BACKGROUND: In-flight transmission risk of Mycobacterium tuberculosis is not well defined, although studies suggest it is low. The impact of flight-related tuberculosis (TB) contact investigations (TBCIs) on TB prevention and control is not well established, and they compete for resources with activities with established benefits. We sought to determine the risks and cost-benefits of using more restrictive criteria in comparison to the Centers for Disease Control and Prevention (CDC) 2008 protocol for TBCIs. METHODS: The risk-benefits of a modified CDC protocol were analyzed in comparison to the 2008 CDC protocol using data from flight-related TBCIs conducted in the United States from 2007 through 2009. We predicted the numbers and characteristics of case-travelers that would be identified using each protocol's criteria, and results of the associated passenger-contacts' TB screening tests. The economic analysis compared the costs of TBCIs to avoided costs of TB treatment and mortality using a Return on Investment model. RESULTS: The estimated in-flight transmission risk using a modified CDC protocol was 1.4%-19% versus 1.1%-24% for the 2008 protocol. Numbers of TBCIs and immediate costs to health departments were reduced by half. Long-term cost-benefits were comparable. CONCLUSIONS: CDC's modified protocol appears to be a feasible alternative that will conserve public health resources without jeopardizing the public's health.

The global spread of the influenza A(H1N1)pdm09 virus (pH1N1) associated with travelers from North America during the onset of the 2009 pandemic demonstrates the central role of international air travel in virus migration. To characterize risk factors for pH1N1 transmission during air travel, we investigated travelers and airline employees from four North American flights carrying ill travelers with confirmed pH1N1 infection. Of 392 passengers and crew identified, information was available for 290 (74%) passengers were interviewed. Overall attack rates for acute respiratory infection and influenza-like illness 1-7 days after travel were 5.2% and 2.4% respectively. Of 43 individuals that provided sera, 4 (9.3%) tested positive for pH1N1 antibodies, including 3 with serologic evidence of asymptomatic infection. Investigation of novel influenza aboard aircraft may be instructive. However, beyond the initial outbreak phase, it may compete with community-based mitigation activities, and interpretation of findings will be difficult in the context of established community transmission.

BACKGROUND: In most years varicella is the vaccine-preventable disease most frequently reported to Centers for Disease Control and Prevention (CDC) by cruise ships. Since 2005, CDC has received numerous isolated case reports of varicella among crew members and has investigated varicella outbreaks aboard vessels sailing into and from US seaports. METHODS: CDC investigators reviewed electronic varicella case reports from 2005 to 2009 and outbreak reports from 2009 to characterize the response and control efforts implemented by cruise ships in accordance with CDC protocols. Outbreak reports from 2009 were manually reviewed for details of case identification, contact investigations, isolation and restriction of cases and contacts, respectively, and number of contacts administered varicella vaccine post-exposure by cruise lines. RESULTS: During 2005 to 2009, cruise ships reported 278 cases of varicella to CDC among predominantly male (80%) crew members, three-quarters of whom were residents of Caribbean countries, Indonesia, the Philippines, or India, and whose median age was 29 years. Cases were more commonly reported during spring and winter months. During 2009, cruise ships reported 94 varicella cases among crew members of which 66 (70%) were associated with 18 reported varicella outbreaks. Outbreak response included isolation of 66 (100%) of 66 cases, restriction of 66 (26%) of 255 crew-contacts, and administration of post-exposure vaccine to 522 close contacts and other susceptible crew members per standard CDC recommendations. DISCUSSION: Most cases reported to CDC during 2005 to 2009 were among non-US resident crew members. Overall, cruise lines sailing into North America have the onboard capability to manage varicella cases and outbreaks and appear responsive to CDC recommendations. Cruise lines should continue to implement CDC-recommended response protocols to curtail outbreaks rapidly and should consider whether pre-placement varicella immunity screening and vaccination of crew members is a cost-effective option for their respective fleet operations.

BACGROUND: Norovirus continues to pose a significant burden on cruise ships, causing an average of 27 confirmed outbreaks annually over the past 5 years. In January 2009, the report of a suspected norovirus outbreak among passengers on a cruise ship prompted an investigation. METHODS: A retrospective cohort study among passengers was conducted on board the ship. Questionnaires about health care-seeking behaviors, hygiene practices, and possible norovirus exposures were placed in every cabin. Stool samples from several ill passengers were tested for norovirus by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) and confirmed by sequence analysis. RESULTS: Of 1842 passengers, 1532 (83.2%) returned questionnaires, and 236 (15.4% of participants) met the case definition. Of these, 95 (40%) did not report to the infirmary. Case passengers were significantly more likely to have an ill cabin mate (relative risk [RR] = 3.0; P < .01) and to have witnessed vomiting during boarding (RR = 2.8; P = .01). Over 90% of all passengers reported increased hand hygiene practices following the outbreak; 38% of ill passengers and 11% of well passengers decreased participation in public activities. Of 14 samples tested, 12 were positive for norovirus by RT-qPCR; 5 of these were confirmed by sequence analysis and typed as GII.4 Minerva. CONCLUSIONS: Person-to-person transmission, including an incident of public vomiting during boarding, likely contributed to this high morbidity outbreak. Infirmary surveillance detected only 60% of acute gastroenteritis (AGE) cases involved in this outbreak. Adjustments to outbreak reporting thresholds may be needed to account for incomplete voluntary AGE reporting and to more rapidly implement control measures.