Tuberculosis

Objectives

This guideline provides Defence Medical personnel with a guide to suspecting and investigating tuberculosis in the deployed setting.

Scope

This guideline covers the major presenting features of tuberculosis, common differential diagnoses and an outline to investigating a patient with suspected tuberculosis. Treatment with anti-tuberculous chemotherapy is outwith the scope of this guideline and should only be undertaken with expert guidance. Infectious specialist advice should be sought with suspected or confirmed cases of tuberculosis, and public health support will be required.

Audience

Defence Medical personnel working in both primary care and secondary care / deployed hospital settings, including those providing prolonged field care.

Initial Assessment & Management

Introduction

Tuberculosis is caused by bacteria in the Mycobacterium tuberculosis complex and causes a chronic infectious illness which can affect any organ system but is most commonly found in the lungs. It is spread person to person by droplets aerosolised from coughing, usually via households or other close contacts and has a global distribution and causes 7-10 million infections/year, with 1.8 billion people infected with latent TB. It is one of the leading causes of death worldwide. 

Incidence varies from country-country, with particularly high prevalence in parts of sub-saharan Africa, South East Asia, and some areas of South America. Poverty and HIV infection are major drivers of infection.  In England, around 5,000 tuberculosis cases are reported each year. Incidence is consistently higher in major urban centres and among groups experiencing social vulnerability, including people without stable housing, those affected by drug or alcohol dependence, individuals in contact with the criminal justice system, and people living with HIV, particularly those with a low CD4 count.

Active tuberculosis has presented in service persons in the firm base and on deployments. TB usually requires prolonged, close, indoor contact with someone who has infectious pulmonary TB.  This means the highest risk is to individuals who have lived or grown up in high endemicity areas, or who are in the healthcare professions, rather than through casual contact.  Foreign and commonwealth service persons from high endemicity countries will be screened for active and latent TB when joining the military.  Partner nation forces or host nation eligible individuals may be at high risk of TB depending on the local prevalence of both TB, and HIV. 

Presentation

Common symptoms (often present for weeks):-

•  Fever
  
  
•  Weight loss
  
  
• Night sweats
  
  
• Enlarged lymph nodes

Tuberculosis presents with the cardinal symptoms of fevers, weight loss and night sweats. It is a sub-acute disease, and these have usually been present for several weeks. Additional symptoms depend on the location of tuberculosis. Lung disease is most common and presents with a productive cough typically, which may or may not be blood stained. 

Lymph node disease is the next most common and presents with enlarged lymph nodes with systemic symptoms. Lymph nodes may be in the axilla, groin, or neck, and may discharge. They are usually ‘cold’ as opposed to purulent hot abscesses caused by other bacteria. Other lymph nodes including mediastinal, or intra-abdominal nodes may be affected and only detected radiologically. 

Every other organ system can be infected with TB with pericardial TB, spinal TB, and CNS infection all common presentations, and worth considering in patients with a pericardial effusion, chronic back pain or headache/seizures respectively.

Investigation

The gold standard for diagnosis of tuberculosis rests on culture of Mycobacteria tuberculosis. This requires a biosecure lab that will not be available on operations. As such clinicians will have to consider:

1.    The clinical picture, particularly features of weight loss, night sweats and fevers as well as epidemiological risk such as long-term residence in a highly endemic country.

2.    Supportive imaging. Chest X‑ray findings can provide strong supportive evidence for pulmonary tuberculosis, particularly when showing apical consolidation, cavitation, or mediastinal lymphadenopathy, features that are highly suggestive of TB. In extra‑pulmonary disease, both plain radiography and cross‑sectional imaging (CT/MRI) can offer similarly supportive patterns in abdominal, spinal, and other sites. Although certain radiological appearances are characteristic of TB, imaging alone is rarely definitive and must be interpreted alongside clinical and microbiological findings.

3.     Microscopy. Microscopy requires a clinical sample, typically sputum, a trained biomedical scientist, and ability to examine sputum safely with a biosafety hood. This is likely only to be present at Role 3 Deployed Hospital Care, and even then not consistently. At least 3 samples should be assessed, sensitivity in open pulmonary TB is still only around 50%. Culture is slow but improves sensitivity substantially. However, it will not be available in a deployed setting from UK facilities.

