As the holiday season approaches, a dramatic rise in cases of the highly contagious norovirus is being reported, according to recent data. Norovirus, notorious for causing severe vomiting and diarrhea, is seeing a significant uptick in infections.

The Centers for Disease Control and Prevention (CDC) has revealed that during the week of November 15, approximately one in seven norovirus tests returned positive results. This equates to 380 positive cases out of just over 2,700 tests conducted, marking a 24 percent increase from the previous week.

While these numbers are concerning, the actual number of Americans affected by the norovirus is likely much higher. Many individuals do not undergo testing despite the virus impacting millions each year.

Comparing this surge to the same period last year, there is a noticeable increase of one-third in norovirus cases, with only one in ten tests returning positive at that time. Moreover, the current figures reveal that positive results have doubled since August, when the virus’s prevalence was at its lowest point in the past year.

Norovirus cases have increased by one-third compared to this time last year, when one in 10 tests came back positive. 

And CDC figures shows norovirus positive tests have doubled compared to August, when test positivity was at its lowest in the last year. 

Last December, a peak of one in four cases were positive, the strongest surge since the Covid-19 pandemic.

Physicians speaking with the Daily Mail warned that as temperatures dip, viruses like norovirus thrive, and holiday gatherings are prime environments for increased spread.

Norovirus symptoms, which include vomiting and diarrhea, typically appear 12 to 48 hours after exposure. Most people recover in a few days, but the virus claims around 900 lives annually, primarily among adults 65 and older

Experts also urged proper sanitation to keep the virus from ripping through families. 

Norovirus infects around 21 million Americans annually and sends around 2 million to their doctor’s offices or urgent care. 

It causes severe diarrhea and vomiting, which can lead to life-threatening dehydration. It spreads through contact with germs from an infected person’s vomit or feces, contaminated food, shared utensils, or surfaces they’ve touched.

While most people recover within a few days, the virus kills around 900 people every year, mostly adults 65 and up. 

Outbreaks are most common in the winter due to a jump in the number of people gathering in groups for holiday festivities, traveling, and staying warm indoors, where pathogens can spread easily. 

Symptoms of norovirus, which include nausea, vomiting, and diarrhea, come on quickly, within 12 to 48 hours of exposure. 

The above data from the CDC shows a spike in positive norovirus tests during the week of November 15, the latest data available

Dehydration is a major concern. Frequent vomiting and diarrhea can quickly cause the body to lose fluids and electrolytes, which can lead to dangerously low blood pressure, reduced blood flow to vital organs, and an electrolyte imbalance that may harm the heart and muscles.

Electrolyte imbalances can also result in seizures and, in some cases, loss of consciousness.

Hand sanitizers alone can’t kill virus particles on the skin, which is why doctors strongly recommend washing one’s hands often.

Dr Olalekan Otulana, physician at Cassiobury Court in the UK, told the Daily Mail: ‘The most effective protection comes from handwashing with soap and water, especially before eating and after using the toilet.’

The latest norovirus figures, from the CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS), show the test positivity rate for norovirus has increased from 11 percent during the week of November 8 to 14 percent the week of November 15. 

The lowest figures reported this year were from the week of August 9, during which 6.5 percent of tests were positive. 

Norovirus tests are usually done by looking at stool or vomit samples. However, tests are only ordered based on symptoms, and mild cases rarely go reported, making actual figures likely much higher. 

Dr Otulana suggests the rise in cases this holiday season ‘is likely down to a combination of seasonal factors and shifting immunity patterns.’

‘Norovirus thrives in winter and as people move indoors and mix more closely so transmission becomes far easier,’ he added. ‘We also tend to see yearly variation in circulating strains and if a slightly different strain predominates then any previous immunity you had doesn’t offer much protection anymore which can lead to sharper spikes.’