Influenza and SARS: the impact of viral pandemics on maritime health.

Global travel and transport play a critical role in the spread of infections. We see this clearly in the first two pandemics of the 21st century: SARS and influenza H1N1-2009. Although air travel contributed to dissemination in these two pandemics, the travel restrictions, quarantines, and heightened vigilance which resulted had an impact on maritime health. Seasonal, pandemic, and avian influenza have some important differences with regards to exposure risks, infectivity, and severity. Most of the data for maritime influenza outbreaks focus on seasonal influenza on cruise ships, but influenza among crew members occurs due to close working conditions and is potentially preventable with staff vaccination programs. To date, avian influenza has low human-to-human transmission; infection typically requires close contact with poultry, but presents with severe disease and a high fatality rate. Pandemic (swine) influenza was readily transmitted between people, including young adults, and caused severe illness in high-risk groups including pregnant women, children, and those with co-morbidities and obesity. In contrast, SARS had lower infectivity compared to influenza, and a longer incubation period. These characteristics slowed its propagation enough that outbreak control measures, such as isolation of infected cases and quarantine of exposed but well persons, were effective in terminating this pandemic. No effective vaccine exists for SARS at this time, whereas countries were able to deploy millions of doses of pandemic influenza vaccine within 7 months after the outbreak was first recognized in Mexico. The lack of a protective vaccine and the higher case fatality rate in SARS will mean that stringent quarantine measures may still be required for outbreak control if SARS ever occurs again. Compliance with international health regulations, and the ability to adapt these to maritime health needs, will be important in the shipping industry.