Infectious diseases in seafaring are recognized as an occupational hazard connected to conditions of working and living on board

 

[1] During the 2010 IMHA workshop on “Infection on board ships in the 21st century” Carter emphasized the important aspects of risk and intervention that are different for infectious diseases in the maritime sector and for similar conditions arising ashore. He stressed the importance of risk reduction for the safety wellbeing of seafarers

[2] The maritime physician must be aware of the features of the work place, e.g. the sailor’s rank, the ship´s route, flag, size, cargo and the age of the vessel. Seafarers experience wide variations in living quarters, food, air and water supply, in the composition of crew and in contact with passengers.

This chapter critically appraises the available evidence from the literature so that the appropriate risks and prevention strategies for the individual seafarer can be assessed by the clinician.

Understanding the sources of data on infectious diseases in seafarers is needed to draw correct conclusions and give valid advice. While medical care on board and in ports and considerations of ship safety are closely interconnected, research activities also focus on controlling risks to public health from the shipping industry

[3] Table 1 shows competing areas of interest which have driven legislation and research efforts on infectious diseases in seafaring.

Table 1: Infectious diseases in seafarers – areas of interest

Methods

A literature search was done using the databases MEDLINE/Pubmed and the Maritime Library of the Institute of Occupational and Maritime Health in Hamburg, Germany.

The search was performed with the terms ships, sanitation, occupational health, travel inconnection with the terms infectious diseases, communicable diseases, emerging communicable diseases and the specific diseases and agents named in the results section e.g. HIV infection, Legionellosis and others.

The review is restricted to studies published in or after 1990. Only studies concerning infectious diseases in seafarers working on merchant ships, navy vessels, ferries and cruise ships were included. Reports on recreational and fishery boats were excluded. Studies and reports published in peer-reviewed journals or presented at international conferences and surveillance reports from National Public Health Institutes were considered in the review. Only those studies that analysed original data and clearly described the source of data, the study population and time and statistical method were included.

The studies were classified as longitudinal studies, cross-sectional (prevalence) studies or case and outbreaks reports

 

[4] as given in table 2. Studies are presented by modes of transmission

[5] in the categories: Skin-Blood Cluster, Droplet-Air Cluster, Faeces-Food Cluster, Zoonotic and Environmental Cluster.

Table 2: Sources of data on infectious diseases in seafarers

Results

74 studies and reports were included in the review (table 2). No randomized trials and no prospective cohort studies in the field of interest were identified. Seven longitudinal studies from retrospective or historical cohorts, 38 cross-sectional (prevalence) and 29 outbreak/case reports were identified as shown in table 2. The studies are published by research groups from the following countries (in alphabetical order): Belgium, China, Croatia, Ethiopia, Denmark, Georgia, Germany, Greece, India, Montenegro, Philippines, Poland, Russian Federation, Sweden, Spain, Thailand, UK, USA, Vietnam.

Burden of infectious diseases in seafarers

Hansen and co-workers performed a retrospective study based on a national register of all seafarers employed on Danish ships during 1986 to 1993. Infectious diseases were more common among seafarers than in the male Danish population in general. Main causes of death on board of Danish merchant ships were infectious, gastrointestinal, heart diseases and  stroke.

 

[6] Out of 866 cases and 1720 radiomedical contacts in 48 consecutive months from U.S. ships at sea to US emergency medicine physicians for advice, 48% of cases were medical, 14% were injuries and 2% were purely psychiatric. 15% of the medical cases were due to respiratory infections.

[7] Schlaich et al. showed in a retrospective study based on medical log-books from merchant ships under German flag that during more than 1.5 million person-days of observation from 2002-2008, nearly one fourth of the visits to the ship’s infirmary were due to communicable diseases (45.8 consultations per 100 person-years).

[8] Data from the radiomedical service in Sweden from 1997, 2002, 2007 and 2009 demonstrated that 33% of all 1290 consultations concerned infections, most often from the respiratory and digestive system. 71% of seafarers completed treatment on board and no further treatment in port or repatriation were necessary.

[9] Overall, the data from these sources show, that the majority of consultations to radiomedical services, of treatments on board and of deaths are due to medical conditions, followed by injuries in frequency. Among the medical conditions, infectious diseases from the respiratory and digestive system were most prevalent.