What causes viral gastroenteritis?
Stomach virus is a highly contagious disease and it can affect anyone. Viruses are the major causes of gastroenteritis around the world. They account for 30-40% of acute diarrhea.
Stomach virus infection is self limiting and the infection subsides without any specific treatment. Vomiting and diarrhea due to stomach virus can cause dehydration. Vomiting and diarrhea treatment essentially involves correcting dehydration. Stomach virus can cause serious effects in infants, children and elderly individuals.
Stomach virus or viral gastroenteritis is not caused by any specific type of virus but by a variety of viruses. These include rotavirus, adenovirus type 40 and 41, norovirus, astrovirus and Torovirus. These viruses cause watery diarrhea in the affected individuals. The viruses affect the lining of the small intestine. The lining of the small intestine is damaged and this results in leakage of fluid causing watery diarrhea. The following are the viruses which are commonly associated with gastroenteritis.
Rotavirus, Calcivirus, Adenovirus, Astrovirus and Torovirus
Rotavirus is the common cause of diarrhea in children and affects children especially between 3 and 15 months of age. It is responsible for childhood diarrhea in 35% of hospitalized and 30% of community based cases. Adults can also get affected though they mostly remain asymptomatic and keep excreting the virus. The virus spreads by the fecal-oral route. In the temperate zones the infection occurs during winter whereas in the tropics it occurs year-round. Vomiting often heralds the illness and is followed shortly by watery diarrhea. The average duration of the illness is 5-7 days.
The calciviruses cause disease in all age groups. The calcivirus comprises of four different types of viruses of which the Norovirus is the most common one. The affected person develops symptoms within 1-3 days of infection and the illness lasts for about 24-48 hours.
Most adenoviruses cause upper respiratory infection. But the types 40 and 41 are responsible for gastroenteritis in children less than 2 years of age and in patients with AIDS. Adenoviruses are responsible for 5-10% of childhood diarrhea. Adenovirus infection can occur during anytime of the year. Unlike the other stomach viruses, adenovirus virus takes a longer time to cause symptoms. It may take up to 10 days before symptoms develop and the symptoms may persist for up to 2 weeks. Adults generally are protected from this infection except those in whom the immunity is compromised as in AIDS.
Astrovirus is a major cause of diarrhea in children. It is responsible for outbreaks of diarrhea in day-care centers and communities with children younger than one year of age. The affected child develops symptoms like watery or mucoid stools, vomiting and occasionally fever. Co-infections with other organisms can occur and repeated infection is also common.
Torovirus commonly affects children younger than 2 years of age. It accounts for 3% of childhood diarrhea. Torovirus can cause both acute and persistent diarrhea in children. Diarrhea is said to be persistent if it lasts for more than 14 days. Affected children have less of vomiting and more of bloody diarrhea. Children who develop persistent diarrhea due to Torovirus are often found to have infected with E.coli also.
Stomach virus is highly contagious. The virus can spread through fecal-oral route. People are exposed to these viruses through contaminated food and water. Affected persons can transmit the virus even after the symptoms subside as the virus is found in the stool even up to 2 weeks after the recovery.
Symptoms of stomach virus infection
The three most common symptoms of stomach virus infection are vomiting, diarrhea and fever. Of these three, diarrhea is invariably present and the other two symptoms may or may not be present in individuals who are affected.
As mentioned earlier, diarrhea is present in all the individuals affected with stomach virus. The viruses damage the inner lining of the small intestine resulting in leakage of fluids and subsequent watery diarrhea. Individuals affected with Torovirus may have bloody diarrhea. Excessive loss of fluids and electrolytes during multiple diarrheal episodes result in dehydration and electrolyte imbalance.
Vomiting may not be present in all those who are affected by stomach virus infection. Those who are affected by Torovirus may have lesser incidence of vomiting than diarrhea. Vomiting can result in dehydration and electrolyte imbalance.
Of the three symptoms mentioned, fever occurs less frequently than the other two.
Stomach virus infection and dehydration
Dehydration is the most common complication of stomach virus infection. It occurs due to loss of fluids from the body due to diarrhea and vomiting. Dehydration can cause symptoms like:
- Dry oral cavity
- Increased thirst
- Sunken eyes
- Decreased tears
- Decreased urine output
Vomiting and diarrhea treatment
The stomach virus infection is self limiting. It resolves over a period of time without any specific medication. Unlike bacterial diarrhea, diarrhea due to stomach virus does not respond to antibiotic treatment. The most important step in the management of stomach virus infection is correction of dehydration. The vomiting and diarrhea treatment essentially involves administration fluids and electrolytes.
Clear liquids should be taken in small sips of 2 ounces every 15 minutes. Dairy products and citrus should be avoided. Some of the fluids that are usually recommended are:
- Diluted fruit juices ( apple juice or grape juice)
- Clear broth
- Caffeine free beverages
- Oral rehydration solutions like Pedialyte, Enfalyte, LiquiLyte, or Rehydralyte
Clear fluids should be taken as mentioned above. Once the vomiting subsides, solid foods should be taken. The recommended food include:
- White toast
If the affected child is breastfed, mother should continue breastfeeding. If the affected individual has severe dehydration or persistent vomiting which does not allow oral intake of fluids, then the person should be hospitalized and intravenous fluids should be administered to correct dehydration.
Medications like loperamide which act on the intestine to stop diarrhea should not be used in cases of diarrhea due to any infection. This type of medications is usually given for diarrhea which is not due to infection.
BRAT diet is commonly prescribed by doctors while treating individuals who are affected with diarrhea. BRAT is an acronym and it stands for Banana, Rice, Apple sauce and Toast. BRAT diet however should not be the exclusive diet during the treatment of diarrhea. It may be added to normal, age appropriate diet that is tolerated. Since BRAT diet is low in protein, fats and fibers, the American Academy of Pediatrics has advised that children affected by stomach virus should resume eating normal well balanced diet within 24 hours of getting sick and this should include fruits, vegetables and yogurt.