What Is Gastroenteritis?

Just a few hours ago, you were enjoying a plate of raw oysters at your favorite restaurant, but now you're doubled over with cramps and vomiting. Or maybe you're stuck in your hotel in Cancun with a bad case of traveler's diarrhea. Then again, maybe your whole family is down with "stomach flu."

If any of these scenarios sound familiar, you or someone in your family may have an intestinal infection caused by a virus (viral gastroenteritis or stomach virus). Although it probably won't make you feel any better, you're not alone. Viral gastroenteritis is one of the most common acute illnesses in the United States, with more than 25 million cases reported annually.

You usually develop gastroenteritis because you've been in contact with someone who's already infected or because you've ingested contaminated food or water. Although many different viruses can trigger intestinal problems, signs and symptoms are usually the same: watery diarrhea, abdominal cramps, and nausea or vomiting.

For some people, especially infants, older adults and those with compromised immune systems, gastroenteritis can be deadly. Every year the disease claims the lives of more than 10,000 Americans. For others, it may mean a week or more of sheer misery, along with missed school and work.

There's no effective treatment for gastroenteritis, so prevention is key. In addition to avoiding food and water that may be contaminated, thorough and frequent hand washing is your best defense.

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Signs and Symptoms

Although it's commonly called stomach flu, gastroenteritis isn't the same as influenza. Real flu (influenza) affects your respiratory system — your nose, throat and lungs. Gastroenteritis, on the other hand, attacks your intestines, causing signs and symptoms such as:

• Watery, usually nonbloody diarrhea. Bloody diarrhea usually means you have a more severe infection.
  
  
• Abdominal cramps and pain.
  
  
• Nausea, vomiting or both.
  
  
• Occasional muscle aches or headache.
  
  
• Low-grade fever.

Depending on the cause, symptoms may appear within a few hours to a few days after you're infected. Symptoms usually last a day or two but occasionally may persist as long as 10 days.

Because the symptoms are similar, it's easy to confuse viral diarrhea with diarrhea caused by bacteria such as salmonella and Escherichia coli (E. coli) and with parasites such as Giardia and Entamoeba, as well as Staphylococcus aureus — the most common cause of food poisoning.

E. coli infections are a particular concern. They can cause serious illness and even death. Older adults and young children are particularly vulnerable.

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Causes

You're most likely to contract viral gastroenteritis when you eat or drink contaminated food or water or share utensils, towels, or food with someone who's infected.

Some shellfish, especially raw or undercooked oysters, can make you sick if they're harvested from contaminated waters. Contaminated drinking water also can cause viral diarrhea. But in many cases, the virus is passed through the fecal-oral route — that is, someone with the virus handles food you eat without washing his or her hands after using the bathroom.

Rotavirus and the Norwalk virus are common causes of viral gastroenteritis:

• Rotavirus. This is the most common cause of infectious diarrhea in young children in the United States. Every year, thousands of American children are hospitalized and nearly 100 die due to complications of the infection. In other parts of the world, rotavirus causes the deaths of between 600,000 and 800,000 children annually. Although rotavirus is especially dangerous for children less than 1 year old, it can infect adults who are exposed to children with the virus. It's also a frequent cause of epidemics in nursing homes. Your child is likely to have rotavirus at least once before age 4, especially if he or she spends time in a child-care center. The risk is highest between 6 months and 24 months of age. Children are usually infected when they put their fingers or other objects contaminated with the virus into their mouths. Even tiny amounts of rotavirus may cause a serious illness. Signs and symptoms — which include diarrhea, nausea and vomiting — can range from mild to severe and last anywhere from 3 to 9 days. Your child may also have a low-grade fever, cramping, headache or muscle pain.
  
  
• Norwalk virus. The Norwalk virus generally affects older children and adults and is often called the winter vomiting disease. It can sweep through families and communities, leaving everyone it infects seriously ill. In addition to diarrhea, nausea and vomiting, you're likely to have muscle aches with this virus. In most cases you pick up the virus from contaminated food or water and are likely to feel sick within 4 to 72 hours.

