A 42-year-old woman presents with a cough productive of green sputum and worsening breathlessness. She has been febrile at home and suffering with rigors. On examination she is tachypnoeic with audible left lower lobe crackles on chest examination. She has no other past medical history of note and is a non-smoker. A chest X-ray is performed which shows an air bronchogram and left lower lobe consolidation.

A 40-year-old man presents with a non-productive cough and marked exertional dyspnoea. He tells you that he used to abuse intravenous drugs. On examination he has marked oral thrush and widespread lymphadenopathy. Respiratory examination reveals scattered crackles and wheeze. His oxygen saturations are 97% at rest but drop to 87% on walking.

A 35-year-old man presents with a one-week history of a dry cough that has now started to produce a little sputum. He is also complaining of myalgia, tiredness, headaches and has had diarrhoea for the past 2 days. On examination he has audible crackles on the right side of his chest. He has developed a rash on the backs of his hands and feet. The rash comprises multiple small circular lesions with central ‘target lesions’.

A 36-year-old man presents with a dry cough and a fever. Today he has also had several episodes of diarrhoea and has developed bilateral pleuritic chest pain. He states that he is short of breath, most notably on exertion. He works as an air conditioning installer and smokes 15 cigarettes per day.

A 40-year-old man presents with a flu-like illness that has been worsening for the past two and a half weeks. He has been unable to return to work at his job at the local slaughterhouse because of this illness. He has high fevers, severe headache and myalgia. He has now also developed a dry cough and diarrhoea. On examination he has no chest signs of note but you can palpate a liver edge 4 cm below the costal margin. His transaminases are elevated but he is not jaundiced.