Pathogen Safety Data Sheets: Infectious Substances – St. Louis Encephalitis Virus
PATHOGEN SAFETY DATA SHEET – INFECTIOUS SUBSTANCES
SECTION I - INFECTIOUS AGENT
NAME: St. Louis Encephalitis Virus
CHARACTERISTICS: SLEV belongs to the family Flaviviridae, genus Flavivirus (formerly grouped with family Togaviridae) (3, 4) and is a member of Japanese encephalitis virus (JEV) serocomplex (5, 6). SLEV is an arthropod-borne, positive-sense ssRNA, enveloped, icosahedral virus with a genome of approximately 11 Kb (5, 6). They are 40-50 nm in diameter (6).
SECTION II – HAZARD IDENTIFICATION
PATHOGENICITY/TOXICITY: Most infections are asymptomatic or result in mild malaise of short duration, especially in young or middle-aged individuals (1). Clinical disease as a result of infection can include encephalitis, meningoencephalitis, encephalomyelitis, high fever, altered consciousness, neurologic dysfunction, aseptic meningitis, stiff neck, headache, myalgia, tremors, nausea, vomiting and urinary tract infection (1, 3, 7-9). Onset of symptoms is often acute (1, 3, 7), and may resolve spontaneously (1). The severity of clinical illness and fatality rate, but not rate of infection, increase with age and are most prevalent in the over-60 population (1, 7-13). Hypertension (11, 12) and vascular disease (12) may be risk factors for infection. Based on observations with other members of the Flavivirus genus, immunocompromised individuals may also be at greater risk of severe illness (14, 15). The fatality rate is 5-20% (1), and acute illness may be followed by prolonged convalescence in 30-50% of cases (1, 3).
EPIDEMIOLOGY: St. Louis encephalitis virus is distributed in Northern, Southern and Central America (1). Several outbreaks have occurred, and the average number of reported cases is slightly more than 100 (16). The greatest number of reported cases was between 1974 and 1976, when more than twelve outbreaks resulted in more than 2000 officially reported cases in Canada and the United States (10, 16). Cases occur primarily in mid-to-late summer or early fall in temperate areas, and can occur year-round in milder climates (1). Higher temperatures may increase the length of the transmission season, and areas with the greatest abundance of mosquitoes relative to number of residents (i.e. rural areas) may be at greater risk of infection (1).
HOST RANGE: Humans, bats, wild birds, domesticated fowl, killer whale, rodents, and possibly other mammals (1, 2, 6, 8, 12, 15, 17). Wild birds are the primary vertebrate host, and develop an immediate viremic response sufficient to infect the mosquito vector, but do not develop apparent illness following infection.
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: The primary source of human infections is the mosquito-wild birds transmission cycle. Infected mosquitoes transmit the virus by biting an infected animal host and then biting a human host (or other animal host). Principal mosquito species known to transmit SLE virus are Culex pipiens, Culex quinquefasciatus, Culex, nigripalpus and Culex tarsalis (1, 9, 10, 13).
COMMUNICABILITY: Person-to-person transmission has not been documented. Virus is not demonstrated in the blood of humans after the onset of disease; however, the viremia response in infected birds is typically detected 1-5 days after infection, depending on the viral strain and bird species (1, 18). Mosquitoes are infected for life.
SECTION III - DISSEMINATION
SECTION IV – STABILITY AND VIABILITY
DRUG SUSCEPTIBILITY: No known drug susceptibility.
SUSCEPTIBILITY TO DISINFECTANTS: SLEV is susceptible to disinfectants including 3–8% formaldehyde, 2% glutaraldehyde, 2–3% hydrogen peroxide, 500–5000-ppm available chlorine, alcohol, 1% iodine, and phenol iodophors (21).
PHYSICAL INACTIVATION: SLEV is completely inactivated at 56°C for 30 min (22) and is sensitive to UV (23) and gamma (7) irradiation. At 50 °C, 50% of infectivity is lost in 10 minutes (21) and SLEV is stable at 4°C (22).
