What Is Astrovirus?

One of Several Viruses That Causes Stomach Flu

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Astrovirus is a group of viruses that causes gastroenteritis (stomach flu). Infants and young children are most likely to develop symptoms, including diarrhea, nausea, and upset stomach. Older adults and people with compromised immune systems are also at risk.

Though astrovirus causes symptoms similar to other viral diarrheal diseases, such as rotavirus and norovirus, it is far less severe and rarely requires medical treatment.

This article takes you through the symptoms, causes, diagnosis, and treatment of astrovirus, including ways to prevent passing or getting the infection.

Symptoms of Astrovirus Infection

Astrovirus symptoms
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Astroviruses are one of several transmittable organisms that cause gastroenteritis. The main symptom is diarrhea. Compared to other organisms that cause gastroenteritis, diarrhea caused by astrovirus is usually mild.

In addition to loose or watery stools, symptoms of astrovirus may include:

  • Nausea
  • Vomiting
  • Stomach ache
  • Loss of appetite
  • Body aches
  • Fever

The symptoms are usually mild and resolve on their own without treatment. Hospitalization is rarely needed. Healthy people generally recover within a few days.

In some cases, a person can be asymptomatic (without symptoms) and not even know they've been infected. Despite having no symptoms, they can still pass the virus to others.

How Do You Get Astrovirus?

Astrovirus is passed when stool containing the virus is accidentally ingested. This is usually caused when traces of stool are found on hands or objects.

If you accidentally touch a contaminated hand or surface and then your own mouth (called the fecal-oral route), you can get infected.

It only takes a small exposure to astrovirus to make a person sick. Once a person is infected, the virus will continually be shed into fecal matter (stools).

Even when the person starts to feel better, they may still be shedding virus and can continue to infect others.

While it is less common than other diarrhea-causing viruses, astroviruses still account for 2% to 9% of all pediatric gastroenteritis cases in the world.

How Long Is Astrovirus Contagious?

Most astrovirus infections last for four days or less. The disease is potentially infectious from the moment symptoms appear until a few days after symptoms have cleared.

Risk Factors

Risk factors for astrovirus include:

  • Poor handwashing and hygiene practices
  • Handling or preparing food with unwashed hands or on contaminated surfaces
  • Living or working in crowded spaces (e.g., dorms, barracks, daycare centers)
  • Living in parts of the world where sanitation is limited
  • Malnutrition

Climate, age, and immune health also factor into your risk.


Astroviruses are present year-round and can cause illness at any time of the year. With that said, astrovirus tends to spike in certain seasons.

Where climates are temperate, infections are common in the winter and spring. In tropical climates, astrovirus rates are highest during the rainy season.


Babies, children under 2, and older adults are at increased risk for astrovirus. They are also most likely to experience complications like dehydration.

Most children will develop immunity to astrovirus by the time they reach 10. This is why astrovirus doesn't usually make most adults sick.

However, immunity tends to wane over time, which is why older age is a risk factor.

Immune Health

People with compromised immune systems (such as those being treated for cancer or living with HIV) are more likely to get astrovirus and experience related dehydration.

The body is not able to fight off this "intruder" the way it normally could if the immune system was functioning optimally.

How Astrovirus Is Diagnosed

Astrovirus can usually be diagnosed with a combination of a physical exam, a review of your medical history, and various blood and stool tests.

Based on a review of your symptoms and risk factors, your healthcare provider may decide to treat you presumptively if your symptoms are mild.

In other cases, your practitioner may order a battery of tests to identify the specific cause of your diarrhea, especially if the symptoms are severe or there is a local outbreak of diarrheal disease.

The tests may include:

The test results are usually ready in one to three days. A positive result means that you have been infected with astrovirus. A negative result means that you have not been infected.

Viral gastroenteritis can be caused by several different microorganisms. In some cases, it is possible to be infected by more than one virus at the same time (called a coinfection).

Astrovirus gets its name from its star-like appearance when viewed under a microscope.

How Do You Treat Astrovirus?

Currently, there are no drugs or vaccines available for the prevention or treatment of viral gastroenteritis.

As such, the treatment for an astrovirus infection is focused on managing symptoms like nausea and diarrhea.

There are several ways to treat stomach flu:

  • Stay well hydrated: Replace lost fluids with water, broth, sports drinks, or unsweetened fruit juice. If your stomach is weak, try sipping a little at a time.
  • Eat "binding" foods: These include white rice, toast, bananas, saltine crackers, and applesauce. Avoid foods that make diarrhea worse, such as fatty foods, dairy, sweetened drinks, and caffeine.
  • Take diarrhea medications: These include over-the-counter drugs like Imodium (loperamide) or Pepto-Bismol or Kaopectate (bismuth subsalicylate).*

*Avoid these medications and see your healthcare provider if you have a fever or blood diarrhea. You may have a bacterial or parasitic infection, not a virus.

Treating Children

Imodium, Pepto-Bismol, and Kaopectate should never be used in children without first speaking with a pediatrician. These drugs can be harmful to babies and toddlers.

How to Prevent Astrovirus

There are things you can do to avoid getting or spreading astrovirus:

  • Wash your hands thoroughly, especially after using the bathroom or changing diapers.
  • Do not share utensils or cups if you or people around you are sick or have diarrhea.
  • Stay home from work or school if you are ill.
  • Avoid handling and preparing food while ill or recovering from illness.
  • Use antiseptic disinfectants to clean surfaces, especially in the bathroom and kitchen.


Astroviruses are one of several types of viruses known to cause gastroenteritis ("stomach flu"). While most infections are mild, care should be taken to avoid infection in people at the greatest risk, including infants, older adults, or those with advanced HIV.

Good hygiene and sanitary practices, along with healthy nutrition, can go a long way toward preventing astrovirus infection in people who are vulnerable.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Bosch A, Pintó RM, Guix S. Human astrovirusesClin Microbiol Rev. 2014;27(4):1048-1074. doi:10.1128/CMR.00013-14

  3. Vu DL, Bosch A, Pintó RM, Ribes E, Guix S. Human astrovirus MLB replication: persistence in extraintestinal cell lines. J Virol. 2019;93(13):e00557. doi:10.1128/JVI.00557-19

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Additional Reading

By Abby Norman
Abby Norman is a freelance science writer and medical editor. She is also the author of "Ask Me About My Uterus: A Quest to Make Doctors Believe in Women's Pain."