What is Viral Gastroenteritis?
Acute infectious gastroenteritis, simply put, is a common stomach bug found globally. It is usually caused by viruses. It often results in short-term diarrhea, especially in developed countries, but can greatly affect the health of young or elderly people. In less developed countries, these viral stomach bugs are a major reason for death, particularly among infants.
As reported by the Centers for Disease Control, these stomach bugs lead to over 200,000 deaths among children worldwide each year. Symptoms include nausea, vomiting, diarrhea, loss of appetite, weight loss, and dehydration. While a person can get the disease individually, it’s generally seen in outbreaks in close-knit communities such as daycare centers, nursing homes, and even cruise ships.
Many different viruses can cause these symptoms, but in a typical medical environment, the exact virus causing the disease is typically not identified. Despite this, the treatment remains the same across different viruses and mainly focuses on improving symptoms and ensuring hydration.
In developed countries like the United States, this disease usually resolves itself within 1 to 3 days. However, for those who are at risk (like young children, elderly individuals, and people with low immune system), hospital care can be necessary if supportive care (like stays and treatment in hospitals) is not provided. This can lead to severe health issues or even death.
What Causes Viral Gastroenteritis?
Several types of viruses, including rotavirus, norovirus, adenovirus, and astroviruses, are the most common reasons for strong bouts of stomach flu, otherwise known as acute viral gastroenteritis. These viruses generally spread when people come in contact with an infected person’s stool, or through eating contaminated food and drinking contaminated water. There is also evidence to suggest that viruses can spread through contaminated surfaces, vomit, and possibly even through the air. Norovirus is specifically a bit harder to kill, even with common sanitizers like chlorine or alcohol.
Rotavirus is named after its wheel-like appearance when seen under a microscope. This virus is very common, with almost all children around the world carrying antibodies against it by the age of 3. Rotavirus typically starts with severe vomiting, which is then followed by several days of diarrhea, stomach cramps, loss of appetite, and mild fevers. Young children who become severely dehydrated are more likely to have rotavirus than other stomach flu viruses. This virus can remain in the body and be spread through stool for up to 10 days. Adults who get infected usually won’t show symptoms, but their bodies will produce more antibodies.
Rotavirus was once the most common cause of severe stomach illness in infants all over the world. However, the number of cases has drastically decreased since an oral vaccine was introduced in 2006. Despite this, rotavirus is still responsible for many deaths among children worldwide, mainly in areas where vaccines aren’t readily available.
Norovirus is another common cause of stomach flu, responsible for more than 90% of the outbreaks. This virus is resilient, and it can survive freezing temperatures, heat, and many disinfectants containing alcohol or chlorine. Norovirus infection usually presents with stomach cramps and nausea, which are then followed by vomiting and/or diarrhea. The symptoms of Norovirus usually last for about 3 days, and most patients recover without any lasting effects. However, elderly people and patients with weakened immune systems may experience a more severe and prolonged illness.
Other viruses like adenovirus, Sapovirus, and astrovirus can cause 2% to 9% of stomach flu cases. These viruses are more common in kids than in adults, especially in less developed countries.
Risk Factors and Frequency for Viral Gastroenteritis
Acute viral gastroenteritis, or a stomach virus, is the most common cause of diarrhea around the world. It affects men and women equally. Responsible for 90% of worldwide diarrhea epidemics and nearly half of all stomach viruses, Norovirus is the top culprit. It accounts for an estimated 19 to 21 million cases of diarrhea sickness every year in the United States alone. In fact, Norovirus is the cause of half of all food poisoning instances related to diarrhea.
Prior to the widespread use of vaccines, the rotavirus was the primary cause of diarrhea in children, leading to approximately 3.5 million cases each year inside the U.S. Almost all kids would have had the rotavirus by the time they turned three. Worldwide, rotavirus caused 440,000 deaths per year. But since vaccinations have been implemented in 2006, the incidence of this virus in the U.S. dropped by 50% to 90% each year.
With more countries starting to regularly vaccinate against rotavirus, the overall number of cases is expected to continue going down. Other viruses like adenovirus, Sapovirus, and astrovirus are responsible for between 2% and 9% of cases around the world, with children more likely to contract them than adults.
Signs and Symptoms of Viral Gastroenteritis
Acute gastroenteritis describes a condition where you experience loose or watery stools more than three times in a day. Additional symptoms may include feelings of nausea, vomiting, a fever, or discomfort in the stomach region. These symptoms usually go away within a week, and often improve after just one to three days. If any symptoms persist for more than two weeks, they are classified as chronic and not as acute gastroenteritis. Patients typically complain about these symptoms starting rather abruptly within a span of one to two hours. Such cases can sometimes be found among family members or close contacts. It’s common to experience a mild fever and subtle stomach discomfort. Vomiting is a symptom for most people, but not everyone. More serious symptoms include high fever, bloody stool, prolonged vomiting, or severe stomach pain. These might suggest to a healthcare professional that another disease may be causing the symptoms. Information about factors like travel history, recent use of antibiotics, exposure to diseases, work-related risks, and immune status can be helpful in identifying the cause. Particular care should be directed towards babies, the elderly, and people with weakened immune systems due to disease or medication.
During a physical exam, any signs of health problems should be noted. While a mild fever is normal in viral gastroenteritis, a high fever (above 39 C) could indicate a non-viral cause. Rapid heart rate and breathing could be due to fever and dehydration. Patients should be checked for dehydration, especially those at high risk such as the very young, the elderly, those with chronic illness, or immunosuppressed individuals. These patient groups face a greater threat of serious complications due to dehydration. Abdominal tenderness might also be felt during the physical examination. However, severe tenderness, significant guarding, rebound, or pointed tenderness may point the healthcare professional toward other causes of the symptoms.
