Typical gastrointestinal symptoms
In gastroenteritis, pathogens colonize and damage the digestive tract. The symptoms of gastroenteritis therefore focus on this area:
- Nausea and vomiting
- diarrhea
- Abdominal cramps and pain
Typically, the symptoms develop very quickly, often within a few hours. The severity of the symptoms depends on the type of pathogen and individual factors such as the patient’s physical condition.
Nausea and vomiting
Nausea and vomiting can be severe in the acute phase of gastroenteritis. Some sufferers vomit several times an hour. The mucous membrane of the stomach and intestines is so irritated during gastroenteritis that the body cannot keep anything down. This can be very debilitating, especially because enormous amounts of fluids and salts (electrolytes) are lost with the vomiting (and diarrhea).
Some people vomit not only through the mouth, but also through the nose, causing the nasal mucous membranes to swell. In the worst case, the vomit can get into the airways, which can lead to pneumonia, which is difficult to treat.
Diarrhea
With diarrhea, the liquid consistency of the stool and the frequent wiping irritate the skin around the anus. In unfavorable cases, the region may even become inflamed.
The sudden and violent onset of diarrhea, the consistency of the stool and whether it may contain blood also depends on the pathogen:
In most cases, diarrhea and other gastroenteritis symptoms set in very suddenly, even downright explosively in the case of certain pathogens such as bacteria of the Campylobacter genus. The stool is often watery, but can also be mushy, especially at the beginning.
Sometimes the stool also appears slimy due to the many destroyed mucosal cells of the gastrointestinal tract. In the case of amoebic dysentery, blood and mucus impurities make the stool look like “raspberry jelly”. Severe forms of cholera cause such watery diarrhea that they are also known as “rice water stools”.
Abdominal cramps and abdominal pain
Diarrhea is usually accompanied by abdominal cramps and abdominal pain, which occur intermittently. After going to the toilet, these cramps often subside for a while.
General gastrointestinal flu symptoms
In addition to the typical gastrointestinal symptoms described above, there are usually also general symptoms – i.e. symptoms that are not characteristic of a specific illness. For example, gastroenteritis can also be accompanied by a fever – a symptom more commonly associated with colds and flu-like infections.
Sometimes such unspecific signs of illness precede the diarrhea for some time, in other cases they occur at the same time as the diarrhea.
Gastroenteritis without symptoms
In some cases, infections with pathogens that usually cause gastroenteritis are completely asymptomatic. For example, many adults do not develop any gastrointestinal symptoms from an EHEC infection. Infection with rotaviruses in this age group is also often subclinical, i.e. without any noticeable signs of illness.
This phenomenon is particularly pronounced in the case of amoebic dysentery and cholera. Both diseases are among the typical travel diseases that occur in many countries with low hygiene standards. Many people are asymptomatic carriers of the amoebae or cholera bacteria without becoming ill themselves. In the case of cholera, only 15 percent of those infected show gastrointestinal symptoms or other signs of illness.
Stomach flu: complications
Although the typical symptoms of gastroenteritis are very unpleasant, they do not normally pose a serious health risk. Under certain circumstances, however, the course of the illness can be particularly severe. This can happen, for example, if the immune system is weakened. Those affected must receive urgent medical treatment, otherwise there is a risk of serious complications:
Dehydration
If the classic gastrointestinal infection symptoms of vomiting and diarrhea are very severe, a serious lack of fluids (dehydration) and electrolytes – especially sodium and potassium – can develop. In extreme cases, this can be fatal without treatment!
Doctors refer to a lack of fluids in the body as dehydration. Massive dehydration is also known as exsiccosis.
Elderly people can also quickly develop a serious lack of fluids and salt if they have severe diarrhea and vomiting.
If babies, small children or elderly people develop gastrointestinal flu symptoms, it is always advisable to see a doctor!
Signs of dehydration
Depending on the extent of the dehydration, various warning signs may appear:
- dry skin and especially dry mucous membranes
- sunken eyes
- Reduced blood circulation and cold extremities
- standing skin folds (e.g. a fold of skin on the back of the hand pulled with the fingers remains standing for some time after release)
- severe and sudden weight loss: in infants, a weight loss of ten percent or more of body weight is already very worrying.
- Increasingly deteriorating general condition
- Drowsiness and unusual sleepiness (somnolence). Sometimes, however, those affected initially also show severe restlessness (agitation) as long as the water shortage persists.
- Dizziness when standing up with risk of falling (orthostatic hypotension)
- Increased heart rate with reduced blood pressure
In severe cases, there are further signs: Gastroenteritis patients who have lost massive amounts of fluids (exsiccosis) also develop
- seizures
- Kidney pain
- Decrease in the amount of urine (oliguria/anuria)
Signs of electrolyte deficiency
In the case of gastroenteritis, salts, bases and acids, known as electrolytes, are lost along with the fluids. In more severe cases, this can lead to changes in the pH value in the blood and subsequently cause cardiac arrhythmia and nerve damage.
Other complications
Gastroenteritis can also lead to the following complications:
- Intestinal perforation: In extreme cases, certain pathogens (such as Shigella and Entamoeba histolytica) not only cause the classic gastrointestinal flu symptoms, but also lead to an intestinal perforation. Food residues and pathogens from the intestine enter the abdominal cavity and can cause peritonitis. This is often life-threatening!
- Toxic megacolon: In connection with some gastroenteritis pathogens, toxic megacolon can also be observed in rare cases. In this case, the large intestine becomes very inflamed and dilated. There is a danger to life!
- Kidney failure: Some toxins produced by gastroenteritis pathogens (especially EHEC and Shigella) can attack the kidneys and trigger hemolytic uremic syndrome (HUS). It is characterized by damage to the blood vessel walls and acute kidney failure. As in the other cases, those affected need medical help quickly!
Gastroenteritis can become problematic in patients with immunodeficiency (e.g. due to certain diseases such as AIDS or as a result of chemotherapy): The gastrointestinal symptoms can last longer than normal. In addition, those affected are more susceptible to certain complications that otherwise only occur very rarely.
For example, gastroenteritis caused by noroviruses can cause symptoms even weeks after the onset of the illness (prolonged course). There is also a risk of systemic infection (sepsis) in these high-risk patients – the pathogens originally limited to the digestive tract also spread to the rest of the body. An example of this is salmonella sepsis, in which the salmonella can colonize the pericardium, meninges and bones.
Symptoms after gastroenteritis
An important example of this is reactive arthritis. Days, sometimes even weeks, after the typical gastrointestinal flu symptoms (or those of another infection) have subsided, inflammation suddenly occurs in various joints, the eye and the urethra (formerly known as Reiter’s triad). However, this phenomenon is very rare overall. The pathogens that trigger reactive arthritis include Shigella and Campylobacter.
In rare cases, the latter also cause Guillain-Barré syndrome. This is an inflammatory disease of the nerves that can lead to severe paralysis and often requires intensive medical treatment.