Karen J. Marienau

Influenza A(H1N1)pdm09 during air travel

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.

Tuberculosis investigations associated with air travel: U. S. Centers for Disease Control and Prevention, January 2007-June 2008.

INTRODUCTION Contact investigations conducted in the United States of persons with tuberculosis (TB) who traveled by air while infectious have increased. However, data about transmission risks of Mycobacterium tuberculosis on aircraft are limited. METHODS We analyzed data on index TB cases and passenger contacts from contact investigations initiated by the U.S. Centers for Disease Control and Prevention from January 2007 through June 2008. RESULTS Contact investigations for 131 index cases met study inclusion criteria, including 4550 passenger contacts. U.S. health departments reported TB screening test results for 758 (22%) of assigned contacts; 182 (24%) had positive results. Of the 142 passenger contacts with positive TB test results with information about risk factors for prior TB infection, 130 (92%) had at least one risk factor and 12 (8%) had no risk factors. Positive TB test results were significantly associated with risk factors for prior TB infection (OR 23; p<0.001). No cases of TB disease among passenger contacts were reported. CONCLUSION The risks of M. tuberculosis transmission during air travel remain difficult to quantify. Definitive assessment of transmission risks during flights and determination of the effectiveness of contact-tracing efforts will require comprehensive cohort studies.

Measles transmission during air travel, United States, December 1, 2008-December 31, 2011.

BACKGROUND Flight-related measles contact investigations in the United States are coordinated by the Centers for Disease Control and Prevention (CDC). To evaluate the efficiency of CDCs measles protocol, we analyzed data from contact investigations conducted December 2008-December 2011. METHODS Cases were defined as travelers diagnosed with measles that were infectious at the time of the flight. Passengers seated within 2 rows of the case-traveler and all babies-in-arms were defined as contacts. Contact information obtained from airlines was distributed to US health departments; reporting of outcomes was requested. We cross-referenced the National Notifiable Diseases Surveillance System and CDCs National Center for Immunization and Respiratory Diseases to identify unreported cases in passenger-contacts and in passengers not identified as contacts. RESULTS Our evaluation included 74 case-travelers on 108 flights. Information for 2673 (79%) of 3399 passenger-contacts was provided to health departments; 9 cases of secondary measles were reported. No additional cases were identified. CONCLUSION Our evaluation provided evidence of measles transmission related to air travel. CDCs protocol efficiently identifies passengers most at risk of exposure and infection for flights into and within the United States.

Economics of United States tuberculosis airline contact investigation policies: A return on investment analysis

BACKGROUND In 2011, the Centers for Disease Control and Prevention modified its 2008 protocol for flight-related tuberculosis contact investigation initiation. The 2011 Modified protocol was implemented and replaced the 2008 CDC protocol based on comparative epidemiologic and economic analyses; this publication reports the economic analysis results. METHODS A return on investment model compared relative changes in tuberculosis disease treatment costs resulting from expenditures on tuberculosis contact investigations and latent tuberculosis infection treatment for the 2008 CDC and Modified protocols. RESULTS At moderate/high rates of latent tuberculosis infection and tuberculosis disease, positive returns on investment indicated each

Rubella contact tracing associated with air travel.

1.00 spent on tuberculosis contact investigations and latent tuberculosis treatment resulted in more than

Three air travel-related contact investigations associated with infectious tuberculosis, 2007-2008.

1.00 of savings from reduced tuberculosis disease treatment costs. Low rates of latent tuberculosis infection and tuberculosis disease resulted in negative returns on investment, indicating economic losses from tuberculosis disease treatment costs. There were smaller economic losses at low latent tuberculosis infection and tuberculosis disease rates with the Modified protocol in comparison to the 2008 CDC protocol, while both identified comparable numbers of persons at risk for tuberculosis. CONCLUSION The Modified protocol for conducting flight-related tuberculosis contact investigations represents a better use of resources and protects public health.

Flight related tuberculosis contact investigations in the United States: Comparative risk and economic analysis of alternate protocols

This report reviews U.S. guidelines for the identification of persons exposed to rubella during air travel. In response to an individual with rubella who traveled on multiple flights, CDC conducted an airline contact investigation that was expanded beyond customary protocol to assess if current operating procedures are adequate. Of 250 potentially exposed airline passengers, 215 (86%) were contacted and none developed a rubella-like rash, arguing against the need to notify passengers beyond the standard protocol in most cases.