Tuberculosis Prevention and Control

• NAVMED 6224/7: Initial Tuberculosis Exposure Risk Assessment
• NAVMED 6224/8: Tuberculosis Exposure Risk Assessment
• NAVMED 6224/9: Monthly Evaluation for Patients Receiving Treatment for Latent Tuberculosis Infection 

NMCFHPC Manual M-6224 Tuberculosis Control Guide for the U.S. Navy Fleet (*CAC required*)
NMCFHPC Manual M-OM 6260 Medical Surveillance Procedures Manual and Medical Matrix
BUMEDINST 6220.12D Medical Surveillance and Response

Clinicians

Risk Factors for TB

Identifying individuals at high risk for TB infection or progression to active disease is critical when evaluating patients for TB. Key risk factors include:

• Exposure: Recent close contact with a person who has infectious active pulmonary TB.
• Geography: Birth, residence, travel, or deployment in regions with high TB prevalence (e.g., parts of Asia, Africa, Eastern Europe, Latin America, and the Middle East).
• Environment: Living or working in high-risk congregate settings (e.g., refugee camps, correctional facilities, homeless shelters).
• Medical Vulnerabilities: Immunocompromise from HIV infection, organ transplant, prolonged corticosteroid therapy, diabetes mellitus, severe kidney disease, or silicosis.
• Substance Abuse: Severe alcohol use disorder or injection drug use.
• Age: Children under the age of 5 years old.

It is essential to remember that completion of LTBI treatment reduces, but does not eliminate, the progression to active TB. Between 2008 and 2021, 30% of active TB cases in active-duty personnel occurred in patients who had completed full courses of LTBI therapy.  TB must remain high in the clinical differential of any prolonged pulmonary symptoms. 

Clinical Presentation

LTBI is asymptomatic and identified exclusively through risk factor identification and screening.

The clinical presentation of active TB can range from asymptomatic to severe. Over half of patients may be asymptomatic in early stages of active TB.

• Pulmonary TB (most common): 
  • Persistent, productive cough lasting more than 2 weeks
  • Chest pain or tightness with coughing or deep breaths
  • Hemoptysis
  • Systemic symptoms: Weakness, fatigue, weight loss, loss of appetite, chills, fever, and night sweats.
  • Extrapulmonary TB (atypical, but more common in children): Symptoms will depend on the part of the body affected (e.g., back pain in spinal TB, blood in urine for renal TB).

TB Screening Tests- IGRA vs TST

There are two screening tests for infection with TB, a Tuberculin Skin Test (TST) and an Interferon-Gamma Release Assay (IGRA) blood test. Both tests rely on identifying an immune response to Mycobacterium tuberculosis antigens, and a positive test with either method indicates infection, but does not distinguish between latent and active disease.

Detailed information about conducting TB screening in Department of Navy personnel may be found in Appendix 1 of BUMEDINST 6224.8D.

Evaluating for Active TB

While TST and IGRA screening tests are used to identify infection with Mycobacterium tuberculosis, they DO NOT differentiate active TB from LTBI.  All positive LTBI testing results must be followed up with:

• Clinical assessment- physical exam and medical history
• Chest Radiograph (CXR) or Chest CT- Essential to identify pulmonary abnormalities consistent with TB disease (e.g., cavitary lesions)
• Sputum Examination- When radiographic signs of TB or clinical symptoms suggesting TB are present, sputum should be examined for Acid-Fast Bacilli (AFB) microscopy, diagnostic nucleic acid amplification testing, and culture.

Sputum collection should not be performed in a shipboard setting due to the risk of aerosol generation. Transfer suspected cases to a shore-based facility as soon as practicable.

Infection Control

Immediate isolation and source control are critical upon suspicion of active TB.

Any symptomatic patient suspected of having active TB should be masked with a surgical mask and immediately isolated pending referral to a pulmonary or infectious disease specialist at an MTF for evaluation, diagnosis and initial treatment.

Patient Isolation: Isolate the patient in a single-occupancy room, ideally an Airborne Infection Isolation (AII) room. Onboard a ship, work with engineering to modify ventilation to create negative pressure with airflow directed to weather decks.

Source Control: The patient should wear a standard surgical mask when outside of their isolation room. They should be instructed to cover their mouth and nose with a tissue when coughing or sneezing.

Personal Protective Equipment (PPE): Healthcare personnel interacting with a suspected or confirmed TB case must wear a fit-tested N95 respirator.

Treatment

Latent TB Infection (LTBI)

In most individuals, Mycobacterium tuberculosis infection is either cleared or contained via immune defense mechanisms, resulting in LTBI.  LTBI patients, while non-infectious, may continue to harbor contained, but viable organisms. These organisms may later overcome immune defenses and cause symptomatic disease.  Treatment of LTBI kills contained organisms, reducing the risk of progression to active TB disease by as much as 90%. 

Treating LTBI is critical to force readiness, as it reduces the likelihood of progression to active disease. Before initiating LTBI treatment, active TB must be definitively ruled out with both a negative symptom screen and a negative CXR or chest CT.

Short-course, rifamycin-based regimens are now strongly recommended over longer, INH-only regimens due to higher completion rates and lower risks of liver toxicity.

Patients on LTBI treatment must receive regular clinical monitoring to assess adherence and to identify adverse drug reactions, particularly hepatotoxicity (e.g., jaundice, dark urine, right upper quadrant pain) associated with INH use. INH should be avoided in patients with underlying liver disease or alcohol abuse history. Baseline and routine laboratory testing are not routinely indicated for patients being treated for LTBI.

