Federal Air Travel Restrictions for Public Health Purposes --- United States, June 2007--May 2008

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Persons with communicable diseases who travel on commercial aircraft can pose a risk for infection to the traveling public (1,2). In June 2007, federal agencies developed a public health Do Not Board (DNB) list, enabling domestic and international public health officials to request that persons with communicable diseases who meet specific criteria and pose a serious threat to the public be restricted from boarding commercial aircraft departing from or arriving in the United States. The public health DNB list is managed by CDC and the U.S. Department of Homeland Security (DHS). To describe the experience with the public health DNB list since its inception, CDC analyzed data from June 2007 to May 2008. This report summarizes the results of that analysis, which indicated that CDC received requests for inclusion of 42 persons on the public health DNB list, all with suspected or confirmed pulmonary tuberculosis (TB). From the requests, 33 (79%) persons were included on the list. The public health DNB list enables public health officials to prevent travel on commercial aircraft by persons who pose a risk for infection to other travelers. State and local health departments in the United States and other countries should be aware of this new public health tool.

The public health DNB list is intended to supplement local public health measures when they are deemed insufficient to prevent persons who are contagious from boarding commercial aircraft. Use of the list is limited to diseases that would pose a serious health threat to fellow air travelers. The list is authorized under the Aviation and Transportation Security Act of 2001* and is managed jointly by DHS and CDC; however, DHS defers to CDC regarding public health decisions and actions.

To request that a person be placed on the public health DNB list, state or local public health officials contact the CDC Quarantine Station for their region^†; health-care providers make requests by contacting their state or local public health departments, and foreign and U.S. government agencies contact the Director's Emergency Operations Center (DEOC) at CDC in Atlanta. To include someone on the list, CDC must determine that the person 1) likely is contagious with a communicable disease that would constitute a serious public health threat should the person be permitted to board a flight; 2) is unaware of or likely to be nonadherent with public health recommendations, including treatment; and 3) likely will attempt to board a commercial aircraft. Once a person is placed on the list, airlines are instructed not to issue a boarding pass to the person for any commercial domestic flight or for any commercial international flight arriving in or departing from the United States. The public health DNB list does not apply to other means of transportation (e.g., buses or trains). Governments of foreign countries are notified when their citizens or persons residing in their countries are placed on the list.

Multiple criteria are used to decide whether a person with a communicable disease constituting a serious public health threat should be placed on the public health DNB list and when a person can be removed. For persons with suspected or confirmed pulmonary TB, criteria have been developed in consultation with subject-matter experts in CDC's Division of Tuberculosis Elimination and the National Tuberculosis Controllers Association, and include initial assessment of contagiousness based on clinical, radiographic, and microbiologic evaluation; treatment adequacy; and mycobacteriologic response (e.g., sputum smear microscopy and culture results). These criteria are derived from existing general guidance on prevention of TB transmission and guidance specific to air travel (3--5). For situations in which multidrug-resistant TB (MDR TB) is confirmed or suspected, more stringent criteria (e.g., evidence of negative culture results) are applied because the consequences of transmission are substantially more severe.

During June 2007--May 2008, CDC received requests to place 42 persons on the public health DNB list. Thirty-three (79%) persons met the criteria and were placed on the list (Figure). Of the other nine persons, four were the subjects of other actions pursued by local health departments (e.g., local isolation orders), three agreed not to attempt to board a commercial aircraft, and two were determined to be noncontagious. Twenty-eight (85%) of the 33 public health DNB placements came from state, territorial, or local health departments in the United States; the greatest number of requests came from Texas (seven) and California (five). Three requests came from Canada, one from Mexico, and one from the U.S. Department of State. Fourteen persons (42%) were placed on the public health DNB list while they were outside the United States.

Of the 33 persons placed on the list, all were thought to have infectious pulmonary TB. Their median age was 41 years (range: 20--77 years), and 20 (61%) were male. Drug-susceptibility testing results were available for 27 (82%) persons, of whom 19 (70%) were susceptible to first-line anti-TB medications. Among the others, seven (26%) had MDR TB, and one had extensively drug-resistant TB (XDR TB). Fifteen (45%) persons on the public health DNB list were citizens of countries designated by the World Health Organization as TB high-burden countries (6).

Public health officials who request placement of a person on the public health DNB list are asked to notify their CDC Quarantine Station as soon as the person on the list is determined to be noncontagious. Once public health authorities confirm that a person is no longer contagious, CDC and DHS remove the person from the list, typically within 24 hours. In addition, on a monthly basis, CDC reviews all persons on the public health DNB list to determine whether they are eligible for removal. During June 2007--May 2008, 18 (55%) of the 33 persons placed on the public health DNB list later were removed because they were determined either to be no longer contagious or not to have TB (Figure). Persons removed during this period had been on the public health DNB list for a median of 26 days (range: 2--193 days). The 15 persons not removed had been on the public health DNB list for a median of 72 days (range: 1--364 days).

