Slapped cheek syndrome (also called fifth disease or parvovirus B19) is a viral infection that’s most common in children, although it can affect people of any age. It usually causes a bright red rash on the cheeks. Although the rash can look alarming, slapped cheek syndrome is normally a mild infection that clears up by itself in one to three weeks. Once you’ve had the infection, you’re usually immune to it for life. However, slapped cheek syndrome can be more serious for some people. If you’re pregnant, have a blood disorder or a weakened immune system and have been exposed to the virus, you should get medical advice.
Your child may have a high temperature, sore throat or headache to begin with. They are most contagious at this point. Up to seven days later they will develop a bright red rash on both cheeks. Finally, the rash will spread to your child’s chest, stomach, arms & thighs. This will usually happen up to four days after the rash on their cheeks.
Until the rash has faded.
Read more about this illness at the NHS website.