NAME: Human rotavirus
SYNONYM OR CROSS REFERENCE: HRV, Human reovirus-like agent, infantile gastroenteritis virus(1), sporadic viral gastroenteritis, severe viral gastroenteritis of infants and children, non-bacterial gastroenteritis of infancy, and rotaviral enteritis.
CHARACTERISTICS: Human rotavirus is classified as a member of genus Rotavirus within the family Reoviridae(2,3). Rotavirus is non-enveloped, with a diameter of about 70 nm, and has a wheel-like appearance. It has an icosahedral shaped, three-layered caspid shell. The viral genome consists of 11 segments of double-stranded RNA (dsRNA). Rotavirus can be classified into seven major serogroups (A - G). Groups A, B, and C infect both humans and animals, while the rest have only been found in animals to date. Group A has been established as the most common rotavirus responsible for causing human illness.
PATHOGENICITY/TOXICITY: HRV predominantly attacks enterocytes, which are mature villous epithelial cells in the small intestine(2,3,4). The disease caused by HRV is self-limiting in general, lasting for about 4-7 days, with symptoms similar to those caused by other gastrointestinal agents, although the symptoms of HRV infections are usually more severe. These include fever, vomiting, and non-bloody diarrhoea (often watery and explosive). This usually leads to mild to severe dehydration (usually isotonic in nature); electrolyte imbalance; and in prolonged cases, to secondary disaccharidase deficiency. Subsequent gastroenteritis infections tend to be less severe compared to previous infections. A temporal association of rotavirus infection with a variety of disease conditions has been described, including upper and lower respiratory infection, intussusception, and others(3). An etiologic association of rotavirus infection with necrotizing enterocolitis, hemorrhagic gastroenteritis, and pneumatosis intestinalis in infancy has been suggested(2). Detection of rotavirus RNA in cerebrospinal fluid of patients with gastroenteritis suggests that neurological disorders such as convulsions may be associated with HRV infection, but this has not been confirmed(5).
EPIDEMIOLOGY: HRV is the major cause of severe diarrhoea (gastroenteritis) in children throughout the world, more so in developing countries, with about 95% of children contracting the infection by 5 years of age(6). Death rate due to rotavirus infection is estimated at about 600,000 child deaths per year worldwide, with yearly death tolls highest in India, Nigeria, China, Pakistan, Congo, Ethiopia, and Bangladesh. Prevalence of disease ranges from ~30% during off season to ~70% during seasonal peaks. Disease outbreaks demonstrate a seasonal pattern in temperate climates, where the disease is more pronounced during drier and cooler months. In the USA and Europe, annual epidemics begin during the months of November/December and January respectively in the Southwest and progress to Northeast by April/May and March, respectively. No specific seasonal trend is observed in tropical climates. HRV infection is generally more severe and clinically significant in children aged 3-35 months, with the first infection being the most severe. Adults tend to be asymptomatic and/or may demonstrate subclinical infection. Immunocompromised individuals are susceptible to developing more severe disease manifestations(2). Chances of spread of infection within families, day care centres, and hospitals are high(3). Nosocomial infections are also common and are a major cause of diarrhoea in newborns and infants(2,7). Several outbreaks have been observed in geriatric groups within hospitals. Serogroup A rotavirus is responsible for ~95% of the rotavirus diarrhoea cases worldwide(6); however, serogroup B rotavirus has caused several large outbreaks of gastroenteritis in adults in various parts of China, and has also been associated with severe diarrheal illness in Bangladesh and India(2).
HOST RANGE: Humans and experimentally infected animals (see SECTION III: RESERVOIR for more detail).
INFECTIOUS DOSE: Unknown
MODE OF TRANSMISSION: The most common mode of transmission for HRV is through faecal-oral spread, either from person-to-person or contact with contaminated environmental surfaces(3,4,6). The possibility of spread through faecally contaminated food and water also exists. Transmission through respiratory droplets has also been suggested; however, more investigation is required.
