Outbreak of bronchiolitis obliterans associated with consumption of Sauropus androgynus in Taiwan

Background In August, 1995, there was an outbreak in Taiwan of rapidly progressive respiratory distress associated with consumption of uncooked Sauropus androgynus, a vegetable with a claimed yet unconfirmed effect on weight control. We report on 23 patients with strikingly similar clinical presentations. Methods A structured questionnaire for clinical manifestations was completed. Radiographic findings, pulmonary physiological changes, immunological and microbiological studies, and pathological examination were evaluated. Findings All patients were young and middle-aged women (mean age 39 years [range 21–52]). They took uncooked S androgynus juice, generally mixed with guava or pineapple juice, for a mean duration of 10 weeks. Progressive dyspnoea and persistent cough were the main symptoms on presentation. Pulmonary function testing uniformly revealed moderate to severe airflow obstruction with mean forced expiratory volume in 1 s (FEV1) of 0·66 L (26% of predicted). No bronchodilator response was observed. Room-air arterial blood gas analysis showed hypoxaemia (mean PaO2 9·6 [SD 1·6] kPa). Chest radiographs were essentially normal. High-resolution computed tomography showed bilateral bronchiectasis and patchy low attenuation of lung parenchyma with mosaic perfusion. Ventilation-perfusion scintigraphic findings were compatible with obstructive lung disease. Histopathology of open lung biopsy specimens in four patients confirmed the presence of bronchiolitis obliterans. Immunohistochemical stains of the open lung biopsy specimens showed predominance of T cells over B cells. Immunofluorescent stains for IgG, IgM, IgA, C1q, C3, and C4 were negative. Serum concentrations of tumour necrosis factor a were higher than those of normal controls. Clinical response to prednisolone was limited. Interpretation We describe an unusual association between bronchiolitis obliterans and ingestion of the vegetable S androgynus. T-cell mediated immunity may be involved in the pathogenesis.