NAME: California serogroup
SYNONYM OR CROSS REFERENCE: Arbovirus, mosquito-borne encephalitis; includes LaCrosse, California encephalitis, Jamestown Canyon, Snowshoe hare, Guaroa, Inkoo, Tahyna, Trivittatus
CHARACTERISTICS: Bunyavirus, ssRNA, enveloped, 90-100 nm diameter, helical capsid
PATHOGENICITY: Onset is abrupt, typically with a severe bifrontal headache, fever, vomiting, lethargy and convulsions; less frequently, there is only aseptic meningitis; fatalities and neurologic sequelae are rare: convalescence may be prolonged
EPIDEMIOLOGY: Viruses originally found in California but disease due to LaCrosse virus occurs mainly in midwestern North America with scattered cases elsewhere; cases occur in summer and early fall and are commonly limited to areas and years of high temperature and many mosquitoes, particularly in young males (4-14 years); Jamestown Canyon is uncommon and disease usually occurs in adults; Snowshoe hare isolated throughout Canada and Alaska
HOST RANGE: Humans, small animals (squirrels and rabbits)
INFECTIOUS DOSE: Unknown
MODE OF TRANSMISSION: By the bite of infective mosquitoes; viruses are transmitted between woodland mosquitoes and small animals - human infection is tangential
INCUBATION PERIOD: Usually 5-15 days
COMMUNICABILITY: Not directly transmitted from person to person; mosquitoes are infective for life
RESERVOIR: Virus maintained by overwintering in mosquito eggs; maintained in mosquitoes by transovarial and venereal transmission
ZOONOSIS: Yes, from infected animals via mosquitoes
VECTORS: Woodland mosquitoes - Aedes triseriatus (LaCrosse), Spring Aedes (Snowshoe hare) California serogroup
DRUG SUSCEPTIBILITY: N/A
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to disinfectants - 1% sodium hypochlorite, 2% glutaraldehyde, 70% ethanol, formaldehyde
PHYSICAL INACTIVATION: Sensitive to heat (infectivity lost at 50-60°C for at least 30 min)
SURVIVAL OUTSIDE HOST: Does not survive for long periods out of host; survives for long periods in mosquito eggs
SURVEILLANCE: Monitor for symptoms of arthropod-borne viral fever; confirmation serologically
FIRST AID/TREATMENT: No specific treatment
IMMUNIZATION: None
PROPHYLAXIS: None
LABORATORY-ACQUIRED INFECTIONS: No reported laboratory-acquired infections
SOURCES/SPECIMENS: Blood, CSF, central nervous system and other tissues, and infected arthropods
PRIMARY HAZARDS: Accidental parenteral inoculation, contact with broken skin or mucous membranes, bites of infected laboratory rodents or arthropods; infectious aerosols may be a potential source of infection
SPECIAL HAZARDS: None
CONTAINMENT REQUIREMENTS: Biosafety level 2 practices, safety equipment, and facilities for activities with potentially infected clinical materials, arthropods, rodents, tissue cultures and embryonated eggs
PROTECTIVE CLOTHING: Laboratory coat; gloves when contact with infectious materials is unavoidable
OTHER PRECAUTIONS: None
SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with a paper towel and apply 1% sodium hypochlorite, starting at perimeter and working towards the centre; allow sufficient contact time before clean up (30 min)
DISPOSAL: Decontaminate before disposal; chemical disinfection, steam sterilization, incineration
STORAGE: In sealed containers that are appropriately labelled
Date prepared: November 1999
Prepared by: Office of Laboratory Security, PHAC
Although the information, opinions and recommendations contained in this Material 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.
Copyright ©
Health Canada, 2001
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