Measles associated with international travel in the region of the Americas, Australia and Europe, 2001-2013: A systematic review

BACKGROUND: Travel volumes are still increasing resulting in a more interconnected world and fostering the spread of infectious diseases. We aimed to evaluate the relevance of travel-related measles, a highly transmissible and vaccine-preventable disease. METHOD: Between 2001 and 2013, surveillance and travel-related measles data were systematically reviewed according to the PRISMA guidelines with extraction of relevant articles from Medline, Embase, GoogleScholar and from public health authorities in the Region of the Americas, Europe and Australia. RESULTS: From a total of 960 records 44 articles were included and they comprised 2128 imported measles cases between 2001 and 2011. The proportion of imported cases in Europe was low at 1-2%, which reflects the situation in a measles-endemic region. In contrast, imported and import-related measles accounted for up to 100% of all cases in regions with interrupted endemic measles transmission. Eleven air-travel related reports described 132 measles index cases leading to 47 secondary cases. Secondary transmission was significantly more likely to occur if the index case was younger or when there were multiple infectious cases on board. Further spread to health care settings was found. Measles cases associated with cruise ship travel or mass gatherings were sporadically observed. CONCLUSIONS: Within both, endemic and non-endemic home countries, pretravel health advice should assess MMR immunity routinely to avoid measles spread by nonimmune travelers. To identify measles spread as well as to increase and sustain high vaccination coverages joint efforts of public health specialists, health care practitioners and travel medicine providers are needed