NAME: Rubella virus
CHARACTERISTICS: Family Togaviridae, Genus Rubivirus. Each virion is 55-89 nm and contains one positive stranded RNA molecule. Genetic material is enveloped in an isometric nucleocapsid. The capsid consists of multiple copies of one virus-specific protein, surrounded in a lipid bilayer containing two virus-specific glycoproteins.
PATHOGENICITY/ TOXICITY: Rubella: Mild infection characterized by rash starting on the face and gradually spreading to the feet, fever, lymphadenopathy, and other flu-like symptoms such as coughing, sore throat, and sneezing(2,3). Older children and adults may experience joint involvement and purpuric rash(2). Rare complications include encephalitis, thrombocytopenia with hemorrhagic manifestations, neuritis, conjunctivitis, and ochitis(3).
Congenital rubella syndrome: Women in their first trimester who contract rubella have an increased risk of passing the infection to the developing foetus(3). When contracted during the first trimester the effects on the child are most marked. Ocular, cardiovascular, and central nervous system defects are common, along with deafness and intrauterine growth retardation. Contraction of rubella later in pregnancy reduces the risk and severity of symptoms. Second trimester infections are associated with deafness, retinopathy, microcephaly, and mental retardation, while third trimester infections are associated with intrauterine growth retardation.
EPIDEMIOLOGY: Worldwide(1,3). Epidemics occurred roughly every 6-9 years but immunisation programmes have greatly reduced the number of cases in developed countries(1,3). Infections peaks in late winter and spring(3).
INFECTIOUS DOSE: Thirty viral units subcutaneously, >10 viral units by pharyngeal spray, and 60 units by nasal drops are sufficient for infection(6).
MODE OF TRANSMISSION: The virus is transmitted by aerosols from the respiratory tract in infected individuals(7). Transmission may also occur via nasal and respiratory tract secretions carried on hands that come in contact with nasal mucosa.
DRUG SUSCEPTIBILITY: Susceptibility to antiviral drugs has not been reported(1).
SUSCEPTIBILITY TO DISINFECTANTS: Rubella virions are susceptible to ether, chloroform, sodium dodecyl sulphate (SDS), saponin, formaldehyde, ethylene oxide and beta- propiolactone(1). 1% sodium hypochlorite and 70% ethanol are also effective disinfectants(7).
PHYSICAL INACTIVATION: Temperatures exceeding 56 °C for 2-20 minutes, 37°C for 48 hours, or -20 °C will inactivate the Rubella virus(1). Virions are also susceptible to UV light. Virions are not stable at a pH less than 6.8 or greater than 8.0(1).
SURVIVAL OUTSIDE HOST: Rubella has a half life of 1 hour at 37 °C outside of the host(9). The mean survival time is 0.9 days.
SURVEILLANCE: Monitor for symptoms. Confirm diagnosis with serological testing(1). Enzyme-linked immunosorbent assays (ELISA), hemagglutination inhibition test (HI), and immunofluorescent antibody assay (IFA) are common methods used. Serologic testing can also be used to confirm congenital rubella syndrome in an infant, which may yield more harm than the rubella virus itself.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Treatment for rubella is supportive(1). There have been no reports of successful treatment with antiviral drugs.
IMMUNISATION: Vaccine available; vaccine is combined with measles and mumps vaccines and is know as the measles, mumps and rubella (MMR) vaccine(2,5). Vaccination for women is suggested 1 month before conception if not previously vaccinated(3). Recent studies show any risk to foetus during the first month of pregnancy from the vaccine is negligible.
PROPHYLAXIS: Vaccination of females of child bearing age decreases the risk of CRS(1,3). Immune globulin given soon after exposure to rubella may modify or suppress symptoms but is not certain to prevent infection, including congenital infection and thus is not recommended for routine use(10).
LABORATORY-ACQUIRED INFECTIONS: Two cases of Rubella in laboratory workers were reported as of 1985, and the source of these infections may have been from the community(11). Health care workers have been known to carry the virus and act as a source of infection to in larger community(12).
SOURCES/SPECIMENS: Blood, faeces, urine, and nasopharyngeal secretions contain the viral agent during the course of infection(2).
PRIMARY HAZARDS: Inhalation of aerosols during manipulation of infectious samples or cultures are the primary hazards associated with the Rubella virus(6,13). Splashing of infectious samples in the eye also poses risk of infection.
SPECIAL HAZARDS: Work with Rubella virus should not be performed by women who are, or may become, pregnant as Rubella is a proven teratogen(14).
RISK GROUP CLASSIFICATION: Risk Group 2(15).
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infected or potentially infected 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(13).
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(13).
SPILLS: Allow all aerosols to settle, and, while wearing protective clothing, cover the spill gently with paper towel and apply appropriate disinfectant, starting at the edges of the spill zone and working inward. Allow an appropriate contact time before clean up(13).
DISPOSAL: Decontamination using steam sterilization, chemical disinfection, or incineration must be performed before disposal of infectious waste(13).
STORAGE: All infectious materials should be stored in sealed containers bearing the appropriate labelling(13).
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