Gastroenteritis: everything you need to know about causes, symptoms and treatment

Introduction

Gastroenteritis is an inflammation of the lining of the stomach and intestines, causing symptoms such as diarrhea, nausea, vomiting, and abdominal cramps. It is an infectious disease caused by viruses, bacteria, or parasites, transmitted through the ingestion of contaminated food or water, or through contact with an infected person or object. Gastroenteritis is a very common disease, affecting millions of people each year worldwide. It can be mild and resolve spontaneously in a few days, or be more severe and require medical care.

Who is at risk?

Anyone can get gastroenteritis, but some people are more vulnerable than others. Children, the elderly, pregnant women, travelers, and those with weakened immune systems are more likely to develop gastroenteritis and suffer complications. The risk factors for gastroenteritis depend on the type of infectious agent involved. For example, rotavirus gastroenteritis is more common in young children, while norovirus gastroenteritis is more common in adults. Escherichia coli gastroenteritis is often associated with food poisoning from animal products, while Campylobacter gastroenteritis is related to drinking non-potable water.

Symptoms of Gastroenteritis

Gastroenteritis presents with clinical signs primarily affecting the digestive system. These symptoms can vary in intensity and duration depending on the cause of the infection, the age, and the health status of the affected person. Recognizing the symptoms of gastroenteritis is important for effective treatment and avoiding complications.

Main symptoms

The main symptoms of gastroenteritis are:

• Diarrhea: This is an increase in the frequency and fluidity of stools, which can be soft, liquid, or watery. Diarrhea may be accompanied by blood, mucus, or pus in the stools, depending on the cause of the infection.
• Vomiting: This is the forceful expulsion of stomach contents through the mouth. Vomiting may be preceded by nausea, which is a feeling of discomfort and disgust.
• Abdominal pain: These are painful sensations located in the belly, which can be cramps, spasms, burns, or twists. Abdominal pain can be diffuse or localized to a specific area, depending on the cause of the infection.
• Fever: This is an increase in body temperature above normal, which is generally 37°C. Fever can be moderate (between 38°C and 39°C) or high (above 39°C), depending on the cause of the infection.
• Loss of appetite: This is a decrease or absence of desire to eat, which may be due to nausea, vomiting, abdominal pain, or fatigue.
• Fatigue: This is a state of physical and mental weakness, which may be due to the loss of fluids and minerals, fever, inflammation, or infection.
• Dehydration: This is excessive loss of fluids and minerals by the body, which can be caused by diarrhea, vomiting, fever, or sweating. Dehydration is characterized by intense thirst, dry mouth, decreased amount and frequency of urine, dry and cold skin, sunken eyes, rapid and weak pulse, low blood pressure, dizziness, headaches, confusion, or drowsiness.
• Headaches: These are painful sensations in the head, which may be due to dehydration, fever, inflammation, or infection.

When to consult a doctor?

Gastroenteritis is generally a mild disease that resolves spontaneously in a few days, with proper hydration and appropriate diet. However, it is recommended to consult a healthcare professional in the following cases:

• If the symptoms are severe or persistent (more than 48 hours for adults, more than 24 hours for children)
• If the symptoms are accompanied by signs of dehydration, blood or pus in the stools, high fever, intense or localized abdominal pain, uncontrollable vomiting, or significant headaches
• If the affected person is an infant, a child, an elderly person, a pregnant woman, an immunocompromised individual, or someone suffering from a chronic disease (diabetes, renal insufficiency, inflammatory bowel disease, etc.)
• If the affected person has recently traveled to a country with precarious hygiene conditions or where certain infectious diseases are endemic (typhoid, cholera, dysentery, etc.)

A medical consultation allows for a diagnosis, identification of the cause of the infection, prescription of appropriate treatment, and prevention of complications.