SURVIVAL OUTSIDE HOST: SLEV is stable in liquid aerosol form for at least 6 hours at room temperature and 23-80% humidity, and in freeze-dried form almost indefinitely at room temperature (21).
SECTION V – FIRST AID / MEDICAL
SURVEILLANCE: Monitor for symptoms and confirm by serology. SLEV antibody titre can be determined through serological testing or lumbar puncture, and seroprevalence rates in free-ranging birds or sentinel chickens can be useful for monitoring transmission activity (1, 18, 22). Passive surveillance of suspected human SLEV infection, as well as active monitoring of high-risk populations may provide indications of human involvement (1). Effective vector control is the only mechanism for reducing virus amplification and human infections (1).
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: There are no vaccines or antiviral agents for SLEV (3). Symptoms and complications as a result of infection are treated with supportive care.
IMMUNIZATION: None currently available.
PROPHYLAXIS: No specific prophylaxis available; however, measures to reduce the likelihood of mosquito bites may be effective (i.e. protective clothing, insect repellents).
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: One laboratory-acquired infection by percutaneous exposure was reported in 1950 (24, 25) and another three of non-aerosol source were reported in a 1979 survey of laboratories in the United States (26).
PRIMARY HAZARDS: Exposure to aerosols of infectious solutions or infected animal blood or urine (i.e. from animal bedding), accidental perenteral inoculation, or broken skin contact (27).
SPECIAL HAZARDS: None known.
SECTION VII – EXPOSURE CONTROLS / PERSONAL PROTECTION
RISK GROUP CLASSIFICATION: Risk Group 3 (30).
CONTAINMENT REQUIREMENTS: Containment Level 3 facilities, equipment, and operational practices for work involving infectious or potentially infectious material, infected animals, or cultures.
PROTECTIVE CLOTHING: Personnel entering the laboratory should remove street clothing and jewellery, and change into dedicated laboratory clothing and shoes, or don full coverage protective clothing (i.e., completely covering all street clothing). Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Eye protection must be used where there is a known or potential risk of exposure to splashes (31).
OTHER PRECAUTIONS: All activities with infectious material should be conducted in a biological safety cabinet (BSC) or other appropriate primary containment device in combination with personal protective equipment. Centrifugation of infected materials must be carried out in closed containers placed in sealed safety cups, or in rotors that are loaded or unloaded in a biological safety cabinet. The use of needles, syringes, and other sharp objects should be strictly limited. Open wounds, cuts, scratches, and grazes should be covered with waterproof dressings. Additional precautions should be considered with work involving animals or large scale activities (31).
SECTION VIII - HANDLING AND STORAGE
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 .
DISPOSAL: Decontaminate before disposal, steam sterilization, and incineration (31).
STORAGE: In sealed containers that are appropriately labelled in a Containment Level 3 laboratory (31).
SECTION IX – REGULATORY AND OTHER INFORMATION
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
- Reisen, W. K. (2003). Epidemiology of St. Louis encephalitis virus. Advances in Virus Research, 61, 139-183.
- Ciota, A. T., Jia, Y., Payne, A. F., Jerzak, G., Davis, L. J., Young, D. S., Ehrbar, D., & Kramer, L. D. (2009). Experimental passage of St. Louis encephalitis virus in vivo in mosquitoes and chickens reveals evolutionarily significant virus characteristics. PloS One, 4(11), e7876. doi:10.1371/journal.pone.0007876
- Gould, E. A., & Solomon, T. (2008). Pathogenic flaviviruses. Lancet, 371(9611), 500-509. doi:10.1016/S0140-6736(08)60238-X
- Collett, M. S., Anderson, D. K., & Retzel, E. (1988). Comparisons of the pestivirus bovine viral diarrhoea virus with members of the flaviviridae. The Journal of General Virology, 69 ( Pt 10)(Pt 10), 2637-2643.
