plague. In the 19th century, the spread of cholera pandemics was thought to have been facilitated by merchant shipping. A World Health Organization (WHO) review identified more than 100 disease outbreaks associated with ships between 1970 and 2003 (Rooney et al., 2004).

Today’s world fleet of propelled seagoing merchant ships of more than 100 billion tonnes comprises 99 741 ships, with an average age of 22 years, registered in more than 150 nations and crewed by more than a million seafarers of virtually every nationality.

 Ships can have significance to public health beyond their role in ship acquired infection. For example, ships can transport infected humans and other vectors, such as mosquitoes and rats, between ports and can therefore act as a means of national and international dissemination of disease and disease agents.