An outbreak of acute GII.17 norovirus gastroenteritis in a long-term care facility in China: The role of nursing assistants.

More than 30 residents and nursing assistants in a geriatric nursing hospital developed acute gastroenteritis from December 7th to December 18th, 2014 in Shanghai, China. An immediate epidemiological investigation was conducted to identify the etiological agent of the outbreak, mode of transmission and the risk factors. Cases were investigated according to an epidemiological questionnaire. Samples from cases, highly transmissible environmental surfaces and drinking water were collected for pathogens detection. A retrospective cohort study was conducted to explore the transmission mode. A total of 34 cases were affected in this acute gastroenteritis outbreak, including 23 residents, 9 nursing assistants and 2 doctors. 13 out of 30 samples were positive for GII.17 norovirus, no other pathogen was detected. Nursing assistants who developed gastroenteritis symptoms had a higher attack rate in residents they cared than those who did not develop any gastroenteritis symptoms (p<0.001). The acute gastroenteritis outbreak was caused by GII.17 norovirus. Person-to-person close contact and contaminated environmental surfaces were the probable transmission route. Nursing assistants were considered to play an important role in the secondary spread of norovirus. The poor medical skill and personal hygiene habits of nursing assistants in China should be paid attention and improved urgently which is critically important to prevent hospital infections.