A chronic infection caused by Mycobacterium tuberculosis complex. It commonly affects lungs but can affect any organ (lymph nodes, bones, meninges, abdomen, kidney).
For more information on the management of TB see:
- Manual of the National TB/Leprosy Programme (NTLP) in Uganda 4th Edition, 2022
- NTLP desk guide
- Latent TB guidelines
- National drug resistant TB guidelines
Cause
- Mycobacterium tuberculosis complex (e.g. tuberculosis, bovis, M. africanum and M. Microti)
- Transmission by droplet inhalation (cough from a patient with open pulmonary TB); can also be through drinking unpasteurised milk, especially M.bovis
Clinical features
General symptoms
- Fevers especially in the evening, excessive night sweats
- Weight loss and loss of appetite
Pulmonary TB
- Chronic cough of >2 weeks (however, in HIV settings, cough of any duration)
- Chest pain, purulent sputum occasionally blood-stained, shortness of breath
Extrapulmonary TB
- Lymphnode TB: Localized enlargement of lymph nodes depending on the site affected (commonly neck)
- Pleural or pericardial effusion
- Abdominal TB: ascites and abdominal pain
- TB meningitis: subacute meningitis (headache, alteration of consciousness)
- Bone or joint TB: swelling and deformity
Complications
- Massive haemoptysis - coughing up >250 mL blood per episode
- Spontaneous pneumothorax and pleural effusion
- TB pericarditis, TB meningitis, TB peritonitis
- Bone TB: can be TB spine with gibbus, TB joints with deformity
- Respiratory failure
TB Case Definitions
CASE DEFINITION |
DESCRIPTION |
Presumptive TB patient |
Any patient who presents with symptoms and signs suggestive of TB or found to have chest x-ray suggestive of active TB disease |
Bacteriologically confirmed TB patient |
Patient in whom biological specimen is positive by smear microscopy, culture, or molecular WHO Recommended Diagnostic (mWRD) test like GeneXpert Truenat or TB LAMP. All such cases should be notified (registered in the unit TB register) |
Clinically diagnosed TB patient |
Patient who does not fulfil the criteria for bacteriological confirmation but has been diagnosed with active TB by a clinician or other medical practitioner on the basis of clinical symptoms and other investigations |
Classification of TB Infection
CRITERIA |
CLASSIFICATION |
Site of the disease |
Pulmonary TB: bacteriologically confirmed or clinically diagnosed case, affecting lung parechyma or tracheobronchial tree. |
Extrapulmonary TB: any other case of TB. Isolated TB pleural effusion and mediastinal lymphadenopathy If the patient has pulmonary and extrapulmonary involvement, he/ she will be classified as pulmonary |
|
History of treatment |
New: no previous TB treatment (or treatment less < 1 month) |
Relapse: patient who completed a previous course of treatment, was declared cured or treatment completed, and is now diagnosed with a recurrent episode of TB |
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Treatment after failure: those who have previously been treated for TB and whose treatment failed at the end of their most recent course of treatment |
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Treatment after loss to follow- up patients: have previously been treated for TB and were declared lost to follow-up at the end of their most recent course of treatment. |
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Treatment history unknown: those who have previously been treated for TB but whose Outcome after their most recent course of treatment is unknown or undocumented |
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HIV status |
Positive: patients who tested HIV positive at time of diagnosis or already enrolled in HIV care |
Negative: patients who tested negative at the moment of diagnosis |
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Unknown: If testing is then performed at any moment during treatment, patient should be re classified |
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Drug susceptibility status (based on drug susceptibility Tests) |
Drug Sensitive TB (DS-TB): These are sensitive to 1st line anti-TB drugs Drug resistant TB (DR-TB): Resistant to any anti-TB drug. Can be classified as follows. Rifampicin resistant: any case of rifampicin resistance (isolated or in combination with other resistance) (RR-TB) |
Monoresistant: resistant to only one first line anti-TB drug |
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Poly drug resistant: resistant to more than one first line anti TB other than both rifampicin and isoniazid |
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Multi drug resistant: resistant to rifampicin and isoniazid (MDR –TB) |
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Extensive drug resistance: resistant to rifampicin, isoniazid (MDR-TB) and any fluoroquinolone and at least one of the 3 second line injectable drugs (capreomycin, kanamycin, amikacin). |
Differential Diagnosis
- Histoplasma pneumonia, trypanosomiasis, brucellosis
- HIV/AIDS
- Malignancy
- COPD, asthma, bronchiectasis, emphysema etc.
- Fungal infection of the lungs e.g. Aspergillosis
Screening and diagnosis of TB disease
TB screening: is defined as the systematic identification of people at risk for TB disease, in a predetermined target group, by assessing using tests, examinations or other procedures that can be applied rapidly
TB screening approaches:
- Symptom screening or CXR
- All individuals seeking health care should be screened for TB at each visit
Investigations for TB Infection
-
Obtain sputum sample or other relevant samples from presumptive TB patients for diagnosis
- Xpert MTB/RIF is the recommended diagnostic test for TB diagnosis
- Where Xpert MTB/RIF test is not available, do
Sputum smear microscopy for AAFBs (ZN stain) but send the sample for Xpert MTB/RIF test.
GeneXpert MTB/Rif: automated DNA test on body samples (sputum, lymphonodes tissue, pleural fluid, CSF etc) which can diagnose pulmonary TB and determine susceptibility to Rifampicin. It is superior to microscopy.
Other investigations -
- X- ray, abdominal ultrasound, biopsies can be used for sputum and GeneXpert negative patients or in case of extrapulmonary TB according to clinical judgement
- TST can be used as a supportive test to guide decision to treat for TB in children
- Sputum culture and Drug susceptibility test: is a confirmatory test for TB and also provides resistance pattern to TB. Do this test for:
-Patients with Rifampicin resistance reported with GeneXpert
-Also patients on first-line treatment who remain positive at 2 months and are reported Rifampicin sensitive on GeneXpert
-Patients suspected to be failing on first-line treatmen
Note: All presumed and diagnosed TB patients should be offered an HIV test