No 12a - 2023

Measles case in the Capital Region of Denmark

Statens Serum Institut has detected a measles case in a young adult residing in the Greater Copenhagen Area.

The person returned to Denmark after travelling abroad in early March and, after being hospitalised, had measles detected by PCR diagnostics in a sample taken on 15 March 2023. The Danish Patient Safety Authority, Supervision and Guidance East, has been informed and has initiated infection tracing measures in relation to the contacts of the infected person, privately as well as any healthcare contacts who may have been exposed to infection before the diagnosis was made.

Physicians, particularly in the Capital Region of Denmark, are encouraged to be extra attentive to the diagnosis in the coming weeks. It is important that any person who is suspected of having measles avoids being in waiting rooms with other patients as measles is extremely infectious.

This is the first detected case of measles in Denmark since January 2020 when a total of four cases were detected; all of which were travel-related and causing infection of one other person in Denmark. The measles-free period is the longest ever recorded in Denmark, which is considered to be due to the combined effect of the fact that Denmark has eliminated measles and that the reduced travel activity during the COVID pandemic reduced the risk of any imported cases of the condition. This new case underlines that all non-immune travellers to areas with a measles risk should have received measles vaccination prior to their departure (in the form of the MMR vaccine).
Sampling

On suspicion of measles, the following samples should be taken:

1. A blood sample for IgM/IgG antibody determination. IgM antibodies may be confirmed by rash.
2. Pharyngeal swab and urine for virus detection (PCR). The greatest possibility for detecting measles virus is in the early phases of the disease course, but the virus is frequently detectable for several weeks after the acute disease occurs. A negative finding does not exclude measles.

We recommend that all measles-positive samples be sent to the National WHO Reference Laboratory for Morbilli and Rubella, Laboratory for Virus Surveillance and Research, Statens Serum Institut for characterisation, which is free of charge.

On suspicion of measles disease, it is important that the diagnostics and work-up are performed as rapidly as practically possible with a view to isolation and treatment of the patient and tracking and possible treatment of anyone who has become exposed to infection. Serological detection is insufficient for measles diagnostics, and virus detection by PCR is necessary. Virus detection by PCR analysis is the quickest and safest method for laboratory diagnostics of measles. The analysis may be performed at the SSI, among others.

The National WHO Reference Laboratory for Measles and Rubella at the SSI handles the characterisation (sequencing and typing) of all measles RNA-positive samples in Denmark. As characterisation of the measles virus is important in relation to infection tracing, all suspected and confirmed measles-positive samples should be forwarded hereto as quickly as is practically possible. We recommend contact by phone to the virologist in charge at the SSI (in the daytime pho.: 40336379, after 15.30 to the epidemiologist on call pho.: 41317404) to inform the laboratory that samples are underway to avoid any unnecessary delay of the diagnosis.

For further details, please see the SSI's measles theme page.

Vaccination and prophylaxis following exposure

The primary form of prevention is MMR vaccination. MMR vaccination is normally offered to all children at 15 months and 4 years of age. As post-exposure prophylaxis (PEP), MMR vaccination may be given to non-immune contacts within 3 days and normal human immunoglobulin within 6 days after certain exposure to infection. Certain exposure is defined as contact with a laboratory-confirmed or epidemiologically linked MMR case. Delimitation of the contacts who need PEP is done by the on-duty physician at the Danish Patient Safety Authority, Division for Supervision and Guidance. Expenses are covered by the regional authorities.

For more details on post exposure prophylaxis, please see here.

Notification

Confirmed cases of measles are notifiable in writing to the Danish Patient Safety Authority, Division for Supervision and Guidance East/North/South as well as to Statens Serum Institut. Notification is made via the electronic notification system (SEI2). For further information and guidance, please see here. In view of the limited window for PEP, it may, nevertheless, be expedient to contact the local Supervision and Guidance unit as soon as the test results arrive to ensure that delimitation of any contacts needing PEP may be established without delay.

(L.K. Knudsen, P.H. Andersen, Department of Infectious Disease Epidemiology and Prevention, K.T. Franck, L.D. Rasmussen, Virology Surveillance and Research, National Reference Laboratory for Measles and Rubella, T.V. Jensen, Danish Patient Safety Authority, Supervision and Guidance East)

21 March 2023