Mumps is caused by a virus that infects the salivary glands in the mouth and can also affect other organs in the body. There is no cure for mumps, but the illness is quite short, lasting 7 to 10 days.

It is spread by coughing and sneezing (this is why there were often outbreaks during the winter before vaccines were introduced), and it takes 14-18 days to develop symptoms after being infected with the virus. It is very contagious and spreads quickly through households.

Typically your baby will develop a slight temperature, tiredness, headache, muscle ache and loss of appetite, before the recognisable swelling of the glands in the neck. Some people (about 1 in 5) show no symptoms and some have very minor cold-like symptoms.

Mumps can cause serious complications, often without many symptoms – about half of all people with mumps will develop a type of meningitis, which means that the membrane surrounding the brain is inflamed. Inflammation (swelling) of the brain can happen but is quite rare.

Commonly, about half of boys (after puberty) with mumps can develop swelling of the testicles (called orchitis) that can lead to fertility problems, and young girls (about 1 in 20) can develop inflammation of the ovaries (oopharitis). Other more serious complications include deafness, inflammation of the heart muscles, arthritis and inflammation of the kidneys. The MMR vaccine protects children from the virus that causes mumps.