Rotavirus
last authored: March 2010, David LaPierre
last reviewed:
Introduction
Rotavirus is the most common cause of severe diarrhea among children, causing death in over 500,000 children annually, and over 2 million hospitalizations, worldwide.
The incubation period for rotavirus disease is approximately 2 days.
The disease is characterized by vomiting and watery diarrhea for 3 - 8 days, and fever and abdominal pain occur frequently.
Immunity after infection is incomplete, but repeat infections tend to be less severe than the original infection.
The Case of Patrice Kiggulu
Patrice Kiggulu is a 6 month-old girl who develops multiple bouts of diarrhea over two days. She becomes increasingly lethargic and is no longer interested in playing. Her mother is concerned she might be dehydrated. What should her mother do?
Epidemiology
The highest rates of illness occur among infants and young children, and most children in the United States are infected by 2 years of age. Adults can also be infected, though disease tends to be mild.
Rotavirus is the most common cause of severe diarrhea in infants, responsible for 500,000 deaths/year, 230,000 of them in sub-Saharan Africa.
There are specific rotavirus seasons in some countries, while in others, infection occurs year-round. In countries with a temperate climate, the disease has a winter seasonal pattern, with annual epidemics occurring from November to April.
Classification and Characteristics
Rotaviruses are nonenveloped, double-shelled viruses. Triple-layered particles.
A rotavirus has a characteristic wheel-like appearance when viewed by electron microscopy (the name rotavirus is derived from the Latin rota, meaning "wheel"). The virus is stable in the environment.
The genome is composed of 11 segments of double-stranded RNA, which code for six structural and five nonstructural proteins.
There are a number of strains of rotavirus.
VP1: RNA polymerase
VP2: core shell protein
VP6:
VP3: capping enzyme
Transmission and Infection
Rotavirus is very infectious, with household attack rates above 80%.
The primary mode of transmission is fecal-oral, although respiratory spread appears also to be possible. Because the virus is stable in the environment, transmission can occur through ingestion of contaminated water or food and contact with contaminated surfaces.
Inside the intestines, rotavirus attaches to mature enterocytes. Entry into enterocytes is followed by RNA synthesis. Some of these are transcribed, while others remain as RNA. These begin to be assembled prior to dsRNA genome replication.
leading to their destruction and to malabsorption of salt, sugar, and water.
Clinical Manifesations
Infection can lead to severe osmotic diarrhea due to bacterial digestion of sugar. Life-threatening dehydration can follow if rehydration therapy is insufficent.
Lactase deficiency can follow enterocyte destruction, and transient milk intolerance is common in the weeks after rotavirus infection.
Diagnosis
When necessary, beyond clinical diagnosis, lab testing can include rapid antigen detection of rotavirus in stool specimens using ELISA testing. Strains may be further characterized by enzyme immunoassay or reverse transcriptase polymerase chain reaction.
Serology can be used to determine IgA levels.
Treatment
For healthy patients, rotavirus gastroenteritis is a self-limited illness, lasting for only a few days. Treatment is nonspecific and consists of oral rehydration therapy to prevent dehydration. About one in 40 children with rotavirus gastroenteritis will require hospitalization for intravenous fluids.
Oral, live attenuated rotavirus vaccines are available against the G1 strain. Crossreactivity is present. They show efficacy in North America, South America, Europe, and Africa. A previous vaccine was withdrawn due to risk of intussucption, though this does not appear to be the case with the new vaccine.
Resources and References
World Health Organization - Rotavirus
Centre for Disease Control - Rotavirus
Swiss Institute of Bioinformatics Expasy - Viral zone
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