Gastroenteritis(stomach flu)

Gastroenteritis(stomach flu) overview and Definition

Stomach flu  result in the acute diarrhoeal symptoms and vomiting.


Mostly bacteria do not survive in the acidic environment of the human being.  These surveying bacteria exit the stomach and reach the small intestine they must propel themselves through the thick mucus that lines the small intestine to reach the intestinal walls where they can attach and thrive. Once the bacteria bacteria enters the intestinal wall they are not dependendant on flagella for locomotion. The bacteria stop producing the protein flagellin to conserve energy and nutrients by changing the mix of proteins that they express in response to the changed chemical surroundings. The toxic proteins produces by the vibrio bacteria produces the watery diarrhoea. This carries the multiplying new generations of bacteria out into the drinking water of the next host if proper sanitation measures are not in place.

The bacteria toxin is an oligomeic compound made up of six protein subunits a single copy of the subunit A and five copies of the subunit B connected by the disulfide bond. The A1 portion of the A subunit is an enzyme that ADP ribosylate protein, while the A2 chain fits into the central pore of the B subunit ring. Upon binding, the complex is taken into the cell via receptor-mediated endocytosis. Once inside the cell, the disulfide bond is reduced, and the A1 subunit is freed to bind with a human partner protein called ADP ribosylation factor 6. Binding exposes its active site, allowing it to permanently ribosylate the Gs alpha subunit of the heterotrimeric protein.This results in constitutive cAMP production, which in turn leads to the secretion of water, sodium, potassium, and bicarbonate into the lumen of the small intestine and rapid dehydration. The gene encoding the bacteria toxin was introduced by horizantal gene transfer.

The bacteria toxins interacts with the host cell and enhances the pumping of chloride ions into the small intestine, creating an ionic pressure which prevents sodium ions from entering the cell. The combination of sodium and chloride ions results in salt water environment in the small intestine which increases the osmosis reaction pull up to six litres of water per dat through the intestinal cells, creating the massive amounts of diarrhoes. The host can become rapidly dehydrated unless treated properly.


By inserting separate, successive sections of bacterial DNA into the DNA  the DNA of other bacteria, such as E.coli that would not naturally produce the protein toxins, researchers have investigated the mechanisms by which bacterial responds to the changing chemical environments of the stomach, mucous layers, and intestinal wall. Researchers have discovered a complex cascade of regulatory proteins controls expression of bacterial virulence determinants.In responding to the chemical environment at the intestinal wall, the bacteria produce the TcpP/TcpH proteins, which, together with the ToxR/ToxS proteins, activate the expression of the ToxT regulatory protein. ToxT then directly activates expression of virulence genes that produce the toxins, causing diarrhea in the infected person and allowing the bacteria to colonize the intestine. Currentresearch aims at discovering "the signal that makes the bacteria bacteria stop swimming and start to colonize that is, adhere to the cells of the small intestine."

Routes of Transmission

Routes of transmission:

The main routes of transmission occurs by faeco-oral route by contamination with food and water.

Poor sanitization might result in infection. Uncooked food might also results in transmission of the disease.

When the children touches the contaminated objects then tend to develop the symptoms.

Clinical signs & symptoms

Diarrhoea: Water loss greater than 1 litre per day.

Nausea and vomiting: Vomiting occurs especially in the early stage of bacteria and can lasts for hours.

Dehydration: Dehydration can result in fluid loss which might result in the mild to severe.

Signs and symptoms of bacteria dehydration include irritability, fatigue, sunken eyes, a dry mouth, extreme thirst, dry and shriveled skin that's slow to bounce back when pinched into a fold, little or no urinating, low blood pressure, and an irregular heartbeat.

Muscle cramps: This might occurs due to potassium, sodium and chloride.

 Shock:This is one of the most serious complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body. If untreated, severe hypovolemic shock can cause death in minutes.


Differential Diagnosis

Stool culture:

Isolation of the organisms and susceptibility profile.

Agar. Serogroup and serotype can be assigned by testing with specific antibodies. 

Molecular and Rapid tests:

This includes immunochromatographic lateral flow devices such as dipsticks

Accurate molecular testing such as PCR including tests that use dried fecal spots, is also feasible, but the practical use of molecular tests has been primarily limited to epidemiologic research and surveillance.


Blood agar: All aerobic bacteria and yeast; detects cytochrome oxidase production

MacConkey EMB agar: Inhibits gram-positive organisms; permits lactose fermentation

XLD agar and HE agar: Inhibit gram-positive organisms and nonpathogenic gram-negative bacilli; permit lactose fermentation and H2S production

Skirrow agar: Selective for Campylobacter species

SM agar: Selective for enterohemorrhagic E coli

CIN agar: Selective for Yersinia enterocolitica

Thiosulfate-citrate-bile-sucrose (TCBS) agar: Selective for Vibrio species

CCFE agar: Selective for C difficil




The prognosis increases when treated at an early stage. The mortality rate (50-60%) might increases if treatment is denied.



Avoid consuming contaminated food and water

Follow proper sanitary protocol

Clean the surrounding

Stay hydrated and take lots of fluids and electrolytes

Heat the food before eating.