How to Tell the Difference Between Shigella and Norovirus as Stomach Flus Rise

If you or someone close to you has been struck down by a stomach bug in the past few weeks, you are not alone.

Cases of norovirus – or “stomach flu” – hit a 12-month high in February and continue to wreak havoc, especially in schools.

At the same time, cases of Shigella bacterial infections are on the rise, and 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 they both start at the same time. But shigella tends to be more diarrhea and less vomiting. You might have stomach cramps. Diarrhea caused by shigella tends to be more watery or bloody, doctors say, while that caused by norovirus tends to follow a bout of vomiting.
The graph above shows the number of shigella outbreaks reported this year (red line) and previously. 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. Virginia schools advise parents to keep children home for 48 hours after clearing symptoms to help stop the spread of norovirus

Dr. Marci Drees is the chief infection control officer at ChristianaCare in Delaware, which regularly cares for patients with these diseases.

When asked how to tell the illnesses apart, she told ABC6: ‘Norovirus tends to start with a lot of vomiting and then progress to diarrhea, or sometimes they both start at the same time.

‘[But] shigella tends to be more diarrhea and less vomiting. You might have stomach cramps.

According to doctors, diarrhea caused by shigella tends to be more watery or bloody, while diarrhea caused by norovirus tends to follow an episode of vomiting.

The two can also be distinguished by their duration. Cases of norovirus normally clear up in three days, but shigella tends to last four to seven days.

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A wave of respiratory and gastric bugs has been sweeping the United States for months, striking earlier and more severely than usual and causing symptoms similar to those of the pandemic virus.

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

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

Diseases can also strike at different types of year.

Norovirus is also known as the “stomach bug” due to its propensity to rise during the cold months of November to April, before dropping off.

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

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

Cases rose earlier than normal this year, the data showed, peaking at 30 outbreaks per week in early January.

But they have since declined. They remained below the levels recorded between 2012 and 2020 before the pandemic.

Virginia, California, Ohio and Michigan have faced the most norovirus outbreaks this year, the data shows.

Earlier this month, schools in Chesterfield, outside of Richmond, Va., told parents to keep children home for an additional 48 hours after their symptoms cleared – suggesting norovirus was at the origin of the disease.

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

Surveillance data from the Centers for Disease Control and Prevention (CDC) suggests that 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 about cases of superbugs across the country that were becoming resistant to antibiotics, making them harder to treat.

About five percent of all cases now involve resistant strains, up from none just six or seven years ago.

Doctors say that in most cases the best treatment for sick children is to get plenty of rest and make sure they are hydrated.

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

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

In these cases, stool tests will be done to determine if an infection is caused by shigella or norovirus.

Because shigella is caused by bacteria, it can be treated with a course of antibiotics.

But there is no similar treatment for norovirus, which is caused by a virus, with doctors focusing instead on managing symptoms.

CDC issues ‘serious public health alert’ regarding national outbreak of drug-resistant stomach bugs

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

The Centers for Disease Control and Prevention (CDC) has warned that around 5% of shigella cases are now drug resistant, up from none in 2015.

About 450,000 patients catch shigella – the bacteria that causes shigellosis – every year, according to estimates. Its main symptoms are sometimes bloody diarrhea, fever, stomach pain and a feeling of need to have a bowel movement even when the intestines are empty.

Naeemah Logan, a CDC physician, said these cases of “superbugs” pose a “serious threat to public health and we want to make sure suppliers are aware of the growing potential for antibiotic failure.”

Most do not need antibiotics and recover within a week after a period of rest and fluids.

But antibiotics are offered to people whose immune systems are weakened because of HIV or the chemotherapy they receive. This can help prevent complications and shorten the duration of illness.

The rise in shigella superbug cases has been particularly strong among gay and bisexual men, travelers, homeless people and people living with HIV.

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