In the United States, more elderly persons live in nursing homes than any other type of residential institution. Approximately 5% of all elderly persons live in a nursing home. However, elderly persons represent 88% of the nation’s approximately 1.7 million nursing home residents. Such concentrations of elderly persons, many of whom are infected with the tubercle bacilli and some of whom are immunosuppressed, create an awareness for personnel to understand the transmission, prevention and control of tuberculosis in long-term care facilities.

Elderly nursing home residents are at a greater risk for tuberculosis than elderly persons living in the community. The incidence of tuberculosis among nursing home residents was 39.2 per 100,000 population as compared to 21.5 cases per 100,000 population in the community (CDC, unpublished data).

Nursing home employees were found to be 3X higher risk to become infected with the tubercle bacilli than the rate expected for employed adults of similar age, race and sex (CDC, unpublished data).

There have been numerous outbreaks in nursing homes in which transmission of tuberculosis was documented among residents and staff.

Because of the intrinsic problems that nursing homes have concerning consistent staff education, it is imperative that nursing homes develop a written exposure control plan for tuberculosis. Even though CDC has recommended this since 1990 and again in 1994 and 1997, and with OSHA’s enforcement rule going into effect in 1998 (possibly after April since final public hearings are scheduled for this time[Federal Register - 29 CFR Part 1910, October 17, 1997]), many nursing homes still have not written a satisfactory policy to address this requirement.

Since the majority of nursing homes do not have the capability of isolating a suspected or a known case of clinical tuberculosis, efforts must be developed to assure that appropriate tuberculosis prevention and control measures are undertaken to protect residents and staff.

2. Surveillance

Surveillance refers to identifying and reporting all cases of tuberculosis in the facility and identifying all infected residents and staff. When an infectious case is identified, additional cases and new infections (as indicated by new PPD skin test conversions) should be examined.

PPD (purified protein derivative - 5 units) should be administered to all new residents and employees as soon as their residency or employment begins unless they have documentation of a previous positive reaction. All tests must be recorded in mm of induration. See Table 1 for an example of how PPD skin tested should be recorded for either personnel or residents.

When tuberculin skin testing of adults is to be repeated periodically, the use of a two-step testing initially can reduce the likelihood that a boosted reaction (anamnestic response - a heightened response to the second or subsequent administration of an antigen, e.g., PPD, some time after the initial administration) will be interpreted as representing a recent infection. If the reaction to the first test is negative, a second test should be given a week later. If the second test result remains below the cutting point for a positive test, the reaction is considered negative (Reference 8). If the reaction to the second test is positive, it probably represents a boosted reaction and not a new infection.

3. TB infection and disease

You can see why it is so important to establish a good employee health program in order to educate persons who are HIV positive on the risk of developing active TB after a TB test conversion, and also that the PPD skin test is read differently than if given to a HIV negative person (Reference 8).

Most cases of TB (approximately 85% occurs in the lungs (pulmonary TB). But disease may occur at any site in the body, such as larynx, the lymph nodes, the brain, the kidneys, or bones (extrapulmonary TB).

4. Symptoms

The signs and symptoms of TB vary according to the location of the disease. General signs and symptoms may include fatigue, feeling ill, loss of appetite, weight loss, fever and night sweats. In addition to the general signs and symptoms, pulmonary TB usually causes cough, chest pain, coughing up sputum, and sometimes coughing up blood (hemoptysis).

5. Contact Investigation (Addendum D)

Contact investigation, one of the best ways to find persons who require treatment or preventive therapy for TB disease or infection, should begin as soon as a person is suspected of having TB. As soon as the laboratory or hospital reports positive acid-fast smears or cultures to the long-term care facility, it should be reported promptly to the health department by the infection control person. Early detection and reporting is essential for the prompt evaluation of contacts of persons who have infectious TB. If a resident’s medical history and clinical findings suggest TB, health care workers should not wait for culture results before starting a contact investigation. Contact investigations can be assisted by the health department (Reference 6). The evaluation should proceed in an orderly manner, starting with residents and staff who are most likely to have been infected. Unfortunately, in a long-term setting, this may involve everyone especially if the suspected resident or staff member had total freedom of movement.

Close contacts of the suspected or confirmed case(s) should be PPD skin tested (unless already positive or has had one within the past 3 months) initially and if negative, repeat in 12 weeks.

Those PPD skin tests which are negative after 12 weeks were not infected from the initial exposure. Chest radiographs should be made of all positive reactors. If the chest film is positive, cultures should be taken to determine whether the lesions were caused by Mycobacterium tuberculosis (Reference 12). It has been recommended by CDC that if someone of high risk (HIV+) had contact with a positive acid-fast stain resident (indicating a highly infectious resident), should be considered for preventive therapy even if their initial tuberculin skin test result is negative (<5 mm induration - see References 8 and 9). A second skin test should be given 12 weeks after contact and if this is negative, preventive therapy may be stopped.

6. Tuberculin skin test reaction in persons vaccinated with BCG

Outside the United States, many countries use Bacille Calmette-Guerin (BCG) vaccination as part of their TB control activities, especially for infants. The size of tuberculin skin test reactions caused by BCG vaccination varies by the strain and dose of the vaccine, the age and the nutritional status at vaccination, the number of years since vaccination, and the frequency of tuberculin testing.. After BCG vaccination, it is usually impossible to distinguish between a tuberculin skin test reaction caused by the tubercle bacillus or by vaccination. Also, because BCG is used more often in countries where the prevalence of TB is high, BCG- vaccinated persons are more likely to have been exposed to TB. Therefore, these persons should be considered infected with Mycobacterium tuberculosis if they have a positive reaction to 5 TU (tuberculin units - intermediate strength [common concentration employed for testing]) of PPD tuberculin (Reference 2). They should also be evaluated for TB disease and managed accordingly. So in summary, for a person who was vaccinated with BCG, the probability that a PPD test reaction results from infection with Mycobacterium tuberculosis increases:

7. Susceptibility and resistance

The risk of infection with the tubercle bacillus is directly related to the degree of exposure and does not appear to be related to genetic or other host factors. The most hazardous period for development of clinical disease is the first 6 - 12 months after a conversion [+PPD skin test] (Reference 1). The risk of developing disease is highest in children under 3 years old, lowest in later childhood, and high again among adolescents, young adults, the very old and the immunosuppressed. Reactivation of long-latent infections accounts for a large proportion of cases of clinical disease in the elderly. Nursing homes must have a protocol in place for testing the elderly in a systematic fashion (yearly with a computer assisted registry).

8. Specific treatment

9. Multidrug-resistant tuberculosis (MDR-TB)

10. Case Reporting

11. Investigation of contacts

Because tuberculosis is transmitted by the airborne route, persons who sleep, live, work, or who are otherwise in contact with an infectious person through a common ventilation system for prolonged time are considered "close contacts" at risk of acquiring infection. These persons may include other residents, staff or visitors. When a person with confirmed tuberculosis appears to be infectious, e.g., pulmonary involvement as seen by chest X-ray, productive cough and/or positive sputum smear, contacts who were previously PPD skin test negative should be retested (Addendum D). If the case occurs in a known tuberculin converter, a search for the person who has the source case ("source patient") should be undertaken by performing X-rays for all persons known to be tuberculin reactors and by submitting sputum specimens for smear and culture for all patients with a cough (Addendum D) or other symptoms that may suggest tuberculosis disease.

12. Assessment

13. Responsibility of the health department (References 2 and 6)