- May, F. J., Li, L., Zhang, S., Guzman, H., Beasley, D. W., Tesh, R. B., Higgs, S., Raj, P., Bueno, R.,Jr, Randle, Y., Chandler, L., & Barrett, A. D. (2008). Genetic variation of St. Louis encephalitis virus. The Journal of General Virology, 89(Pt 8), 1901-1910. doi:10.1099/vir.0.2008/000190-0
- Buck, C., Paulino, G. P., Medina, D. J., Hsiung, G. D., Campbell, T. W., & Walsh, M. T. (1993). Isolation of St. Louis encephalitis virus from a killer whale. Clinical and Diagnostic Virology, 1(2), 109-112.
- Jones, S. C., Morris, J., Hill, G., Alderman, M., & Ratard, R. C. (2002). St. Louis encephalitis outbreak in Louisiana in 2001. The Journal of the Louisiana State Medical Society : Official Organ of the Louisiana State Medical Society, 154(6), 303-306.
- Spinsanti, L. I., Diaz, L. A., Glatstein, N., Arselan, S., Morales, M. A., Farias, A. A., Fabbri, C., Aguilar, J. J., Re, V., Frias, M., Almiron, W. R., Hunsperger, E., Siirin, M., Da Rosa, A. T., Tesh, R. B., Enria, D., & Contigiani, M. (2008). Human outbreak of St. Louis encephalitis detected in Argentina, 2005. Journal of Clinical Virology : The Official Publication of the Pan American Society for Clinical Virology, 42(1), 27-33. doi:10.1016/j.jcv.2007.11.022
- Gubler, D. J., Kuno, G., & Markoff, L. (2007). Flaviviruses. In D. M. Knipe, D. E. Griffin, R. A. Lamb, S. E. Staus, P. M. Howley, M. A. Martin & B. Roizman (Eds.), Fields Virology (5th ed., pp. 1153). Philadelphia: Lippincott Williams & Wilkins, a Wolters Kluwer Business.
- Monath, T. P., & Tsai, T. F. (1987). St. Louis encephalitis: lessons from the last decade. The American Journal of Tropical Medicine and Hygiene, 37(3 Suppl), 40S-59S.
- Bleed, D. M., Marfin, A. A., Karabatsos, N., Moore, P., Tsai, T., Olin, A. C., Lofgren, J. P., Higdem, B., & Townsend, T. E. (1992). St. Louis encephalitis in Arkansas. The Journal of the Arkansas Medical Society, 89(3), 127-130.
- Marfin, A. A., Bleed, D. M., Lofgren, J. P., Olin, A. C., Savage, H. M., Smith, G. C., Moore, P. S., Karabatsos, N., & Tsai, T. F. (1993). Epidemiologic aspects of a St. Louis encephalitis epidemic in Jefferson County Arkansas, 1991. The American Journal of Tropical Medicine and Hygiene, 49(1), 30-37.
- Reimann, C. A., Hayes, E. B., DiGuiseppi, C., Hoffman, R., Lehman, J. A., Lindsey, N. P., Campbell, G. L., & Fischer, M. (2008). Epidemiology of neuroinvasive arboviral disease in the United States, 1999-2007. The American Journal of Tropical Medicine and Hygiene, 79(6), 974-979.
- Roukens, A. H., & Visser, L. G. (2008). Yellow fever vaccine: past, present and future. Expert Opinion on Biological Therapy, 8(11), 1787-1795. doi:10.1517/14712522.214.171.1247
- Diamond, M. S., Mehlhop, E., Oliphant, T., & Samuel, M. A. (2009). The host immunologic response to West Nile encephalitis virus. Frontiers in Bioscience : A Journal and Virtual Library, 14, 3024-3034.
- Centers for Disease Control and Prevention. (2009).
Confirmed and Probable St. Louis Encephalitis Virus Neuroinvasive Disease Cases, Human, United States, 1964-2008, By State (as of 4/7/2009)
- Siirin, M. T., Duan, T., Lei, H., Guzman, H., da Rosa, A. P., Watts, D. M., Xiao, S. Y., & Tesh, R. B. (2007). Chronic St. Louis encephalitis virus infection in the golden hamster (Mesocricetus auratus). The American Journal of Tropical Medicine and Hygiene, 76(2), 299-306.
