Acute infectious nonbacterial gastroenteritis is a type of stomach infection caused by viruses or parasites. Other types of gastroenteritis are caused by bacteria.

Acute nonbacterial gastroenteritis typically lasts less than 14 days, and most cases resolve in just a day or two.

Symptoms most often include nausea, vomiting, and diarrhea. The infection is typically mild, but medical treatment is sometimes necessary, especially for young children.

This article will look at what causes acute infectious nonbacterial gastroenteritis, how to reduce your risk, and treatment options.

Acute infectious nonbacterial gastroenteritis is a type of infectious gastroenteritis caused by viruses or parasites. These viruses and parasites are most often found in food or water.

According to The Centers for Disease Control and Prevention (CDC), there are about 350 million cases of acute infectious gastroenteritis in the United States each year.

This type of gastroenteritis makes up about 60% to 85% of infectious gastroenteritis cases per year. This condition is contagious and can spread quickly throughout a household or workplace.

The symptoms of acute infectious nonbacterial gastroenteritis can be mild or severe. The infection usually lasts less than 14 days, although most cases resolve in just a few days.

Symptoms may include:

When to call a doctor

In most cases, this type of gastroenteritis resolves quickly without the need for medical attention. However, the infection can sometimes be severe.

It’s important to call a doctor if you:

  • have been vomiting or have had diarrhea for more than 2 days
  • have been unable to drink water or other liquids without vomiting for over 24 hours
  • begin throwing up blood
  • notice blood in your stool
  • have a fever of over 104 degrees
  • have signs of dehydration such as:
    • lightheadedness
    • weakness
    • dark-colored urine or no urine output
    • dry mouth

It’s important to call a doctor if your child has acute infectious nonbacterial gastroenteritis and:

  • is extremely tired
  • has changes in mood
  • has a fever of over 102 degrees
  • has bloody diarrhea
  • has been vomiting frequently
  • has a sunken soft spot on the top of their head
  • has signs of dehydration such as:
    • reduced urine output or reduced diaper wetting
    • crying without tears
    • dry mouth
    • excessive thirst

There are multiple types of viruses and parasites that can cause acute infectious nonbacterial gastroenteritis.

The easiest way to pick up this infection is by eating or drinking something that’s been contaminated. It’s also common to develop this type of gastroenteritis after coming into contact with an infected person, especially if you share food, straws, utensils, toiletries, clothes, or towels with them.

About 50% to 70% of all cases of acute infection nonbacterial gastroenteritis are viral. Viruses that can cause acute infectious nonbacterial gastroenteritis include:

  • Norovirus: Norovirus is one of the most common causes of acute infectious nonbacterial gastroenteritis. This virus is most often found in contaminated food and can easily spread through households, families, and communities.
  • Rotavirus: Rotavirus is especially common in children. Children often contract rotavirus after putting contaminated objects or their own unwashed hands into their mouths. In the United States, a rotavirus vaccine is available.

Parasites cause about 10% to 15% of all acute infectious nonbacterial gastroenteritis cases. Common parasitic causes of acute infectious nonbacterial gastroenteritis include:

  • Cryptosporidium: Cryptosporidium is often found in lakes, pools, and other bodies of water. You can develop an infection after drinking water that’s contaminated with Cryptosporidium.
  • Giardia: Giardia is typically found in water, soil, and some foods. It’s easily passed along among humans.

Risk factors for acute infectious nonbacterial gastroenteritis

People of all ages can contract acute infectious nonbacterial gastroenteritis. This type of infection is very common and can affect anyone. However, there are a few risk factors that can make you more susceptible to this type of gastroenteritis, such as:

  • being a very young child or an older adult
  • eating raw or undercooked meats
  • not washing your hands before eating or working with food
  • living in a dormitory or other communal setting
  • working in or attending daycare or school
  • working or living in a skilled nursing or assisted living facility
  • having a weakened immune system
  • traveling to areas of the world that don’t have strict sanitation standards

Most people recover without any medical treatment. Often, the infection clears up on its own after a few days of rest at home. While you’re recovering, it’s a good idea to take at-home self-care steps such as:

  • drinking plenty of fluids
  • getting lots of rest
  • not forcing yourself to eat if you feel nauseous
  • eating easily digestible foods such as crackers, noodles, or rice until the infection passes
  • avoiding caffeine, alcohol, nicotine, high-fat foods, and spicy foods

Medications that calm the stomach and prevent nausea can be helpful for more severe infections.

Medical treatment for dehydration

Sometimes, acute infectious nonbacterial gastroenteritis can lead to dangerous dehydration which may require medical treatment. This could include intravenous (IV) fluids or a prescription for medical rehydration solutions.

Medical treatment for parasitic infections

Although antibiotics won’t help treat this condition, there are prescription medications that can cure some parasitic infections.

If your doctor suspects your infection is caused by a parasite, they’ll run tests to find out what kind of parasite you have. This normally involves collecting a stool sample and testing it in a lab.

Once it’s confirmed that your case is caused by a parasite, you may be prescribed medication to help fight the infection.

Acute infectious nonbacterial gastroenteritis is common, but there are steps you can take to lower your risk of infection.

  • Get the rotavirus vaccine for your child. This vaccine is normally given in the first year of a child’s life.
  • Wash your hands thoroughly, especially before eating or preparing food, after touching objects that other people have touched or used, and after using the bathroom.
  • Carry hand sanitizer to use when soap and water aren’t available.
  • Wash fruits and vegetables before eating them.
  • Make sure the surfaces you use to prepare food are clean.
  • Cook food safely and avoid eating or serving raw meats.
  • Avoid sharing personal objects such as towels, clothes, or toiletries.
  • Avoid sharing straws and utensils.
  • Disinfect surfaces and common household objects like doorknobs, light switches, remote controls, refrigerator handles, if anyone in your home is sick.
  • Drink bottled water and avoid ice cubes when you’re visiting a part of the world with limited sanitation.

Acute infectious nonbacterial gastroenteritis is a common infection. It causes symptoms such as stomach pain, vomiting, and diarrhea. This type of infectious gastroenteritis is caused by viruses or parasites and is often passed to humans through contaminated food and water.

In many cases, no treatment is needed. Most people recover at home by resting and staying hydrated.

However, sometimes treatments such as medical rehydration, anti-nausea medications, or prescription medications to kill parasites are required. It’s important to see a doctor if your symptoms are severe or if you have signs of dehydration.