Investigation of an Outbreak of Diarrhea and Vomiting among Residents and Staff at One Care Center for the Severely Handicapped in Taipei City

Donald Dah-Shyong Jiang

2007 Vol.23 NO.8

Correspondence Author: Donald Dah-Shyong Jiang


from Chinese version, pp,420-430
In the morning of September 26, 2006, a collective case of diarrhea, vomiting, and slight fever broke out among the residents of a care center for the severely handicapped in Taipei City. An epidemiological investigation ensued to accomplish the objectives of estimating the epidemic scale of the incident, finding out the transmission route, identifying the pathogen responsible for the outbreak, searching for the source of infection, and eventually assessing the effectiveness of the control measures taken. In this particular case, the investigation team collected stool specimens from 17 residents who displayed diarrhetic or vomiting symptom, and in 15 of those specimens, norovirus was detected. On the other hand, the team also collected some stool specimens from 12 asymptomatic employees of the care center, and only one such sample showed evidence of the presence of that virus. Therefore, we conclude that norovirus is by far the most likely pathogen
Received: Jan 31, 2007; Accepted: Feb 26, 2007.
Correspondence author: Donald Dah-Shyong Jiang; Address: 5F, No.9, Sec.1, Zhongxiao E. Rd., Taipei City, Taiwan, R.O.C.

causing the collective outbreak of diarrhea and vomiting among the residents of this severely handicapped care center. Since 22 out of the entire 48 residents exhibited symptoms that met the case definition, the attack rate was estimated at 45.8%. Besides, only one employee was detected having norovirus, i.e. an attack rate of 4.0%. After ruling out some point-source exposure possibilities, such as sharing drinking water or food, transmission from one particular person as a common source, and through a common household utensil, we have to conclude that the transmission was likely to have occurred in the person-to-person mode. However, our effort to identify the infection source through tracking down the personal, temporal, and geographical connections between the individual patients has been in vain. As to the countermeasures implemented in this case, the care center started on September 28 to quarantine the sick residents, restrict the movement of the its workers while performing their routine duties, and conduct a blanket sterilization program of the living quarters as well as all facilities on the premises. The outcome appeared to be a success as no more individuals have fallen sick since October 1. Four days later, on October 5, the epidemic control measures were lifted.
Key words:Norovirus, outbreak, person-to-person transmission.