Tuberculosis poses a real risk for deployed Sailors and Marines. Foreign travel is a key risk factor. However, tuberculosis infection can result from exposures in the United States. In addition, if active tuberculosis occurs in a service member in the closed-ventilation environment of a ship, the rate of transmission of tuberculosis infection to shipmates can be high, even up to 25 percent.

Key Points

The Navy’s Tuberculosis Control Program addresses the risks of Tuberculosis by providing guidance for the prevention and management of this disease. The following areas are discussed at length in BUMEDINST 6224.8

• Annual tuberculin skin test (TST) with purified protein derivative (PPD) to identify newly infected persons.

• Provision of preventive treatment with isoniazid (INH).

• Monitoring those known to be infected for evidence of active disease.

• Early identification and treatment of persons with active tuberculosis to limit transmission.

• Contact investigations.

While the GMO is accountable for the program, a preventive medicine technician or another trained corpsman normally does the routine testing and tracking of reactors that are being treated with INH. The GMO evaluates suspected reactors, initiates and then monitors INH treatments. Good entries in the medical records are essential, including; date and size (in mm) of tuberculin skin test results; INH start and stop dates; and compliance.

Tuberculin Skin Test (TST)

Routine TST programs are administratively challenging, since testing requires two visits. Be persistent. A corpsman can read tests in a workspace to avoid return visits to the medical spaces. If a test is not read in 2-3 days, re-administer the PPD. Periodically check that corpsmen continue to use good intradermal technique. Ensure all tests are read (induration only, not erythema) and accurately recorded: "not read" if not read; "zero mm" if no reaction. All other reactions must be measured and recorded in millimeters. Small reactions (<10mm) are important.

Service members receive TSTs upon entering the service (and receive INH if they have a reaction >10mm). Annual TSTs are performed on all personnel stationed on ships or in deployable billets; all health care workers; and for personnel in certain high-risk locations overseas. Other personnel receive TSTs at least every 3 years. A TST reactor is a converter based upon size of induration, active TB exposure history, and age.

A TST reactor is summarized and categorized as follows:

• If there is a >5mm induration AND the individual is a contact of a known case of active TB, or they are HIV positive

• If there is a >10mm induration, under age 35 AND, they were born in a high risk overseas location or resident of a correctional facility (shipboard due to confined or restricted ventilation systems) or were a recent PPD convertor.

• If there is a >15mm induration, under age 35, AND no risk factors.

• If there is a >15mm induration, over age 35, AND a recent PPD convertor.

More detail is included in BUMEDINST 6224.8.

Key questions in evaluating a TST convertor include:

• Does the patient have active disease?

• Are there contraindications to INH therapy?

A convertor receives 6 months of INH preventive therapy, unless there is a medical contraindication. Even in an otherwise healthy young patient, baseline liver function tests (LFTs) are recommended, but not required. Converters and others with reactive TSTs are not contagious; they may deploy whether or not they received INH.