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After vaccination of Dutch children against mumps started in 1987 through the National Immunisation Programme the incidence of mumps decreased greatly. However, outbreaks of mumps have been occurring since the end of 2009, especially among students. We describe a vaccinated 20-year-old woman with uncomplicated mumps, a vaccinated 20-year-old student with mumps orchitis, and an unvaccinated 14-year-old boy who developed one-sided permanent deafness as a complication of mumps. Mumps outbreaks are likely caused by factors including incomplete protection following vaccination, waning of immunity, and intensive crowding. Mumps currently affects mainly people who were vaccinated more than 10 years ago. Outbreak response concentrates on surveillance, outbreak investigations, disease awareness, and provision of catch up vaccination to unvaccinated or incompletely vaccinated students. Adequate surveillance, important for building evidence for possible changes in mumps vaccination recommendations, depends on recognizing mumps and its complications.

The influenza vaccine is considered safe, but information on vaccine-related adverse events is limited and a nationwide overview of adverse events is lacking. In 2006, after deaths occurred in Israel and the Netherlands following influenza vaccination, the Dutch Ministry of Health, Welfare and Sport (VWS) asked the National Institute for Public Health and the Environment (RIVM) twice for a recommendation regarding the continuation of the national vaccination campaign. After 4 deaths were reported in Israel in October 2006 following administration of Vaxigrip, the Dutch vaccination campaign was suspended for one week. One month later, 4 additional deaths were reported after influenza vaccination in the Netherlands. The newly appointed outbreak management team concluded that a causal relationship between vaccination and the deaths was highly unlikely, based on data regarding the individual cases, background mortality rates and prior reports of adverse events. Further suspension of the vaccination campaign was deemed unnecessary this time. A centralised nationwide registry of adverse events has since been established to provide further insight into the incidence of adverse events following influenza vaccination. Physicians are advised to report potential adverse events following influenza vaccination to the Netherlands Pharmacovigilance Centre Lareb (www.lareb.nl).

A 58-year-old woman was admitted due to a pseudomembranous pharyngitis. The patient had not been vaccinated against diphtheria. Corynebacterium ulcerans was cultured from a throat swab. The production of diphtheria toxin by these bacteria was demonstrated with PCR and an immunoprecipitation test. The patient was cared for in respiratory isolation and was treated with benzylpenicillin. She quickly recovered and was discharged four days after admission. A contact investigation did not reveal any dissemination of the toxin-producing C. ulcerans and a source was not found. In spite of the large-scale vaccination against diphtheria which has taken place in the Netherlands since 1953, a physician has to consider diphtheria in the differential diagnosis of patients who present with a clinical syndrome compatible with this disease. Either Corynebacterium diphtheriae or C. ulcerans could be the pathogen responsible.

Lassa, Ebola, Marburg and Crimean-Congo haemorrhagic fever viruses are the most important causes of viral haemorrhagic fever which is transmitted from person to person through contact with blood or excreta. A non-specific fever may be the initial symptom of viral haemorrhagic fever. By means of carefully noting where the patient has travelled, possible exposure to ill persons, vectors or an animal reservoir, and the incubation period (< or = 21 days versus longer), it is possible to estimate the risk of infection with one of these viruses. Using this approach it is possible to diagnose high-risk patients in good time and to take appropriate measures.