West Nile Virus (WNV)

Characteristics

Morphology An icosahedral, enveloped virus of 40 to 50 nm in diameter. It has a single stranded, positive-sense RNA genome. 
Growth Conditions

Tissue culture.

Health Hazards

Host Range

Humans, mosquitoes, ticks, birds, horses, alligators, tree squirrels, eastern chipmunks, eastern cottontail rabbits, lake frogs; as well as a broad range of common North American wild and domestic mammals, such as dogs, deer, feral swine, coyotes, foxes, opossums, raccoons skunks, bats and other small rodents.

Modes of Transmission

Primarily from infected mosquitoes. Other possible routes include: blood transfusion, vertical transmission, breast milk, organ transplantation, contact of the conjunctiva with contaminated bodily secretions from infected birds, and laboratory accidents involving sharps.

Signs and Symptoms
  • Sudden onset fever with chills, headache, backache, malaise, arthralgia, myalgia and eye pain
  • Nausea, vomiting, diarrhea, sore throat & cough
  • Less than 1% of WNV infected individuals develop meningitis, encephalitis and/or acute flaccid paralysis
Infectious Dose Unknown
Incubation Period 2-6 days, but could extend to 14 days.

Medical Precautions/Treatment

Prophylaxis None currently available.
Vaccines None currently available.

Treatment

None currently available for WNV fever. Supportive therapy for encephalitis include: intravenous fluid, electrolyte management, assisted respiration, anticonvulsants, management of cerebral edema, and prevention of secondary bacterial infections.
Surveillance Monitor for symptoms, confirm via virus isolation from blood or cerebrospinal fluid
Emory Requirements Report all exposures. Emory EHSO provided medical alert card should be carried by researcher at all times.

Laboratory Hazards

Laboratory Acquired Infections (LAIs) Twenty cases have been reported of workers who acquired WNV following percutaneous inoculation while handling infected fluids and tissues with no deaths.
Sources Blood, cerebrospinal fluid, tissues, infected arthropods, oral and cloacal swabs and feather pulp.

Supplemental References

Containment

BSL-2+

In vitro work with the virus or clinical samples.

ABSL-3

Manipulation of virus in animals.

Spill Procedures

Small Notify others working in the lab. Allow aerosols to settle. Don appropriate PPE. Cover area of the spill with paper towels and apply an EPA registered disinfectant, working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.
Large

Contact Emory’s Biosafety Officer (404-727-8863),
the EHSO Office (404-727-5922), or
The Spill Response Team (404-727-2888).

Exposure Procedures

Mucous membrane Flush eyes, mouth or nose for 15 minutes at eyewash station.
Other Exposures Wash area with soap and water for 15 minutes.
Reporting Immediately report incident to supervisor, complete an employee incident report in PeopleSoft.
Medical Followup 

7am-4pm (OIM): EUH (404-686-7941) EUHM (404-686-7106) WW (404-728-6431)

After Hours: OIM NP On Call 404-686-5500 PIC# 50464

Needle Stick (OIM): EUH (404-686-8587) EUHM (404-686-2352)

Yerkes: Maureen Thompson Office (404-727-8012) Cell (404-275-0963)

Viability

Disinfection Susceptible to disinfectants such as 3 to 8% formaldehyde, 2% glutaraldehyde, 2 to 3% hydrogen peroxide, 500 to 5,000 ppm available chlorine, alcohol, 1% iodine, and phenol iodophors.
Inactivation Inactivated by heat (50 to 60°C for at least 30 minutes), ultraviolet light, and gamma irradiation.
Survival Outside Host Low temperatures preserve infectivity, with stability being greatest below -60°C. When added to ELISA wash buffer there is a 10-fold decrease in titer per 24 hour period at 28°C.

Personal Protective Equipment (PPE)

Minimum PPE Requirements At minimum, personnel are required to don gloves, closed toed shoes, lab coat, and appropriate face and eye protection prior to working with West Nile Virus. Additional PPE may be required depending on lab specific SOPs.
Additional Precautions Not applicable.

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