Measles during arbovirus outbreak: a diagnostic challenge.

Introduction: Dengue fever is a major public health problem in New Caledonia, like in many Pacific Islands Countries and territories. In 2017 New Caledonia faced multiple circulations of arboviruses with a major outbreak of dengue and a co-circulating Zika virus. New Caledonia is considered as a non-endemic territory for measles since the mid 1990's.

Case presentation: A 41-year-old male presented fever, headache, sinusitis and exanthematous maculopapular rash. A clinical diagnosis of arbovirus was first suspected due to the local epidemic context. A few days later the patient was admitted to the main hospital. The real time RT-PCR for dengue and Zika virus were negative on the first blood sample. A drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome and other infectious diseases including measles were then suspected. ELISA tests for measles were positive for IgM and equivocal for IgG. A throat swab was immediately shipped to a reference laboratory for measles nucleic acid testing. After a week, the patient recovered and the presence of measles RNA was confirmed. No secondary cases were reported among contacts of the patient and the source of his infection could not be ascertained.

Conclusion: Diagnosis of measles during an arbovirus outbreak in a country where measles disease is rare can be a pitfall for healthcare professionals. The introduction of measles via returned travellers or tourists from areas where measles remains endemic is a real threat to countries with high vaccine coverage.