What Is Measles?
A highly contagious viral disease that remains a leading cause of death among young children globally, preventable by the MMR vaccine.
Pathogen: Measles morbillivirus (Paramyxoviridae family)
Type: Virus
Transmission
Airborne via respiratory droplets and aerosolised particles. Extremely contagious — the virus can remain infectious in the air for up to 2 hours after an infected person has left the room. One of the most contagious diseases known (R0 of 12-18).
Vector: No arthropod vector. Airborne person-to-person transmission.
Symptoms
High fever (often >40°C), cough, runny nose (coryza), conjunctivitis (red watery eyes), Koplik spots (tiny white spots inside the mouth — pathognomonic), followed by a characteristic red blotchy rash starting on the face and spreading downward. Complications include pneumonia, encephalitis, and death.
Incubation period: 7 – 21 days
Usually 10-14 days from exposure to fever onset, 14 days to rash onset. Infectious from 4 days before to 4 days after rash onset.
Timeline: Prodromal phase (cough, coryza, conjunctivitis, fever) lasts 2-4 days. Koplik spots appear 1-2 days before the rash. The rash appears on day 14 (approximately) after exposure, starting on the face and spreading to the body over 3 days. Rash lasts 5-6 days.
Case fatality rate: 1-2 per 1,000 cases in developed countries. Up to 3-6% in developing countries. Higher in malnourished or immunocompromised individuals. Subacute sclerosing panencephalitis (SSPE) is a rare, invariably fatal late complication.
Diagnosis & Treatment
Diagnosis: Measles IgM serology (blood or oral fluid, from rash onset). Measles PCR on throat swab, nasopharyngeal swab, or urine. Clinical diagnosis is often possible based on the characteristic presentation (fever, rash, cough, coryza, conjunctivitis).
Treatment: No specific antiviral treatment. Supportive care: rest, fluids, paracetamol for fever. Vitamin A supplementation reduces severity and mortality, particularly in children (WHO recommends for all children with measles). Antibiotics for secondary bacterial infections. Hospitalisation for complications.
Prevention
- MMR (measles, mumps, rubella) vaccination — 2 doses for full protection
- Check vaccination status before travel (many Australian adults born 1966-1994 may have only received 1 dose)
- Post-exposure vaccination (within 72 hours of exposure) can prevent or modify disease
- Immunoglobulin (within 6 days of exposure) for immunocompromised contacts
- Isolate suspected cases to prevent spread
Post-Exposure
If you are not immune (two documented MMR doses or positive IgG) and are exposed to measles, the MMR vaccine given within 72 hours of exposure may prevent disease. Normal human immunoglobulin (NHIG) given within 6 days may prevent or attenuate disease in those who cannot receive the vaccine. Notify your state or territory public health unit.
Long-Term Effects
Subacute sclerosing panencephalitis (SSPE) is a rare but invariably fatal degenerative brain disease that can develop 7-10 years after measles infection, mainly in those infected in early childhood. Measles also causes 'immune amnesia' — wiping out a proportion of existing immune memory, increasing susceptibility to other infections for months to years.
📋 Measles is a nationally notifiable disease in Australia. Cases are uncommon due to high vaccination coverage but outbreaks occur regularly, often seeded by returned travellers. Approximately 30-200 cases are notified annually depending on importation events.
Frequently Asked Questions
Am I vaccinated for measles?
Australians born before 1966 are generally considered immune (likely had measles naturally). Those born between 1966 and 1994 may have received only one dose of measles vaccine and should have a second MMR dose before travel. Those born after 1994 should have received two doses as part of the childhood schedule. Check your records on the Australian Immunisation Register (AIR) via MyGov. If unsure, a blood test (measles IgG) can confirm immunity, or you can simply receive an MMR — it is safe even if already immune.
Do I need a measles booster before travel?
If you have documented evidence of two MMR doses, no booster is needed. If you have had only one dose or are unsure, a second dose of MMR is recommended before travel. This is particularly important for travel to Southeast Asia, the Indian subcontinent, the Pacific Islands, and Africa, where measles remains endemic. The vaccine should be given at least 2 weeks before travel.
How contagious is measles?
Measles is one of the most contagious diseases known. Up to 90% of non-immune people exposed to measles will become infected. The virus is airborne and can remain infectious in a room for up to 2 hours after an infected person has left. A single case can infect 12-18 other susceptible individuals (compared to 2-3 for influenza). This is why high vaccination coverage is so important.
Can adults get measles?
Yes. Adults who are not fully vaccinated (two doses) or who have not had measles are susceptible. Adults tend to have more severe complications than children, including pneumonia and encephalitis. Travel to endemic countries is the most common source of measles infection for Australians. Ensure you have had two documented MMR doses before travelling.
Is measles still a risk in 2026?
Yes. Measles remains a significant global health threat. While Australia has eliminated endemic measles, importation of cases from overseas is ongoing. Large outbreaks have occurred in Southeast Asia, the Pacific (Samoa 2019), Europe, and Africa in recent years. Declining vaccination rates in some countries have led to resurgences. Any unvaccinated traveller is at risk.
What is the Samoa measles outbreak and what can we learn from it?
In 2019, Samoa experienced a devastating measles epidemic with over 5,700 cases and 83 deaths (mostly children) in a population of just 200,000. The outbreak was driven by very low vaccination coverage (around 31%). It demonstrates how quickly measles can spread in under-vaccinated populations and the importance of maintaining high vaccine coverage. The outbreak prompted mass vaccination campaigns.
Can measles cause brain damage?
Yes. Measles encephalitis (brain inflammation) occurs in approximately 1 in 1,000 cases and can cause permanent brain damage, seizures, or death. Subacute sclerosing panencephalitis (SSPE) is a rare but invariably fatal degenerative brain disease that can develop 7-10 years after measles infection. These serious complications are preventable by vaccination.
What is immune amnesia from measles?
Research has shown that measles infection can destroy 11-73% of existing protective antibodies, effectively wiping part of the immune system's memory. This 'immune amnesia' leaves measles survivors more vulnerable to other infections for 2-3 years after recovery. This is an additional, often overlooked reason why measles prevention through vaccination is so important.
Sources & References
Last updated: April 2026