Cough for three weeks
A cough that has lasted more than two weeks is not a simple chest infection until proven otherwise. Where TB is common, it is presumptive TB: the job at first-level care is to recognise it, get the right sample to the right test, and find the people for whom it cannot wait.
- Setting: Health centre that can collect sputum and send it to a hub laboratory
- For clinical officers, nurses and doctors at first-level facilities
- Reviewed October 2026
The presentation
Joseph, 45, works in a stone quarry. He has had a cough for 3 weeks. Antibiotics from a pharmacy 2 weeks ago did not help. He says he feels tired and his trousers are loose.
| Vital sign | Value |
|---|---|
| Temperature | 37.9 °C |
| Pulse | 96 per minute |
| Breathing rate | 22 per minute |
| Blood pressure | 118/76 mmHg |
| SpO2 | 95% on air |
| Weight | 54 kg (60 kg at a visit last year) |
Tests at hand: Sputum sample sent for a rapid molecular TB test · HIV rapid test · Haemoglobin (Hb) · Blood glucose (finger-prick) · Pulse oximetry (SpO2) · Peak expiratory flow (PEF)
- Pulmonary tuberculosis Must not missStill possible
- Slow-resolving bacterial pneumoniaStill possible
- COPD (smoke or dust exposure)Still possible
- AsthmaStill possible
- Cough after a viral infectionStill possible
- HIV with an opportunistic chest infection Must not missStill possible
- Lung cancer Must not missStill possible
- Heart failureStill possible
Work through it
Read each question and decide your own answer first. Then open the model answer and see how the differential changes.
- Step 1 of 6 · Look
First: is Joseph seriously ill? Which signs would make you refer him today, before any test?
Model answer
In a person with presumptive TB, seriously ill means any one of: breathing over 30 per minute, temperature over 39 °C, pulse over 120 per minute, or unable to walk unaided. Also refer the same day for coughing a lot of blood, severe breathlessness, or headache with neck stiffness, confusion or fits (possible TB meningitis).
Joseph walks in, breathes 22 per minute, pulse 96, temperature 37.9 °C. He is not seriously ill. You have time to assess him properly today.
Differential now- Pulmonary tuberculosis Must not missStill possible
- Slow-resolving bacterial pneumoniaStill possible
- COPD (smoke or dust exposure)Still possible
- AsthmaStill possible
- Cough after a viral infectionStill possible
- HIV with an opportunistic chest infection Must not missStill possible
- Lung cancer Must not missStill possible
- Heart failureStill possible
- Step 2 of 6 · Ask
What do you ask? Think of TB symptoms, TB risk, other lung diseases and HIV.
Model answer
- Cough: how long, sputum, blood in the sputum.
- Fever, night sweats, weight loss, loss of appetite.
- Breathlessness, wheeze, whether symptoms come and go (asthma) or slowly worsen over years (COPD).
- Contact with anyone with TB, especially at home.
- Previous TB treatment, and whether it was completed.
- Smoking, cooking smoke, dust or silica at work.
- HIV status and last test; diabetes.
- Swollen legs or breathlessness lying flat (heart failure).
Joseph coughs up sputum every morning and saw streaks of blood once. He sweats at night and has lost weight. His wife finished TB treatment 8 months ago. He has never had TB treatment. He smokes about 10 cigarettes a day and cuts stone without a mask. His last HIV test was 5 years ago. No wheeze, no leg swelling.
Differential now- Pulmonary tuberculosis Must not missLeading (moved up)
- COPD (smoke or dust exposure)Still possible
- HIV with an opportunistic chest infection Must not missStill possible
- Lung cancer Must not missStill possible
- Slow-resolving bacterial pneumoniaLess likely (moved down)
- AsthmaLess likely (moved down)
- Cough after a viral infectionLess likely (moved down)
- Heart failureLess likely (moved down)
- Step 3 of 6 · Look
What do you look for on examination?
Model answer
- General: wasting, pallor, enlarged lymph nodes in the neck or armpits.
- Mouth: white plaques of oral thrush (a sign of advanced HIV).
- Chest: crackles, reduced breath sounds or dullness (effusion), wheeze.
- Fingers: clubbing. Legs: swelling. Neck: raised veins.
He is thin with mild pallor. There is oral thrush. Crackles at the top of the right lung. No wheeze, no clubbing, no leg swelling, neck veins normal.
Differential now- Pulmonary tuberculosis Must not missLeading
- HIV with an opportunistic chest infection Must not missLeading (moved up)
- Lung cancer Must not missStill possible
- Slow-resolving bacterial pneumoniaLess likely
- COPD (smoke or dust exposure)Less likely (moved down)
- Cough after a viral infectionLess likely
- AsthmaSet aside for now (moved down)
- Heart failureSet aside for now (moved down)
- Step 4 of 6 · Test
Which samples and tests do you arrange today?
Model answer
- Sputum for a rapid molecular test (for example Xpert MTB/RIF Ultra or Truenat). It is the recommended first test, not smear microscopy, and it also shows rifampicin resistance. One good-quality sample is enough for an adult; show him how to cough deeply, outside or in a well-ventilated space.
- HIV test, offered to everyone with presumptive or confirmed TB. Use the national testing algorithm.
- Glucose: diabetes raises the risk of TB and changes care.
- Haemoglobin, as he is pale.
- Peak flow is not needed now: nothing suggests asthma.
Results today: HIV test reactive, confirmed by the national algorithm. Hb 10.9 g/dL. Random glucose 6.1 mmol/L. Sputum sent; result expected in 2 days.
Differential now- Pulmonary tuberculosis Must not missLeading
- HIV with an opportunistic chest infection Must not missLeading
- Slow-resolving bacterial pneumoniaLess likely
- COPD (smoke or dust exposure)Less likely
- Cough after a viral infectionLess likely
- Lung cancer Must not missLess likely (moved down)
- AsthmaSet aside for now
- Heart failureSet aside for now
- Step 5 of 6 · Do
Joseph has HIV and presumptive TB, with oral thrush. What does that change?
Model answer
Oral thrush makes this WHO clinical stage 3, which is advanced HIV disease. People with advanced HIV disease and TB symptoms are at high risk of dying and need the full package: a CD4 count, a urine LF-LAM test for TB (recommended for people with HIV who have TB symptoms), cryptococcal antigen screening if the CD4 is low, and co-trimoxazole prophylaxis.
ART: WHO now advises not delaying the start of ART while TB is being investigated, with close follow-up within days, unless meningitis is suspected. If TB is confirmed, TB treatment starts first and ART follows within 2 weeks. Agree the timing with your HIV and TB programme.
Common pitfallNever treat a 3-week cough with repeated courses of antibiotics. Each course delays the TB diagnosis by weeks.Differential now- Pulmonary tuberculosis Must not missLeading
- HIV with an opportunistic chest infection Must not missLeading
- Slow-resolving bacterial pneumoniaLess likely
- COPD (smoke or dust exposure)Less likely
- Lung cancer Must not missLess likely
- AsthmaSet aside for now
- Cough after a viral infectionSet aside for now (moved down)
- Heart failureSet aside for now
- Step 6 of 6 · Do
Where should Joseph be managed, and what else must you do before he leaves?
Model answer
- Refer him within days, not today, to the clinic that provides the advanced HIV disease package and TB care, with his results and the sputum request details.
- Make sure someone traces the sputum result in 2 days and contacts him the same day if it is positive.
- Infection control: cover the cough, sleep in a well-ventilated room, spend time outdoors, and if possible sleep apart from young children until treatment is under way.
- Ask him to bring all household members, especially children, for TB screening, and offer HIV testing to his wife.
- Advise stopping smoking and using a mask at work.
Your cough may be TB, and your test shows HIV. Both can be treated, and people do very well on treatment. We need to start quickly, so please go to the clinic this week, and bring your family to be checked.
Must-not-miss conditions
| Condition | Clues | What to do at first-level care |
|---|---|---|
| TB in a seriously ill person | Breathing over 30 per minute, temperature over 39 °C, pulse over 120 per minute, unable to walk unaided. | Refer the same day; send any samples already collected with the patient; do not wait for results. |
| Advanced HIV disease | Oral thrush, severe weight loss, WHO stage 3 or 4 signs, CD4 below 200. | HIV test for everyone with presumptive TB; refer within days for CD4, LAM, cryptococcal screening, co-trimoxazole and rapid ART. |
| TB meningitis or other severe extrapulmonary TB | Headache with neck stiffness, confusion or fits; severe breathlessness from an effusion. | Refer urgently. |
| Rifampicin-resistant TB | Previous TB treatment, contact with drug-resistant TB, or resistance shown on the molecular test. | Refer promptly to the drug-resistant TB service. |
| Lung cancer | Older smoker, blood in the sputum, weight loss and a negative TB work-up. | Refer for a chest X-ray and specialist assessment if TB tests are negative and symptoms persist. |
Decision at first-level care
Joseph has presumptive pulmonary TB with newly diagnosed HIV and signs of advanced HIV disease. He is not seriously ill, so this is not an emergency transfer, but he should reach the HIV and TB clinic within days for the advanced HIV disease package. The health centre has already done the most important things: sputum sent for a rapid molecular test, HIV diagnosed, household contacts identified.
Source: WHO consolidated guidelines on tuberculosis, Modules 2 to 4 (2021 to 2025); WHO consolidated HIV guidelines (2021).
- Bacteriologically confirmed, drug-susceptible TB in a person who is not seriously ill, where your facility is a TB treatment site: register and start treatment per national programme.
- Asthma or COPD confirmed on peak flow, with TB excluded: stepwise WHO PEN treatment.
- Cough under 2 weeks after a cold, no weight loss, no TB risk, well: symptomatic care and return if not better.
- Negative molecular test but symptoms persist: review in 2 weeks, repeat the test or use other samples.
- Seriously ill, coughing a lot of blood, or possible TB meningitis: the same day.
- Advanced HIV disease with presumptive TB: within days.
- Rifampicin resistance or previous treatment failure.
- No way to collect or test samples at your facility.
- Symptoms persisting after negative tests: for chest X-ray and clinical review.
Key learning points
- Cough for 2 weeks or more is presumptive TB where TB is common; any cough counts in people with HIV.
- A rapid molecular test on sputum is the first TB test; it also shows rifampicin resistance.
- Offer an HIV test to everyone with presumptive TB; HIV changes the speed and place of care.
- Look for seriously ill signs first: they mean same-day referral without waiting for results.
- Household contacts, especially children, need screening; repeated antibiotics only delay the diagnosis.
Sources
- World Health Organization. WHO consolidated guidelines on tuberculosis. Module 2: screening – systematic screening for tuberculosis disease. 2021. Symptom screens; cough of 2 weeks or more; any symptom in people with HIV.
- World Health Organization. WHO consolidated guidelines on tuberculosis. Module 3: diagnosis – rapid diagnostics for tuberculosis detection, third edition. 2024. Rapid molecular test as the initial test; urine LF-LAM in people with HIV.
- World Health Organization. WHO consolidated guidelines on tuberculosis. Module 4: treatment and care. 2025. Seriously ill criteria; ART within 2 weeks of starting TB treatment.
- World Health Organization. Consolidated guidelines on HIV prevention, testing, treatment, service delivery and monitoring. 2021. HIV testing for presumptive TB; advanced HIV disease package; starting ART while TB is investigated.
- World Health Organization. WHO package of essential noncommunicable (PEN) disease interventions for primary health care. 2020 (ISBN 9789240009226). Cough for more than 2 weeks: check for TB; asthma and COPD assessment with peak flow.