Overview Of The Rotavirus Disease

The Pathogenic Organism

Viruses are small, tremendously small in comparison to cells. In fact, if your where to magnify a cell to the size of a basketball a virus would still only be about the size of the tip of a pen. Virus are unable to be seen by the human eye a special device is needed to view them called an electron microscope, which magnifies them between 20-300 nm. The Rotavirus particles resemble a wheel with short spokes and a well-defined rim. Because of this its name was derived from the Latin word rota meaning wheel like. Mature Rotavirus particles are non-enveloped and possess a multilayered icosahedral protein capsid composed of an outer layer, an inner layer and a core. The genome of the rotavirus is from the family Reoviridae which is made up of 11 unique double helix molecules of dsRNA which are 18,555 nucleotides in total. Each segment is numbered 1 to 11 by decreasing size. Each gene codes for one protein except genes 9 which code for two. These RNA strands give the coding for 6 structural proteins which code for the capsid and envelope. Interestingly the virus has an envelope in its early stages which it loses in its mature stages. The other 5 of the 11 dsRNA are nonstructural proteins, which is what is used in the infected cells. The virus is replicated by entering cells by receptor mediated endocytosis when virions enter the host cell and form the endospore. Viral mRNA is transcribed using the viral RNA polymerase that is already present in the virion to form structural protein units of the capsid. The mRNA segments are assembled into the immature capsid and then replicated to form the double strained RNA genome. This all takes place in the cytoplasm of the infected cell. Because viruses are not living things so they do not metabolize on their own. Rather upon entry into a cell dramatically modify cellular metabolism of the cell which in turn causes the cell to produce more of the virus.

Description of the Disease

The Rotavirus is the most common cause of viral gastroenteritis in humans and domesticated animals. The virus was first discovered in 1973 By Dr. Ruth Bishop at the Royal Children’s Hospital in Melbourne, Australia. Dr. Bishop and her colleges examined the virus by negative stain electron microscopy this allowed them to determine the size and shape of the virus. Although the virus was discovered in 1973 the first vaccine for the virus didn’t come along until 1998 and was removed from the market in 1999. It was then found to cause intussusception which is the twisting and blockage of the intestine which can be fatal. Currently there are two active vaccines for the Rotavirus on the market right now. The incubation period for a rotavirus last approximately two days during this time infected individual can still pass the virus to others even before displaying symptoms themselves. The Rotavirus is typically categorized by extreme diarrhea, vomiting, and fever often followed by abdominal pain and dehydration which last approximately 5 to 7 days. Diagnosis may be made by rapid detection of rotavirus antigen in stool specimens #7. It can also be identified by enzyme immunoassay or reverse transcriptase polymerase chain reaction but this testing is rarely used.

Epidemiology of the Disease

Individuals that are most commonly affected by the Rotavirus are children and infants under the age of five Rotavirus is responsible for 2 million hospitalizations worldwide and is the leading cause of death for children under the age of 5 accounting for 20 to 25% of all deaths in this age group. Although individuals of all ages can be affected by this virus children are more vulnerable to the virus because of their under developed immune systems. The virus is highly contagious spread via the fecal oral route which mean from the waste of infected person to the mouth of another individual. This could be done by direct contact via contamination of hands or objects such as toy or food.

Control of Rotavirus

Rotavirus affect millions of children and adults it is still the leading cause of viral gastroenteritis related complications and deaths in children under the age of five. Although practicing proper hygiene is important to prevent the spread of this virus that alone may not be enough to prevent this virus from being spread. In recent year two vaccines have been approved for use in infants in the United States. These vaccines have been effective providing 85 % to 98% protection against severe rotavirus related illnesses. The CDC recommends routine vaccination of infants with either of the two available vaccines. These vaccines work by attempting to replicate the natural protect from the virus that comes with aging. RotaTeq was licensed in 2006 and is given in three doses at ages 2, 4, and 6 months. The other Rotarix was licensed in 2008 and is given in two doses at ages 2, and 4 months.