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Gastro-Intestinal Infections (GI, stomach flu) : Symptoms, Causes, Diagnosis and Treatment

What is Gastro-Intestinal Infections?

Gastrointestinal infections can cause diarrhea, vomiting, and many other unpleasant symptoms.

Bacteria, viruses, and parasites can cause gastrointestinal infections.

Treatment typically focuses on staying hydrated and getting plenty of rest but may vary depending on the type of infection.

This article breaks down the symptoms, types, and treatments for a variety of common gastrointestinal infections.

Gastrointestinal disorders include such conditions as constipation, irritable bowel syndrome, hemorrhoids, anal fissures, perianal abscesses, anal fistulas, perianal infections, diverticular diseases, colitis, colon polyps and cancer. Many of these can be prevented or minimized by maintaining a healthy lifestyle, practicing good bowel habits and submitting to cancer screening.

There are three main types of gastrointestinal infections:


Bacterial gastrointestinal infections include foodborne infections and food poisoning.

Common sources of bacterial gastrointestinal infections include:

While almost any contaminated food can cause an infection, some foods pose more risks than others. These include:

  • undercooked or raw meat, eggs, or poultry
  • unpasteurized dairy and juices
  • contaminated water
  • food, particularly meat and egg products, that is not refrigerated well
  • deli meats
  • unwashed or raw fruits and vegetables

Additionally, people who have bacterial gastrointestinal infections may spread the bacteria to the food they touch. This food could then infect someone else if they consume that food.


Viral gastrointestinal infections are very common, and often people refer to these as the stomach flu.

Norovirus is a type of viral gastroenteritis. According to the National Institute of Diabetes and Digestive Diseases (NIDDK), norovirus causes 19 to 21 million cases of stomach flu in the United States each year.

Other viruses that can cause viral gastrointestinal infections are less common in the U.S.

Vaccines can prevent some types of viral infections, including rotavirus.


Intestinal helminths, or worms, and protozoan parasites cause parasitic gastrointestinal infections.

The two most common parasitic infections are giardiasis and cryptosporidiosis.

Contact with human feces in the soil can spread these parasites. People can also contract these infections by drinking or swimming in contaminated water.

Some parasitic infections can spread from animals to humans. These include toxoplasmosis, which people can come into contact with in cat feces.

Gastro-Intestinal Infections is also known as GI, stomach flu. Gastro-Intestinal Infections belongs under the category of Bacterial disease. Bacterial, Viral, Parasitic are some common types of Gastro-Intestinal Infections. Generally Male, Female, Child are the victim of the Gastro-Intestinal Infections. Seriousness of this disease is Low.

Symptoms of Gastro-Intestinal Infections are :

  • Dehydration
  • aches and pains
  • Body aches are a common symptom of many conditions. The flu is one of the most well-known conditions that can cause body aches. Aches can also be caused by your everyday life, especially if you stand, walk, or exercise for long periods of time.

    You may just need rest and some treatment at home to relieve your body aches. But some aches, especially ones that last a long time, may mean that you have an underlying condition. In these cases, you may need to see your doctor for a diagnosis. They can create a long-term treatment plan to can relieve your aches and other associated symptoms.

  • bloody stools
  • Seeing blood in the toilet, on the outside of your stool, or with wiping after a bowel movement is common. Fortunately, most of the causes of such rectal bleeding are not life-threatening; common causes include hemorrhoids and anal fissures. However, the only way to be certain of the cause is to be evaluated by a healthcare provider.

    • Rectal bleeding is the passage of blood through the anus. The bleeding may result in bright red blood in the stool as well as maroon colored or black stool. The bleeding also may be occult (not visible with the human eye).
    • The common causes of rectal bleeding from the colon include anal fissure, hemorrhoids, diverticulosis, colon cancer and polyps, colonic polyp removal, angiodysplasias, colitis, proctitis, and Meckel's diverticula.
    • Rectal bleeding also may be seen with bleeding that is coming from higher in the intestinal tract, from the stomach, duodenum, small intestine, or Meckel's diverticulum.
    • Rectal bleeding may not be painful; however, other symptoms that may accompany rectal bleeding are diarrhea, and abdominal cramps due to the irritation caused by the blood in the stool.
    • Rectal bleeding is commonly evaluated and treated by gastroenterologists and colorectal or general surgeons.
    • The origin of rectal bleeding is determined by history and physical examination, anoscopy, flexible sigmoidoscopy, colonoscopy, radionuclide scans, visceral angiograms, upper gastrointestinal endoscopy or capsule endoscopy of the small intestine, and blood tests.
    • Rectal bleeding is managed first by correcting any low blood volume and anemia if present with blood transfusions and then, determining the site and cause of the bleeding, stopping the bleeding, and preventing future rebleeding.
    • Rectal bleeding can be prevented if the cause of the bleeding can be found and definitively treated, for example, by removing the bleeding polyp or tumor. In addition, it may be appropriate to search for additional abnormalities, for example, polyps or angiodysplasias that have not yet bled but may do so in the future. This may require either gastrointestinal endoscopy or surgery.
  • Weight loss
  • Sudden, noticeable weight loss can happen after a stressful event, although it can also be a sign of a serious illness.

    It's normal to lose a noticeable amount of weight after the stress of changing jobs, divorce, redundancy or bereavement.

    Weight often returns to normal when you start to feel happier, after you've had time to grieve or get used to the change. Counselling and support may be needed to help you get to this stage.

    Significant weight loss can also be the result of an eating disorder, such as anorexia or bulimia. If you think you have an eating disorder, talk to someone you trust and consider speaking to your GP. There are also several organisations that can provide you with information and advice, such as the eating disorders charity Beat.

    If your weight loss wasn't due to one of the causes mentioned, and you didn't lose weight through dieting or exercising, see your GP, as you may have an illness that needs treating.

  • Loss of appetite
  • Fatigue is a constant state of tiredness, even when you?ve gotten your usual amount of sleep. This symptom develops over time and causes a drop in your physical, emotional, and psychological energy levels. You?re also more likely to feel unmotivated to participate in or do activities you normally enjoy.

    Some other signs of fatigue include feeling:

    • physically weaker than usual
    • tired, despite rest
    • as though you have less stamina or endurance than normal
    • mentally tired and moody

    Loss of appetite means you don?t have the same desire to eat as you used to. Signs of decreased appetite include not wanting to eat, unintentional weight loss, and not feeling hungry. The idea of eating food may make you feel nauseous, as if you might vomit after eating. Long-term loss of appetite is also known as anorexia, which can have a medical or psychological cause.

    It may be a warning sign from your body when you feel fatigue and loss of appetite together. Read on to see what conditions may cause these symptoms.

  • Vomiting
  • Vomiting, or throwing up, is a forceful discharge of stomach contents. It can be a one-time event linked to something that doesn?t settle right in the stomach. Recurrent vomiting may be caused by underlying medical conditions.

    Frequent vomiting may also lead to dehydration, which can be life-threatening if left untreated.

  • Nausea
  • Nausea and vomiting are common signs and symptoms that can be caused by numerous conditions. Nausea and vomiting most often are due to viral gastroenteritis ? often mistakenly called stomach flu ? or the morning sickness of early pregnancy.

    Many medications can cause nausea and vomiting, as can general anesthesia for surgery. Rarely, nausea and vomiting may indicate a serious or even life-threatening problem.

  • Severe Headache
  • Headaches are a common health problem ? most people experience them at some time.

    Factors that lead to headaches may be:

    Frequent or severe headaches can affect a person?s quality of life. Knowing how to recognize the cause of a headache can help a person take appropriate action.

  • Medium Fever
  • A fever is a higher-than-normal body temperature. It?s a sign of your body's natural fight against infection.

    • For adults, a fever is when your temperature is higher than 100.4F.
    • For kids, a fever is when their temperature is higher than 100.4F (measured rectally); 99.5F (measured orally); or 99F (measured under the arm).

    The average normal body temperature is 98.6 Fahrenheit (or 37 Celsius). When you or your child?s temperature rises a few degrees above normal, it?s a sign that the body is healthy and fighting infection. In most cases, that?s a good thing.

    But when a fever rises above 102F it should be treated at home and, if necessary, by your healthcare provider if the fever doesn?t go down after a few days.


    Gastro-Intestinal Infections can be caused due to:

    Here are a few common types of GI infections.


    • E. coli. E. coli bacteria are found in the intestines of people and animals. Most varieties are harmless, but some strains ? such as E. coli O157:H7 ? secrete a toxin that can cause abdominal cramps, vomiting, and bloody diarrhea. E. coli spread through contaminated water or food that came into contact with animal manure. E. coli can also spread through direct person-to-person contact.
    • Salmonella. Salmonella infection is commonly caused by eating raw or undercooked poultry, meat, and eggs. The majority of salmonella infections can be classified as gastroenteritis.


    • Norovirus. Noroviruses are the most common cause of foodborne illness worldwide. It?s especially likely to spread among people in confined spaces. Although in most cases the virus is spread through contaminated food or water, person-to-person transmission is also possible.
    • Rotavirus. According to the Mayo Clinic, rotavirus is the leading cause of viral gastroenteritis in children worldwide. Children are commonly infected when they touch objects contaminated with the virus and then put their fingers in their mouths. There?s a rotavirus vaccine available in some countries.


    • Giardiasis. Giardia is a parasite that spreads easily through human contact and contaminated water. It?s resistant to chlorine and can spread in public swimming pools. Infection can occur from drinking water from and bathing in contaminated lakes and streams.
    • Cryptosporidiosis. A leading cause of waterborne disease in the United States, Cryptosporidium is a microscopic parasite which causes cryptosporidiosis. It has an outer shell that helps it survive outside of a host and tolerate chlorine disinfection.

    What kind of precaution should be taken in Gastro-Intestinal Infections?

    The best ways to prevent gastrointestinal infection include:

    • Proper hand-washing
    • Disinfecting of contaminated surfaces with bleach
    • Washing of soiled articles of clothing
    • Identifying infected patients as soon as possible to implement extended infection control
    • There are no vaccines for most gastrointestinal infections. Exceptions:
      • Rotavirus
      • Adenovirus (limited availability)
    • For C. difficile: avoid prescribing antibiotics unnecessarily

    Treatment measures for gastrointestinal infection include:

    • Rehydration ? oral and sometimes intravenous
    • For many cases of bacterial gastroenteritis, only symptomatic treatment (for fever, diarrhea?) is required.
    • Antibiotics are not usually recommended as they have no effect on viral infections, may cause side effects and overuse increases the risk of resistant bacteria developing.
    • Antibiotics may be recommended in particularly severe cases of gastroenteritis, or if a specific bacteria has been identified as the cause.

    How it can be spread?

    Spread by bacteria

    Treatment for the Gastro-Intestinal Infections


    When symptoms point to a possible gastrointestinal infection, diagnosis can be confirmed through laboratory tests used for culture or antigen detection from stool specimens. In certain cases (e.g. for E. coli, Salmonella, C. difficile ?), antibiotic susceptibility testing is used to determine microbial resistance to antibiotic therapy, if appropriate. Particularly in hospital settings, rapid diagnosis provides important information for implementing infection control measures.

    To diagnose the cause of a diarrhea, it is helpful to consider where the context is a food-borne outbreak or ?travelers? diarrhea?.

    Food-borne outbreaks:

    • Often local ? a group of people eating together suffer the same illness.
    • A public health concern when widespread, affecting people in different places and over a longer period of time.
    • Important to recognize and track epidemiologically, to prevent more people from being infected.
    • E. coli, Salmonella, Campylobacter and Staphylococcus are among the most common pathogens causing food-borne outbreaks.

    Travelers? diarrhea:

    • Most common travel-related illness.
    • Contracted by people travelling in places where there are different pathogens from what they are used to, especially in regions where food/water contamination is more prevalent.
    • Most commonly transmitted through ingestion of food or water contaminated with feces.
    • Most cases caused by bacteria including E. coli, Salmonella and Shigella.


    In most cases, self-care measures are the recommended treatment. Antibiotics will not help GI infections from viruses or parasites.

    Although antibiotics can help with complicated cases of bacterial infection, in uncomplicated cases, antibiotics may actually prolong the condition and increase risk of relapse.

    Additionally, in certain infections, antibiotics may lead to dangerous complications. Your doctor can help determine if you or your child need antibiotics.

    Your doctor might recommend that you stay away from high-fiber foods that could make diarrhea worse. They might also recommend over-the-counter medications that neutralize stomach acid or that treat nausea, abdominal pain, and diarrhea.

    The most important self-care treatment for adults and children with a GI infection is to stay hydrated.

    Possible complication with Gastro-Intestinal Infections

    Gastroenteritis, a common illness that?s also known as the ?stomach flu,? causes diarrhea, vomiting, and stomach pain that usually lasts less than a week.

    What you might not know is this condition can sometimes trigger unusual complications ? or secondary problems.

    Many of these issues will eventually go away, while others may linger.

    Dehydration: A Common Risk?

    Dehydration is the most common complication of gastroenteritis. It happens because your body loses fluids and electrolytes that aren?t replaced when you vomit or have diarrhea.

    Being dehydrated is especially dangerous for small children, the elderly, and people with weakened immune systems.

    If you have severe dehydration, you might have to go to the hospital to have fluids delivered intravenously (through an IV).

    Dehydration can lead to more serious problems, such as:

    • Heat Injury If you don?t have enough fluids while you?re physically active, you could have a life-threatening heatstroke.
    • Urinary and Kidney Issues A long or repeated episode of dehydration can trigger kidney stones, urinary tract infections (UTIs), or kidney failure.
    • Seizures When your electrolytes are out of whack, you could develop seizures.
    • Hypovolemic Shock This life-threatening condition happens when low blood volume causes a drop in blood pressure and the amount of oxygen in your body.

    You may be able to prevent dehydration by drinking extra fluids, and in some cases, taking an oral rehydration solution.### Gut Changes

    Researchers have found that gastroenteritis can actually change the microbiome balance in your body. This means you?ll have a decrease in the variety and quantity of good bacteria in your gut.

    In one study, about 1 in 5 people who had norovirus, a common culprit for gastroenteritis, experienced changes in their microbiota.

    Post-Infectious IBS

    One possible complication of gastroenteritis is something called post-infectious irritable bowel syndrome (IBS).

    This condition resembles IBS and causes symptoms such as diarrhea, nausea, stomach cramps, or constipation.

    Studies have shown post-infectious IBS affects between 5 and 32 percent of people who have gastroenteritis.

    Symptoms can last months or even years. The good news is they usually do go away.

    Colitis and Crohn?s

    Some people with gastroenteritis may develop ulcerative colitis or Crohn?s disease ? conditions that cause inflammation of your digestive tract.

    Researchers believe an abnormal immune system reaction may be the trigger. When your immune system tries to fight off a virus or bacteria, it might also attack the cells in your digestive tract.

    Another type of colitis, called hemorrhagic colitis, can happen when you have gastroenteritis caused by Escherichia coli (E. coli) bacteria. With this condition, E. coli infects the large intestine and produces a toxin that causes bloody diarrhea and other problems.

    Gastroenteritis and Pregnancy Complications

    As many as one-third of pregnant women will have gastroenteritis during their pregnancy.

    While most pregnant women will recover from the sickness without any problems, it can lead to complications.

    Severe dehydration from the illness may prompt preterm labor. (8)

    In a study published in September 2017 in the Journal of Clinical and Diagnostic Research, gastroenteritis during pregnancy was also been linked to miscarriages, low birth weight, and still birth.

    It?s a good idea to see your doctor if you?re pregnant and have symptoms of gastroenteritis. If you do develop the stomach flu, be sure to drink plenty of liquids and get adequate rest.

    Gastroenteritis and Aneurysms

    Having gastroenteritis may up your risk of developing an aortic aneurysm ? a bulge in the wall of the major blood vessel that carries blood from your heart to the rest of your body.

    In one Swedish study, published in the journal Emerging Infectious Diseases, researchers found a person?s risk of an aortic aneurysm was higher within three months after having a salmonella infection.

    Aortic aneurysms may not cause any symptoms at first, but if they burst, they can be deadly.

    Gastroenteritis and Reactive Arthritis

    A bout of gastroenteritis can lead to reactive arthritis ? a painful form of inflammatory arthritis. It used to be called Reiter?s syndrome.

    Reactive arthritis can occur ?in reaction? to an infection caused by salmonella, campylobacter, yersinia, shigella, E. coli, vibrio, or other bacteria.

    In one study, published in the journal Clinical Infectious Diseases, about 29 percent of people who had a salmonella infection developed symptoms of reactive arthritis.

    Reactive arthritis may cause painful, red, and swollen joints, especially in the knees, ankles, and feet. Additionally, some people experience swelling of the membrane lining the eyes (conjunctivitis) or inflammation of the urinary tract.

    Recovery for this type of arthritis varies from person to person. Some people get better after their first flare of symptoms. Symptoms usually last from 3 to 12 months. For about 30 to 50 percent of people, symptoms return or become chronic.


    1 https://www.biomerieux-diagnostics.com/gastrointestinal-infections#Prevention%20/%20Treatment 2 https://www.healthline.com/health/gastrointestinal-infection#treatment 3 https://www.medicalnewstoday.com/articles/gastrointestinal-infection#summary 4 https://www.infectiousdiseaseadvisor.com/home/decision-support-in-medicine/hospital-infection-control/gastrointestinal-tract-infections/ 5 https://my.clevelandclinic.org/health/articles/7040-gastrointestinal-disorders 6 https://muschealth.org/medical-services/ddc/patients/digestive-diseases/small-intestine/infections-of-the-small-intestine 7 https://www.everydayhealth.com/gastroenteritis/complications/