NAME: Semliki Forest Virus
CHARACTERISTICS: Family Togaviridae, Genus Alphavirus (6, 7). Virions have an approximate diameter of 50-70 nm and contain one positive stranded RNA molecule. Genetic material is enveloped in an icosahedral nucleocapsid.
PATHOGENICITY/TOXICITY: Most infections caused by the Semliki Forest Virus (SFV) are asymptomatic or very mild (3). When symptoms are present they are mild. During the acute phase of infection they are indistinguishable from those of malaria, influenza, or other febrile illnesses (3, 8). When present, symptoms include headache, fever, myalgia and athrolgia. Rare symptoms of abdominal pain, diarrhea, and conjunctivitis have been reported. The acute phase lasts 2-4 days and is followed by a long period marked by weakness. In the only case reported to end in death the symptoms worsened and loss of speech, convulsions, coma, and cardiovascular and respiratory failure followed (9). The patient had a history of compromised immune system.
EPIDEMIOLOGY: Found throughout Africa and parts of Asia (8, 9). Possibly present in central and southern Europe (10). Human infections may be common, as indicated by serosurveys (9). Reports of disease are very rare. Outbreaks have occurred in regions of Africa, but no other fatalities have been reported.
INFECTIOUS DOSE: Unknown.
INCUBATION PERIOD: Unknown.
COMMUNICABILITY: Not communicated person-to-person.
SUSCEPTIBILITY TO DISINFECTANTS: 1% sodium hypochlorite and 70% ethanol are effective disinfectants (6).
SURVIVAL OUTSIDE HOST: SVF can survive in aerosol spray of culture fluid up to 22 hours in 90% relative humidity (13). SVF survival exceeds 24 hours in aerosol sprays if culture fluid in 20-84% relative humidity.
SURVEILLANCE: Monitor for symptoms. Identification may be performed by real time PCR. Enzyme linked immunoabsorbant assays may also be performed for identification of virus specific antibodies (5).
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: No specific antiviral treatment is available (1, 5). Supportive treatment is provided for those with more severe symptoms. Arthritis treatment may be required for those who develop such symptoms (1).
LABORATORY-ACQUIRED INFECTIONS: One reported case as of 2001, resulting in the death of a 26 year old laboratory worker (5, 9, 14). No information reported on mode of transmission. Two other cases of infections with the Semliki Forest virus were reported; neither was fatal (5, 14).
SOURCES/SPECIMENS: Blood, cerebral spinal fluid (5).
PRIMARY HAZARDS: Accidental inoculation with needle containing infectious material and inhalation of aerosols (5).
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2 (15).
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 (16). Respirator should be used when exposed to infectious aerosols.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC) (16).
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 (16).
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up (16).
DISPOSAL: Decontamination using steam sterilization, chemical disinfection, or incineration must be performed before disposal of infectious waste (16).
STORAGE: All infectious materials should be stored in sealed containers bearing the appropriate labelling (16).
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