Infectious gastroenteritis

What is infectious gastroenteritis? What link does it have with the gut microbiota?

A diarrheal disease, gastroenteritis frequently involves severe symptoms which disappear rapidly in most cases.⁴ Patients display an imbalance of the gut microbiota,⁵ which may persist after the resolution of the infection, and which has been associated with an increased risk of developing chronic disorders.⁶

Generally benign in Western countries, infectious gastroenteritis is a leading cause of death in the developing world, particularly among children under 5 years of age.⁴ It accounts for 10% of all child deaths in developing countries, where it represents a major public health concern.¹ The high mortality rates in developing countries⁸ are often⁹ linked to the severe dehydration that it causes. The disease is caused by the ingestion of pathogenic (sidenote: Pathogen A pathogen is a microorganism that causes, or may cause, disease. Pirofski LA, Casadevall A. Q and A: What is a pathogen? A question that begs the point. BMC Biol. 2012 Jan 31;10:6. ) microorganisms, most frequently viruses, in which case it is known as viral gastroenteritis.

Rotavirus is one of the main causes of viral gastroenteritis worldwide and of fatal diarrhea in children in developing countries, despite the availability of a vaccine.¹⁰ Other viruses, such as norovirus or adenovirus, may also be to blame.⁴ Moreover, gastroenteritis can also be caused by bacteria (bacterial gastroenteritis) or parasites, particularly during travel.⁷ However, the pathogen involved is rarely identified.¹¹

Contamination occurs via contaminated food or water, or directly through physical contact aggravated by poor hygiene.⁶ Although data on the association between the gut microbiota and gastroenteritis are still very limited, patients display a gut imbalance (dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) ) during infection, regardless of the cause.^5,12,13 Studies show that children with severe or complicated viral gastroenteritis, and particularly those infected with rotavirus, display a lower gut microbiota diversity than healthy children.¹⁴ Lastly, other studies suggest that changes in the gut microbiota may persist over the long term and could have adverse effects on health, such as contributing to the development of irritable bowel syndrome.¹⁵ However, current data on the gut microbiota’s contribution to the development, complications and outcome of the disease require further investigation.

Symptoms at times severe but not long-lasting

In addition to diarrhea (defined as three or more loose or watery stools in one day)⁶, symptoms may include nausea, vomiting, abdominal cramps, fever or anorexia.¹⁶ Symptoms of viral gastroenteritis typically last less than a week and usually improve within 1-3 days.⁴ Special attention should be paid to children, the elderly and immunocompromised individuals, who are at greater risk of dehydration.⁴ In some cases, the doctor may order additional tests (stool analysis, blood tests, etc.) to rule out other conditions.⁴

Antibiotics often ineffective or even counterproductive 

Regardless of the cause of infectious gastroenteritis, the treatment is symptomatic.⁴ For diarrhea, rehydration is the main treatment.⁶ Antibiotic treatment is not essential and is only justified where a bacterial cause has been established for the diarrhea.¹¹ With viral gastroenteritis, antibiotics may even be counterproductive.¹¹ On the other hand, probiotics, which aim to restore the gut microbiota, may limit the severity and duration of symptoms.^7,17

BMI 21.19