NAME: Murray Valley encephalitis
SYNONYM OR CROSS REFERENCE: Australian X disease, mosquito-borne encephalitis, arbovirus, viral encephalitis, Australian encephalitis is a proposed name
CHARACTERISTICS: Family Flaviviridae (formerly Togaviridae); 40-50 nm diameter, enveloped, positive sense ssRNA; member of the Japanese encephalitis (JE) antigenic complex
PATHOGENICITY: Acute inflammatory disease of short duration involving brain, spinal cord and meninges; acute onset, headache, high fever, followed by nuchal rigidity, neurologic signs, stupor, coma, spastic quadriplegia, convulsions and paralysis including respiratory, progressive CNS damage; progresses rapidly in infants; up to 60% case fatality rate; neurologic sequelae in up to 40% of mild cases and all severe cases including paraplegia, impaired gait and motor control, decreased intellect; no asymptomatic infections have been recorded.
EPIDEMIOLOGY: Murray Valley encephalitis recognized in parts of Australia, New Zealand and New Guinea
HOST RANGE: Humans, wild birds, other mammals
INFECTIOUS DOSE: Unknown
MODE OF TRANSMISSION: By bite of infective mosquitoes
INCUBATION PERIOD: Usually 5-15 days
COMMUNICABILITY: Not directly transmitted from person-to-person; virus is not demonstrated in blood of human after onset of disease; viremia in birds 2-5 days; mosquitoes are infective for life
RESERVOIR: Principally large water birds, other mammals may contribute
ZOONOSIS: Yes, from infected animals via mosquitoes; infected animals do not develop disease
VECTORS: Mosquitoes - Culex spp. especially Culex annulirostris
DRUG SUSCEPTIBILITY: N/A
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to disinfectants - 1% sodium hypochlorite, 2% glutaraldehyde, 3-8% formaldehyde, alcohol, iodine, phenol iodophors, and organic solvents/detergents
PHYSICAL INACTIVATION: Inactivated by heat; 50% reduction in 10 min at 50o C, complete inactivation in 30 min at 56o C; inactivated by UV and gamma irradiation
SURVIVAL OUTSIDE HOST: Does not survive out of host
SURVEILLANCE: Monitor for symptoms of arthropod-borne viral fever; serological identification and antibody titre
FIRST AID/TREATMENT: No specific treatment; supportive care
IMMUNIZATION: None
PROPHYLAXIS: None
LABORATORY-ACQUIRED INFECTIONS: 3 reported infections with Murray Valley
SOURCES/SPECIMENS: Blood, CSF, urine and exudates
PRIMARY HAZARDS: Exposure to aerosols of infectious solutions and animal bedding, accidental parenteral inoculation, broken skin contact
SPECIAL HAZARDS: None
CONTAINMENT REQUIREMENTS: Biosafety level 3 practices, containment equipment and facilities for activities using potentially infectious clinical materials and infected tissue culture, animals or arthropods
PROTECTIVE CLOTHING: Laboratory coat; gloves and gown with ties in back and tight wrists when working with agent
OTHER PRECAUTIONS: None
SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with paper towels and apply 1% sodium hypochlorite, starting at perimeter and working towards the centre; allow sufficient contact time before clean up
DISPOSAL: Decontaminate before disposal; steam sterilization, incineration
STORAGE: In sealed containers that are appropriately labeled (in a locked level 3 facility)
Date prepared: March, 2001
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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