[Epidemiological investigation and analysis of an outbreak of mycoplasma pneumoniae pneumonia in adult].

Objective: To conduct an epidemiological investigation and analysis of an outbreak of mycoplasma pneumonia in adults. Methods: The first case was a 23-year-old male came from the Third Military Medical University, who served as an intern in the Fuzhou General Hospital of PLA and presented on July 16, 2015 with a history of low-grade fever, dizziness, fatigue and chest tightness. Chest CT revealed pulmonary nodules shadow. It was found that other 11 individuals who had been in close contact with the first patient also had similar pulmonary nodules shadow after chest CT examination. Immediately, the health and epidemic prevention department of the ministry of health of Nanjing Military Command and the disease prevention and control center of the Nanjing Military Command received a phone call from Fuzhou General Hospital of PLA. Upon arrival, the prevention and control team conducted a series of epidemiological investigations and on-site prevention, control and disposal of the event, and conducted chest CT screening for other 289 students and staff who volunteered to be examined living in the same area. After the patients with similar pulmonary nodules shadow were screened out, mycoplasma antibody titer detection and chest CT re-scanning were performed for compliance patients. Results: There were 301 students living in the dormitories (Building A and B) of the student living area, and they were screened by chest CT, and it was found that 27 of them had pulmonary nodules shadow, including single pulmonary nodules shadow (48.1%, 13 out of 27) and multiple pulmonary nodules shadow (51.9%, 14 out of 27). And halo sign was observed in 25 of 27 patients (92.6%). The majority of the 27 patients were asymptomatic, only 2 patients got cough, a few of them had systemic symptoms such as fever, dizziness, fatigue. The positive rate of pulmonary nodules shadow was 32.8% (22/67) in building A (poor environmental hygiene), 2.14% (5/234) in building B, and the total incidence rate was 8.97%. Four-fold increase in the mycoplasma pneumoniae (MP) antibody titer in the paired sera was observed in first 12 patients. Measures such as disinfection, isolation and sanitation were taken to control the spread of the epidemic. There was no serious and death cases on the basis of active treatment on the affected patients. Conclusions: The outbreak of mycoplasma pneumoniae pneumonia often occur in crowded places. And the clinical and imaging features of mycoplasma pneumoniae pneumonia are atypical. Standard epidemiological intervention should be adopted for the sudden onset of respiratory diseases with unknown causes.