It is not by accident that ships have historically played a significant role in the carriage and transmission of infectious diseases around the world. Some of the earliest recorded evidence of attempts to control human disease transmission via ships dates as far back as the 14th century, when ports denied access to ships suspected of carrying bubonic plague. In the 19th century, the spread of cholera was thought to have been a consequence in the boom in merchant shipping. In a 2004 study, it is estimated that as many as 100 disease outbreaks were attributable to ship movements between 1970 and 2003. As of 2022, the global merchant fleet is smaller than in earlier years, yet the size and capacity of individual ships have grown exponentially. Whilst the risk of carrying infectious diseases is on the one hand limited by the lower number of hulls, the very fact that ships are larger today than ever before makes them a hazard waiting to happen. For this reason alone, it is imperative that the global shipping industry accepts its responsibility for ensuring the highest possible standards in ship sanitation and hygiene. This is not a burden carried by the shipping industry alone, however; the aviation industry also shares this burden, with people more mobile today than at any point in human history. Since 1999, there have been 11 major outbreaks of infectious diseases around the world. Some of these were local or regional, such as the 1999-2002 outbreak of West Nile Virus and 2006 Mumps pandemic in the US. Other outbreaks have been able to spread globally and with relative ease in part because of the globalised nature of travel and commerce. In 2003, SARS-CoV, 2009 H1N1 Virus (Swine Flu), 2012 MERS CoV, 2014 Ebola, 2016 Zika Virus and of course in 2019, Covid. These events represent the risk we all face in the battle against existing, emerging and new diseases. As humans spread further into the chartered regions of Africa and Asia in search of new materials and commercial opportunities, so does the risk of contracting and spreading infections. Recognising this risk, and taking appropriate actions is just the start of safeguarding against this very real modern-world problem. It is equally important, however, to recognise that tropical and exotic diseases are not the only problem that faces the modern seafarer. Poor personal hygiene, and ineffective shipboard sanitation are both key causes of common - and preventable - illnesses such as food poisoning, hepatitis, dental issues, stress and anxiety, depression, amongst many more. Living and working at sea is a difficult and isolated existence, which affects seasoned mariners as much as those new to the profession. Whilst this book does not profess to be an encyclopaedia of medical problems and treatments, it is hoped that by following the simple advice and guidance contained in these pages the shipping industry can be a little bit healthier, and therefore safer.