My young son recently contracted the herpes virus and was really unwell for a couple of weeks and had cold sores in and around his mouth.

I thought cold sores weren't too painful?

Usually, when you first become infected with the herpes simplex virus (known as the primary infection), there are no symptoms. You may not know that you have contracted the virus until you get an outbreak of cold sores sometime later.

However, if the primary infection causes symptoms, these can be quite severe. These symptoms are most likely to occur in children under the age of five and include:

€¢ swollen and irritated gums with small, painful sores in and around the mouth (known as herpes simplex gingivostomatitis, see below)

€¢ sore throat and swollen glands

€¢ producing more saliva than normal

€¢ fever

€¢ dehydration (a lack of water in the body)

€¢ nausea

€¢ headaches

If your child develops herpes simplex gingivostomatitis, it can last 7-14 days and may take up to three weeks for the sores to heal. However, gingivostomatitis does not often recur after the primary infection. It is usually young children who get gingivostomatitis, although it is possible for adults to get it.

My children have been ill with a sickness bug a couple of times in the last few months. How can they have picked up the same illness again?

There are at least 25 different strains of noroviruses known to affect humans. They're the most common cause of stomach bugs in the UK.

Each year, it's estimated that between 600,000 and 1 million people in the UK catch norovirus. The illness is sometimes called the "winter vomiting bug" because it's more common in winter. However, you can catch the virus at any time of the year.

Norovirus is easily spread. If an infected person doesn't wash their hands before handling food, they can pass the virus on to others. You can also catch it by touching contaminated surfaces or objects.

Follow the measures below to help prevent the virus spreading.

€¢ wash your hands frequently

€¢ don't share towels and flannels

€¢ disinfect surfaces that an infected person has touched

Outbreaks of norovirus in public places, such as hospitals, nursing homes and schools, are common because the virus can survive for several days on surfaces or objects touched by an infected person.

If you have norovirus, you may continue to be infectious for a short period after your symptoms stop. You should therefore avoid preparing food and direct contact with others for at least 48 hours after your symptoms disappear.

What is Mumps?

Mumps is a highly contagious viral infection that usually affects children. The most common symptom of mumps is a swelling of the parotid glands.

The parotid glands are located on one side, or both sides, of the face. The swelling gives a person a distinctive 'hamster face' appearance.

Once a person has had mumps, they will usually develop immunity against further infections.

Before the introduction of the measles, mumps and rubella (MMR) vaccine in 1988, mumps was a common childhood infection that was responsible for 1,200 hospital admissions a year in England and Wales.

After the MMR vaccine was introduced as part of the routine childhood vaccination programme, the number of mumps cases fell sharply, with less than a 100 cases reported in 1996.

However, in recent years, there has been an upsurge in the incidence of mumps, and in 2005, there was a mumps epidemic that resulted in over 43,000 cases in England and Wales. Most cases affected teenagers and young adults.It is thought that the recent mumps epidemic was due to people in this age group not receiving the MMR vaccination, but also not having a natural immunity to mumps due to not having previously been infected. Children who have not been immunised with the MMR vaccine are at greater risk of getting mumps if it is spreading in the community.