Measles

Measles causes no malformations – unlike rubella. Even so it is among the infections that cause most worry in pregnancy: it runs a more severe course in pregnant women, raises the likelihood of miscarriage and premature birth, and vaccination is not possible during pregnancy. Here too, what counts is what happened beforehand.

What measles is

Measles is caused by a virus that occurs only in humans. It is the most contagious known pathogen of all: in an unprotected environment one person with measles infects twelve to eighteen others on average. By comparison, with seasonal influenza it is one to two.

The virus is transmitted by the finest droplets, which float in the air for hours. To be infected it is enough to enter a room that someone with measles left two hours earlier. Anyone unprotected who has had contact falls ill with a probability of over ninety per cent. There is hardly an infection for which the idea that you might get through by being careful holds so little.

Someone with measles is infectious as early as four days before the rash, that is during the cold-like phase in which nobody yet thinks of measles.

How measles runs its course

After eight to ten days the first phase begins with high fever, a runny nose, conjunctivitis and a dry cough. The eyes are sensitive to light and the feeling of illness is marked. During this time whitish spots are sometimes found on the lining of the cheek – Koplik spots, the only truly conclusive sign before the rash.

After one to two days without fever the temperature rises again and the rash begins: large-spotted, starting behind the ears, then over the face and body. The spots run together – unlike in rubella, where they stay separate. After four to seven days it fades with peeling.

What is dangerous about it is not the rash but the temporary weakening of the immune system. Measles erases a considerable part of immunological memory – antibodies against infections gone through earlier are lost. This effect lasts months to years and explains why other infections are more frequent and more severe in the years after measles. The technical term for it is immune amnesia.

Immediate complications are middle ear infection, diarrhoea and pneumonia. In about one in a thousand cases encephalitis occurs, which in some leaves lasting damage. And very rarely, after years, subacute sclerosing panencephalitis develops – a disease of the brain that is invariably fatal. The risk of it is highest in children who fall ill in their first year of life.

Measles in pregnancy

The good news first: the measles virus is not teratogenic. It causes no malformations of the kind seen with rubella, and confirmed contact is no occasion for far-reaching decisions about the pregnancy.

The bad news: pregnant women become more severely ill. Measles pneumonia – pneumonia caused by the virus itself – occurs more often in them and runs a more severe course, with a corresponding risk of intensive care. Pregnancy suppresses certain parts of the immune defence, and towards the end the diaphragm has less room.

For the baby, measles in the mother means a raised risk of miscarriage, premature birth and low birth weight. If the mother falls ill shortly before the birth, the baby can be born with the infection – a severe course treated in a neonatal unit, for which the baby receives immunoglobulins.

There is no treatment directed at the cause. What remains is prevention, and that means vaccination before the pregnancy.

Why the vaccination has to come first

The measles-mumps-rubella vaccine is a live vaccine with weakened but reproducing viruses. Such vaccines are not given in pregnancy. No harm has ever occurred in the registers of inadvertently vaccinated pregnant women – but a theoretical residual risk cannot be excluded, and so the caution remains.

In practice that means: after an MMR vaccination, pregnancy should be avoided for a month. Two doses at least four weeks apart count as full protection, and on current knowledge that lasts for life.

If vaccination has inadvertently been given in an existing pregnancy, no further measures follow from it. After the birth, on the other hand, the vaccination is unproblematic and expressly recommended where protection is missing – including while breastfeeding.

Anyone planning a pregnancy should therefore check both at once: measles and rubella protection. Both are in the same vaccine, both require the same lead time, and both are in the same vaccination card. There is more on this under rubella and in the screening planner.

Who has a gap in Austria

Measles is often regarded as a childhood illness. For Austria that has not been true for years: a considerable proportion of reported cases concerns adolescents and adults. The reason is a gap that can be named quite precisely.

• Those born from about 1970 on: too young to have reliably had measles, and at the same time from a period in which a second dose was not yet taken for granted. Many have exactly one vaccination – and one is not enough.
• Those born before 1970 are as a rule regarded as immune, because practically everyone had measles at the time.
• Anyone who grew up abroad should have their vaccination card checked – programmes differ considerably.

For women of childbearing age this gap coincides with precisely the age at which a pregnancy comes into question. That is why the question about the vaccination card in pre-conception counselling is not routine but a concern.

The MMR vaccination is available free of charge in Austria for all age groups – at the public vaccination services and from doctors in private practice who take part in the programme.

What to do after contact

Here hours count, and the approach differs according to whether there is a pregnancy.

Not pregnant, unvaccinated: vaccination within 72 hours of contact can still prevent or soften the illness. This post-exposure vaccination is the first choice, because it also builds lasting protection.

Pregnant, unprotected: vaccination is not an option. Instead immunoglobulins are given – ready-made antibodies, effective within six days of contact. They do not always prevent the illness but do soften it considerably. The same applies to babies under six months and to people with a weakened immune system.

In both cases: do not wait, but ring the same day. And: do not walk into a waiting room unannounced. If you think measles possible, ring ahead so that the practice can take precautions – a single visit can otherwise affect a whole waiting room.

