M. tuberculosis, the bacterium that causes TB, is spread from person to person, usually through coughing, sneezing, or speaking. TB disease occurs when the bacteria actively multiply in the lungs or other sites in the body. If left untreated, a person with TB disease can spread the bacteria to an average of 10 to 15 people each year. Also, without proper treatment, TB can be fatal. Because the bacteria that cause TB are naturally slow- growing, final confirmed diagnosis of TB disease, including a determination of drug resistance, can take from 6 to 16 weeks, according to CDC. This lengthy process, along with other factors, makes diagnosis of TB difficult. (Fig. 1 provides information about the characteristics of TB.) TB disease is treated with a combination of TB medications that must be taken regularly. Individuals who have TB bacteria that are not resistant to drugs can be treated with 6 to 9 months of the most effective medications. Those with TB bacteria that are resistant to at least two of the most effective medications (multiple-drug-resistant TB) require treatment for 18 to 24 months with other TB medications that are much less effective, usually have more negative side effects, and are more expensive. Nonadherence to the drug regimen can lead to the development of drug- resistant TB, which can be transmitted from a person with active disease to an uninfected person in the same way that non-drug-resistant TB is transmitted. If a person infected with a drug-resistant strain of TB develops TB disease, his or her strain will be drug resistant as well. Because adherence to treatment regimens is essential to prevent TB bacteria from becoming resistant to available medications, individuals diagnosed with TB disease in the United States are typically treated via directly observed therapy. In such therapy, patients take their medications in the presence of a health care provider, from several times a week to every day. Individuals enrolled in directly observed therapy are more likely to complete their treatment regimens. State and local health departments and federal agencies are to work together to prevent the spread of TB in the United States. In addition to day-to-day care and treatment for patients with TB disease, state and local health departments have the primary responsibility for TB control efforts. Each state health department has a state TB controller who oversees TB prevention and control programs in the local health departments, where in most cases their workers provide care and treatment for TB patients, including directly observed therapy. State and local health departments are to work closely with staff at CDC to alert them to problems as they arise and, if necessary, request CDC assistance with nonadherent individuals with TB. Individuals with or exposed to certain diseases, including TB disease, are also subject to state and federal isolation and quarantine authorities. State and local jurisdictions have the primary legal authority to issue isolation and quarantine orders, and consequently do not regularly involve the federal government when attempting to locate individuals who are or may become nonadherent to their drug regimens. Isolation and quarantine laws vary across states; officials in some states must obtain a court order or establish that a patient is not adhering to medical advice or treatment prior to issuance of an isolation order. Furthermore, states may vary in their enforcement of such orders. However, according to state and federal health officials, the majority of TB patients adhere to treatment recommendations, including remaining in isolation units in hospitals or in isolation at home until they are no longer infectious. HHS has largely delegated to CDC the task of preventing the introduction, transmission, and spread of communicable diseases, such as infectious TB, from foreign countries into the United States, including the ability to apprehend, detain, isolate, or conditionally release a person entering the United States believed to be infected with certain communicable diseases. CDC’s overall mission is to protect the health of all Americans through health promotion, disease prevention, and preparedness. CDC’s centers, divisions, and offices also develop and disseminate guidance to state and local health departments on federal recommendations and procedures for disease control and prevention. CDC also provides resources and funding and collaborates with U.S. and Mexican health agencies for TB care and treatment for U.S. or Mexican citizens who cross the U.S.-Mexico border frequently. Within CDC, the Division of Tuberculosis Elimination is responsible for directing TB prevention and control programs in the United States, formulating national TB policies and guidelines, and helping to control TB worldwide. The Division of Tuberculosis Elimination also provides programmatic consultation, technical assistance, outbreak response assistance, and laboratory support to state and local health departments, and provides technical assistance to TB programs in other countries by collaborating with international partners. CDC’s Division of Global Migration and Quarantine (DGMQ) is responsible for working to reduce illness and death from infectious diseases, such as TB, among immigrants, refugees, international travelers, and other mobile populations that cross international borders, as well as for preventing the introduction of infectious diseases