History A 19-year-old woman has presented to the emergency department complaining of fevers and malaise after returning from South Africa. Over the preceding 3–4 days she noticed a rash and sore throat and is now feeling generally tired and unwell. She has no significant medical history and does not take any regular medications or recreational drugs. She does not smoke, nor drink alcohol. She admits to several episodes of unprotected sexual intercourse with a man she met in South Africa.

Examination The young woman is febrile and tachycardic. Her heart sounds are normal, her chest clear and her abdomen soft and non-tender. She has widespread lymphadenopathy: the lymph nodes are 2 cm in diameter and are soft and tender on palpation. There is an erythematous, maculopapular rash covering her trunk. Observations: temperature 37.8°C, heart rate 98/min, blood pressure 110/88 mmHg, respiratory…