Description

Mycobacterium tuberculosis is a rod-shaped bacterium that can cause disseminated disease, but is most frequently associated with pulmonary infections. The bacilli are transmitted by the airborne route and, depending on host factors, might or might not lead to active disease. Tuberculosis (TB) can usually be treated successfully with multiple medications.

Occurrence

In many other countries, TB is much more common than in the United States, and it is an increasingly serious public health problem.

Risk for Travelers

To become infected, a person usually would have to spend a long time in a closed environment where the air was contaminated by a person with untreated TB who was coughing and who had numerous M. tuberculosis organisms (or tubercle bacilli) in secretions from the lungs. TB infection is generally transmitted through the air; therefore, there is virtually no danger of its being spread by dishes, linens, and items that are touched, or by food. However, it can be transmitted through unpasteurized milk or milk products.

Travelers who anticipate possible prolonged exposure to TB (for example, those who could be expected to routinely come in contact with hospital, prison, or homeless shelter populations) should be advised to have a tuberculin skin test before leaving the United States. If the reaction is negative, they should have a repeat test after returning to the United States. Because people with human immunodeficiency virus (HIV) infection are more likely to have an impaired response to the tuberculin skin test, travelers with HIV infection should be advised to inform their physicians about their HIV status. Except for travelers with impaired immunity (for example, HIV infection), travelers who already have a positive tuberculin reaction are unlikely to be reinfected.

Centers for Disease Control and Prevention (CDC) and state and local health departments have published the results of six investigations of possible TB transmission on commercial aircraft. In these six instances, a passenger or a member of a flight crew traveled on commercial airplanes while infectious with TB. In all six instances the airlines were unaware that the passengers or crew members were infected with TB. In two of the instances, CDC concluded that TB was probably transmitted to others on the airplane. The findings suggested that the risk of TB transmission from an infectious person to others on an airplane was greater on long flights (8 hours or more). The risk of exposure to TB was higher for passengers and flight crew members sitting or working near an infectious person because they might inhale droplets containing TB bacteria.

Based on these studies and findings, the World Health Organization (WHO) issued recommendations to prevent the transmission of TB in aircraft and to guide potential investigations. The risk of TB transmission on an airplane does not appear to be greater than in any other enclosed space. To prevent the possibility of exposure to TB on airplanes, CDC and WHO recommend that people known to have infectious TB travel by private transportation (that is, not by commercial airplanes or other commercial carriers), if travel is required. CDC and WHO have issued guidelines for notifying passengers who might have been exposed to TB aboard airplanes. Passengers concerned about possible exposure to TB should be advised to see their primary health care provider for a TB skin test.

Preventive Measures

Vaccine

The Bacille Calmette-Guerin (BCG) vaccine is used in most developing countries to reduce the severe consequences of TB in infants and children. However, BCG vaccine has variable efficacy in preventing the adult forms of TB and is, therefore, not routinely recommended for use in the United States and other developed countries.

Other

Travelers should be advised to avoid exposure to known TB patients in crowded environments (for example, hospitals, prisons, or homeless shelters). Travelers who will be working in hospitals or health care settings where TB patients are likely to be encountered should be advised to consult infection control or occupational health experts about procedures for obtaining personal respiratory protective devices (that is, N-95 respirators), along with appropriate fitting. Additionally, TB patients should be educated and trained to cover coughs and sneezes with their hands or tissues. Otherwise, no specific preventive measures can be taken or are routinely recommended for travelers.

Treatment

People who are infected or who become infected with M. tuberculosis can be treated to prevent TB. Recent data from the WHO suggest that isoniazid resistance is relatively common in different parts of the world. If a traveler experiences a tuberculin skin test conversion associated with international travel, consideration should be given to the possibility of drug resistance. Updated American Thoracic Society (ATS)/CDC recommendations for treatment of latent TB infection suggest that 2 months of rifampin plus pyrazinamide is a reasonable alternative to isoniazid. In settings where multidrug-resistant TB is common, experts in infectious diseases or pulmonary medicine should be consulted to determine alternative treatment regimens. Travelers who suspect that they have been exposed to TB should be advised to inform their physicians of the possible exposure and receive appropriate medical evaluation. CDC and the ATS have published updated guidelines for targeted tuberculin skin testing and treatment of latent TB infection.

© Center for Disease Control

Credits: National Center for Infectious Diseases