It is often jokingly said that “A stomach flu is the best way to reach your weight goal”. The stomach flu is so common that both children and adults are equally affected by it worldwide.
The “stomach flu” or “stomach bug”, also known as gastroenteritis, is the inflammation of your gastrointestinal tract—the stomach and the intestine. Symptoms of gastroenteritis may include diarrhea (watery stools), vomiting and abdominal pain. Fever, lack of energy, and dehydration (loss of excessive water from your body) may also occur.
Viruses, microscopic agents that replicate inside living cells, are the most common cause of stomach flu. It is usually contracted from an infected person or by consuming contaminated food or water.
If you're a healthy individual, you'll likely recover without complications. But for infants, children, and older adults, viral gastroenteritis can be troublesome and sometimes, even deadly.
Viral gastroenteritis symptoms may start to appear after one to three days of being infected and can range from mild to severe. Symptoms usually last just a day or two (acute gastroenteritis), but in some cases, they may present for as long as 10 days. Most times, viral gastroenteritis gets better on its own without medical treatment. Its management usually involves taking rest and replacing lost fluids to prevent dehydration.
Acute Gastroenteritis and its Causative Agents
Acute gastroenteritis is one of the most common diseases in humans and continues to be a significant cause of mortality worldwide. Acute gastroenteritis is defined as the rapid onset of diarrheal disease, with or without accompanying symptoms or signs such as nausea, vomiting, fever, or abdominal pain.
Children under 5 years of age particularly fall sick with acute gastroenteritis, which often requires hospitalization. The viruses associated with acute gastroenteritis have steadily increased over the past few decades and a lot of research has been done to study each of the groups of viruses. The ones that top the list are:
1. Rotaviruses are members of the Reoviridae family and are double-stranded RNA (Ribonucleic acid) viruses. They are the most common cause of diarrhoeal disease among infants and young children. Rotavirus is present in the stools of infected people and the virus spreads easily via contaminated hands and objects, such as toys.
Rotavirus gastroenteritis is a mild to severe disease characterized by vomiting, watery diarrhoea, and low-grade fever.
Once a child is infected by this virus, it takes about two days for the symptoms to appear. Symptoms often start with vomiting followed by four to eight days of severe diarrhoea.
There is no specific medicine to treat rotavirus infection, but your doctor may recommend medicine to treat the symptoms.
2. Human adenoviruses belong to the Adenoviridae family. Human adenoviruses (Ads) are small, nonenveloped DNA (Deoxyribonucleic acid) viruses, that are capable of causing a wide range of infections, the most common ones being the gastrointestinal tract and upper respiratory tract (the upper airways that include your nose, sinuses, throat, and larynx) infections.
Adenoviruses spread from person to person via coughing or sneezing, just like the way a common cold or the flu spreads.
Symptoms of acute gastritis caused by adenovirus include nausea, diarrhea, stomach pain or discomfort, and vomiting.
Adenovirus gastroenteritis infections last for about three to seven days. Medical treatment is not required for most adenovirus infections.
3. Astroviruses are small round viruses of 28 nm with an appearance like that of a five- or six-pointed star. They belong to the Astroviridae family and are commonly known to cause diarrheal illness (gastroenteritis). Astroviruses infect infants, the elderly, and those with compromised immune systems.
The main symptoms of astrovirus gastroenteritis are diarrhoea, followed by nausea, vomiting, fever, malaise (a general sense of being unwell), and abdominal pain.
Studies show that the incubation period (time period between when you catch a virus and when your symptoms start) of the diarrheal disease caused by astrovirus is approximately three to four days.
Astrovirus infection is not usually severe and there are currently no antiviral (an agent that kills or suppresses a virus’s ability to replicate) treatments to cure them.
4. Human caliciviruses (HuCV) are members of the Caliciviridae family. They are positive-sense, single-stranded RNA which is not segmented. Currently, human caliciviruses are divided into two groups, the noroviruses, and the sapoviruses.
Norovirus, sometimes referred to as the winter vomiting bug, is a very contagious virus that causes vomiting and diarrhea. Sapoviruses can be transmitted from person to person via contact with infected feces, vomitus, materials, or surfaces.
HuCV (including both noroviruses and sapoviruses) are emerging as a common cause of diarrhea or acute gastroenteritis in humans worldwide.
The incubation period is short (usually 1-2 days) with calicivirus-caused gastroenteritis. Typical signs and symptoms include nausea, vomiting, diarrhea, abdominal pain, and a low fever.
Symptoms usually do not last longer than 3 days.
5. Other gastroenteritis-producing viruses. Some other uncommon viruses that are known to cause gastroenteritis include:
Torovirus. Torovirus is a single-stranded RNA genome (all genetic material of an organism). They are associated with persistent and acute diarrhea in children and may represent an important cause of nosocomial (a disease originating in a hospital) diarrhea.
Coronavirus. A coronavirus is a group of common viruses that causes an infection in your nose, sinuses, or upper throat (also known as upper respiratory tract infections). Coronavirus is known to produce gastrointestinal symptoms in patients with respiratory diseases.
Picobirnaviruses (PBV). These are small viruses, without an envelope, 30 to 40 nm in diameter. PBV has been detected in outbreaks of acute gastroenteritis.
Diagnosis and Management of Acute Viral Gastroenteritis
The detection of these gastroenteritis-producing viruses is carried out using a technique called electron microscopy. Electron microscopy (EM) is a technique for obtaining high-resolution images of biological and non-biological specimens to take a closer look at the tissues and cells. Electron microscopy is widely used in virology because viruses are generally too small for a direct inspection by light microscopy.
Another method, called the PCR (Polymerase chain reaction) technique has been developed for many of the viruses that produce gastroenteritis. They are useful for the confirmation of the results of other techniques.
Treatment of viral gastroenteritis is symptomatic, and its aim is to prevent or treat the dehydration that occurs as a result of the disease. Dehydration is usually treated by replenishing the fluid levels in your body. This can be done by consuming clear fluids such as water, clear broths, frozen water or ice pops, or intravenous (IV) fluids in order to rehydrate.
Fluids in the form of ORS (Oral rehydration solution) and OTC (over the counter) medications to reduce the temperature (if present), with a bland diet needs to be given. ORS is a mixture of electrolytes (salts) and carbohydrates (in the form of sugar) dissolved in water, which is used to treat fluid loss that occurs in your body from diarrhoea and vomiting.
In addition to this, taking a lot of rest and eating light, nutritious meals can help you recover from gastrointestinal symptoms at the earliest.
If you have repeated episodes of acute gastroenteritis, consult your physician immediately.
1. IJARKE Business & Management Journal, 2019. https://storage.googleapis.com/wzukusers/user-34065638/documents/5cdc55a83662aHOFZKLa/09-IBMJ%20Vol1%20Issue4%2009.pdf. 1(4).
2. Oude Munnink BB, van der Hoek L. Viruses Causing Gastroenteritis: The Known, The New and Those Beyond. Viruses. 2016;8(2):42. Published 2016 Feb 8. doi:10.3390/v8020042
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