Nurses Can Contribute to TB Control

27 May 2008

Charlotte Carneiro RN, BSN, MS, COHN-S, CIC

Tuberculosis (TB) once thought a disease of the pharaohs and the Victorian literati and relatively obscure, remains the number one killer by a single infectious agent worldwide.

HIV/TB co-infection deaths also lead worldwide mortality rates but taken alone TB remains the lead. Global health organizations including the United States fund programs to assure directly observed therapy to contain the disease that continues to emerge in its morbidity and mortality. Statistics belie the devastation and stigmatization to families with a single ill member. Strides have been made in the United States but the District of Columbia leads the nation with 10.2 TB cases /100,000 population (2007).

Nurses in every capacity and every role need the knowledge of this disease to participate in the identification, control and containment of TB. This column will focus on the opportunity of the occupational health nurse (OHN) to clarify our knowledge and educate others by deciphering the complexities of Mycobacterium tuberculosis infection versus disease.

Probably the most common question a worker would ask an OHN is “what does a positive TB skin test mean?” The interpretation of PPD TST (Purified Protein Derivative Tuberculin Skin Test) is based on the epidemiology of the person receiving the test and the reason for the test. This methodology stems from longitudinal population studies of risk which improves the sensitivity and specificity of the skin test.

A common example of this is in a routine pre-employment screening for a health care worker with no other risk factors with a >10 mm reading of induration or swelling, not the extent of redness. The OHN would read the test as significant. The report to the worker would be that the “tuberculosis germ is in your body and will remain in your body for the remainder of your life.” It is erroneous to say, “You have been exposed.” A positive skin test means infection and antibody response. A chest x-ray will determine if the germ has any activity or is dormant or sleeping. If it is dormant, and the worker is eligible by age and risk factors, he would be offered preventive therapy for latent TB infections (LTBI) for six months. This therapy will reduce the chance of developing active TB to 1% instead of 10% if untreated for infection.

A TST reading of 10 MM is still used for someone with a history of receiving a BCG vaccine, which is used in most countries of the world except the United States. In using a 10 mm cut off, there will be persons for whom the reaction is attributed to the vaccine; however there are many TB cases in vaccinated persons because of the waning immunity of the vaccine. The TST should be offered to anyone except in someone with a self-reported history of a blistered/bleb reaction. In fact, WHO has just recommended that targeted TST be done on children 2-14 years who live in countries with high rates of TB >20 cases per 100,000 population MMWR March, 2008 /57.

The PPD TST is a poor test for determining infection but is the one most widely used. The Interferon Gold is being used in some areas and can determine an early infection. The disadvantage is that the required blood draw needs an immediate deposit to a reputable laboratory for evaluation and this is not yet widely available.

The language used by the OHN and worker in eliciting a TB history is critically important. What does “have you been treated for TB” really ask? Is that preventive therapy for an infection for six months or four or more drug therapy for 12-24 months? One suggested question might be “have you taken any pills or injections for TB?”

If yes, then ask “what type and for what duration?” Incomplete therapy for infection or disease places the worker at risk for multi-drug resistant TB (MDRTB) and needs a thorough assessment.

Any person with a significant skin test needs to have a chest radiograph to rule out active tuberculosis and to be offered preventive therapy, usually Isoniazid twice per day. Nurses have an opportunity to intervene effectively for a complete assessment of this type of reaction and to assure complete health evaluation.

MWAOHN nurses see workers who have international exposure within their jobs either abroad or interchanges within DC. Baby boomers are of an age where they may have had an exposure as children from a senior family member. A good history can direct the OHN to plant a PPD or refer for one. Other interventions include offering enablers and incentives to the worker for taking preventive therapy for LTBI. A worker who has been cleared to return to work after initiating therapy for active tuberculosis may need the OHN to assist with this transition with management. The OHN may also play an active role in directly observed therapy for active tuberculosis with legal oversight from the local health department.

“Think TB” has been a mantra of the US TB Control Program since the surge in the 90’s but it is no less relevant today. Nurses can review many of these principles in CDC’s TB Self Learning Modules (http://www.cdc.gov/tb/pubs/Interviewing/selfstudy/introduction.htm as well as keep abreast of current World Health Organization recommendations (http://www.who.int/mediacentre/factsheets/fs104/en/ ).

For questions or comments contact Charlotte Carneiro.