How measles is diagnosed

Diagnosis by sight is not enough, and for a practical reason: because measles has become rare, a large proportion of doctors practising today have never seen a case. Conversely, other rash illnesses are regularly taken for measles.

The diagnosis is confirmed in two ways. Detection of viral genetic material by PCR from a throat swab or from urine is most reliable in the first days after the rash appears. In parallel, blood is examined for IgM antibodies, which indicate a recent infection; these are not always detectable in the first three days of the rash, however, which is why testing is repeated where the result is negative and suspicion persists.

For a pregnant woman confirmation is particularly important. It determines whether immunoglobulins are given, whether the maternity hospital has to be informed and whether the baby is treated after the birth. “Probably measles” is not enough for that.

What notification means

Measles is notifiable in Austria, and already on suspicion. The notification goes to the district authority, which starts an investigation of contacts: it establishes who had contact, checks their vaccination status and orders measures.

For unprotected contacts a ban on entering community facilities can follow – school, nursery, workplace – which can last up to two weeks. Anyone vaccinated is not affected. This is an aspect that rarely comes up in consultations and has considerable everyday consequences: a single case of measles in a school class can mean two weeks without childcare for unvaccinated families.

So if you are wondering whether a vaccination that supposedly nobody needs any more is worth the effort: it spares you not only the illness but the procedure around it.

Why measles keeps coming back

For the virus to be unable to maintain itself in a population, about 95 per cent of people have to be protected, because of its exceptional infectiousness. That is one of the highest thresholds there is – for most other pathogens 80 to 90 per cent is enough.

Austria has not consistently reached this mark for the second dose for years. Five per cent of gap sounds small, but with twelve to eighteen infections per case it is enough for an imported infection to spread. That is why outbreaks continue here while the illness has disappeared in other countries – and why it can reappear there at any time as well.

For an individual woman, however, these statistics are not the decisive figure. Whether 92 or 96 per cent of the country is vaccinated changes nothing about whether she herself is protected. That is exactly the point at which a general debate turns into a personal decision – and that one can be made with a look in a vaccination card.

Maternal protection – and its limit

As with other infections, maternal antibodies pass to the baby in the final third of pregnancy and protect it in the first months of life. The baby’s own measles vaccination in Austria begins from the completed ninth month.

There is an honest qualification to this that is rarely stated: the protection passed on by mothers who are vaccinated is weaker and lasts a shorter time than that from mothers who had measles. The reason is that having had the illness leaves higher antibody levels than vaccination does.

That is not an argument against vaccination – the illness would have meant many times the risk. It is an argument that protecting a baby in the first months of life cannot depend on the mother alone, but on the vaccination of those around her: siblings, parents, grandparents, carers. This is exactly the thinking behind the recommendation for whooping cough as well.

Measles and breastfeeding

Antibodies also pass to the baby through breast milk, though in smaller amounts and with limited effect. Breastfeeding replaces neither maternal protection nor vaccination.

If a breastfeeding mother develops measles, breastfeeding is as a rule not interrupted – the baby has had contact anyway, and the milk transmits protective antibodies. The decision is taken together with the paediatrician, who also decides about immunoglobulins for the baby.

The MMR vaccination itself is safe while breastfeeding. If you find during the postnatal period that protection is missing, make it good then rather than waiting for the next pregnancy – by then it is too late again.

How well the vaccination is tolerated

The MMR vaccine contains weakened viruses that multiply to a limited extent in the body. The typical pattern of side effects follows exactly from that: in about five in a hundred vaccinated people, a slight fever and a fleeting rash appear one to two weeks after the injection – so-called vaccine measles. They are not infectious and settle by themselves.

In adults, particularly in women, temporary joint pain occasionally comes with it; it goes back to the rubella component and heals without consequence. Swelling of the parotid gland as a reaction to the mumps component is rare.

What matters is the interval between live vaccines: if MMR and the chickenpox vaccination are not given on the same day, at least four weeks should lie between them. Both at once is possible; anything in between is not.

Vaccination is not given with marked immune deficiency, during immunosuppressive treatment, or in pregnancy. An allergy to hen’s egg is, contrary to the widespread assumption, no obstacle – today’s vaccines are not grown on hens’ eggs.

Two claims that persist

“The MMR vaccination causes autism.” This claim goes back to a publication from 1998 that was retracted; its author was struck off for manipulating data. Since then, studies of several million children have found no connection – most recently a Danish study of over 650,000 children. It is one of the most thoroughly refuted claims in medicine.

“Having measles strengthens the immune system.” The opposite is true. Measles erases part of immunological memory and weakens the defences for months to years – the effect of immune amnesia described above. The vaccination does not produce this damage.

Where to go from here

Look in your vaccination card before a pregnancy occurs. If two MMR doses are recorded, the matter is settled. If there is one or none, it can be resolved completely with two appointments and a month’s wait. Make an appointment.

If you cannot find the vaccination card: that is the commonest situation and no problem. Ask first at the GP or paediatric practice of your childhood – vaccinations are documented there and kept for years. If that leads nowhere, a blood test for the titre is enough, or vaccination is given without further ado: an additional MMR dose where protection already exists does no harm, it is simply neutralised by the immune system. Settling your status is in any case less trouble than the uncertainty of not knowing it.