Viruses that can kill
Older teachers may well have experienced the misery of mumps and measles in childhood. And anyone who escaped chickenpox as a youngster clearly didn't have a mother who, like most, believed that it made sense to help you to catch it.
Be warned: these diseases have not been stamped out. It is still possible for adults who either haven't had them or been immunised against them, in the case of mumps and measles,to be struck down.
MANAGING WITH MUMPS
The least infectious of the three but the one with the longest incubation period - up to three weeks - is mumps. This viral infection is spread by direct contact with saliva or droplets of saliva from an infected person.
Symptoms include a dry mouth, headache, high temperature and difficulty swallowing, but the diagnosis is confirmed when the sufferer takes on an uncanny resemblance to a hamster with food in its cheeks. This is caused by swelling of the salivary glands which can result in considerable discomfort and may continue for up to a week.
THE MISERY OF MEASLES
About 1 million children around the world die from measles each year.
However, in the UK, the incidence of both mumps and measles is now relatively rare (although rising again recently) because of the introduction of the MMR vaccine in 1988.
The measles virus, which is highly contagious, is spread by droplets in the air breathed out through the nose and mouth when people sneeze or cough.
In the first stage of measles, symptoms include a runny nose, red eyes, cough and an increasing and often sporadic high temperature. The rash, which starts as small red spots which then join together to make larger, flat patches of red or brown, appears on around day four. It usually begins on the forehead, spreads downwards over the face, neck and body, and lasts around a week.
CHECKING OUT CHICKENPOX
Chickenpox is also highly infectious and uncommon in adults. Fever, aches and a headache may herald its appearance, followed by spots - few or many - that appear in crops anywhere on the body. The spots develop into itchy blisters but gradually dry up, scab and fade over a period of a week or so.
There is no treatment for the viruses that cause mumps, measles and chickenpox, although bed rest, painkillers and taking plenty to drink will all help ease the symptoms. Calamine lotion, or something similar from your pharmacist, can help soothe the itching spots of chickenpox.
Your school will almost certainly have a policy on exclusions for infectious diseases, but, since infectious periods often pre-date any symptoms, this is not a great deal of help! Prevention is always better than cure and your best protection is to ensure that all your immunisations are up to date.
Traditionally thought of as childhood illnesses, all these diseases tend to be more severe in adults and carry a small risk of complications. Possibly the best known - or most feared - occurs in men who contract mumps: they experience a painful swelling of the testicles, known as orchitis, which is estimated to affect around one in five older males.
This may cause sub-fertility in a minority of those affected, so if swelling occurs, it is important to take a doctor's advice immediately.
Oophoritis, or the inflammation of the ovaries, is a small risk for women who contract mumps but has no effect on fertility.
Other possible complications with mumps include deafness, pancreatitis and meningitis or encephalitis.
For measles, the risks include a severe cough and breathing difficulties, ear infections, pneumonia and conjunctivitis. Scarring from spots, infected spots, pneumonia and - rarely - encephalitis feature in the complications list for chickenpox.
If you catch mumps or measles, take some comfort from the reward you gain: lifelong immunity to the infection. This is not true of chickenpox, which can re-appear in later life as shingles.
In all cases, keep away from pregnant women who have not had whichever of these illnesses you are suffering from. Their unborn babies may be at risk.
WHAT YOU SHOULD KNOW ABOUT MUMPS
Mumps: the salivary glands swell; you can look like a hamster
* It was made a notifiable disease in the United Kingdom in October 1988.
This means that doctors have a statutory duty to notify a "proper officer"
of the local authority of suspected cases of certain infectious diseases.
* Confirmed cases have been rising significantly over the past three years.
* The incidence of the disease peaks in winter and spring.
* Possible complications include swollen testicles, deafness, and meningitisencephalitis.
* According to the Health Protection Agency, 90 per cent of confirmed cases last year were in people aged 15 years and over.
Measles: starts with a rash, visible from day four
* Measles is also a notifiable disease (see mumps - left).
* The virus is most infectious before the rash develops.
* Anyone who has not already had measles, or been immunised against it, can get the virus.
* Possible complications include ear infections, pneumonia, fits and meningitis or encephalitis.
* Measles can be fatal - 1 in 2,500 to 5,000 die - or it can lead to continuing disability.
Chickenpox: starts with spots that develop into itchy blisters
* Most people have chickenpox as a child - about 9 in 10 people have had it by the age of 15.
* Symptoms are usually more severe in adults and complications more common.
* Chickenpox is infectious until the spots dry up.
* The virus particles remain dormant in your nervous system and can, at a later stage, cause shingles.
* You should see a doctor urgently if you become breathless, confused or have any unusual symptoms.