What is measles?
Measles is a very contagious infectious disease that generally occurs in childhood. Nowadays children in the Western world are vaccinated against the measles virus, which has made the disease extremely rare. In parts of the world where vaccination is not usual, however, many children still die of measles each year.
What are the signs?
After infection, complaints first arise that resemble a cold: fever, coughing and red eyes. Then small white spots appear in the mouth (the so-called Koplik spots) and a red rash develops, usually first on the face and later over the rest of the body. This rash consists of countless small red spots — such a rash is called a viral exanthem. In most children measles passes without complications, but a small proportion can develop serious complications that can sometimes even be fatal.
How is it transmitted?
The virus is transmitted by coughing and sneezing. People are contagious from 2 days before the signs appear until about 5 days after the red rash has appeared. The measles virus is extremely contagious. For many years, however, vaccination against measles has been part of the childhood vaccination programme.
Who is at risk of getting measles?
Anyone who has had measles in the past or been vaccinated has, in principle, lifelong protection. People who for whatever reason are not vaccinated are of course at risk. Every few years a small epidemic occurs in areas where “herd immunity” is reduced for this reason. People who are vaccinated but have strongly reduced resistance through medicines (such as prednisone or other immunosuppressants) or serious immune-lowering diseases (such as HIV/AIDS or cancer) can also become ill after infection.
Because the great majority of the population is immune, the chance that a susceptible person actually becomes infected is small — a phenomenon called herd immunity, whereby the virus cannot maintain itself in the population. People with reduced immunity or who are unvaccinated therefore have a relatively small chance of catching measles where coverage is high, but when travelling to a region where measles is endemic the risk of infection is clearly present.
When to see a doctor
See a doctor if measles is suspected (cold-like symptoms with fever, red eyes and a spreading red rash), especially in a baby, a pregnant woman or someone with reduced immunity, and urgently if there are signs of a complication such as breathing difficulty or drowsiness.