German measles - Diagnosing rubella

If you suspect that you or your child have rubella, phone your GP surgery or NHS 111 straight away for advice.

Do not visit your GP surgery without phoning first, as arrangements may need to be made to reduce the risk of spreading any infection to other people. In particular, contact with pregnant women should be avoided if possible because rubella can cause serious problems in an unborn baby (although this is very rare nowadays).

Your GP should be able to arrange a time for you to visit that won't put other people at risk, or they may come out to visit you or your child.

You should keep your child away from school (or yourself away from work) until you have seen your GP.

Your GP may suspect that you have rubella from your symptoms, but as other viral infections often have similar symptoms, testing a sample of saliva or blood is the only way to confirm a diagnosis.

Saliva and blood tests

If rubella is suspected, a sample of saliva from your mouth or a sample of blood from a vein in your arm can be taken and tested for certain antibodies.

Antibodies are proteins that your body produces to destroy disease-carrying organisms and toxins. If you have rubella or you have had it in the past, your saliva or blood will test positive for certain antibodies, which are listed below:

• The IgM antibody will be present if you have a new rubella infection.
• The IgG antibody will be present if you have had the rubella infection in the past, or you have been vaccinated against it.

If neither antibody is present, you do not have rubella and you have not been immunised against it.

Diagnosis in pregnancy

If you are pregnant, a blood test to check if you are immune to rubella will usually be carried out as part of your antenatal care. This is because a rubella infection in early pregnancy carries a risk of causing serious problems in your baby (see complications of rubella for more information).

Most women are immune to rubella, and rubella infections during pregnancy are very rare in the UK. However, if the test shows you are not immune to the condition, you will be offered advice about avoiding the infection and what to do if you think you may be infected.

If you are not immune to rubella, you should contact your GP or midwife as soon as possible if:

• you have had face-to-face contact with someone who has rubella
• you have spent more than 15 minutes in the same room as someone who has rubella
• you have symptoms of rubella

It is unlikely that you have rubella in these circumstances, but a further blood test may be necessary to check for the condition.

In the rare cases where testing shows that you do have rubella, you will be referred to a doctor who specialises in conditions that can affect unborn babies (an obstetrician).

The obstetrician may carry out tests such as an ultrasound scan and amniocentesis to check for any signs of problems in your baby.

You will also be offered counselling so you can make an informed decision about whether you wish to proceed with the pregnancy if serious problems are found.

Antibodies

Antibodies are your body's natural defence against any foreign antigens that enter your blood. An antibody is a protein that is produced by the body to neutralise or destroy disease-carrying organisms and toxins.