Orthobunyaviruses
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Morphology
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Orthobunyaviruses (over 170 species, including Batai virus, Ngari virus, Inkoo virus,
Jamestown Canyon virus, Tahyna virus, Keystone virus, Bunyamwera virus) are a genus
of single-stranded, tri-segmented negative-sense RNA viruses that belong to the family
Peribunyaviridiae. Orthobunyaviruses are endemic to many areas of the world, including
Africa, Europe, Asia, and North America. All viruses are of zoonotic origin and are
transmitted primarily by contact with infected mosquitoes.
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Disease
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Batai virus; Bunyamwera virus (Bunyamwera fever); Inkoo virus; Jamestown Canyon virus;
Keystone virus; Oropouche virus; Tahyna virus
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Zoonosis
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Yes. The only documented transmission of orthobunyaviruses have been through zoonotic
means (mosquito bites, tick bites, Culicoid flies).
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Host Range
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Mosquitoes. Humans are accidental hosts. Other mammals, including hares, rabbits,
hedgehogs, rodents, and seals may serve as accidental or amplifying hosts.
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Modes of Transmission
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Transmission is primarily through mosquito bites. Disease has not been documented
to show transmission from human to human. If working in an endemic area or near mosquitoes
that may be infected with Orthobunyaviruses, be sure to minimize skin exposure and
use personal protectants containing N, N-diethyl-meta-toluamide (DEET).
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Signs and Symptoms
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Most cases report sudden onset of fever, stiff neck, lethargy, headache, nausea, vomiting.
Symptoms usually end within 7 days. Mosquitoes begin to become infectious approximately
1-2 weeks after ingestion of the virus (extrinsic incubation period). High viremia
is essential for neuroinvasion.
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Infectious Dose
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Unknown.
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Incubation Period
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The incubation period is approximately 3 to 7 days.
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Prophylaxis
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None.
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Vaccines
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None.
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Treatment
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There is no proven antiviral treatment for orthobunyavirus infections. Ribavirin treatment
has been studied in humans, though was not proven to reduce either viral load or mortality.
Management is mainly supportive. If severe enough, blood product transfusion may be
necessary. Data is insufficient regarding the use of steroids, intravenous immunoglobulin,
or plasma exchange. However, some advocate the use of IVIG from patients endemic to
the area of infection, as there is a higher probability of antibodies against the
virus.
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Surveillance
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Diagnosis relies primarily on serologic methods, as the virus is generally absent
from blood or secretions during CNS disease. Hemagluttinin inhibition testing is sensitive
for these viruses, though neutralization and RT-PCR with nucleotide genome sequencing
are needed to confirm the diagnosis. ELISA may also be used, but has not been widely
studied.
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MSU Requirements
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Report any exposures.
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Laboratory Acquired Infections (LAIs)
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Unknown.
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Sources
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Cultures, frozen stocks, other samples described in IBC protocol.
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Canadian MSDS:
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n/a
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BMBL
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CDC
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n/a
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NIH Guidelines
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Risk Group 2
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Agents that are associated with human disease which is rarely serious and for which
preventive or
therapeutic interventions are often available. |
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BSL2
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For all procedures involving suspected or known infectious specimen or cultures..
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ABSL2
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For all procedures utilizing infected animals.
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Small
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Notify others working in the lab. Remove PPE and don new PPE. Cover area of the spill
with absorbent material and add fresh 1:10 bleach:water. Allow 20 minutes (or as directed)
of contact time. After 20 minutes, cleanup and dispose of materials.
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Large
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• Immediately notify all personnel in the lab and clear all personnel from the area.
Remove any contaminated PPE/clothing and leave the lab.
• Secure the area by locking doors, posting signage and guarding the area to keep people out of the space. For assistance, contact MSU's Biosafety Officer (406-994-6733) or Safety and Risk Management (406-994-2711). |
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Mucous membrane
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Flush eyes, mouth, or nose for 5 minutes at eyewash station.
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Other Exposures
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Wash area with soap and water for 5 minutes.
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Reporting
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Immediately report incident to supervisor, complete a First Report of Injury form, and submit to Safety and Risk Management.
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Medical Follow-up
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During business hours: After business hours: |
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Disinfection
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1:10 dilution of bleach; 70% Ethanol
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Inactivation
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Treatment with lipid solvents or nonionic detergents removes the viral envelope and
results in loss of infectivity for arthropods and mammals. Inactivated moist heat
(1 hour at 121°C).
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Survival Outside Host
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Unknown.
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Minimum PPE Requirements
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Lab coat, disposable gloves, safety glasses, closed toed shoes, long pants
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Additional Precautions
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Additional PPE may be required depending on lab specific SOPs and IBC Protocol.
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