Diarrhea is defined as loose bowel movements with or without vomiting. Acute diarrhea is usually sudden in onset and lasts for only a limited time. This is usually called gastroenteritis and is caused by several pathogens leading to infection of the gastrointestinal tract.  

The pathogens causing acute diarrhea may include several bacteria, viruses, or parasites. There are several non-infectious causes of acute diarrhea as well but these are usually less common.

Acute diarrhea usually stops in a few days to a week but carries the risk of dehydration especially in children and the elderly.

In case of identification of the causative pathogen, an antibiotic or an anti-parasitic agent may be used. If the cause is a virus, the antibiotics are not effective.

Symptoms of acute diarrhea

Acute diarrhea usually begins suddenly. The bowel motions are loose and frequent. In children and babies the motions may be involuntary as well.

Viral diarrhoeas are usually watery in nature with little or no fecal matter. In some forms of acute diarrhea there may be presence of blood in the stools. This may be more common if bacteria are the cause of acute diarrhea.

There may be accompanying vomiting along with diarrhea. Other symptoms may include abdominal cramps and fever. Fever is commonly seen in bacterial and viral diarrhoeas.

Causes of acute diarrhea

There are many possible causes of gastroenteritis. The most common causes include:

• Viruses – Rotavirus, Norovirus, enteric adenoviruses. Diarrhea caused by viruses usually goes away on its own and there is no need for antibiotics
• Bacteria - Diarrhea can be caused by infections with bacteria such as Salmonella, Shigella, Escherichia coli, Campylobacter etc. These usually spread by contaminated food and water. Some of these infections are treated with antibiotics.
• Parasites – Several parasite infestations may cause diarrhea. Common ones include Giardia lamblia, Strongyloides, Cryptosporidium etc. These infections are common in travellers. Antiparasitic agents are used in parasitic infestations.
• Other causes include food allergies, food poisoning etc.

Possible complications of diarrhea

The main and most important complication of diarrhea is dehydration. Diarrhea leads to loss of water and essential electrolytes and chemicals from the body. Vomiting also leads to water and electrolyte loss.

Dehydration is more common and deteriorates rapidly especially in children and infants.

Symptoms of dehydration

• In adults:-
  • Increased thirst
  • Fatigue, dizziness and light headedness
  • Loss of appetite
  • Nausea
  • Dry tongue
  • Sunken eyes
  • Muscle cramps
  • Rapid heart rate
• In children:-
  • Increased thirst
  • Cold, pale and clammy skin
  • Irritable or drowsy
  • Passing urine infrequently and passing dark coloured urine
  • Cold hands and feet
  • Dry tongue
  • Sunken eyes and no tears
  • There are sunken cheeks and sunken soft spot over the skull
  • Skin stays pinched up and takes time to return to normal.
  • Severe dehydration includes symptoms of no tears when crying and excessive sleepiness and drowsiness.

Prevention of acute diarrhea

Diarrhea due to infections can be prevented by maintaining good hygiene, hand washing before eating, and preparing foods and after using the toilet.

Treatment of acute diarrhea

If the cause of the diarrhea is detected, and it is due to bacteria or parasites, agents useful against these pathogens may be used.

Dehydration should be prevented in all cases by ensuring adequate fluid intake. Special solutions, such as Pedialyte may be used to replace lost body fluids as well as electrolytes.