2025-01-14 19:29:00
In a worrying winter surge, the cases of norovirus have risen to more than double last year’s peak, CBS News has reported citing data from the Centers for Disease Control and Prevention (CDC).
During the New Year’s holidays, nearly 28% of norovirus tests came back positive in a significant surge from the 13.52% positivity rate during last year’s wave in March, the report said.
Norovirus is a leading cause of foodborne illness and is highly contagious. It causes vomiting and diarrhea.
The CDC tracks cases through public health labs, testing stool samples from sick individuals. These tests can detect the virus up to 10 days after symptoms appear. Data shows that norovirus rates are at or above last year’s peak across all US regions, with the Midwest seeing the highest numbers, from Kansas to Michigan.
Many cases of norovirus can go undetected since most people recover without seeing a doctor, similar to Covid-19.
The CDC uses test positivity rates and other indicators like wastewater sampling to track trends.
Recent data from WastewaterSCAN signalled that the virus is currently most prevalent in the Midwest and Northeast. BioFire Diagnostics also reported higher-than-usual norovirus levels this season.
The reason behind the winter surge this year can be attributed to a new strain, GII.17[P17], which has replaced the dominant strain from the past decade, the report said.
The CDC said that this new strain has caused over 70% of outbreaks this season, including on cruise ships. Experts believe lower immunity to this new strain is driving the current surge.
Unlike recent years, when norovirus cases typically peaked in March or April, this season has seen an earlier spike. Pre-COVID-19, norovirus outbreaks often peaked in December or January.
Experts have urged people to take precautions amid a surge in cases, including frequent handwashing and avoiding contaminated food and water.
