Measles virus
|
Morphology
|
Measles virus is a negative-sense, single stranded RNA virus, which belongs to morbillivirus
genus in the Paramyxoviridae family. It consists of a helical nucleocapsid, 100-300
nm in diameter, surrounded by an envelope. The envelope is lined by matrix proteins
and carries transmembrane hemagglutinin and fusion glycoproteins which are the virulence
factors.
|
|---|---|
|
Disease
|
The Measles virus may cause measles, a systemic infection starting in the respiratory
epithelium of the nasopharynx. Measles may lead to severe complication and can cause
death.
|
|
Zoonosis
|
None known, but humans may communicate the disease to non-human primates.
|
|
Host Range
|
Humans, non-human primates.
|
|---|---|
|
Modes of Transmission
|
Measles can be spread by respiratory droplets and by direct contact with secretions
from nose and throat of an infected person. Direct contact is the primary mode of
transmission, and airborne droplet and indirect contact are less common modes of transmission.
|
|
Signs and Symptoms
|
After an incubation period of 8-12 days, fever (approximately 38.3°C) and malaise
develop over 24 hours, followed by cough, coryza (inflammation of the nasal mucous
membranes) and conjunctivitis. After 2-3 days of cough, coryza and conjunctivitis,
Koplik spots (white and granular lesions in the lateral buccal mucosa) appear. On
the forth day, a macropapular rash appears on the head and neck, behind the ears.
The rash then spreads to the rest of the body and persists for 3-5 days before fading.
Other symptoms include anorexia and dyspnea.
|
|
Infectious Dose
|
0.2 units by intranasal spray.
|
|
Incubation Period
|
8-12 days
|
|
Prophylaxis
|
Immunization with live virus vaccine can be given up to 72 hours post-exposure to
prevent measles in unvaccinated persons. Passive immunization with measles immunoglobulin
(0.25 mL/kg, for a maximum of 15 mL) between 72 hours and 6 days following exposure
or in persons for which measles vaccine is contraindicated can be given to prevent
or decrease the severity of measles.
|
|---|---|
|
Vaccines
|
Trivalent vaccine using live-attenuated virus of measles, mumps and rubella (MMR),
but this vaccine requires constant cold for storage and transport, which is a problem
in developing countries. The first dose is given in the first year, and the second
at the beginning of schooling (4-6 years of age) to allow full coverage. Pregnant
women should not take MMR.
|
|
Treatment
|
There is currently no treatment for measles other than supportive care. In cases of
malnourishment or vitamin A deficiency, vitamin A may be prescribed to help avoid
complications.
|
|
Surveillance
|
Monitor for symptoms, microbiological and serological testing for measles virus or
anti-measles antibodies.
|
|
MSU Requirements
|
Report any exposures.
|
|
Laboratory Acquired Infections (LAIs)
|
One case.
|
|---|---|
|
Sources
|
MV may be isolated from urine, conjunctiva, nasopharynx, and blood. Cultures, frozen
stocks, other samples described in IBC protocol.
|
|
Canadian MSDS:
|
|
|---|---|
|
BMBL
|
|
|
CDC
|
|
|
NIH Guidelines
|
|
Risk Group 2
|
Agents that are associated with human disease which is rarely serious and for which
preventive or
therapeutic interventions are often available. |
|---|---|
|
BSL2
|
For all procedures involving suspected or known infectious specimen or cultures..
|
|
ABSL2
|
For all procedures utilizing infected animals.
|
|
Small
|
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.
|
|---|---|
|
Large
|
• 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). |
|
Mucous membrane
|
Flush eyes, mouth, or nose for 5 minutes at eyewash station.
|
|---|---|
|
Other Exposures
|
Wash area with soap and water for 5 minutes.
|
|
Reporting
|
Immediately report incident to supervisor, complete a First Report of Injury form, and submit to Safety and Risk Management.
|
|
Medical Follow-up
|
During business hours: After business hours: |
|
Disinfection
|
MV is susceptible to povidone iodine, formaldehyde, 1% sodium hypochlorite, 70% ethanol,
glutaraldehyde, phenolic disinfectants, peracetic acid, hydrogen peroxide
|
|---|---|
|
Inactivation
|
Heat (30 min at 56°C), acidic pH, and trypsin. Inactivated moist heat (1 hour at 121°C).
|
|
Survival Outside Host
|
Agent may survive less than 2 hours on surfaces or objects. Respiratory droplets can
remain infective for at least 1 hour in a close space.
|
|
Minimum PPE Requirements
|
Lab coat, disposable gloves, safety glasses, closed toed shoes, long pants
|
|---|---|
|
Additional Precautions
|
Additional PPE may be required depending on lab specific SOPs and IBC Protocol.
|