Author(s): Alida Gertz, Francisco Alvarado-Ramy

The Centers for Disease Control and Prevention (CDC) has a regulatory mission to protect the public health of the United States by preventing the introduction, transmission, and spread of communicable diseases from foreign countries into and within US states and territories. For diseases of concern that have received special designation by the President of the United States, CDC may issue federal public health orders for quarantine, isolation, and conditional release. Diseases falling under this specific federal public health authority (Table 8-03) include cholera, diphtheria, infectious tuberculosis, measles, plague, smallpox, yellow fever, viral hemorrhagic fevers, severe acute respiratory syndromes (e.g., Middle East respiratory syndrome [MERS], coronavirus disease 2019 [COVID-19]), and influenza due to novel or reemergent viruses that are causing (or have the potential to cause) a pandemic. The list of federally quarantinable diseases can be revised by executive order when a communicable disease becomes a significant public health threat. For more information, see Specific Laws and Regulations Governing the Control of Communicable Diseases.

Protecting the Public’s Health Before, During & After Travel

In the United States, CDC conducts public health actions before, during, and after commercial flights and cruise travel to prevent or mitigate the introduction and spread of diseases of public health concern. Many of these actions are carried out by CDC quarantine station personnel working in collaboration with state, tribal, local, and territorial (STLT) public health officers. CDC quarantine stations are located at the 20 ports of entry, including land border crossings, where most travelers arrive to or transit through the United States. See more information on CDC quarantine stations.

Before Travel

In 2007, CDC and the US Department of Homeland Security (DHS) developed a public health Do Not Board (DNB) list to prevent people from boarding commercial aircraft if they are known to have, are suspected of having, or were exposed to a communicable disease of public health concern. A person placed on the DNB list will not be issued a boarding pass for any commercial airline flight originating from or arriving to a US airport.

STLT public health authorities notify CDC when people with communicable diseases of public health concern are at risk of traveling on a commercial flight; they also can recommend to CDC that people who meet certain criteria be added to the DNB list. For more information about the DNB list, see FAQs for Public Health Do Not Board and Lookout Lists.

During Travel

Federal regulations mandate that before arrival, the person in charge of a conveyance destined for a US port of entry must report to the CDC quarantine station of jurisdiction any death or “ill person” among passengers or crew. For the definition of an ill person, see CFR Title 42 §71.21: Report of death or illness and Box 8-08.

Airlines, DHS’s US Customs and Border Protection, and emergency medical personnel at arriving airports can each provide CDC quarantine station staff with reports of illness and/or death that occurs during commercial air travel. Most reports of illness or death on commercial, seagoing vessels are received directly from the ship’s medical staff or from a shipping agent. Airline and cruise ship illness and death reports also can originate from other federal partners or STLT health departments.

Air Travel Response

CDC’s goals in responding to reports of illness during air travel are to determine whether the illness poses (or has the potential to pose) a public health threat and to take appropriate public health actions. When responding to reports of illness during air travel, public health officials can either allow ill air passengers to resume travel if their illness does not pose a meaningful public health risk; recommend ill air passengers with a suspected communicable disease seek medical care and delay further commercial travel until noninfectious; or require ill air passengers to be medically evaluated if they are suspected of having a quarantinable communicable disease.

Together with airport and public health response partners (e.g., emergency medical services, public health authorities), CDC staff board arriving airplanes to conduct public health assessments of ill travelers and to make recommendations regarding potentially exposed passengers. Potentially exposed travelers might be asked to provide their contact information before disembarking so that health authorities can follow up and provide additional health information if the ill traveler is diagnosed with a disease of public health concern.

CDC provides guidance to airlines on reporting and managing ill travelers on airplanes at Airline Guidance: Reporting Death/Illness and Airline Guidance: Managing Ill Passengers/Crew.

Cruise Ship Response

For public health responses to ill cruise ship passengers and crew, control measures typically are initiated while the ship is still at sea. CDC quarantine station personnel obtain clinical and epidemiologic information about the ill or deceased person(s), determine public health risk, and provide guidance to the ship’s clinicians about case findings, infection control measures, and contact investigations.

CDC quarantine station personnel might respond by meeting a ship at the port of entry to further investigate or to assist the responding health department with surveillance and control measures. CDC personnel also might provide onsite response for outbreaks or clusters of disease, quarantinable communicable diseases, and some vaccine-preventable diseases (e.g., measles, rubella). CDC’s Vessel Sanitation Program is responsible for responding to reports of acute gastroenteritis on cruise ships.

CDC provides guidance to cruise lines on reporting and managing ill travelers at Cruise Ship Guidance: Reporting Death or Illness on Ships and Cruise Ship Guidance: Disease-specific Management of Ill Passengers/Crew.

After Travel

When a US or foreign public health authority notifies CDC of an illness of public health concern in airplane or cruise ship travelers who have reached their final destination, CDC conducts, or assists STLT health departments in conducting, a public health contact investigation. The primary purpose of the contact investigation is to identify and notify potentially exposed passengers and crew, so they can be offered clinical evaluation, postexposure prophylaxis (when necessary), and health education, including recommended quarantine periods.

Reporting Posttravel Illness

Travelers who become ill at their destination or after returning home should inform their health care providers of where, when, and on what type of conveyances they traveled. Report cases of communicable diseases of public health concern in returning travelers to appropriate public health authorities according to the state’s specific reportable disease requirements.

When a risk for communicable disease transmission during travel is possible, health departments can notify CDC by contacting either the quarantine station with jurisdiction for their region or the CDC Emergency Operations Center (770-488-7100; eocreport@cdc.gov).

Report cases of travel-associated legionellosis to CDC to travellegionella@cdc.gov, and cases of acute gastroenteritis associated with cruise travel to vsp@cdc.gov.