COMMUNICABILITY: Person-to-person transmission appears to be fairly common through the faecal-oral route. Rotavirus shedding rate is the highest during the diarrhoeal stage of the disease, which occurs during the first 2-5 days of illness(3).
RESERVOIR: Humans are the only reservoir for HRV; however, infection by group A rotaviruses (GARVs) has been reported in calves, pigs, foals, cats, dogs, and some birds. The GARVs found in animals appear to be very closely related to HRV(8). Evidence for some interspecies infection by GARVs does exist. More importantly, it has been suggested that reassortment and interspecies transmission may generate novel human GARVs; and hence it is important to consider these animals as relevant reservoirs for HRV.
DRUG SUSCEPTIBILITY: Unknown.
SUSCEPTIBILITY TO DISINFECTANTS: HRV, either in suspension or on inanimate surfaces, is susceptible to glutaraldehyde (2%); chlorinated disinfectants (>20,000 p.p.m. chlorine); iodinated disinfectants (>10,000 p.p.m. iodine); combinations of quaternary ammonium compounds with alcohols (>40%), some acids (HCl), some bases (sodium metasilicate); and combinations of phenolic compounds with strong anionic surfactants(9,10). Longer exposure times are required for disinfecting contaminated surfaces as compared to contaminated suspensions/solutions. HRV has also been shown to be very susceptible to Lysol brand disinfectants (79% ethyl alcohol, 0.1% o-phenylphenol)(11). Other disinfectants include formalin (2%) and sodium hypochlorite (2%).
SURVIVAL OUTSIDE HOST: HRV can survive ambient temperatures (30-35 °C)(14) and can remain infectious on inanimate objects for up to 60 days(3). They tend to be more stable at medium or low humidity levels.
SURVEILLANCE: Monitor for symptoms of disease. Electron microscopy is still the gold standard diagnostic technique for HRV; however, it is slightly less sensitive and more expensive than some new diagnostic techniques(3,6). These include enzyme-linked immunosorbent assays (ELISAs) and latex agglutination assays used for the detection of HRV (group A) antigen in stool samples.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Supportive therapy is needed to prevent dehydration by replacement of fluid and electrolyte losses(3,6). This can be done using the World Health Organization (WHO) formulation(15) or other commercial formulations, or through intravenous fluids in cases of severe diarrhoea, intractable vomiting, acidosis, and/or shock accompany the illness. Resumption of normal diet should be promoted after rehydration(3).
IMMUNISATION: In the past, the rhesus-human rotavirus reassortment-tetravalent vaccine (Rotashield) had been recommended for use by the US Advisory Committee on Immunization Practices (ACIP), but its use was suspended in 1999(3). Health Canada has approved RotaTeq and Rotarix vaccines in Canada; however, they are not part of the routine immunization programs that are currently available(16). RotaTeq is a live, oral, human-bovine, reassortment rotavirus vaccine developed from a strain of bovine rotavirus, approved by the US Food and Drug Administration (FDA). Rotarix is a live, oral human rotavirus vaccine developed from the most common strain of human rotavirus, also approved by FDA.
LABORATORY-ACQUIRED INFECTIONS: No cases of laboratory-acquired infection have been reported to date.
PRIMARY HAZARDS: Ingestion of feces or stool samples and other contaminated materials. Exposure of mucous membranes to contaminated droplets. Importance of aerosol exposure may also present a primary hazard.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2(17).
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes(18).
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities(18).
SPILLS: Allow aerosols to settle. While wearing protective clothing, gently cover the spill with absorbent paper towel and apply appropriate disinfectant, starting at perimeter and working towards the centre. Allow sufficient contact time before clean up(18).
DISPOSAL: Decontaminate, either by steam sterilization, incineration, or chemical disinfection, before disposal(18).
STORAGE: The infectious agent should be stored in sealed containers that are appropriately labelled, preferably at -20 °C(14). For long term (<1 year) storage, it should be stored at -70 °C to -80 °C; however, the presence of a cryoprotectant is not necessary(18).
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: September 2010
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2010