Measles Flashcards
Learn public health information about measles
Is measles nationally notifiable?
Yes.
Urgent. Labs and doctors.
What is the measles infectious agent?
Morbillovirus genus (paramyxovirus)
What is the measles reservoir?
Humans
How is measles transmitted?
- Airborne droplets
- Direct contact with discharges from respiratory mucous membranes
- Articles soiled with nose/throat secretions
What are the clinical features of measles?
- Prodrome (2-4 days) - fever, conjuctivitis, coryza, cough, Koplik spots (lasts 2-4 days)
- Maculopapular rash - 2-7 days after prodrome; (non-itchy) from face, upper neck becoming generalised (lasts 4-7 days)
- Other symptoms - anorexia, diarrhoea (infants), generalised lymphadenopathy, Koplik spots (may be present briefly on buccal mucosa)
5 Cs - constitutional symptoms, coryza, conjunctivitis, cough, C(K)oplik spots.
Complications - otitis media, viral/bacterial bronchopneumonia, acute encephalitis, rarely subacute sclerosing panencephalitis (1 in 100,000 cases)
People who have received 1-2 doses of measles vaccines may develop attentuated infection with mild symptoms
Who is at increased risk of measles?
- Unvaccinated or under-vaccinated people
- Children < 5 years, adults >20 years (complications more common)
- Malnourised children (particularly with Vitamin A deficiency)
- Pregnant women - increased risk of premature labour, spontaneous abortion, low birth weight
- Immunocompromised (particularly T-cell deficiency)
What is the case definition for measles?
Confirmed - isolation / detection / seroconversion OR clinical + epi
Probable - clinical + IgM if not recently vaccinated
How is measles diagnosed?
- PCR preferred (resp specimen, blood, urine)
- Viral culture possible.
- Serology - IgM is sensitive (100% cases within 7 days) and specific but can persist for 1-2 months.
- Genotyping - do for all sporadic cases.
VIDRL = reference lab (VIC).
What is the measles incubation peroiod?
7-18 days (average 10 days)
10 days to onset of fever (7-18 days). 14 days to onset of rash.
Incubation period can be longer if immunoglobulin is given early in the incubation period.
What is the measles infectious period?
24 hours prior to prodrome to
4 days after the onset of rash
What is the disease status of measles in Australia?
In 2014, the WHO verified that Australia had achieved “measles elimination status” meaning the absence of endemic transmission in a defined geographical area for >= 12 months.
Two dose vaccination schedule introduced in 2014.
Why does Australia continue to have measles cases?
Imported cases - overseas visitors and returning residents with the potential for limited transmission and small to moderate-sized outbreaks.
What resources are available for the public health management of measles?
SoNG, DH protocol.
How are cases of measles managed?
- Supportive care
- Contact clinician
- Case/collateral interview - visits to high-risk settings (CC, HCW, RACF), Sx, Vax, travel hx, sick contacts, locations visited during infxs period
- Education
- Isolation (including suspected cases) until 4 days after rash onset; negative pressure room in hospital, airborne precautions, vaccinated staff only, daily compliance phone calls
How would you conduct active case finding for a measles outbreak?
Clinician alert - GP, ED, labs
Media alert - community
What is the definition of a measles contact?
Anyone who has/may have shared the same air-space (enclosed area) for any length of time with an infectious case.
What are the principles of contact management in a measles cases / outbreak?
- Identify high-risk settings
- Identify high-risk / susceptible contacts
- Offer PEP - MMR / NHIG
- Education
- Exclusion of susceptible contacts
- Contact tracing
Which contacts are particularly susceptible to measles?
- Immunocompromised/no evidence of immunity
- Evidence = born after 1966 with 2 doses OR born before 1966 OR documented immunity/prior infection OR infant < 6mo where mother is immune
Who are priority contacts for measles?
- Household
- Overnight same room
- ECEC
- School
- Waiting areas
- Work settings
- Other settings - notify via media release
- Healthcare settings - work with facility to institute appropriate management plan
Which measles contacts recieve PEP?
Susceptible contacts (i.e. unvaccinated, no previous exposure, inadequate levels of immunity)
What is given as PEP for measles?
MMR, NHIG.
Within 72 hours of exposure - MMR unless immunocompromised, pregnant or infant < 6mo»_space; NHIG
73-144 hours - NHIG if 0 doses/unknown, usually reserved for those at highest risk.
NHIG = normal human immunoglobulin.
Immunocompromised people cannot receive MMR (live-attenuated) and should receive NHIG.
In settings with many individuals with uncertain vaccination history / immunity, what is recommended for PEP?
MMR vaccine (even if >72hr)
E.g high schools, workplaces
What education should be given to contacts?
- Symptoms
- Monitoring for 7-18 days
- Avoid contact with < 12mo, pregnant, hospitals, immunocompromised
- Self-isolate and test if Sx
- Fact sheet
When should contacts be excluded?
Exclude susceptible contacts from primary school / ECEC / HCW (staff not work / isolate patients) until 18 days after contact.
However, they can return if receive MMR/NHIG within 72/144hrs, respectively.
Immunocompromised children/staff should be excluded (regardless of their measles
vaccination status) until 14 days after the onset of the rash in the last case occurring at the facility. Exclusion is advised for their own safety, even if they receive NHIG.
Which situations / settings do not require contact tracing for measles?
- Same educational institution and may have been in vicinity but not in the same classroom as the case»_space; media alert
- Passengers on an airplane
- Present in general area of the case
Why is contact tracing no longer rountinely recommended for airplane exposures?
- Not time and resource efficient
- Can cause delays in PEP
Use general media alerts, email/SMS if airline can provide details or undertake messaging on behalf of PHU (using a provided script)
Individual contact tracing can be justified if diagnosis and notification have been early, flight manifests readily available and passenger contact info provided promptly, multiple infectious cases (esp. children) on a flight.
