Cases of norovirus infection, a common cause of viral gastroenteritis in long-term care facilities, have risen steadily across the US in recent months, according to the latest data from the Centers for Disease Control and Prevention.
There were 225 norovirus outbreaks reported between Aug. 1, 2022, and Jan. 8, 2023, by the 14 states participating in the CDC’s NoroSTAT tracking program. That’s compared with 172 outbreaks reported during the same period in the last seasonal year, according to the agency.
During the 2019-2020 respiratory illness season, COVID-19 infection control measures likely prevented outbreaks of many infectious diseases, including norovirus. The current rise in gastroenteritis appears to be a return to an expected, pre-pandemic range, CDC spokesperson Kate Grusich told NBC News.
“As pandemic restrictions have relaxed, the number of norovirus outbreaks has returned to levels similar to pre-pandemic years,” she said.
Effect on nursing homes
Prepandemic norovirus characteristics also have returned, with nursing homes accounting for the majority of outbreaks in the US. In fact, 59% of outbreaks occurred in those facilities during the 2021-2022 season, according to CDC data from September. The pre-pandemic range of occurrence in those settings ranged between 53% and 68%.
The US is not the only country experiencing an uptick. Britain’s health agency has reported a 66% rise in norovirus cases this season compared with average seasonal rates. Most confirmed infections have occurred in adults aged 65 years and over, with the majority in nursing homes, Reuters has reported.
Norovirus typically causes the most severe illness in older adults, people with comorbid illness and children. It can cause vomiting and diarrhea and can be especially dangerous if it causes severe dehydration. On average each year in the US, norovirus causes 900 deaths, mostly among older adults.
Long-term care facilities have a high burden of norovirus outbreaks, with prepandemic rates averaging four per 100 facilities annually, according to one federal study of data between 2009 and 2018. For every 1,000 cases during that time period, there were 22 hospitalizations and 2.3 deaths, the researchers found.
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