Rotavirus

Definitions & Key takeaways

Rotavirus is a double-stranded RNA virus from the reovirus family. It's a contagious virus transmitted via the fecal-oral route, and is known to cause severe viral gastroenteritis especially in children. It mainly affects the small intestine and causes symptoms like acute onset vomiting, watery diarrhea, abdominal pain, and fever, and severe cases can be fatal. A vaccine is available to prevent rotavirus infection. Good hygiene practices, such as washing hands with soap and water can also help prevent its spread.

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Rotavirus is a common cause of viral gastroenteritis, commonly called the stomach flu, in children. In fact, it’s believed that almost every child has had the vaccine or been infected by this virus at least once before the age of five.
There are at least eight strains of rotaviruses, named A to H, but most rotavirus gastroenteritis infections in humans are due to group A strains.Rotavirus is part of the reovirus family, where reo- stands for respiratory, enteric, and orphan.
This tells us that this family of viruses affect either the respiratory system, the intestines, or they’re “orphans” who don’t cause any disease, as far as we can tell.
They are surrounded by a double icosahedral capsid, which is a two-layered spherical protein shell made up of 20 equilateral triangular faces.
And they’re “naked” because the capsid isn’t covered by a lipid membrane. They’re RNA viruses with double stranded linear RNA with 10 to 12 segments.
This means that they must first transcribe their genetic material into single stranded mRNA before host cell ribosomes can use it to make viral proteins.
Transcription happens inside the capsid, using a viral enzyme called RNA-dependent RNA polymerase.Then the mRNA enters the host cell’s cytoplasm where ribosomes are found.
Rotavirus is transmitted from person to person via the fecal-oral route.In other words, you catch it by ingesting the stool or vomit particles of someone who is sick.
Yuck. This can happen if infected stool ends up in the water supply or on agricultural fields, if flies land on it, and transfers stool particles to other places, or by touching contaminated surfaces.
You can summarize it as the four Fs: fluids, fields, flies, and fingers. As a result, rotavirus can end up in food and drinking water - and from there, it makes its way to the small intestine.
Now, the small intestine has lots of tiny ridges and grooves, each of which projects little finger-like fibers called villi.
And in turn, each villus is covered in teeny tiny little microvilli. This is called the brush border.
All of this gives the small intestines plenty of surface area to absorb nutrients. The brush border is also where many digestive enzymes are produced by intestinal epithelial cells, or enterocytes.
Rotavirus lowers the intestine’s ability to absorb nutrients by decreasing activity of digestive enzymes, like maltase and lactase, and by producing a viral protein called non-structural protein 4.
Non-structural protein 4 damages villi by inducing apoptosis, or cell death, of mature enterocytes, which are replaced by immature enterocytes that are less effective absorbers.
Rotavirus also activates the enteric nervous system, which is the division of the autonomic nervous system that helps regulate the activity of the GI tract, and this triggers secretion of electrolytes, like sodium and potassium ions, and water into the intestinal lumen.
Ok, now rotavirus is very contagious, so you only need to come in contact with a small amount to catch it. As a result, it spreads quickly in close-quarter settings like hospitals and daycares.
In temperate climates, infection rates are higher in the winter months, while in tropical regions it stays the same year-round.
And in terms of who gets sick, children between 6 and 24 months of age are particularly at risk because they don’t have immunity to the virus yet.Symptoms usually show up after a short incubation period of 24 to 48 hours, and they last an average of 8 days.
They include acute onset vomiting, followed by watery diarrhea linked to malabsorption of nutrients like lactose, decreased brush border enzyme activity, and increased intestinal secretion.
A low-grade fever is also common. Complications from rotavirus include severe dehydration, temporary lactose intolerance from secondary lactase deficiency, and seizures from the presence of rotavirus in the cerebrospinal fluid.
Rotavirus has also been associated with intussusception, where a segment of the small intestine gets pushed inward, so you get doubling up of the intestinal wall, a bit like when a telescope retracts.
This can be dangerous because it can cause intestinal obstruction. In adults, rotavirus symptoms tend to be very mild, but in children and immunocompromised individuals they range from mild to severe to fatal.
Individuals who are infected with rotavirus can potentially shed the virus in their stool for up to 10 days afterward.Diagnosis of rotavirus infection involves testing stool samples.
It can be done with immune-based tests, like enzyme-linked immunosorbent assay and latex agglutination test, which test for antibodies against rotavirus, or with polymerase chain reaction, which tests for viral RNA.Treatment for rotavirus is mostly supportive, with oral rehydration or IV fluids.
Antidiarrheal medications are not recommended because they delay clearing of the virus from the intestines.On the bright side, there’s a live attenuated rotavirus vaccine that’s given orally which is now part of routine childhood immunization in many countries.
It’s usually a 2-part or 3-part series of vaccines given to infants. It’s not recommended for individuals with a history of intussusception or severe combined immunodeficiency.
Other preventive measures include proper water and sanitation facilities, which block fecal-oral transmission by fluids, flies, and fields - 3 of the 4 F’s.
Hand washing with antiseptic soap and water and sanitizing surfaces that would’ve come into contact with stool can prevent transmission by fingers.
##SummaryAll right, as a quick recap… Rotavirus is a double-stranded RNA virus from the reovirus family. It’s the most common cause of severe viral gastroenteritis in children and it’s transmitted via the fecal-oral route.
It mainly affects the small intestine and causes symptoms like acute onset vomiting and watery diarrhea, and severe cases can be fatal.In addition to vaccination, prevention for rotavirus is proper handwashing, sanitizing surfaces, and having effective water and sanitation facilities.