into the United States and promoting the health of people living along the U.S. borders. To facilitate this work, DGMQ operates CDC’s 20 quarantine stations at U.S. ports of entry. Quarantine station officials are responsible for assessing whether ill persons can enter the country and determining what measures should be taken to prevent the spread of infectious diseases into the United States. Most of the quarantine stations are located in airports and work closely with state and local health departments and CBP officers at nearby or collocated ports of entry. DGMQ trains CBP officers on how to identify and respond to travelers, animals, and cargo that may pose an infectious disease threat. CDC’s Coordinating Office for Terrorism Preparedness and Emergency Response works under the Assistant Secretary for Preparedness and Response in HHS and is responsible for directing and coordinating CDC’s response to public health threats. This office operates the Director’s Emergency Operations Center (DEOC), which collects information about potential public health threats 24 hours a day, 7 days a week, and is the central location for CDC’s public health response activities for specific incidents. The DEOC is responsible for sharing information with, and if necessary, requesting additional resources from HHS through its Secretary’s Operations Center (SOC) during a response to a public health incident. The SOC, managed by HHS’s Office of the Assistant Secretary for Preparedness and Response, is the focal point for synthesis of critical public health and medical information on behalf of the U.S. government. Both the SOC and the DEOC are intended to provide a formal, central point of management and oversight at their respective agencies to enable senior agency officials and subject-matter experts to take advantage of agency resources and capabilities in responding to an incident. DHS is responsible for coordinating with federal, state, local, and private entities to secure the nation, prevent terrorist attacks within the United States, and provide emergency management and planning, among other activities. According to statute, DHS is to aid HHS in the enforcement of federal quarantine rules and regulations. The Office of Health Affairs (OHA), which began operations in April 2007, serves as DHS’s principal agent for medical and health matters. It is responsible for managing DHS’s biodefense programs, ensuring the nation’s health preparedness in the event of terrorism or natural disasters, and protecting the health of DHS’s workforce. Also, TSA, CBP, and the Office of Operations Coordination operate within DHS. TSA is responsible for ensuring the security of the national transportation network while ensuring the free movement of people and commerce. TSA has responsibility for safeguarding all modes of transportation, including strengthening the security of airport perimeters and restricted airport areas; screening passengers against terrorist watch lists, such as the No Fly list; and inspecting passengers, baggage, and cargo at over 400 commercial airports nationwide. TSA is tasked with preventing a public health threat on commercial air carriers through its broad authority to protect the transportation system against any threat that could endanger individuals during travel. TSA’s Freedom Center is the primary coordination point for the federal, state, and local agencies dealing with transportation security on a daily basis. A key part of CBP’s mission is to prevent the entry of terrorists into the United States. CBP screens people, conveyances, and goods entering the United States, while facilitating the flow of legitimate trade and travel into and out of the United States. CBP’s mission also includes carrying out traditional border-related responsibilities, including narcotics interdiction, enforcing immigration and customs laws, protecting the nation’s food supply and agriculture industry from pests and diseases, and enforcing trade laws. All travelers requesting to enter the United States, including U.S. citizens, are subject to examination. Individuals may be referred for enhanced inspection for a variety of reasons, such as criminal records, inclusion on a national registry for sex offenders, or prior immigration or customs violations, or may be randomly selected. As appropriate, CBP also conducts searches of people, merchandise, and conveyances entering or exiting the United States, to ensure that merchandise may be lawfully imported or exported and duties collected. CBP officers are responsible for conducting inspections to permit admissible individuals to enter the country. In general, U.S. citizens who demonstrate their citizenship are to be admitted, although those citizens believed to be infected with or exposed to TB or other communicable diseases specified by Executive Order may be subject to isolation or quarantine immediately upon admission. Noncitizens seeking entry must establish that they are admissible under U.S. immigration law; those determined to have a communicable disease of public health significance are inadmissible, unless granted a waiver. During the inspection process, CBP officers are to use TECS—CBP’s computerized border screening and inspection system—in addition to other databases to assess admissibility and purpose for entering the country and to corroborate information. Individuals may be admitted or denied entry and returned to the country of origin.