Reported by: S Penfield, MD, Texas Dept of State Health Svcs. J Flood, MD, Center for Infectious Diseases, California Dept of Public Health. W Lang, MD, M Zanker, MD, Office of Health Affairs, US Dept of Homeland Security. MB Haddad, MSN, Div of Tuberculosis Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention; F Alvarado-Ramy, MD, L Leidel, MSN, G Fowler, MPH, S Modi, MD, C Brown, MD, F Averhoff, MD, MS Cetron, MD, Div of Global Migration and Quarantine, National Center for Preparedness, Detection, and Control of Infectious Diseases, CDC.

Editorial Note:

The public health DNB list is a new tool that federal, state, local, and international public health officials can use to help prevent the spread of communicable disease via commercial air travel. Judicious use of the public health DNB list can obviate the human and economic costs associated with conducting contact investigations when persons with communicable diseases travel on commercial aircraft (7,8).

Although the public health DNB list can be used only for commercial air travel, other public health tools can be used to restrict travel by air and other conveyances (e.g., ships), including isolation and border lookout records. Additionally, retrospective contact investigations among exposed persons can help to prevent disease transmission. A border lookout record is a mechanism by which CDC, acting through DHS Customs and Border Protection (CBP), can alert border authorities when public health officials determine that a person with a communicable disease who might pose a serious threat to public health might attempt to enter the country through a seaport, airport, or land border. The lookout record prompts CBP staff, in collaboration with CDC quarantine staff, to conduct a thorough inquiry and evaluation of such persons when they attempt to enter the United States. Persons who are included on the public health DNB list also are routinely assigned a lookout record.

Backup measures such as border lookout records are important adjuncts to the public health DNB list. Two (6%) of the 33 persons on the public health DNB list during June 2007--May 2008 are known to have attempted to evade the U.S. air travel restriction. Both persons were successfully detected by CBP officers before they were admitted into the United States and were taken to local hospitals for evaluation and care of TB.

CDC and DHS regularly evaluate the public health DNB mechanism to ensure that it is operating effectively and that the list is used only when other measures are unlikely to prevent air travel. Ensuring the accuracy of information such as name, date of birth, and other unique identifiers, is especially critical. CDC also works with local and state public health officials and other partners to close any gaps not covered by the list. For example, compulsory local, state, or federal isolation orders might be required to restrict movement of certain persons who attempt to contravene official travel restrictions or who are otherwise noncompliant with public health recommendations and present a serious threat to the public. To enable effective use of such orders, state and local public health officials should be familiar with their legal authorities and operational procedures, including law enforcement capabilities, for implementing isolation or quarantine orders.

The public health DNB list is not limited to those communicable diseases for which the federal government can legally impose isolation and quarantine^§; the list can be used for other communicable diseases that would pose a serious health threat to air travelers. However, to date, the list has only been used for persons with suspected or confirmed pulmonary TB, which is transmitted via the respiratory route and which has had transmission documented during commercial air travel. Persons with TB also can remain contagious for long periods, especially when infected with MDR TB (3,9,10).

Before June 2007, when the public health DNB list was established, CDC Quarantine Station officers worked directly with airlines and health departments to prevent persons known or suspected of having communicable diseases that posed serious threats to fellow passengers from traveling on commercial flights. Under certain circumstances, airlines may decline to board passengers with communicable diseases pursuant to regulations promulgated under the authority of the Air Carrier Access Act of 1986. Air carriers must base their decisions on reasonable judgment that relies on current medical knowledge or on the best available objective evidence, including that from public health authorities.^¶

Public health DNB list procedures are reviewed periodically by CDC and DHS to ensure privacy protections and assess ethical issues. In addition, CDC works with state and local public health departments to ensure that 1) persons placed on the public health DNB list are notified of the action taken, 2) criteria for being removed from the list are known, and 3) steps are taken to obtain appropriate public health management of the person's communicable disease.

State and local health departments may obtain more information about the process for requesting federal assistance with travel restrictions through the CDC Quarantine Station for their region. Information also is available from CDC's DEOC at 770-488-7100. International health officials should call the DEOC for information about travel restrictions. Health-care providers who are concerned that a patient with infectious TB, or another communicable disease posing a serious public health threat, is planning to travel by commercial aircraft despite instructions to the contrary should contact their local health department.

This report is based, in part, on contributions from P Cruise, B Heath, Texas Dept of State Health Svcs; and the Quarantine and Border Health Svcs Br, Div of Global Migration and Quarantine, CDC.

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