What is a gastrointestinal infection?
Emetic diarrhea, gastrointestinal infection, infectious gastroenteritis, stomach flu – there are many names that all refer to the same illness. Namely an inflammation of the gastrointestinal tract, which is accompanied by diarrhea, nausea and vomiting. Despite its colloquial name, gastroenteritis has little to do with the real flu. But there is one thing they do have in common: a gastrointestinal infection can also be caused by viruses. Noroviruses are often the cause. Norovirus is a pathogen that is particularly contagious. In Switzerland, it is estimated that around 400,000 people contract gastroenteritis caused by noroviruses every year. In children, it is often rotaviruses that cause diarrhea. There are also a large number of other viruses that can be considered, for example COVID-19 strains can also cause mainly gastrointestinal symptoms with almost no cough or sore throat.
Another possible cause of gastroenteritis is bacteria, for example of the Escherichia coli type (usually abbreviated as E. coli). Bacterial infections are common all over the world and can affect not only the stomach or intestines, but also the skin, bladder and respiratory tract, among others. Seasonally, other bacteria can also be transmitted, for example through undercooked chicken. Salmonella is more common in the summer months than in winter.
All age groups are affected by gastrointestinal infections, men as well as women and very often also children. How long the incubation period lasts for a gastrointestinal infection depends on the pathogen causing it. There are usually a few days to a week between infection and the appearance of the first symptoms. In some cases, however, the symptoms appear after just a few hours – or only after several weeks if, for example, Giardia parasites are the cause of the stomach flu.
Causes: How does a gastrointestinal infection develop?
Inflammation of the stomach is medically known as “gastritis”, while inflammation of the intestines is called “enteritis”. In gastroenteritis (or gastrointestinal infection), both the mucous membranes of the stomach and the intestines are inflamed, which is why this disease is referred to as “gastroenteritis”.
In addition to viruses and bacteria, in rare cases parasites (unicellular protozoa) or worms can trigger gastrointestinal complaints.
Gastrointestinal infections are contagious and are transmitted from person to person. This can happen in two ways: through direct or indirect transmission of the disease-causing pathogens.
Direct transmission of pathogens
The fastest and most direct way of infection is through the air: someone who is not yet infected inhales droplets of the pathogen that come from a person who already has a gastrointestinal infection. In this case, we speak of a droplet infection.
Indirect transmission of pathogens
You can also become infected if you come into contact with the excretions of someone who is already ill. Often all it takes is a tiny amount of dirt that is invisible to the naked eye, for example on a toilet seat, a door handle or a towel. Infection occurs when such an object contaminated with pathogens is touched with the hand and from there enters the body via further contact with the mouth. In this case, we speak of a contact infection.
Disease-causing viruses can still be excreted even if infected persons are free of symptoms. The norovirus is particularly dangerous: it is very temperature-resistant and can persist on surfaces and clothing for up to two weeks. Sometimes a contact infection can last even longer.
Gastrointestinal infection caused by viruses
Various types of viruses can cause gastroenteritis. They usually belong to one of these groups:
- Rotaviruses (the most common cause of gastrointestinal infections with diarrhea in children)
- Noroviruses (the norovirus is highly contagious, just a few pathogens are enough)
- Enteroviruses
- Adenoviruses
- Sapoviruses
- Astroviruses
Gastrointestinal infection caused by bacteria
Although the human organism is familiar with bacteria, they can still become a problem. Pathogens of the Escherichia coli (E. coli) type, for example, are found in healthy intestinal flora, but are often the cause of gastroenteritis. Gastroenteritis can be triggered by several types of bacteria:
- Campylobacter
- Shigella
- Salmonella
- Escherichia choli
- Yersinia
- Clostridia
- Vibrio cholerae
Symptoms: How does a gastrointestinal infection manifest itself?
Anyone who has ever had the stomach flu knows how miserable it can make you feel. Nausea, abdominal cramps and vomiting are almost always accompanying symptoms of infectious gastroenteritis, as is diarrhea, which is often watery. Sick people feel ill and weak, sometimes they also have a fever.
If Escherichia coli bacteria of the EHEC or EIEC subtype are the cause of the gastrointestinal infection, the disease can lead to bloody diarrhea. If you notice these symptoms in yourself or in a relative (especially a child), you should seek medical help immediately, as otherwise there is a risk of life-threatening complications.
Diagnosis: How can a gastrointestinal infection be diagnosed?
As the signs of gastroenteritis are usually clear, it is usually not difficult for your doctor to make a diagnosis of gastroenteritis. You may have already experienced the symptoms of a gastrointestinal infection and know what they are: Vomiting diarrhea is typically accompanied by symptoms such as nausea, vomiting, abdominal pain and mushy to liquid stools. In some cases, however, it makes medical sense to investigate which pathogens could be the cause of the gastrointestinal infection. Is it bacteria? Or viruses? And which subgroup do they belong to?