Testing for Viral Gastroenteritis
In many clinics and emergency departments, testing for viruses isn’t easily available. So, if you’re feeling unwell and your doctor thinks you might have viral gastroenteritis, also known as a stomach virus, the diagnosis will be based more on your symptoms rather than a specific test. If you seem well-hydrated and aren’t at risk of severe illness, you probably won’t need further testing.
The tests your doctor might use are mainly to rule out other causes of your symptoms. A complete blood count might show a slight increase in white blood cells, which can be a sign of viral gastroenteritis. Other markers that can show inflammation might also be slightly elevated. If you’ve become significantly dehydrated, tests might show a concentration of red and white blood cells and platelets in your blood, as well as disturbances in the balance of your body’s electrolytes, which are minerals that help your body function properly. Dehydration can also lead to acute kidney injury, which would show up on a chemistry panel test as changes in the levels of BUN (blood urea nitrogen) and creatinine, waste products that your kidneys normally filter out of your blood.
If you have imaging studies of your abdomen done, they’ll most likely look normal. CT scans might show slight thickening of the wall of your colon or other changes in your bowel, but these signs aren’t specific to viral gastroenteritis. A CT scan should only be done to rule out other, more severe causes of your symptoms. Stool studies might be done, but the tests that are readily available in labs usually only look for bacterial causes, not specific viral ones. If your stool is bloody, if you have a high fever, severe abdominal pain, or severe dehydration, stool studies might be needed, as these symptoms don’t usually occur with a simple stomach virus.
Treatment Options for Viral Gastroenteritis
Treatment of viral gastroenteritis, also known as the stomach bug, is primarily focused on relieving symptoms. The main goal of treatment is to prevent dehydration and replace any fluid and electrolytes that have been lost due to vomiting or diarrhea. For this, fluid therapy, providing fluids either orally or through an IV, is essential.
Doctors could provide IV fluids if a person is significantly dehydrated or cannot keep fluids down. Anti-nausea medications, such as ondansetron or metoclopramide, may be given to help control symptoms of nausea and vomiting. In more severe cases, if a person is extremely dehydrated or cannot stop vomiting, they may need to be admitted to the hospital for ongoing IV fluids and careful monitoring of their electrolyte levels. Electrolytes are minerals that help balance the amount of water in your body and are essential for your nerves, muscles, heart, and brain to function properly.
There’s a bit of debate regarding the use of medications to stop diarrhea. Some doctors don’t recommend antidiarrheal drugs like diphenoxylate/atropine or loperamide for patients 65 or older. Younger patients might benefit from these medications. However, some doctors believe that if a patient is staying well hydrated, there’s no need to take antidiarrheal medication.
For rehydration, some research suggests that rehydration solutions containing electrolytes, which are available in drug stores, work better than sports drinks or other forms of oral rehydration. But other research suggests that there’s no difference between drinking these special solutions or other liquids of your choice, especially for children with mild dehydration.
There’s no universal diet advice for patients with viral gastroenteritis. Some suggest sticking to bland foods like bananas, rice, apples, tea, and toast. But research hasn’t shown a significant difference in recovery between this diet and regular diets.
Most adults can safely recover from viral gastroenteritis at home. It often helps adults to have anti-nausea medication on hand, although this is generally not recommended for young children. People might need to be hospitalized if they show signs of severe dehydration, can’t stop vomiting, have major changes in electrolyte levels, are experiencing acute kidney failure, severe stomach pain, or are pregnant.
What else can Viral Gastroenteritis be?
Acute viral gastroenteritis, or the stomach flu, usually gets better on its own in developed countries. But still, doctors need to watch out for and rule out other serious conditions that could be causing the same symptoms. Food poisoning due to bacterial toxins can cause symptoms very similar to the stomach flu. The treatment for both is often the same.
However, some types of gastroenteritis caused by bacteria and tiny parasites could mimic the symptoms of the stomach flu, but often need different treatments and may have more serious health risks. Bugs like Salmonella, E. Coli, Shigella, Campylobacter, Giardia lamblia, and C. Difficile could cause similar symptoms and should be considered in patients whose symptoms don’t match the usual ones for the stomach flu.
Doctors also need to consider other abdominal conditions if the patient’s history or physical exam hints at them. Conditions like:
- Acute appendicitis
- Diverticulitis
- Inflammatory bowel disease
- Bowel obstruction
- Cholecystitis (gallbladder inflammation)
These should be checked if necessary since these diseases are often mistaken for viral gastroenteritis. Even viral upper respiratory illnesses and certain types of bacterial pneumonia can look like the stomach flu.
What to expect with Viral Gastroenteritis
In most instances, the prognosis or predicted outcome is positive. The majority of the time, the condition resolves itself. Nevertheless, it’s crucial that individuals keep themselves hydrated by drinking fluids even if they don’t seek medical assistance. It’s worth noting that in the very old, very young, or those with a weakened immune system, death can sometimes occur.
Currently, a group of viruses known as Calciviruses are associated with more fatalities than rotaviruses, which is another type of virus. Noroviruses, which are a type of Calcivirus, have been responsible for many severe diarrhea outbreaks in nursing homes. Newer and more aggressive strains of norovirus are emerging and continue to present a challenging health concern.