4.     PCR testing. PCR‑based assays have transformed global tuberculosis diagnostics by providing rapid, sensitive and specific detection of Mycobacterium tuberculosis. These platforms require trained personnel, appropriate biosafety measures, and reliable access to equipment and consumables, resources typically available only when a fully deployed laboratory is in place and TB is an anticipated threat (e.g., R3 capability in certain operations). Sensitivity and specificity are high for pulmonary TB, particularly when using validated nucleic acid amplification tests, but performance is slightly reduced for extra‑pulmonary specimens such as CSF. Results therefore require careful clinical interpretation, and consultation with infection reach‑back services remains essential to ensure safe, accurate decision‑making.

The differential diagnosis for tuberculosis can include a range of extremely important diagnoses. For example, in a patient with lymph nodes and B symptoms lymphoma or disseminated solid malignancy can present identically. A first presentation of IBD can mimic intra-abdominal TB and purulent bacterial infection can be hard to distinguish from TB for spinal or pericardial disease. Pneumonia is the main differential for pulmonary TB, though lung malignancy can look similar.

HIV and TB frequently co-exist and an HIV test should be performed when available.

For the above reasons patients with suspected tuberculosis should be discussed with a military infection consultant. Given the difficulty of diagnosis, and the broad differential patients with suspected pulmonary TB are highly likely to need to be evacuated to the firm base for further assessment.

Management

Treatment of TB in deployed setting is discouraged. Seek medical evacuation of service personnel with suspected TB.

Management of tuberculosis is with long (at least 6 months) of anti-tuberculous combination chemotherapy, typically with rifampicin, isoniazide, pyrazinamide and ethambutol. Serious side effects of therapy are not uncommon, and these include hepatotoxicity, eye and peripheral neuropathy. Nutrition is key, and patients should be monitored for response to treatment. Patients can can take weeks to improve. Treating drug resistant tuberculosis is even trickier, using second line drugs which are hard to obtain, unfamiliar, and have significant toxicity.

Management of tuberculosis. Active management of tuberculosis in deployed settings is generally discouraged. Service personnel with confirmed or suspected active TB should be evacuated to the firm base for definitive assessment and treatment. Partner‑nation or local‑national patients are best managed within the existing in‑country tuberculosis services. Almost all countries maintain national, regional, or local TB programmes, and even in unstable environments these services are often sustained by WHO, MSF, or other international health organisations.

Emergency anti‑TB therapy. When emergency initiation of anti‑tuberculosis treatment is being considered—for example, in a critically unwell patient with a high clinical suspicion of TB—urgent reach‑back consultation with military infection specialists is essential. Expert input is required to guide safe empiric therapy, ensure appropriate diagnostics, and manage the significant operational, biosafety and treatment implications.

Public Health & Infection Control considerations

Patients with suspected active pulmonary TB should ideally be cared for in single room isolation with negative pressure.  In the deployed setting this is not practicable and therefore maximizing natural ventilation and separating the patient from shared clinical spaces is essential.  All staff should wear FFP3/N95 equivalent respirators (GSR will suffice) when entering the clinical space.  Patients should wear a facemask when being moved or if close contact with others is unavoidable.  Avoid aerosol generating procedures where possible. Advice from infection consultants and infection control specialists should be sought early. Non-pulmonary tuberculosis is generally not infectious.

When tuberculosis (pulmonary or extra-pulmonary, latent or active) is diagnosed in a service person Public Health should be notified, and an FMed 85 completed. Given the nature of military deployments which involve close contact and shared accommodation, urgent advice on contact tracing is likely to be required in cases of active pulmonary tuberculosis, and this should be sought at the earliest opportunity, and liaison with the chain of command initiated.

Paediatric Considerations

Children with tuberculosis may be present differently to adults, with diagnosis even more difficult, due to difficulty obtaining samples. Expert paediatric infectious diseases advice should be sought early where this is suspected.