[A small epidemic focus of pulmonitis caused by Legionella]

A mini-epidemic consisting of 5 cases of Legionnaire's disease treated during september 1983 is reported. These patients shared many of the symptoms distinguishing the most common form of this disease in its severe or very severe form and some characteristic features of this case series are emphasised. It was impossible to trace the source of the outbreak, in spite of the fact that the mini-epidemic took place in an open situation. It is underlined that diagnosis is mainly clinical. The Legionella pneumophila bacteria should always be considered as one of the causal agents of bronchopneumonia, particularly when the following conditions are fulfilled: a) the disease takes the form of a confined, out-of-season, mini-epidemic; b) it is accompanied by multisystemic symptomatology and/or much greater involvement of general conditions that is usually to be expected in normal cases of bronchopneumonia. Since the disease is often fatal, erythromycin or rifampicin treatment should be started upon the slightest suspicion of contagion.