Causes of Gastroenteritis

Gastroenteritis is an inflammation of the lining of the stomach and intestines, which can have different causes. It is most often an infection by a virus, bacteria, or parasite, but it can also be a reaction to a chemical toxin or a medication. The causes of gastroenteritis can influence the symptoms, mode of transmission, treatment, and prevention of the disease. Here are the main causes of gastroenteritis:

Viral Gastroenteritis

Viral gastroenteritis is the most common cause of the disease, accounting for about 66% of cases. The viruses responsible for gastroenteritis are numerous and varied, but the most common are rotavirus, norovirus, adenovirus, calicivirus, and astrovirus. These viruses are mainly transmitted via the fecal-oral route, i.e., through contact with infected feces, directly or indirectly (for example, through contaminated objects, surfaces, or food). Viral gastroenteritis typically presents with watery diarrhea, vomiting, abdominal pain, and fever. It is often mild and resolves spontaneously in a few days without specific treatment. The main complication is dehydration, which can be prevented by proper hydration. Vaccines exist against some viruses, such as rotavirus, which can reduce the risk of gastroenteritis in children.

Bacterial Gastroenteritis

Bacterial gastroenteritis is the second most common cause of the disease, accounting for about 20% of cases. The bacteria responsible for gastroenteritis are also numerous and varied, but the most common are Salmonella, Campylobacter, Shigella, Escherichia coli, Vibrio, Yersinia, and Clostridium difficile. These bacteria are mainly transmitted through the ingestion of food or water contaminated with infected feces, causing food poisoning. The most commonly involved foods are minced meat, leafy vegetables, shellfish, unpasteurized dairy products, and eggs. Bacterial gastroenteritis typically presents with bloody diarrhea, vomiting, abdominal pain, fever, and sometimes general signs such as chills, headaches, or muscle aches. It can be more severe and longer-lasting than viral gastroenteritis and may require antibiotic treatment. The main complication is dehydration, which can be prevented by proper hydration. There is no vaccine against the bacteria that cause gastroenteritis, but good food hygiene can reduce the risk of contamination.

Parasitic Gastroenteritis

Parasitic gastroenteritis is the least common cause of the disease, accounting for less than 10% of cases. The parasites responsible for gastroenteritis are mainly protozoa, such as Entamoeba histolytica, Cryptosporidium, and Giardia. These parasites are also transmitted via the fecal-oral route, through the ingestion of food or water contaminated with infected feces. Parasitic gastroenteritis typically presents with chronic diarrhea, bloating, flatulence, abdominal pain, and weight loss. It can last several weeks or months and may require antiparasitic treatment. The main complication is malnutrition, which can be prevented by a balanced diet. There is no vaccine against the parasites that cause gastroenteritis, but good food hygiene and safe drinking water can reduce the risk of contamination.

Transmission of Gastroenteritis

Gastroenteritis is a highly contagious disease that can be transmitted in different ways. It is important to know the modes of transmission of gastroenteritis to adopt appropriate preventive measures and avoid spreading the infection. Here are the main modes of transmission of gastroenteritis:

Interhuman Transmission

Interhuman transmission of gastroenteritis occurs through direct or indirect contact with an infected person. Direct contact can occur through saliva, sneezing, coughing, kissing, or sexual intercourse. Indirect contact can occur through hands, objects, surfaces, or foods contaminated with infected feces or vomit. The viruses, bacteria, or parasites that cause gastroenteritis can survive several hours or even days on inert supports and thus be transmitted to other people. Interhuman transmission of gastroenteritis is more common in the winter period, when people live more confined and share more common spaces. It is also more frequent in places with a high concentration of people, such as daycare centers, schools, hospitals, nursing homes, public transport, or public places.

