2025 Annual Australian Measles and Rubella Genotyping Surveillance Program Report
DOI:
https://doi.org/10.33321/cdi.2026.50.068Keywords:
genomic surveillance, molecular epidemiology, outbreak investigation, public health surveillanceAbstract
Molecular characterisation is a critical component of Australia's measles and rubella surveillance systems, supporting outbreak investigations, identifying sources of infection, and providing evidence for the continued maintenance of Australia’s measles and rubella elimination status. This annual report summarises measles and rubella molecular epidemiology in Australia during 2025 and evaluates the utility of whole genome sequencing (WGS) for measles surveillance. In 2025, there were 181 confirmed measles cases notified in Australia, representing a 217.5% increase on the number notified in 2024. Measles virus genotypes B3 and D8 were detected, together with 21 vaccine-associated genotype A cases. Genotype B3 predominated during the first half of the year and was largely associated with importations from Vietnam, whereas genotype D8 predominated during the second half of the year and was primarily associated with importations from Indonesia. Thirty-one epidemiologically confirmed outbreaks were identified, comprising 13 genotype B3 outbreaks and 17 genotype D8 outbreaks. The discriminatory power and concordance with epidemiological data in the context of outbreak investigations was substantially greater for WGS data than for conventional N450-based genotyping. Viruses sharing the same N450-based distinct sequence identifier (DSid) differed by up to 33 single nucleotide polymorphisms (SNPs) for genotype B3 and 36 SNPs for genotype D8, whereas genomes obtained from epidemiologically linked cases differed by a maximum of four SNPs. Despite increased national case numbers in 2025, available molecular and epidemiological evidence indicated that cases were associated with importations or import-related transmission events, with no evidence of sustained endemic measles transmission. Rubella activity remained extremely low, with no rubella virus detections identified among 157 specimens tested by polymerase chain reaction (PCR) and only two notified cases nationally, neither of which had material available for genotyping. These findings support the continued absence of endemic measles and rubella transmission in Australia and highlight the value of WGS for enhancing measles surveillance and outbreak investigations.
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