The incubation period for Legionella pneumonia is usually 2 to 10 days, and most patients have a prodromal phase, similar to influenza, with peripheral malaise, fever, headache, and myalgia. Patients present with a cough, initially sputum-free, followed by mucus-like sputum, characterized by high fever, sometimes with a relatively slow pulse, diarrhea is also common, and mental changes may appear as confusion, with drowsiness or delirium being rare. Unilateral patchy lung segments or large lobar alveolar infiltrates are seen in the early stages of the disease on chest x-ray, and as the disease progresses, many patients develop bilateral lesions and pleural effusions are more common. Occasionally, a few patients present with pulmonary abscesses and multiple round dense shadows indicating septic emboli. cerebrospinal fluid examination is normal in those with altered mental status. blood and leukocytes are absent in the stool of patients with diarrhea. most patients have moderate leukocytosis with a peripheral leukocyte count of 10,000-15,000/μl. other common laboratory findings are low blood sodium, low blood phosphate and abnormal liver function tests. Occasionally, patients have microscopic hematuria, sometimes with impaired renal function. How is Legionella pneumonia diagnosed? There are four diagnostic tests to identify Legionella: bacterial culture, direct fluorescent antibody staining of exudate, serologic examination using indirect fluorescent antibody and urine antigen analysis, all of which are specific but not particularly sensitive. Pathogenic bacteria can be found in sputum, tracheal aspirate, bronchial aspirate or brushings, lung biopsy tissue, pleural fluid or blood. Legionella is not part of the normal flora, so positive culture has diagnostic value, but for cases confirmed by other techniques, sputum culture positive rate is only 30%-70%, culture and direct immunofluorescence staining require high technology. Urine antigen analysis is relatively easy to perform and can be positive for a long time after the start of treatment, but this method can only detect serotype 1 Legionella pneumophila (70% of all cases), and a serologic diagnosis can be made by demonstrating a 4-fold increase in titer (at least ≥1:128). A single recovery serum showing a titer of ≥1:256, together with corresponding clinical signs, strongly supports the diagnosis. Diagnostically significant titer elevations do not usually occur when a treatment decision is needed, but usually 3-6 weeks after onset. How is Legionella pneumonia treated? The treatment of choice is erythromycin, 1-2 g per day in 4 oral doses, with severe cases given intravenously for 2-3 weeks. Rifampicin can be added, 10mg/kg once daily orally; doxycycline 200mg once daily orally for more than 3 weeks, otherwise it is easy to relapse. Aminoglycosides and penicillin and cephalosporin antibiotics are not effective against this disease. Care of patients with Legionella pneumonia Legionella is more resistant to heat and can survive for 139 days in distilled water and settle in artificial piped water sources, infecting the population by aerosolized fog inhalation. Therefore, attention should be paid to regular opening of windows and ventilation to keep the indoor air fresh, the table tops should be wiped with 0.5% decontamination, and oxygen tubes, wetting bottles and nebulizers should be thoroughly disinfected once a week. Pay attention to the patient’s warmth when ventilating, and avoid direct blowing or convection of cold air. Absolute bed rest during the acute period and high fever, and appropriate activities during the recovery period. For those with severe chest pain, take the affected side to relieve the pain. For those who have difficulty in breathing, take a semi-recumbent position and give oxygen inhalation. Give high protein, high caloric, high vitamin, easy to digest diet and encourage patients to drink more water, at least 2000ml-4000ml per day. Observation and care of symptoms and complications 1. Hyperthermia: physical cooling methods such as ice bag warm water bath and warm alcohol bath are feasible to reduce patients’ pain and increase their comfort. As saliva secretion decreases during hyperthermia, the mouth and lips are dry and cracked, and stomatitis can easily occur. 2, cough: legionella pneumonia occurs in the elderly and frail, they are less active, sputum more accumulation in the body, unable to cough out. At this time, the patient can be instructed to learn effective coughing methods and encouraged to cough up sputum on their own. If the sputum is sticky and not easy to cough out or unable to cough out, nebulized inhalation, turning, postural drainage and application of expectorant are feasible to keep the respiratory tract unobstructed. 3, water, electrolyte disorders and renal function abnormalities: Legionella can release toxins to cause hyponatremia, so the patient’s blood electrolytes, urinary routine and renal function should be checked regularly. Abnormalities found to actively assist doctors in treatment and rescue. 4, drug therapy observation and care: erythromycin for the treatment of Legionella pneumonia of the road selected drugs, can be taken orally, but also intravenous infusion, the general course of treatment for 2-3 weeks. Infusion of the patient may appear local pain, gastrointestinal discomfort (nausea, vomiting), so it is appropriate to slow drip and do a good job of life care, timely removal of vomit, encourage patients to eat less and more meals, moderate amount of food. 5, health education: pneumonia is mostly due to the lowering of the body’s resistance, bacteria take advantage of the situation, caused by the winter and spring season. Therefore, should strengthen the body’s own cold ability exercise, avoid cold, prevent colds, develop good habits of non-smoking, non-drinking alcohol. At the same time, attention should be paid to keep the surrounding environment clean and avoid the pollution of water sources.