If your immune system is compromised by the human immunodeficiency virus (HIV) or AIDS, you're at risk of other types of gastroenteritis. They include:

• Cytomegalovirus (CMV). Although otherwise healthy people with CMV may never develop symptoms, the virus can be extremely serious if you have HIV or AIDS. In addition to severe diarrhea, CMV may cause blurred vision or blindness, and pain, weakness, or numbness in your legs. The virus is spread through body fluids, such as saliva, blood, semen, urine, vaginal secretions and breast milk. Although you can get CMV from sexual activity, you can also get it if you simply touch infected fluids and then your mouth or nose. Mothers with CMV can pass the virus to their infants in their breast milk. You can also acquire CMV through blood transfusions or organ transplants. The best way to avoid infection is by using condoms and washing your hands thoroughly and often. If you expect to have a blood transfusion, talk to your doctor. Most blood banks don't screen for CMV.
  
  
• Herpes simplex virus. If you have a compromised immune system, you're at risk of gastrointestinal infections with the herpes simplex virus. Signs and symptoms include anal pain and bloody diarrhea. You may also have pain in the back of your thighs or tingling in your buttocks or anus. Warm sitz baths and pain relievers such as aspirin can ease some of these symptoms. In some cases the antiviral drug acyclovir (Zovirax) may make the initial attack less severe and help prevent future attacks.

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Risk Factors

Gastroenteritis occurs all over the world, affecting people of every age, race and background. In developing nations it's the leading cause of death in children.

In the United States, children in child-care centers and older adults living in nursing homes are especially vulnerable. That's because children's immune systems aren't mature until about age 6, and adult immune systems tend to become less efficient later in life.

But intestinal infections can flourish anywhere people congregate — from schools and dormitories to campgrounds and luxury cruise ships. Adults whose resistance is low — often because their immune systems are compromised by HIV, AIDS or other medical conditions — are especially at risk.

Each gastrointestinal virus has a season when it's most active. If you live in the Northern Hemisphere, you're more likely to get rotavirus or the Norwalk virus between October and April.

When To Seek Medical Advice

If you're an adult, call your doctor if you're not able to keep liquids down for 24 hours, if you're vomiting for more than 2 or 3 days, if you vomit blood or become dehydrated. Signs of dehydration include excessive thirst, dry mouth, deep yellow urine or little or no urine, and severe weakness, dizziness, or lightheadedness. In addition, seek medical care if you notice blood in your bowel movements or have a fever over 100 F.

See your doctor right away if your child has a temperature of 102 F or higher, seems lethargic or very irritable, is in a lot of discomfort or pain, has bloody diarrhea, or seems dehydrated. Watch for signs of dehydration in sick infants and children by comparing how much they drink and urinate with how much is normal for them.

If you have an infant, remember that while spitting up may be an everyday occurrence for your baby, vomiting is not. Babies vomit for a variety of reasons, many of which may require medical attention. Call your baby's doctor right away if vomiting lasts more than 3 hours or if your baby has any of the following signs and symptoms:

• Hasn't had a wet diaper in 8 hours
  
  
• Has bloody stools or severe diarrhea
  
  
• Has a dry mouth or cries without tears
  
  
• Is unusually sleepy, drowsy or unresponsive

Screening and Diagnosis

Your doctor will likely diagnose gastroenteritis based on your symptoms, a physical exam and sometimes on the presence of similar cases in your community. A rapid stool test can detect rotavirus, but there are no quick tests for other viruses that cause gastroenteritis. In some cases your doctor may have you submit a sample of your stool to rule out a possible bacterial or parasitic infection.

Complications

Dehydration — a severe loss of water and essential salts and minerals — is the most common serious complication of gastroenteritis. If you're a healthy adult and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration shouldn't be a problem. But infants, older adults and people with suppressed immune systems may become severely dehydrated when they lose more fluids than they can replace. In that case, they may need to be hospitalized and receive intravenous fluids. In extreme cases dehydration can be fatal.

