In May, 2007, a 46-year-old woman came to the emergency department at our hospital, for the third time in 6 weeks. For 6–8 weeks, she had had a fl u-like illness: headache, muscle and joint pains, and fatigue. Shortly after symptoms began, she developed fever, and a diff use maculopapular rash. The fever was episodic, as was the rash, which recurred every 5–7 days, lasted 24–48 h, and did not itch. Several blood cultures had been negative. The patient had previously been healthy. She had no other medical history of note. On both previous visits to the emergency department, she had been diagnosed with a viral illness, and discharged. She had a fever (39·5°C); her heart rate was 99 beats per min. A maculopapular rash covered her torso, arms, and legs. The spots had a diameter of around 10 mm; some had purpuric centres (fi gure). General, neurological, and rheumatological examination revealed nothing else of note. Serological testing for hepatitis B and C, EpsteinBarr virus, HIV, and cytomegalovirus gave negative results, as did urinalysis and a throat swab. Blood testing showed mild anaemia (haemoglobin concentration 112 g/L), severe neutrophilia (18×109 cells per L), and further evidence of infl ammation (ESR 38 mm/h, concentration of C-reactive protein 192 mg/L). We did a lumbar puncture; analysis of cerebrospinal fl uid showed nothing abnormal. Nor did CT of the head and thorax. CT of the abdomen showed a fatty liver, but nothing else of note. A dermatologist reviewed the rash, and suspected meningococcaemia. We took a further set of blood cultures, and a skin-punch biopsy of the rash, and gave the patient a course of intravenous ceftriaxone. Neisseria meningitidis grew in the blood; histological analysis of the biopsy sample showed leucocytoclastic vasculitis, consistent with chronic meningococcaemia. Within 24 h of the start of antibiotic treatment, the fever started to abate, and the rash to recede. We contacted the public-health authorities, and treated the patient’s close contacts prophylactically, with rifampicin 600 mg twice daily for 48 h. The patient was discharged after 72 h of treatment. When last seen, in June, 2007, she was well. N meningitidis is inhaled in fi ne droplets, suspended in the air, that have been breathed out by infected people. Most infections occur in the winter or early spring. Chronic meningococcaemia is rare. It is characterised by recurrent fever, rash, and joint pains; other common symptoms include headache and muscle pains. The neck stiff ness and photophobia characteristic of meningitis are usually absent. The rash typically develops 12–24 h after the onset of fever: it can be maculopapular, petechial, pustular, or nodular. The rash generally resolves spontaneously, over a few days, as the fever recedes. The diff erential diagnosis includes subacute gonococcaemia, subacute bacterial endocarditis, and Henoch-Schonlein purpura. Blood cultures are negative, in most cases, in the early stages of the disease, but often yield positive results later, if taken when the patient has a fever. Histopathological analysis of the rash typically shows fi ndings consistent with leucocytoclastic vasculitis—including a perivascular infl ammatory infi ltrate, and damage to the vessel wall—rather than the diplococci that can be seen in acute meningococcaemia. Treatment generally consists of a 7-day course of penicillin. Third-generation cephalosporins are also eff ective. Close contacts should receive prophylaxis with rifampicin. In cases of recurrent meningococcal infection, the possibility of an immuno logical defi ciency (in terminal complement, or an IgG subclass) should be considered. Accurate diagnosis of chronic meningococcaemia is crucial; not least because it can resolve without treatment—or lead to endocarditis, meningitis, or death.