This is a harmless viral infection of the skin. It causes a rash consisting of crops of firm round pearly white spots 1-3mm in size that contain a tiny pit in the centre. Each spot contains a small capsule that is full of cheesy material containing the virus. The rash is often seen on the trunk, buttocks, face and arms. The virus is spread by person to person contact and it takes between 2 weeks and 2 months to develop the rash. We commonly see it in children and it is relatively unusual in adults although it can be spread sexually causing spots on the penis, scrotum or vulva and  can be a more severe problem when your immune system is compromised. It tends to spread to damaged skin and the spots can become secondarily infected if scratched. The condition resolves on its own after several months. The individual spots can be pricked to express the contents. This kills the individual spot but if there are many this can be unpleasant for children and it may be best to leave well alone until the body's own immune system clears the infection naturally. The problem tends to worry parents more than the children but they should be discouraged from scratching the spots.