Ahoy! Epidemiology of U.S. Maritime Illness and Death Reporting and Public Health Response, 2010-2014

BACKGROUND: Each year, millions of travelers arrive in U.S. ports of entry by cruise and cargo vessels from countries that may have lower vaccine coverage and less available healthcare; the majority arrive on cruise ships. Deaths and certain illnesses onboard ships arriving at U.S. ports are reported to Centers for Disease Control and Prevention (CDC) Quarantine Stations under CDC’s regulatory authority, and entered into the Quarantine Activity Reporting System (QARS), a secure online database. This is the first comprehensive analysis of U.S. maritime illness and death reporting and response and provides vital public health information about maritime travelers.

METHODS: We conducted a descriptive analysis of maritime illnesses and deaths recorded in QARS from January 1, 2010 to December 31, 2014. Reports were analyzed by presumptive illness diagnosis or cause of death, age, year, gender, type of traveler, type of vessel, and associated Quarantine Station. Contact investigations for diseases of public health concern and outcomes were summarized; since 2010, CDC has delegated uncomplicated varicella contact investigations to cruise ships.

RESULTS: From 2010-2014, 2,891 cases of maritime illnesses (2,221, 76.8%) and deaths (670, 23.2%) were reported to CDC. Of 1,546 cases with known gender, 1,079 (69.7%) were male. The mean traveler age for illness was 36.1 years and 65.7 years for deaths. Travelers on cruise ships accounted for 1,970 (90.7%) illnesses and 616 (93.2%) deaths, while 201 (9.3%) illnesses and 45 (6.8%) deaths were in travelers on cargo vessels. The most frequent individual illnesses reported were upper/lower respiratory infections (876, 39.4%) and varicella (797, 35.9%), and the most frequently reported causes of death were cardiovascular- or pulmonary-related conditions (533, 79.6%). CDC coordinated contact investigations for 43 cases (1.5% of reports): 30 (69.8%) tuberculosis, 3 (6.9%) measles, 3 (6.9%) meningococcal disease, 3 (6.9%) pertussis, 2 (4.7%) mumps, and 2 (4.7%) rubella. There were 662 contacts identified, of whom 483 (73.0%) were evaluated. Of contacts with known traveler status, 321 (70.7%) were passengers and 133 (29.3%) were crew members. 

CONCLUSIONS: These data provide a picture of U.S. maritime illness and death reporting and response. A majority of the reports involved cruise ship travelers, which is expected given the larger cruise ship populations. However, this may also reflect under-reporting by cargo ships and additional projects are in development to answer this question. Contacts identified were more likely to be passengers than crew, and most reports did not result in a public health contact investigation.