How to Tell the Difference Between Shigella and Norovirus When Stomach Flu Rises



If you or a loved one have been struck down by a gastrointestinal virus in the past few weeks, you are not alone.

Cases of norovirus – or the “stomach flu” – hit a 12-month high in February and are still wreaking havoc, especially in schools.

At the same time, cases of Shigella bacterial infection are on the rise, and public health officials are concerned about an antibiotic-resistant strain growing in the United States.

The two bugs – which are the leading cause of gastroenteritis in American schools – have very similar symptoms, making it difficult to tell them apart.

But there are ways to tell the difference between the two:

Norovirus tends to start with a lot of vomiting and then progress to diarrhea, or sometimes both start at the same time. But Shigella tends to be more diarrhea and not vomit as much. You could have stomach cramps. Diarrhea caused by Shigella tends to be more watery or bloody, medical professionals say, while diarrhea caused by norovirus tends to follow a bout of vomiting
The graph above shows the number of reported Shigella outbreaks this year (red line) and earlier. The season started early but has since declined. It remained below pre-pandemic levels
This map shows the number of reported outbreaks by state. It was most common in Virginia, California, Ohio and Michigan – with cases still ongoing. Schools in Virginia are advising parents to keep children home for 48 hours after symptoms resolve to stop the spread of norovirus

dr Marci Drees is the senior infection prevention officer at ChristianaCare in Delaware, which regularly engages with patients with the diseases.

When asked how to tell the diseases apart, she told ABC6: “Norovirus usually starts with a lot of vomiting and then progresses to diarrhea, or sometimes both start at the same time.

‘[But] Shigella tends to have more diarrhea and less vomiting. You could get stomach cramps.”

Diarrhea caused by Shigella tends to be more watery or bloody, medical professionals say, while diarrhea caused by norovirus tends to follow a bout of vomiting.

The two can also be distinguished by their duration. Norovirus cases usually clear up within three days, but Shigella typically lasts four to seven days.

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For months, a wave of respiratory and gastric diseases has swept across the United States, striking earlier and more severely than usual, causing symptoms similar to the pandemic virus.

In severe cases, it can take weeks to months for the gut of people with the bacterial infection to return to normal.

Other differences are that Shigella patients are more likely to have a fever than those with norovirus.

The diseases can also appear in different seasons.

Norovirus is also known as the “stomach bug” because it tends to rise before falling during the cold months of November through April.

Shigella, on the other hand, tends to transmit at a constant rate throughout the year.

Norovirus causes up to 21 million cases in the United States, 109,000 hospitalizations and 900 deaths each year, according to statistics.

Data suggests cases were increasing earlier than normal this year, peaking at 30 outbreaks a week in early January.

But they have since declined. They remained below pre-pandemic levels between 2012 and 2020.

Data suggests that Virginia, California, Ohio and Michigan have faced the most norovirus outbreaks this year.

Earlier this month, schools in Chesterfield, outside of Richmond, Virginia, urged parents to keep children at home for an additional 48 hours after their symptoms have resolved – suggesting norovirus is behind the disease.

Shigella, on the other hand, causes fewer diseases than norovirus each year.

Surveillance data from the Centers for Disease Control and Prevention (CDC) suggests the bacterial infection causes about half a million cases each year, resulting in 5,400 hospitalizations and 38 deaths.

Last month, a “serious public health alert” was issued across the country about cases of superbugs becoming resistant to antibiotics, making them difficult to treat.

About five percent of all cases now involve resistant strains, compared to none six or seven years ago.

Medical professionals say that in most cases, the best treatment for sick children is getting plenty of rest and making sure they are hydrated.

Some patients may also be able to eat small amounts of bland foods like soup, rice, pasta, or bread, they suggest.

Children only need to see a doctor if they start showing symptoms such as bloody diarrhea, persistent fever, severe stomach cramps, or dehydration.

In these cases, stool tests are done to determine if infection is caused by Shigella or norovirus.

Because Shigella is caused by a bacterium, it can be treated with a range of antibiotics.

But there is no similar treatment for norovirus, which is caused by a virus, and doctors are instead focusing on treating the symptoms.

CDC issues “grave public health alert” over nationwide rise in drug-resistant gastric disease

America is facing a “serious public health threat” after a sharp rise in infections from an antibiotic-resistant stomach bug, officials have warned.

The Centers for Disease Control and Prevention (CDC) warned that about 5 percent of Shigella cases are now drug-resistant, compared to none in 2015.

It is estimated that around 450,000 patients contract Shigella – the bacteria that causes shigellosis – every year. The main symptoms are diarrhea, which is sometimes bloody, fever, abdominal pain and a feeling of having a bowel movement even though the bowels are empty.

Naeemah Logan, a CDC physician, said these “superbug” cases pose a “serious public health threat and we want to make sure providers are aware of the increasing potential for antibiotics to fail.”

Most do not require antibiotics and recover within a week after rest and hydration.

But antibiotics are offered to people who have weakened immune systems because of HIV or any chemotherapy they are receiving. It can help prevent complications and shorten the duration of the disease.

The rise in superbug Shigella cases has been particularly sharp among gay and bisexual men, travellers, the homeless and people living with HIV.

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