Repeat exposure to active tuberculosis and risk of re-infection
A 20-year-old woman of Indo-Fijian background who had lived in Australia for 10 years presented to the emergency department with a 3-day history of pain in the lower back and right hip. She had been coughing for 3 months and reported fevers and weight loss of 6 kg over the same period. Her medical history included treatment for latent (dormant) tuberculosis infection (LTBI) at 13 years of age with an unproblematic 6-month course of isoniazid 300 mg daily at a hospital chest clinic when her father, who lived in the same household, had sputum smear-positive pulmonary tuberculosis (TB). She had had a positive tuberculin skin test result of 15 mm before commencing treatment for LTBI, and had been given the BCG vaccine as a baby. Chest x-rays at the beginning and end of her treatment for LTBI had been normal. Her older sister, who also lived in the same household, was diagnosed with sputum smear-positive miliary TB 16 months after the father was diagnosed with TB (and 10 months after our patient had completed treatment for LTBI). Although our patient lived in the same household as her sister at that time, she did not receive a repeat course of preventive TB treatment. Six years after the sister was diagnosed with TB, our patient developed the symptoms described above.
When our patient presented at the emergency department, she had a heart rate of 120 beats/min, was normotensive,…