Measles

Question 1

What is the measles infectious agent?

Answer 1

Morbillovirus genus (paramyxovirus)

Question 2

What is the measles reservoir?

Answer 2

Humans

Question 3

Measles mode of transmission

Answer 3

Airborne droplets, direct contact with discharges from respiratory mucous membranes, articles soiled with nose/throat secretions

Question 4

Measles incubation peroiod?

Answer 4

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.

Question 5

Measles infectious period

Answer 5

24 hours prior to onset of prodrome to 4 days after the onset of rash

The infectious period is used to identify contacts.

Question 6

What is the clinical presentation of measles?

Answer 6

• Prodrome = fever, conjuctivitis, coryza, cough (lasts 2-4 days)
• 2-7 days after prodrome - maculopapular rash (non-itchy) from face, upper neck spreading distally and 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.

People who have received 1-2 doses of measles vaccines may develop attentuated infection with mild symptoms

Complications - otitis media, viral/bacterial bronchopneumonia, acute encephalitis, rarely subacute sclerosing panencephalitis (1 in 100,000 cases)

Question 7

Who is at increased risk of measles?

Answer 7

• Unvaccinated or under-vaccinated people
• Immunocompromised (particularly T-cell deficiency)
• Malnourised children (particularly with Vitamin A deficiency)
• Children <5 years, adults >20 years (complications more common)
• Pregnant women - increased risk of premature labour, spontaneous abortion, low birth weight

Question 8

What is the disease status of measles in Australia?

Answer 8

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.

Question 9

Why does Australia continue to have measles cases?

Answer 9

Imported cases - overseas visitors and returning residents with the potential for limited transmission and small to moderate-sized outbreaks.