The Epidemiology and Diagnosis of Measles—Special Aspects Relating to Low Incidence

Measles is a highly contagious viral disease (contagion index near 100%) with a complication rate of up to 30%. The worldwide incidence for 2022 was calculated as 29 cases per million people. Measles can be eliminated if 95% of the population is either vaccinated or immune and measures are taken to limit its spread as soon as an initial suspected case is encountered. However, the worldwide immunization rate has fallen since 2020 (from 86% in 2019 to 81% in 2021).

To assess the epidemiological situation and describe the state of scientific knowledge regarding laboratory tests for measles, we analyzed recent epidemiological data from the Robert-Koch Institute (RKI) and reviewed pertinent publications retrieved by a selective literature search.

Repeated importations of measles virus have led to a new rise in case numbers in Germany since last year. 79 cases of measles were reported to the RKI in 2023, and 475 in the first eight months of 2024. The latter figure corresponds to the pre-pandemic level. There are still immunization gaps in the population: for instance, by the age of 24 months, 93.7% of children have received their first immunization, and only 80.5% have received the second. Every suspected case must be confirmed by laboratory testing so that targeted measures can be initiated. Serology is no longer considered sufficiently reliable; a reliable diagnosis now requires a poly merase chain reaction (PCR) test. The specimen can be a throat swab or a urine sample. PCR also enables the differentiation of measles virus variants and the tracing of transmission chains.

Reliable laboratory testing makes it possible to detect measles cases rapidly, initiate measures to slow the spread of the disease, trace infection chains, and assess the risk exposure for measles in Germany.