- Patiris, P. J., Oceguera, L. F.,3rd, Peck, G. W., Chiles, R. E., Reisen, W. K., & Hanson, C. V. (2008). Serologic diagnosis of West Nile and St. Louis encephalitis virus infections in domestic chickens. The American Journal of Tropical Medicine and Hygiene, 78(3), 434-441.
- Herbold, J. R., Heuschele, W. P., Berry, R. L., & Parsons, M. A. (1983). Reservoir of St. Louis encephalitis virus in Ohio bats. American Journal of Veterinary Research, 44(10), 1889-1893.
- Reisen, W. K., Lothrop, H. D., Chiles, R. E., Cusack, R., Green, E. G., Fang, Y., & Kensington, M. (2002). Persistence and amplification of St. Louis encephalitis virus in the Coachella Valley of California, 2000-2001. Journal of Medical Entomology, 39(5), 793-805.
- Gritsun, T. S., Lashkevich, V. A., & Gould, E. A. (2003). Tick-borne encephalitis. Antiviral Research, 57(1-2), 129-146.
- Fang, Y., Brault, A. C., & Reisen, W. K. (2009). Comparative thermostability of West Nile, St. Louis encephalitis, and western equine encephalomyelitis viruses during heat inactivation for serologic diagnostics. The American Journal of Tropical Medicine and Hygiene, 80(5), 862-863.
- Parquet, M. C., Kumatori, A., Hasebe, F., Mathenge, E. G., & Morita, K. (2002). St. Louis encephalitis virus induced pathology in cultured cells. Archives of Virology, 147(6), 1105-1119. doi:10.1007/s00705-002-0806-6
- Mediannikov, O. I., Likhoded, L. I., Penkina, G. A., Manzeniuk, O. I., Fatalieva, S. F., & Tarasevich, I. V. (2005). Bartonella and bartonellosis--emerging and re-emerging infections: epidemiology, clinical course, diagnosis. Zhurnal Mikrobiologii, Epidemiologii, i Immunobiologii, (1), 83-89.
- Taye, A., Chen, H., Duncan, K., Zhang, Z., Hendrix, L., Gonzalez, J., & Ching, W. (2005). Production of recombinant protein Pap31 and its application for the diagnosis of Bartonella bacilliformis infection. Annals of the New York Academy of Sciences, 1063, 280-285.
- Zeaiter, Z., Fournier, P. -., Greub, G., & Raoult, D. (2003). Diagnosis of Bartonella endocarditis by a real-time nested PCR assay using serum. Journal of Clinical Microbiology, 41(3), 919-925.
- Brooks, T. J., & Phillpotts, R. J. (1999). Interferon-alpha protects mice against lethal infection with St Louis encephalitis virus delivered by the aerosol and subcutaneous routes. Antiviral Research, 41(1), 57-64.
- Luby, J. P., Stewart, W. E.,2nd, Sulkin, S. E., & Sanford, J. P. (1969). Interferon in human infections with St. Louis encephalitis virus. Annals of Internal Medicine, 71(4), 703-709.
- Coleman, P. H., Lewis, A. L., Schneider, N. J., & Work, T. H. (1968). Isolations of St. Louis encephalitis virus from post-mortem tissues of human cases in the 1962 Florida epidemic. American Journal of Epidemiology, 87(3), 530-538.
- Human pathogens and toxins act. S.C. 2009, c. 24, Second Session, Fortieth Parliament, 57-58 Elizabeth II, 2009. (2009).
- Public Health Agency of Canada. (2004). In Best M., Graham M. L., Leitner R., Ouellette M. and Ugwu K. (Eds.), Laboratory Biosafety Guidelines (3rd ed.). Canada: Public Health Agency of Canada.
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