Transmission via Food and Water

Transmission via food and water of gastroenteritis occurs through the ingestion of contaminated food or drinks with infected feces or vomit. It is often food poisoning, which can be caused by viruses, bacteria, or parasites. The most commonly involved foods are minced meat, leafy vegetables, shellfish, unpasteurized dairy products, and eggs. Water can also be contaminated by sewage, runoff water, surface water, or groundwater. Transmission via food and water of gastroenteritis is more common in countries where hygiene conditions are precarious or where certain infectious diseases are endemic, such as typhoid, cholera, dysentery, or amebiasis. It can also occur during travels abroad, where the body is not accustomed to the local microbial flora.

Diagnosis of Gastroenteritis

The diagnosis of gastroenteritis is based on the patient’s history and clinical examination. It may also require certain additional tests, depending on the suspected cause, the severity and duration of the disease, and the risk of complications. Here are the main methods of diagnosing gastroenteritis:

Diagnostic Methods

The diagnostic methods for gastroenteritis are as follows:

• Anamnesis: it consists of collecting the following information:
  • The present symptoms, their onset date, frequency, intensity, and evolution
  • Personal and family medical history, including chronic diseases, allergies, ongoing treatments, vaccinations, and surgical interventions
  • Dietary habits, including consumption of animal products, dairy products, raw fruits and vegetables, tap water, or uncontrolled sources
  • Recent travels, especially to countries with precarious hygiene conditions or where certain infectious diseases are endemic
  • Contacts with sick people or animals, or carriers of germs responsible for gastroenteritis

• Physical examination: it involves assessing the general condition, degree of dehydration, temperature, pulse, blood pressure, respiratory rate, weight, and height of the affected person. It also includes an examination of the abdomen, looking for signs of pain, distension, mass, or peritonitis. A rectal examination may be performed to detect the presence of blood, mucus, or pus in the stool.
• Blood tests: they measure the levels of white blood cells, red blood cells, platelets, electrolytes, creatinine, urea, proteins, liver enzymes, bilirubin, and other parameters. They can reveal an infection, inflammation, anemia, dehydration, renal failure, liver damage, or other anomalies.
• Stool tests: they search for the presence of blood, mucus, pus, parasites, bacteria, viruses, or toxins in the stool. They can be done by microscopic examination, culture, immunological test, antigenic test, molecular test, or antibiotic sensitivity test. They can identify the cause of gastroenteritis and guide treatment.
• Other tests: they may be indicated in certain cases, especially if the gastroenteritis is severe, persistent, recurrent, or associated with signs of severity. It can involve an abdominal X-ray, abdominal ultrasound, digestive endoscopy, intestinal biopsy, or functional coproscopy.

Alternative Diagnoses

The diagnosis of gastroenteritis must be differentiated from other diseases that can cause similar symptoms, such as diarrhea, vomiting, abdominal pain, or fever. These diseases can be of digestive or non-digestive origin and require specific management. Among these diseases, we can mention:

• Appendicitis: This is an inflammation of the appendix, a small organ located at the junction of the small intestine and the colon. It manifests as intense abdominal pain, localized in the lower right quadrant, which worsens with pressure, movement, or coughing. It can be accompanied by nausea, vomiting, fever, loss of appetite, or constipation. It requires urgent surgical intervention to prevent perforation of the appendix and peritonitis.
• Diverticulitis: This is an inflammation of diverticula, which are small pouches that form in the wall of the colon. It manifests as abdominal pain, localized in the lower left quadrant, and can be accompanied by fever, chills, nausea, vomiting, diarrhea, or constipation. It requires antibiotic treatment and sometimes surgical intervention in case of complications.
• Crohn’s Disease: This is a chronic inflammatory disease of the intestine, which can affect any part of the digestive tract, from the mouth to the anus. It manifests with abdominal pain, often located in the lower right quadrant, and can be accompanied by diarrhea, blood or mucus in the stool, fever, weight loss, anemia, or fistulas. It requires medication treatment with anti-inflammatories, immunosuppressants, or anti-TNF, and sometimes surgical intervention in case of complications.
• Ulcerative Colitis: This is a chronic inflammatory disease of the intestine, which only affects the colon and rectum. It manifests with abdominal pain, often located in the lower left quadrant, and can be accompanied by diarrhea, blood or pus in the stool, fever, weight loss, anemia, or rectitis. It requires medication treatment with anti-inflammatories, immunosuppressants, or anti-TNF, and sometimes surgical intervention in case of complications.
• Irritable Bowel Syndrome: This is a functional disorder of the intestine, characterized by abdominal pain, bloating, flatulence, and a change in bowel habits, alternating between diarrhea and constipation. There is no inflammation or organic lesion, and symptoms are often triggered or worsened by stress, anxiety, or certain foods. It requires symptomatic treatment with antispasmodics, antidiarrheals, laxatives, or probiotics, and psychological management.
• Lactose Intolerance: This is a deficiency in lactase, the enzyme that digests lactose, the sugar present in milk and dairy products. It manifests with abdominal pain, bloating, flatulence, and diarrhea, which occur after consuming dairy products. It requires a low-lactose diet or taking lactase tablets before meals.
• Celiac Disease: This is a permanent intolerance to gluten, a protein found in wheat, barley, rye, and oats. It manifests with abdominal pain, bloating, flatulence, diarrhea, weight loss, anemia, fatigue, or depression. It requires a lifelong gluten-free diet.

Treatment of Gastroenteritis

The treatment of gastroenteritis aims to relieve symptoms, prevent complications, and eliminate the cause of the infection. It is mainly based on rehydration, the use of medications, and the intake of probiotics. Here are the principles of treatment for gastroenteritis:

Importance of Rehydration

Rehydration is the cornerstone of gastroenteritis treatment, as it compensates for the loss of fluids and minerals caused by diarrhea and vomiting. It is essential to avoid dehydration, which can be serious, especially in children, the elderly, and fragile individuals. Rehydration is done orally by drinking water or oral rehydration solutions (ORS) available in pharmacies. ORS contain glucose, sodium, potassium, and other electrolytes, which promote the absorption of water by the intestine and restore the hydro-electrolytic balance. It is recommended to drink small amounts of liquid, often and regularly, based on thirst and the person’s weight. In case of vomiting, wait until it stops before resuming rehydration, in small sips or with a spoon. In cases of severe dehydration, intravenous rehydration may be necessary in a hospital setting.

Use of Medications

The use of medications can be helpful in relieving the symptoms of gastroenteritis, but they are not always essential or without risk. Therefore, it is important to follow the indications, dosages, and precautions for each medication. Here are the main medications used in the treatment of gastroenteritis:

• Antiemetics: These are intended to reduce nausea and vomiting. They can be taken in the form of tablets, syrup, suppositories, or oral lyophilisates. The most common is metoclopramide (Primpéran®), which acts on the vomiting center in the brain. It should be avoided in cases of glaucoma, epilepsy, Parkinson’s disease, or pregnancy. It can cause side effects such as drowsiness, dizziness, tremors, or spasms.
• Antidiarrheals: These are intended to slow down the intestinal transit and reduce the frequency and volume of stools. They can be taken in the form of capsules, tablets, sachets, or syrup. The most common is loperamide (Imodium®), which acts on the opioid receptors of the intestine. It should be avoided in cases of fever, blood in the stools, ulcerative colitis, or pregnancy. It can cause side effects such as constipation, bloating, abdominal pain, or allergic reactions.
• Antispasmodics: These are intended to relieve abdominal pain related to intestinal spasms. They can be taken in the form of tablets, capsules, suppositories, or injectable solution. The most common is butylhyoscine (Buscopan®, Spasmocalm®), which acts on the smooth muscle fibers of the intestine. It should be avoided in case of allergy to phloroglucinol or any of the excipients. It can cause side effects such as nausea, vomiting, headaches, or allergic reactions.
• Antibiotics: These are intended to treat bacterial or parasitic infections responsible for gastroenteritis. They must be prescribed by a doctor, after a clinical examination and possibly stool tests. They must be taken according to the dosage and duration indicated, without interruption or modification. The choice of antibiotic depends on the type of germ involved, its sensitivity to antibiotics, the age, and health condition of the person. The most common antibiotics are azithromycin (Zithromax®), metronidazole (Flagyl®), or vancomycin (Vancocine®). They can cause side effects such as nausea, vomiting, diarrhea, candidiasis, allergic reactions, or bacterial resistance.

The Contribution of Probiotics

Probiotics are living microorganisms, such as bacteria or yeast, that have beneficial effects on health, particularly on the digestive system. They can be taken in the form of capsules, sachets, tablets, syrup, or dairy products. They can be useful for preventing or treating gastroenteritis, by restoring the balance of the intestinal flora, strengthening the immune defenses, inhibiting the growth of pathogenic germs, and reducing the duration and severity of symptoms. The most common probiotics are lactobacilli (Lactobacillus rhamnosus GG, Lactobacillus reuteri, Lactobacillus casei), bifidobacteria (Bifidobacterium longum, Bifidobacterium bifidum, Bifidobacterium lactis), or saccharomyces (Saccharomyces boulardii). They are generally well-tolerated, but can cause side effects such as bloating, gas, or infections in immunocompromised individuals.

Prevention of Gastroenteritis

Gastroenteritis is a highly contagious disease that can easily spread from one person to another, or through the ingestion of contaminated food or water. To avoid contracting or transmitting gastroenteritis, there are simple and effective prevention measures based on respecting basic personal hygiene principles and the importance of vaccination. Here are the main prevention measures for gastroenteritis:

Basic Principles of Personal Hygiene

Personal hygiene is essential to prevent gastroenteritis, as it helps to limit contact with the germs responsible for the infection. The basic principles of personal hygiene are as follows:

• Regularly and thoroughly wash hands with water and soap for at least 15 seconds, especially before eating, before preparing meals, after using the toilet, after changing a diaper, after touching an animal or a dirty object, or after being in contact with a sick person. In the absence of water and soap, use a hand sanitizer.
• Avoid touching your mouth, nose, or eyes with your hands, as germs can enter through these routes.
• Use disposable tissues to blow your nose, sneeze, or cough, and dispose of them immediately after use. Wash your hands afterward.
• Cover your mouth and nose with your elbow or shoulder when sneezing or coughing if you don’t have a tissue.
• Avoid sharing utensils, glasses, toothbrushes, towels, or cosmetics with others, especially if they are sick.
• Regularly clean and disinfect surfaces, objects, clothes, or toys that may be contaminated with germs, using bleach or a disinfectant.
• Follow food hygiene rules, such as washing fruits and vegetables, cooking food thoroughly, refrigerating leftovers, avoiding expired or dubious products, and drinking potable or bottled water.
• Avoid close contact with sick individuals, and limit outings and group activities if you are sick yourself.

Importance of Vaccination

Vaccination is an effective way to prevent gastroenteritis caused by certain viruses or bacteria, by stimulating the body’s immune defenses. Vaccination is recommended for people at risk of complications, such as infants, the elderly, pregnant women, travelers, or immunocompromised individuals. The available vaccines against gastroenteritis are:

• Rotavirus Vaccine: This is an oral vaccine, which comes in the form of drops to swallow. It protects against rotavirus gastroenteritis, the most common cause of severe diarrhea in young children. It consists of two or three doses, to be administered from the age of 6 weeks, with an interval of at least 4 weeks between doses.
• Typhoid Fever Vaccine: This is an injectable vaccine, administered as an intramuscular injection. It protects against typhoid fever, a severe bacterial infection caused by Salmonella typhi. It consists of a single dose, to be administered at least 15 days before traveling to a risk area.
• Cholera Vaccine: This is an oral vaccine, which comes in the form of granules to dissolve in water. It protects against cholera, a severe bacterial infection caused by Vibrio cholerae. It consists of two doses, to be administered 1 to 6 weeks apart, at least 10 days before traveling to a risk area. It is not reimbursed by health insurance, and its effectiveness is limited. Therefore, it is reserved for people exposed to a high risk of cholera.

Vaccination should be performed by a physician, after checking for contraindications, such as an allergy to a component of the vaccine, a febrile illness, or immunosuppression. Vaccination should be accompanied by adherence to personal hygiene measures, as it does not provide 100% protection against gastroenteritis.

Possible Complications

Gastroenteritis is generally a mild disease that heals spontaneously in a few days. However, in some cases, it can lead to complications that can be serious and require medical care. The most common complication is severe dehydration.

Severe dehydration is an excessive loss of fluids and minerals by the body, which can be caused by diarrhea, vomiting, fever, or sweating. It is characterized by intense thirst, dry mouth, decreased quantity and frequency of urine, dry and cold skin, sunken eyes, rapid and weak pulse, low blood pressure, dizziness, headache, confusion, or drowsiness. Severe dehydration can lead to complications such as renal failure, coma, or death. It requires intravenous rehydration in a hospital setting. Prevention of dehydration relies on good oral hydration, with water or oral rehydration solutions.

Rare Complications

• Hemolytic Uremic Syndrome: This is a rare but serious complication that can occur in children after an infection with certain toxin-producing strains of Escherichia coli. It is characterized by the destruction of red blood cells, a decrease in platelets, and acute renal failure. It presents with anemia, bruises, bleeding, oliguria, hematuria, high blood pressure, or seizures. It requires treatment with dialysis, blood transfusions, or plasmapheresis.
• Sepsis: This is a generalized infection of the blood, which can occur in immunocompromised individuals after an infection with certain germs, such as Listeria monocytogenes, Salmonella typhi, or Vibrio cholerae. It is characterized by an excessive inflammatory reaction of the body, which can lead to septic shock. It presents with fever, chills, tachycardia, hypotension, confusion, or coma. It requires treatment with broad-spectrum antibiotics, intravenous fluids, and organ failure management.
• Encephalitis or Meningitis: This is an inflammation of the brain or meninges, which can occur in immunocompromised individuals after an infection with certain germs, like Listeria monocytogenes. It is characterized by an impairment of neurological functions, which can lead to sequelae or death. It presents with headaches, neck stiffness, photophobia, fever, seizures, consciousness disorders, or focal signs. It requires treatment with antibiotics, corticosteroids, and management of neurological complications.

Conclusion: The Crucial Role of Prevention and Appropriate Treatment

Gastroenteritis is a common and contagious disease, which can affect the quality of life and health of those who suffer from it. It can have various causes, such as viruses, bacteria, or parasites, transmitted via the fecal-oral route or by ingesting contaminated food or water. It is characterized by symptoms such as diarrhea, vomiting, abdominal pain, or fever, which can lead to complications like dehydration, malnutrition, anemia, or sepsis, especially in at-risk individuals, such as infants, the elderly, pregnant women, or immunocompromised people.

To prevent and treat gastroenteritis, there are simple and effective measures based on respecting basic personal hygiene principles, the importance of vaccination, rehydration, medication use, and the intake of probiotics. These measures help limit contact with the germs responsible for the infection, stimulate the body’s immune defenses, compensate for the loss of fluids and minerals, relieve symptoms, eliminate the cause of the infection, and restore the balance of the intestinal flora. They must be adapted to each case, depending on the suspected cause, the severity and duration of the disease, and the risk of complications. They should be accompanied by a medical consultation, which will allow for diagnosis, prescription of appropriate treatment, and monitoring of the disease’s progression.

Gastroenteritis is therefore a disease that can be avoided or cured, provided that hygiene rules are respected and medical advice is followed. It is important to know the causes, symptoms, diagnosis, treatment, and prevention of gastroenteritis, to act effectively and quickly in case of infection.