These questions arise, for example, if the stomach flu is accompanied by a fever, lasts an unusually long time or if the patient’s diarrhea is bloody. In the case of these symptoms and other complications, it may be helpful to take a stool sample. The microorganisms it contains are examined in the laboratory. With this knowledge, your doctor can then initiate targeted therapy and rule out other diseases that cause symptoms similar to a gastrointestinal infection. For example, a chronic inflammatory bowel disease.
An ultrasound of the intestine can provide information as to whether it is a more severe inflammation of the intestine (in which case the intestinal wall becomes thicker) or a superficial inflammation as in uncomplicated viral gastroenteritis.
Traveler’s diarrhea (traveler’s diarrhea)
Gastrointestinal infections do not always occur in familiar surroundings and are not always transmitted from person to person. This can be triggered, for example, by eating contaminated food, which can then lead to traveler’s diarrhea and food poisoning. Its symptoms are similar to those of “normal” intestinal flu or gastroenteritis.
Millions of vacationers suffer from gastrointestinal infections every year after becoming infected with pathogens in distant regions. Bacteria are usually the cause, for example the Escherichia coli subgroups ETEC and EAEC or Campylobacter, Shigella or Samonella. However, viruses (e.g. norovirus, rotavirus) and, in rare cases, parasites can also cause traveler’s diarrhea, which is also known medically as traveler’s diarrhea. Infection usually occurs via food or drink containing pathogens that are directly infectious or form toxins. Diarrhea usually occurs within one day and rarely lasts longer than three days. Travelers with a weakened immune system are particularly susceptible to traveler’s diarrhea.
Food poisoning
Food poisoning – also known as food intoxication – is gastroenteritis caused by toxins. Unlike a contagious gastrointestinal infection, food poisoning is not transmitted from person to person. It is caused by the consumption of spoiled food or drinks that contain pathogens, for example bacteria such as listeria or salmonella. Unlike a gastrointestinal infection, the symptoms of food poisoning can appear very quickly – sometimes within an hour.
How does a gastrointestinal infection progress?
Depending on the type of pathogen, it can take several hours to several days for the first symptoms of gastroenteritis to appear after infection. During this period – known as the incubation period – infected people can already be contagious even though they do not yet notice any symptoms of the disease.
The duration of a gastrointestinal infection is usually manageable: the unpleasant symptoms often subside after a few days. People with a weakened immune system often experience a prolonged illness. Medical help is usually just as important for them as it is for the elderly, small children and babies. Even if you do not belong to one of these risk groups: If you feel unsure, you should not be afraid to visit a doctor’s office or hospital if you have persistent gastrointestinal complaints. For example, it could be that Salmonella or Campylobacter pathogens have caused your gastrointestinal infection – in this case, it is possible that your diarrhea will last for a week or longer and should be treated by a doctor.
The main danger of gastrointestinal illness is the loss of fluids caused by frequent vomiting and diarrhea. The loss of fluids (called dehydration) can lead to circulatory problems and, in severe cases, kidney failure. If you feel dizzy or confused during a gastrointestinal infection or if you have muscle cramps, these could be signs of dehydration. In this case, you should seek medical help immediately.
Therapy: What to do in the event of a gastrointestinal infection?
If you suffer from diarrhea, you lose fluids and minerals that your body needs. The loss of fluids should therefore be compensated for. So drink as much as possible if you have the stomach flu. For example, lightly sweetened tea with a pinch of salt or a broth is suitable. Drink slowly and in small sips to avoid vomiting again.
Medication for gastrointestinal infections
Do not take any medication to stop diarrhea without a doctor’s instructions – it excretes pathogens and toxins that cause illness, which you can get rid of in this way. In most cases, home remedies are sufficient to get a gastrointestinal infection under control within a few days. If this is not the case, there are various therapeutic options available to your doctor – for example, an antibiotic if bacteria are the cause of the stomach flu, or an infusion to counteract severe diarrhea with fluid loss.
Nutrition for gastrointestinal infections
What can I eat with a gastrointestinal infection? Those who ask themselves this question usually feel a little better. If this is the case, easily digestible solid foods can help you get back on your feet. These include low-fat foods such as rusks, pretzel sticks, grated apples and cooked oatmeal. Boiled carrots or a mashed banana can also be added to the menu.
To avoid infection in your environment, you should observe the usual hygiene rules. Above all, this includes washing your hands frequently and thoroughly with your own towel, keeping as much distance as possible from other people and airing rooms frequently. If possible, healthy and sick people should not share the kitchen, bathroom or toilet during the acute phase of the gastrointestinal infection.