Prevention

In 1998 a vaccine to help prevent the most serious effects of rotavirus in young children became available. But the drug was later withdrawn when it appeared to cause a rare intestinal disorder (intussusception) in some children. For now, the best way to prevent the spread of intestinal infections is to follow these common-sense measures:

• Wash your hands and your children's hands thoroughly. If your children are older, teach them to wash their hands, especially after using the bathroom. It's best to use warm water and soap and to rub hands vigorously for at least 10 seconds, remembering to wash around cuticles, beneath fingernails and in the creases of the hands. Then rinse thoroughly.
  
  
• Avoid sharing eating utensils, glasses and plates.
  
  
• Use separate towels in the bathroom.
  
  
• Avoid close contact with anyone who has the virus, if possible.
  
  
• Make sure child-care centers have separate rooms for changing diapers and preparing or serving food. The room with the diaper- changing table should have a sink as well as a sanitary way to dispose of diapers.

When you're traveling in other countries, you can become sick from contaminated food or water. To help reduce your risk:

• Drink only well-sealed bottled or carbonated water.
  
  
• Avoid ice cubes. Ice cubes may be made from contaminated water.
  
  
• Use bottled water to brush your teeth.
  
  
• Avoid raw food that has been touched by human hands. This includes peeled fruits, raw vegetables and salads.
  
  
• Avoid undercooked meat and fish.

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Self-Care

Unfortunately, there's often no specific medical treatment for gastroenteritis. Antibiotics aren't effective against most viruses, and overusing them can contribute to the development of antibiotic-resistant strains of bacteria. To help keep yourself more comfortable and prevent dehydration while you recover, try the following:

• Stop eating and drinking for a few hours until your stomach has settled.
  
  
• Try sucking on ice chips or taking small sips of water. You might also try drinking clear soda such as 7UP or Sprite, clear broths, or noncaffeinated sports drinks such as Gatorade. Adults should try to drink at least 8 to 16 glasses of liquid every day, taking small, frequent sips.
  
  
• Gradually begin to eat bland, easy-to-digest foods such as soda crackers, toast, gelatin, bananas, rice and chicken. Stop eating if your nausea returns.
  
  
• Avoid dairy products, caffeine, alcohol, nicotine, and fatty or highly seasoned foods until you're feeling better.
  
  
• Get plenty of rest.
  
  
• Use medications such as ibuprofen (Advil, Motrin) sparingly, if at all. They can make your stomach more upset. Use acetaminophen (Tylenol, generics) cautiously. It can cause liver toxicity, especially in children.

When your child has an intestinal infection, the most important goal is to replace lost fluids and salts. These suggestions may help:

• Give your child chips of ice to suck or water to sip. Water won't replace electrolytes, however. That's why the best choice may be an oral hydration solution such as Pedialyte. You can find these solutions in most grocery stores. Talk to your doctor if you have questions about how to use them. Avoid giving your child apple juice for rehydration. White grape juice is a good choice.
  
  
• Gradually introduce bland, easy-to-digest foods, such as toast, rice, bananas and potatoes.
  
  
• Avoid giving your child dairy products and sugary foods, such as ice cream, sodas and candy. These can make diarrhea worse.
  
  
• Make sure your child gets plenty of rest.
  
  
• Don't give children or teenagers aspirin. It may cause Reye's syndrome, a rare, but potentially fatal, disease. Avoid giving your child over-the-counter antidiarrheal medications such as Imodium unless advised by your doctor. They can make it harder for your child's body to eliminate the virus.

If you have a sick infant, let your baby's stomach rest for 30 to 60 minutes, then offer small amounts of liquid. If you're breast-feeding, let your baby nurse. If your baby is bottle-fed, offer a small amount of an oral rehydrating formula (Pedialyte, Kao Lectrolyte, Infalyte) or regular formula. Although your baby may be dehydrated, never dilute formula.

— September 24, 2001 —