Disease
Rotavirus infections

Author
Chrissy Blake, BIOL 230, Spring 2009

Causative Agents
Rotavirus is the leading cause of severe diarrhea in infants and young children.  The rotavirus is a member of the Reoviridae family.  The Rotavirus is a non-enveloped, double-stranded RNA virus 60-80 nm in size.  There are 7 different strains of the virus: A, B, C, D, E, F, and G, with Rotavirus A being the most common cause of viral gastroenteritis.

Epidemiology
Worldwide, over 500,000 children die from rotavirus each year.  In the U.S., there are more than 2.7 million cases yearly of gastroenteritis (def) in children with about 60,000 requiring hospitalization and 37 deaths resulting from the side effects. 

There are seroprevalence (def) studies that show that most infants have been infected with rotavirus by age 3.  The virus tends to affect infants and children 3 months to 2 years old.  It is thought that there is a transplacental (def) antibody transfer from mother to baby that protects the younger infants from the virus.  In adults, asymptomatic infections are commonly seen. 

Rotavirus infections tend to peak during the winter months in the U.S. (from November to May) but is steady year-round in the tropics. 

Transmission
The rotavirus is infects the intestinal tract of humans and animals.  It is highly contagious and is usually transmitted via the fecal-oral route.  Since it is resistant to hand washing, the rotavirus is easily transmitted person to person from infected stool via fomites (def).  The virus can be spread a few days before symptoms arise and also a few days after symptoms subside. 

It is also possible for the rotavirus to be spread via food and water-borne pathogens as well as by respiratory discharge. 

Signs and Symptoms
Most commonly, rotavirus A causes gastroenteritis (def) in young children, leading to severe diarrhea and dehydration.  The symptoms begin with nausea and fever, which can be of high grade (def) in some individuals.  Diarrhea begins within a few days which is usually very watery but contains no blood.  Diarrhea can last from 3-9 days but can be longer especially in immunosuppressed individuals.  Diarrhea causes dehydration which is generally the cause of hospitalization of individuals infected by rotavirus. 

In adults, rotavirus A generally causes asymptomatic infections due to an immunity acquired during childhood.  Although no symptoms are seen, these infections add to the spread of rotavirus from person to person. 

Rotavirus B, also known as adult diarrhea rotavirus (ADRV) has been linked to an outbreak in China, causing severe diarrhea in people of all ages.  This was caused by contaminated drinking water. 

Prevention and Treatment
Since the risk rotavirus is only limited by sanitation and hand washing, not prevented, vaccination is the main form of prevention.  The first vaccine in the United States was issued in 1998.  It prevented 80-100% of individuals from having severe diarrhea as a result of a rotavirus A infection.  It was quickly deemed potentially harmful since it lead to a heightened risk for intususseption (def).  It was taken off the market in 1999. 

Two oral vaccines were put out in 2006, Rotarix and RotaTeq, which contain disables live forms of the virus.  They have both been found to be effective and safe for children.

Once infected with rotavirus, most children recover without medical attention.  In some severe cases, hospitalization is required to rehydrate the individual via intravenous treatment. 

Bibliography

Center for Disease Control and Prevention, "Rotavirus (cause of severe diarrhea)". Department of Health and Human Services. April 17, 2009 <http://www.cdc.gov/rotavirus/>.

Directors of Health Promotion and Education, "Rotavirus". April 17, 2009 <http://www.dhpe.org/infect/rot.html>.

Wikipedia, "Rotavirus". April 17, 2009 <http://en.wikipedia.org/wiki/Rotavirus>.