No 32/33 - 2023

Two measles cases in the Region of Central Denmark and the Region of Southern Denmark

Clinical Microbiology at Aarhus University Hospital has detected a measles case in a child residing in the Central Denmark Region. The child returned to Denmark in late July after travelling abroad. During a brief hospitalisation in isolation, the child had measles detected by PCR diagnostics of a sample taken on 2 August 2023. Statens Serum Institut (SSI) has genotyped the virus belonging to genotype D8. This is a frequently occurring genotype globally.

The SSI has also detected a measles case in a child living in the Region of Southern Denmark. The child returned to Denmark in early August after having travelled to the same country as the case described above, but - according to the available information - no other association exists between the two cases. The diagnosis was made by PCR diagnostics of a sample taken in general practice on 4 August 2023. The genotype has yet to be determined.

The Danish Patient Safety Authority, Supervision and Guidance West, has been informed of both cases and has initiated infection tracing measures in relation to the contacts of the infected persons, privately as well as any healthcare contacts who may have been exposed to infection before the diagnosis was made.

The latest case travelled in the infectious period of the condition. Therefore, information about the case was also passed on to the authorities of the countries that the patient visited.

Physicians, particularly in the Central Denmark Region and the Region of Southern 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.

The two detected cases underline 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. Pharyngeal swab and urine for detection of measles virus (morbili virus) RNA by PCR. The best chance of detecting measles virus exists 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.
2. A blood sample for measles virus IgM/IgG antibody determination. IgM antibodies may be confirmed by rash.

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 continued isolation and treatment of the patient and also tracking and possible treatment of any non-immune persons who may have 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 virus-RNA-positive samples in Denmark. As characterisation of the measles virus is important in relation to infection tracing, all suspected and confirmed measles virus-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. In Denmark, MMR vaccination is offered to all children at 15 months and at four years of age as part of the Danish childhood vaccination programme. Following certain exposure to infection, i.e. contact to a laboratory-confirmed or epidemiologically linked case, MMR vaccination may be given within three days of exposure to infection and normally human immunoglobulin within six days as post-exposure prophylaxis (PEP) to non-immune contacts. 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 of the area in question. Subsequently, expenses are reimbursed by the regional authorities.

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

Notification

Confirmed measles cases are notifiable in writing to the Danish Patient Safety Authority, Division for Supervision and Guidance East/West as well as to Statens Serum Institut. Notification is made via the electronic notification system (SEI2). See link for further information and guidance. In view of the limited window for PEP, it is, nevertheless, 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.

(M.K. Thomsen, DCM, Aarhus University Hospital, S.S. Rasmussen, B. Bødker, K.T. Franck, Virus Monitoring & Research, National Reference Laboratory for Measles and Rubella, L.K. Knudsen, P.H. Andersen, Department for Infectious Disease Epidemiology and Prevention, J.D. Thomsen, D. Halmes, the Danish Patient Safety Authority, Supervision and Guidance West)