Imporving Attack Rate of Norovirus Gastroenteritis in a Nursing Home

Improving Attack Rate of Norovirus Gastroenteritis Outbreak in a Brooklyn Nursing Home

 Alejandro M. Villegas, MD¹, Louis M. Mudannayake, MD², Olga Badem, MD^3, Douglas V. Sepkowitz, MD³

¹Maimonides Medical Center/Long Island College Hospital, Brooklyn, New York, USA ²Cobble Hill Health Center, Brooklyn, New York, USA

³Long Island College Hospital, Brooklyn, New York, USA

Background: Noroviruses, the leading cause of gastroenteritis epidemics, cause self-limited, and generally mild acute gastroenteritis. Reported attack rates ranged from 38-84% in long-term care facilities.  Objective: The focus study was to follow strict infection control measures to limit the attack rate. Methods: This is a retrospective cohort study of a norovirus gastroenteritis outbreak from December 26, 2008 to February 5, 2009. Cobble Hill Health Center is a 360 bed long-term care facility with 5 floors and 9 units.  A case was defined by having two or more episodes of liquid stools in a 24 hour period or vomiting during the outbreak period. Stool specimens were sent to the CDC (Centers for Disease Control and Prevention) for RT- PCR (reverse transcriptase- Polymerase Chain Reaction) detection of norovirus. The diagnosis of the viral illness was clinical. C. difficile toxin assay and stool culture specimen were sent if suspected.  Patients with vomiting or diarrhea of other causes were excluded.

Infection control measures were implemented on December 29, 2008.  All suspected cases were confined to a room until 72 hours after symptoms resolved. Contact precautions included hand washing before and after entering the room, as well as using gloves and gowns. Every shift environmental surfaces such as door handles, light switches, toilets seats, faucets, bedside tables were cleaned with a 10% bleach solution.  Mop heads and solution was changed after cleaning rooms.   Special attention was paid to the identification of the newly ill.  Daily reports were given by nurse managers to the medical director. Gathering of patients was discouraged and patients remained within each unit.

Results: There were 380 residents exposed to the outbreak environment and 33 patients met the case definition with median age of 83 years.  All subjects had diarrhea and 27.3% had vomiting.  Six of 9 units were affected with a maximum of 12 cases in one unit.  Three units had 3 or less cases. Two of the 33 were hospitalized and there were no deaths.  The attack rate was 8.7%, considerably lower than other long-term care facilities.

Conclusions: Norovirus outbreaks have significant impacts on long-term care facilities. Preventing the spread of the virus from contaminated surfaces, food, and person to person contact is an enormous task.  This study confirms that effective strategies for containment, prevention and termination of these outbreaks can limit the attack rate and shorten the duration of the outbreak in a long-term care facility.