Is it or is it not? Lessons learned from a case of suspected vaccine strain measles

Abstract

Objective: Measles continues to be a threat to Australia. While post-eradication risks are low, imported measles cases from overseas travellers who are non-immune can cause small outbreaks. This case report discusses the challenge of identifying wild-type measles in an individual who was recently vaccinated with measles-containing vaccine (MCV). Methods: A positive polymerase chain reaction (PCR) result for measles for an adult who had recently received a measles-containing vaccine was notified. Investigation revealed no known epidemiological link, recent overseas travel or contact with recent measles cases during the incubation period. Results: The results of the initial sequencing to distinguish between wild-type and vaccinestrain measles were inconclusive. A decision was made to re-run the genotyping, collect additional specimens and quarantine the case until a definitive result was obtained. Sequencing and genotyping revealed that this indeed was a wild-type measles strain. Conclusions: Changing epidemiology of measles means distinguishing between wild-type and vaccine–strain measles has become a new challenge. Implications for public health: The reflection of the public health management of this case has provided a valuable teaching tool for public health professionals globally, particularly in low incidence measles countries.