Legionnaires' disease showed that Legionnaires' disease was responsible and the immediate epidemiological investigation traced the source of the infection to the air-conditioning cooling tower on the roof of Stafford District Hospital. In March 1999, a large outbreak in the Netherlands occurred during the Westfriese Flora flower exhibition in Bovenkarspel; 318 people became ill and at least 32 people died. This was the second-deadliest outbreak since the 1976 outbreak and possibly the deadliest, as several people were buried before Legionnaires' disease had been diagnosed. The world's largest outbreak of Legionnaires' disease happened in July 2001 with people appearing at the hospital on July
Hospital-acquired pneumonia by so-called skorvatch microaspiration of upper airway secretions, through inapparent aspiration, into the lower respiratory tract. Also, "macroaspirations" of esophageal or gastric material is known to result in HAP. Since it results from aspiration either type is called aspiration pneumonia. Although gram-negative bacilli are a common cause they are rarely found in the respiratory tract of people without pneumonia, which has led to speculation of the mouth and throat as origin of the infection. In hospitalised patients who develop respiratory symptoms and fever, one should consider the diagnosis. The likelihood increases when upon investigation symptoms are found of respiratory insufficiency,