Detailed information about interpreting TB screening and managing LTBI in Department of Navy personnel may be found in Appendix 2 of BUMEDINST 6224.8D.

Active TB Disease

Treatment requires a multi-drug regimen for at least 6 months and should be managed by an infectious disease or pulmonary specialist. Patients are considered non-infectious after they have been on appropriate treatment for at least two weeks, show clinical improvement, and have three consecutive AFB negative sputum smears.

Reporting

Active TB is an urgently reportable medical event within the DON. Suspected or confirmed active TB cases must be reported to Preventive Medicine authorities and/or the closest Navy Environmental and Preventive Medicine Unit (NEPMU) within 24 hours per BUMEDINST 6220.12D The Disease Reporting System internet (DRSi) is the preferred reporting system. Case Classification details may be found in the Armed Forces Medical Reportable Events Guide. The NMCFHPC Medical Surveillance and Reporting webpage contains in-depth information to facilitate case reporting.  Navy Environmental and Preventive Medicine Unit (NEPMU) staff can advise on and/or assist with outbreak investigation and risk communication.

If the patient spent significant time in the community during their infectious period, civilian public health authorities will also need to be notified for contact tracing purposes.

Public Health and Surveillance

Routine LTBI Screening

• Initial Entry: Nearly 40% of active TB is identified at accessions. Because of the extremely high transmission risk in both the accessions and shipboard environments, all USN and USMC military personnel receive TB testing upon entry into naval service.

• Periodic Screening: Annual TB screening (via NAVMED 6224/8 form) is required for military personnel, and may be performed in conjunction with the Periodic Health Assessment (PHA). Actual testing (TST or IGRA) is only administered if the screening form identifies a new risk factor, exposure or clinical symptoms of TB.

• Force Health Protection: Additional TB exposure screening may be directed as part of Force Health Protection guidance (e.g. pre- or post- deployment). 

Transmission

TB is transmitted person-to-person through the air via droplet nuclei (1–5 µm) that are expelled when a person with infectious pulmonary or laryngeal TB coughs, speaks, sneezes, or sings. The likelihood of transmission depends on the infectiousness of the person, the duration and proximity of exposure, and the susceptibility of the contact. Transmission typically requires prolonged, close quarters contact.

Outbreak Response

Ensure local Preventive Medicine assets are engaged for support.  The cognizant  Navy Environmental and Preventive Medicine Unit (NEPMU) can advise on and/or assist with outbreak investigation activities. 

Contact Investigation: Upon confirmation of an active TB case, a contact investigation must be initiated immediately to identify, screen, and test individuals who may have been exposed. The period of infectiousness is generally considered to be the three months prior to symptom onset. TB testing after an exposure as part of a contact tracing investigation should be guided by preventive medicine personnel, who will provide contact tracing guidance and testing recommendations as part of their overall reach-back support.

Routine, shore-based contact tracing can proceed per the Guidelines for the Treatment of Latent Tuberculosis Infection: Recommendations from the National Tuberculosis Controllers Association and CDC, 2020

Guidance with amplifying information on conducting TB contact investigations aboard ship can be found in the NMCFHPC TB Fleet Guide (*CAC Required*)

Resources

NMCFHPC TB Fleet Guide (*CAC Required*) Detailed guide for managing a suspected shipboard case of active TB.

Guidelines for the Treatment of Latent Tuberculosis Infection: Recommendations from the National Tuberculosis Controllers Association and CDC, 2020.

Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. 

CDC Core Curriculum on Tuberculosis

National Tuberculosis Coalition of America: Testing and Treatment of Latent Tuberculosis Infection in the U.S.: A Clinical Guide for Health Care Providers and Public Health Programs

Epidemiology and Selected Publications

Centers for Disease Control and Prevention (CDC). Latent tuberculosis infection among sailors and civilians aboard U.S.S. Ronald Reagan--United States, January-July 2006. MMWR Morb Mortal Wkly Rep. 2007 Jan 5;55(51-52):1381-2. PMID: 17205034.

Kenyon TA, Valway SE, Ihle WW, Onorato IM, Castro KG. Transmission of multidrug-resistant Mycobacterium tuberculosis during a long airplane flight. N Engl J Med. 1996 Apr 11;334(15):933-8. doi: 10.1056/NEJM199604113341501. PMID: 8596593. (*CAC Required*)

Lamar JE 2nd, Malakooti MA. Tuberculosis outbreak investigation of a U.S. Navy amphibious ship crew and the Marine expeditionary unit aboard, 1998. Mil Med. 2003 Jul;168(7):523-7. PMID: 12901459. (*CAC Required*)

Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin Infect Dis. 2017;64(2):111-115. doi:10.1093/cid/ciw778

NMCFHPC Pulmonary Tuberculosis in Department of Navy Beneficiaries: 2022 Report (NMCFHPC) (*CAC Required*) This report summarizes active TB cases from 2008 to 2021 among DON beneficiaries, including active-duty service members, recruits, retirees, and their family members.

Sanchez JL, Cooper MJ, Myers CA, Cummings JF, Vest KG, Russell KL,
Sanchez JL, Hiser MJ, Gaydos CA. 17 June 2015. Respiratory infections in the U.S.
military: recent experience and control. Clin Microbiol Rev
doi:10.1128/CMR.00039-14. (*CAC required for full text link*)

Sterling TR, Njie G, Zenner D, et al. Guidelines for the Treatment of Latent Tuberculosis Infection: Recommendations from the National Tuberculosis Controllers Association and CDC, 2020. MMWR Recomm Rep. 2020;69(1):1-11. Published 2020 Feb 14. doi:10.15585/mmwr.rr6901a1