Rubella is one of the common rash diseases of childhood. It is sometimes called German measles because a German physician wrote a clear description of it in 1760.
Rubella is caused by the rubella virus. There is only one strain of the virus, which continually circulates all around the world. It is strictly a human virus and so can only spread from one person to another. It is shed from the throat and in the urine of an infected person. A person is most infectious a few days before they develop any symptoms of rubella. Infected droplets are released from the throat, and are inhaled by another nearby person. This might happen during conversation or over a distance in a closed room. Rubella is fairly contagious, so it will easily spread to anyone who has not been vaccinated or infected before.
It is quite possible and not uncommon to have rubella with no symptoms at all.
The feature that usually alerts parents to their child’s illness is the rash. This is made up of pinkish, slightly raised spots. The rash starts on the face and spreads to the chest and back, and finally to the limbs. It can be difficult to distinguish the rash of rubella from some of the other rash diseases of childhood. Measles, roseola, parvovirus (“slapped cheek disease”) and enterovirus infections can all be confused with rubella. A strong clue that you or your child has rubella is the presence of enlarged lymph glands behind the ears and at the base of the skull at the back of the neck. A mild fever is usual. There can be a sore throat and conjunctivitis (red eyes).
Sometimes aching joints, and even swelling, warmth and redness of the joints, can occur a few days into the illness. This is much more common in adults, especially women. Any joint may be affected, but most often it is the finger joints and knees. Significant joint problems will take a few weeks to clear up, and in a few people the joint problems can persist or recur over a number of years.
There are two other rare complications of rubella. Approximately 1 in 1 500 people has a bleeding complication due to a drop in blood platelets. This is usually noticeable as small purple spots where there is bleeding into the skin. An even rarer complication is an encephalitis (inflammation of the brain) which affects approximately 1 in 6 000 people. The symptoms of encephalitis are headache, vomiting, stiff neck, drowsiness and sometimes convulsions.
Seemingly single cases of rubella can occur at any time, but there can be outbreaks involving schools or other large groups of children. Adults (teachers and parents) may also be infected in these outbreaks. There is a seasonal pattern, with rubella activity increasing in spring. In South Africa, about 90% of people will have had rubella by adulthood.
It takes two weeks from the day a person is infected before any symptoms of rubella appear. A day or two of feeling unwell and a mild fever usually heralds the rash. The rash disappears in about three days. The lymph glands in the neck enlarge before the rash appears and will stay enlarged for some days after the rash has disappeared. Uncomplicated rubella is a short-lived illness.
Any person who has not had rubella before, or who has not been vaccinated is vulnerable to rubella infection.
The major risk of rubella is that it may be acquired in pregnancy. Rubella is not a significant risk for a pregnant woman herself, but puts her foetus at risk. The risk to the foetus is only during the early stages of its development, especially during the first 18 weeks of pregnancy when the organs (like the heart, liver and brain) of the foetus are developing. (Beyond the first 18 weeks of pregnancy, rubella infection in pregnancy should not cause concern.)
The consequence of rubella infection in early pregnancy is that the baby is highly likely to be born with physical and mental abnormalities:
- Low birth weight, with an enlarged liver and spleen
- Mental retardation
- Abnormalities of the heart valves or major arteries taking blood from the heart to the rest of the body
- Eye defects such as cataracts, sometimes resulting in blindness
The combined picture of abnormalities is called congenital rubella syndrome or CRS. There is about an 80% risk that one or more features of the syndrome will occur if the mother contracts the infection in the first trimester of pregnancy (the first 16 weeks). The most consistent feature of CRS is deafness due to nerve damage. Infection before 12 weeks of pregnancy carries the greatest risk of heart, eye and brain
abnormalities in addition to deafness, whereas infection between 13 and 18 weeks can result in deafness alone.
Even with very sophisticated methods to investigate a baby still in the uterus, it is very difficult to diagnose whether, and how severely, a baby has been affected before it is born. For this reason the parents and the doctor involved have to base a decision about terminating the pregnancy on information about the probable outcome for the baby, which is based on the experience of many previous cases.
When to see a doctor
During an outbreak of rubella, when many children in your community are infected, it may be easy to diagnose rubella yourself. It is likely that you will still want confirmation by your GP. If your child develops a rash illness out of the blue, it is advisable to see your GP, as there are a number of possible causes.
Many children with rubella only feel mildly ill and should simply have a few quiet days at home. All that is required is to keep an eye out for any sign of the complications mentioned above, as any of these will require a visit to the GP for management. Respond immediately to signs of encephalitis, and if your GP is not available, take your child to a hospital emergency unit.
Many doctors will make a diagnosis of rubella based on the clinical picture of the child, and thus avoid a blood test. However, suspected rubella in a pregnant woman must be confirmed by a blood test sent to a laboratory. This is essential because of the serious implications of the diagnosis.
Of importance for pregnant women is that rubella can be easily confused with parvovirus infection, as the rash is similar. Blood tests will sometimes help to distinguish between the two infections. Parvovirus can also affect the foetus, but the effects are quite different and management by your obstetrician will take a very different course.
There is no specific treatment available for rubella (as for most viral infections). A child with fever or a sore throat may be treated at home with a preparation of mefenamic acid (also called Ponstan). Consult your GP about medication if joint symptoms occur. Serious or persistent inflammation of joints after rubella infection may warrant a specialist consultation; anti-inflammatory drugs or cortisone may be necessary.
A child with rubella is infectious from about five days before to five days after the rash has appeared. There is nothing that can be done about exposure of other people to the infection before the rubella becomes apparent. However, you should still try to limit your child’s contact with other people once you know the diagnosis. The main danger is that a pregnant woman may be put at risk. Staying home from school until the five days are up is an appropriate measure.
Rubella vaccination is not part of the routine vaccination schedule provided by the state in South Africa. This is because vaccinations for more serious diseases have to take priority when there is a limited budget. If you can afford private medicine, it is advisable for your child to have the combined measles, mumps and rubella (MMR) vaccine at 15 months of age. This is routinely given by many GPs. Another option is for girls to be vaccinated with rubella vaccine alone at around 12 years old. Here the objective is primarily to prevent rubella during pregnancy later on. In South Africa there are numerous babies born with congenital rubella syndrome each year; this is preventable.
The rubella vaccine is a live but harmless laboratory version of rubella virus. It still activates the necessary immune response to wild rubella virus. One of the consequences of activating the immune response is that the joint symptoms of rubella can also occur after vaccination, but this is less frequent.
Because of the very serious risks of rubella in pregnancy, all women who are planning a pregnancy should have a blood test to see whether they are immune to rubella. If not, they should be vaccinated against rubella before falling pregnant. The rubella vaccine should not be given to a woman once she is already pregnant since this is a live attenuated vaccine preparation and may cause harm to the foetus, but there has never been any proof or evidence that a baby has been affected in this way by accidental administration of the vaccine during pregnancy. (Therefore accidental administration of rubella vaccine during pregnancy is not cause for too much concern and is definitely not regarded as a reason to terminate the pregnancy.)
Natural infection with rubella virus gives life-long immunity and re-infection is very rare. Unfortunately the immunity after vaccination is not as strong and lessens over time, so that re-infection with the wild rubella virus can occur in vaccinated individuals, however, a re-infection usually is a much milder disease. Re-infections in the early weeks of pregnancy do also pose a risk to the foetus, but the risk is about a tenth of the risk of a first or primary infection.
(Reviewed by Dr Eftyhia Vardas, University of the Witwatersrand)