Gastroenteritis

Gastroenterology (12%) Core Clinical Conditions

1A: Able to diagnose and manage

Jump to content

Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management

Gastroenteritis is a commonly occurring medical condition that refers to the inflammation or irritation of the stomach and the intestines. It is typically caused by an infection, most commonly viral or bacterial, but can also be caused by parasites or toxins.

1. Viruses: Viral gastroenteritis is the most common form of this illness. Several types of viruses can cause gastroenteritis, including rotavirus, norovirus, adenovirus, and arbovirus. These viruses are highly contagious and can spread through person-to-person contact, contaminated food or water, or contact with infected surfaces. Outbreaks of viral gastroenteritis often occur in crowded places such as schools, nursing homes, or cruise ships.

2. Bacteria: Certain types of bacteria can also cause gastroenteritis. The most well-known is perhaps Salmonella, which is usually transmitted through contaminated food, such as undercooked poultry or eggs. Another common bacterium responsible for gastroenteritis is Campylobacter, often found in raw or undercooked meat, unpasteurized milk, or contaminated water. Other bacteria, including Escherichia coli (E. coli) and Shigella, can also cause gastroenteritis, usually due to consumption of contaminated food, water, or poor hygiene habits.

3. Parasites: Gastroenteritis caused by parasites is less common but can occur, particularly in developing countries with limited access to clean water and sanitation. Giardia and Cryptosporidium are two common parasites that cause gastroenteritis. These parasites are usually transmitted through contaminated water or food, and they can survive for long periods in the environment.

4. Toxins: Certain toxins produced by bacteria can lead to gastroenteritis. For example, the Staphylococcus aureus bacteria release a toxin that causes symptoms similar to gastroenteritis when ingested through contaminated food. Similarly, the bacteria Clostridium difficile produces a toxin that can damage the lining of the intestines, leading to diarrhoea and abdominal pain.

5. Non-infectious Causes: Not all cases of gastroenteritis can be attributed to infectious agents. Non-infectious causes, such as food allergies, intolerances, medications, or certain medical conditions like inflammatory bowel disease, can also lead to similar symptoms.

The initial stage of gastroenteritis involves the invasion of the gastrointestinal tract by pathogens. Viruses such as norovirus, rotavirus, and adenovirus, and bacteria like Escherichia coli, Salmonella, and Campylobacter, are common culprits in causing this distressing condition. These pathogens often enter the body through contaminated food or water, or by direct contact with infected individuals.
Once the pathogens find their way into the gastrointestinal tract, they target the epithelial cells lining the intestines. In the case of viral gastroenteritis, viruses infect the epithelial cells of the small intestine primarily, whereas bacterial gastroenteritis can involve various parts of the gastrointestinal tract. The pathogens adhere to the epithelial cell surface and launch their offensive manoeuvres.
Under normal circumstances, the epithelial cells play a vital role in maintaining the integrity and function of the gut. These cells are responsible for absorbing nutrients and fluids while acting as a barrier against harmful agents. However, during an episode of gastroenteritis, the pathogens disrupt these functions and inflict damage on the delicate epithelial layer.
This disruption triggers various pathophysiological processes. The pathogens release toxins or enzymes that compromise the integrity of the epithelial barrier, leading to increased permeability. Consequently, there is an influx of fluid and electrolytes into the intestinal lumen, impairing the absorption function of the gut and resulting in diarrhoea. Additionally, the release of inflammatory mediators, such as cytokines, induces inflammation and further exacerbates gastrointestinal symptoms.
The disruption of the intestinal barrier also disturbs the intricate balance of the gut microbiota. The gut microbiota, comprising various beneficial bacteria, plays a pivotal role in maintaining the overall health of the gastrointestinal tract. However, the invasion of pathogens in gastroenteritis alters this delicate balance and reduces the abundance of beneficial bacteria, allowing the pathogens to gain further foothold and perpetuate the infection.
Furthermore, the body's immune response comes into play during gastroenteritis. The immune system launches an inflammatory response to combat the invading pathogens, aiming to eradicate the infection. This immune response manifests as symptoms such as fever, abdominal pain, vomiting, and nausea. However, an overly robust immune response can sometimes lead to collateral damage, causing tissue inflammation and destruction.
As the body fights off the infection, the gastrointestinal tract gradually recovers. The epithelial cells regenerate, and the intestinal barrier is restored. The gut microbiota also returns to its normal state, promoting a healthy gut environment once again.

1. Contaminated Food and Water: Consuming food or water that is contaminated with bacteria, viruses, or parasites is a significant risk factor for developing gastroenteritis. Improperly stored or undercooked food, as well as untreated water sources, can introduce harmful pathogens into the body.

2. Poor Hygiene: Inadequate hand hygiene plays a significant role in the spread of gastroenteritis. Failing to wash hands thoroughly with soap and water, especially after using the bathroom or before handling food, can facilitate the transmission of viruses and bacteria.

