Signs and symptoms
Measles infection generally presents with a prodrome of fever and any of cough, coryza and conjunctivitis (the three C’s), accompanied by malaise. This will usually be followed three to four (up to 7) days later by a maculopapular rash which commences on the head and neck, before spreading to the torso. The rash is not itchy and lasts for 4-7 days, resolving in the order in which it appeared. Fever is always present at rash onset.
Koplik spots are small spots with white or bluish white centres on an erythematous base, on the buccal mucosa.
Other symptoms can include anorexia, diarrhoea (particularly in young children), and generalised lymphadenopathy.
Common complications of measles include otitis media, viral or bacterial bronchopneumonia, acute encephalitis (1/1000), and in 1/100000 cases, a sub-acute sclerosing panencephalitis will develop in the years following infection.
Susceptibility to measles
People are susceptible to measles if they have:
- never had measles infection
- not received two doses of measles containing vaccine.
Immunocompromised people may be susceptible to measles, even if they have received two doses of vaccine in the past, depending on their degree of immune suppression.
Pregnancy does not generally result in suppression of existing immunity to measles; however measles infection in non-immune, pregnant women may severely impact the foetus.
Susceptibility is determined through receipt of documented evidence of receiving two doses of vaccine, or having had measles infection. Suitable evidence includes previous serology identifying the presence of measles specific antibody, record of receipt of vaccine doses or medical records describing past measles infection. Self or parental recall is not considered to be sufficient evidence.
Public health staff can assist in determining whether or not a person is immune to measles, through databases such as the Australian Immunisation Register and the school immunisation database. Your local public health unit can be contacted on 1300 066 055.
Vaccination with two doses of measles containing vaccine is successful in providing lifelong protection against measles in 99% of people vaccinated.
Documented evidence of a patient having received two doses of vaccine may lower the index of suspicion, however, where a convincing exposure risk (such as contact with a known case) exists in the presence of clinical symptoms, testing should be undertaken in case of vaccine failure. Measles infections in fully vaccinated individuals can arise from:
- primary vaccine failure (those who did not develop antibodies in response to the vaccine) or
- secondary vaccine failure (those who did develop antibodies, which are not effectively preventing infection).
Secondary vaccine failure cases often have atypical, or mild presentations (“modified measles”).
Vaccine-induced “measles” is a modified form of measles occurring in between 5-15% of non-immune vacinees, 5-12 days after measles vaccination. Symptoms include malaise and fever (up to 39.5°C) lasting 1-2 days. Rash, coryza, mild cough, and Koplik spots may occasionally occur. It is not known to be transmissible, and testing is not required unless the patient has also been exposed to an infectious case. In these circumstances a nasopharyngeal swab and urine should be collected. PCR tests in NSW performed at ICPMR and SAVID-SEALS routinely distinguish wild from vaccine measles strains.
The incubation period for measles is usually 10 days to the onset of fever and approximately 14 days to the onset of rash. Incubation of up to 18 days is not uncommon, and has been recorded as far as 21 days.
Travel history should be assessed for all patients presenting with febrile illness.
As measles is no longer endemic to Australia, the most common risk exposures for Australians are:
- travel to endemic countries resulting in acquisition of infection prior to return to Australia
- exposure to visitors from endemic countries, whether through receiving visitors in their home, or incidental exposure in a public place in Australia.
Measles remains endemic in many parts of the world, including destinations popular with Australian travellers. This includes both those travelling for leisure, and those travelling to visit friends and relatives.
In instances where a case of measles has potentially exposed the public to the infection locally, an alert detailing potential exposure sites and times will be posted on NSW measles alerts.
Where an individual has been identified as having direct contact with an infectious measles case, public health staff will conduct an assessment of immunity and, where relevant, provide preventive therapy or advice.
For patients in whom measles infection is suspected, respiratory specimens (nose and throat) and early pass urine should be collected and referred for urgent PCR testing. Nasopharyngeal aspirate may be collected for infants in lieu of the nasopharyngeal swab.
Serology testing is not recommended for diagnostic purposes for measles, unless more than three days has elapsed since the onset of rash. As measles specific immunoglobulin responses may not be detectable early in the infection (until 72 hours after rash onset), PCR is the preferred method of diagnosis.
Where serological samples are requested (either for late diagnosis or supplemental evidence), both IgM and IgG assays should be requested to aid in interpretation.
NSW Health advises individuals experiencing symptoms consistent with measles to notify staff prior to, or upon arrival when seeking medical care, so that isolation measures can be put in place.
Patients suspected of measles infection should remain isolated with airborne and droplet precautions in place until:
- a negative PCR result is obtained for all specimens collected (ie respiratory and urine), or
- until 4 days have passed since rash onset.
Confirmed cases of measles must be notified to public health by:
It is advisable however to contact your local public health unit on 1300 066 055 on clinical suspicion of measles, rather than waiting for confirmation. By involving your local public health team early on, they can provide assistance in:
- expediting and interpreting test results
- assessing potential risk exposures, including vaccination status
- assessing potential contacts
- implementation of control measures (including preventive therapy and isolation)
- providing advice to you, the patient, and their contacts.
Two doses of measles containing vaccine provides lifelong protection. Most people born before 1966 will have been exposed to wild measles virus and therefore do not require vaccination. The National Immunisation Program (NIP) now offers two doses to all children at 12 months (as MMR) and 18 months (as MMRV).
A single dose of measles containing vaccine was gradually introduced into immunisation programs in Australia from the late 1960's to the early 1970's. However the important second dose was not introduced until the 1990's and was at first given in primary school and then moved to a preschool dose. These changes in schedule mean that many adults have unknowingly missed out on one or both doses of measles vaccine and remain susceptible to infection if exposed. To ensure all people have the opportunity to be protected from measles, NSW provides free MMR to people born during or after 1966, who do not have documented evidence of having received two doses of measles containing vaccine. It is safe to receive more than two doses, so if your patient does not have evidence of immunity to measles, and has no contraindications, you can safely provide an MMR vaccine.
For more information about measles vaccination, refer to: