Infectious Diarrhea: Everything You Need To Know

Infectious diarrhea occurs alongside other symptoms, such as fever, abdominal cramps, nausea, dizziness, and malaise. The causes depend on the variety of microorganisms involved.
Infectious diarrhea: everything you need to know

Diarrhea is a pasty or liquid defecation, with a frequency equal to three or more times a day. In addition to being a pathological symptom, infectious diarrhea is the second most common cause of death in the poorest countries, according to data released by the World Health Organization (WHO).

In Western countries (with a developed health system) diarrhea does not represent a health problem, but in other countries it does, especially for children. Whether you are driven by curiosity or by prevention, knowing this condition becomes fundamental. Today we explain everything you need to know about infectious diarrhea.

What is infectious diarrhea?

Pasty-like defecation that occurs more than three times a day is considered diarrhea. According to studies, children under the age of two speak of diarrhea when the same number of droppings occurs within 12 hours or, alternatively, there are traces of blood, mucus or pus.

Infectious diarrhea is caused by pathogens, meaning it is not caused by food poisoning or gastrointestinal disorders such as irritable bowel syndrome. It is therefore due to viruses, bacteria or protozoa.

Beyond medical information, it is essential to contextualize this medical picture globally. The World Health Organization offers us a series of data including:

  • It is the second leading cause of death in children under the age of five worldwide. This translates into approximately 525,000 infant deaths each year.
  • Numerous cases could be avoided in the presence of adequate health facilities and adequate food supervision.
  • This condition can lead to severe malnutrition, loss of years of health and, in severe cases, the death of the patient.
Woman with stomach pain.
Infectious diarrhea can affect both adults and children.

Causes of infectious diarrhea

Some scientific studies report that infectious diarrhea is caused by viruses, bacteria or protozoa, but also by more complex parasites. Below we briefly describe the different pathogens.


Bacteria are responsible for only 10% -20% of infectious diarrhea cases. Among the most common enteropathogens are Shigella spp , Salmonella spp , Vibrio cholerae , enterohemorrhagic Escherichia coli , Aeromonas spp and Yersinia enterocolitica .

The bacterium Campylobacter jejuni deserves special mention , which is one of the four main causes of diarrhea globally.


Many viruses are responsible for diarrhea, including noroviruses and rotaviruses. They are the most common responsible for acute diarrhea. These viral soft stool episodes are also known as viral gastroenteritis or intestinal flu.

Protozoa and other parasites

Some protozoa present in water, such as Entamoeba histolytica or Giardia lamblia , can cause infectious diarrhea. This picture is also caused by more complex parasites, such as intestinal worms, scientifically known as Ascaris lumbricoides .

Main transmission channels

The transmission channels are many and of different nature. For example, a virus is transmitted through droplets emitted by the infected person through coughing and sneezing; a bacterium must be ingested with certain foods.

How to prevent infectious diarrhea?

According to the Centers for Disease Control and Prevention (CDC), the best form of prevention of infectious diarrhea is to sanitize kitchen surfaces, not to consume unfiltered water and to ingest only cooked or pasteurized foods.

The microorganisms mentioned, in fact, are transmitted through direct contact with the mouth or with the consumption of water or certain foods.

Escherichia coli bacterium.
The bacterium Escherichia coli is known to be responsible for infectious diarrhea.

What other symptoms occur?

Beyond liquid or pasty stools, infectious diarrhea can be accompanied by different symptoms depending on the agent responsible. According to the National Institute of Diabetes and Digestive and Kidney Disease (NIH), some of the main clinical symptoms may be the following:

  • Blood in the stool.
  • Fever and chills.
  • Nausea and dizziness.
  • He retched.
  • Abdominal pain and swelling.

Prevent with nutrition

Infectious diarrhea can be caused by various pathogens: bacteria, viruses and other parasites. In most Western countries this clinical picture does not represent a problem, but in areas with poor environmental sanitation it is the second cause of death. 

The best preventive measure of diarrhea (except for the viral variant) is to avoid eating raw, undercooked or processed foods in an environment with poor hygiene.

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