3. Close Contact with Infected Individuals: Being in close proximity to someone who has gastroenteritis increases the risk of contracting the illness. Direct contact with infected individuals through activities such as caring for sick family members, sharing utensils, or touching contaminated surfaces can rapidly spread the causative agents.

4. Weakened Immune System: People with weakened immune systems, such as individuals with HIV/AIDS, undergoing chemotherapy, or those with certain chronic conditions, are at a higher risk of developing gastroenteritis. Their compromised immune systems make it more difficult for the body to fight off pathogens effectively.

5. Age: Infants, young children, and the elderly are particularly susceptible to gastroenteritis due to immature or weakened immune systems. This vulnerability increases the risk of severe complications and dehydration, requiring prompt medical attention.

6. Traveling to High-Risk Areas: Visiting regions with poor sanitation and hygiene practices increases the risk of acquiring gastroenteritis. Developing countries or areas with limited access to clean water and proper sewage systems may harbor infectious agents that can cause the illness.

7. Community Settings: Certain community settings, such as daycare centres, schools, nursing homes, and cruise ships, can facilitate the rapid spread of gastroenteritis. The close interaction between individuals in these environments makes it easier for the illness to pass from person to person.

1. Abdominal Pain: Gastroenteritis is often characterized by abdominal cramps and discomfort. The pain may range from mild to severe and can be centralized or diffuse across the entire abdomen.

2. Nausea and Vomiting: Nausea is a common symptom of gastroenteritis, typically followed by episodes of vomiting. These gastrointestinal disturbances can be quite distressing and may lead to dehydration if they persist.

3. Diarrhoea: Another hallmark symptom of gastroenteritis is Diarrhoea. This refers to the passage of loose, watery stools, often accompanied by an urgent need to use the bathroom frequently. Diarrhoea can lead to dehydration, especially in young children and the elderly.

4. Fever: Many cases of gastroenteritis are accompanied by fever. This elevation in body temperature can range from mild to high-grade, and it is the body's response to fight off the infection causing the illness.

5. Loss of Appetite: Gastroenteritis can also lead to a loss of appetite. The feeling of fullness, coupled with nausea and abdominal discomfort, often results in decreased food intake.

6. Fatigue: Gastroenteritis can cause fatigue and generalized weakness, making individuals feel drained and exhausted. This can be a result of dehydration, lack of nutrition, or the body's effort to combat the infection.

7. Headache and Body Aches: Some individuals with gastroenteritis may experience headaches and body aches. These symptoms are often associated with viral infections and can contribute to overall discomfort and malaise.

8. Dehydration: Due to the excessive loss of fluids from vomiting and diarrhoea, dehydration is a common complication of gastroenteritis. Symptoms include dry mouth, decreased urine output, dark-coloured urine, and feeling lightheaded or dizzy.

• Patient History: The initial step in diagnosing gastroenteritis involves obtaining a comprehensive patient history. Mainly the duration and severity of Diarrhoea, presence of blood in stool, recent travel, exposure to contaminated water or food, and any underlying medical conditions that may contribute to gastrointestinal issues.

• Physical Examination: a physical examination may aid in assessing the patient's overall condition. Check for signs of dehydration, such as dry mucous membranes, reduced skin elasticity, and rapid heart rate. The examination may also reveal abdominal tenderness, distention, or abnormal bowel sounds, which could further support a diagnosis of gastroenteritis.

• Stool Sample Analysis: a fresh sample is collected and sent to a laboratory for testing. Microbiological examination is conducted to identify the causative agents, including bacteria, viruses, or parasites. This test helps differentiate between infectious and non-infectious causes of gastroenteritis, guiding proper treatment decisions.

• Blood Tests: Blood tests can be useful in investigating gastroenteritis, especially when systemic symptoms are pronounced or concerning. A full blood count (FBC) can reveal elevated white blood cell counts, indicating an inflammatory response.

• Imaging Studies: In certain cases, imaging studies may be employed to investigate gastroenteritis further. Abdominal X-rays or ultrasounds can help identify any structural abnormalities, such as bowel obstruction or appendicitis, which may mimic or complicate the symptoms of gastroenteritis. These imaging techniques are crucial in ruling out other potential causes and evaluating the severity of the condition.

• Oral rehydration therapy is recommended as the first line of treatment for mild to moderate cases.

• In cases where oral rehydration is not possible or if the patient's condition worsens, intravenous fluid therapy may be necessary.

• If necessary, antiemetic medications can be considered to alleviate nausea and vomiting.

• Good hygiene practices. This includes regular handwashing with soap and water, particularly after using the toilet and before handling food.

• Advice people affected by gastroenteritis should refrain from attending school or work until at least 48 hours after the last episode of diarrhoea or vomiting to minimize the risk of transmission to others.

Jump to other topics below: