At this time of year there is usually an outbreak of tinsellitis. You may notice sparkly matter on the scalp, neck or elsewhere. There may be a momentary irritation but this should not be lasting. Should you feel an urge to shout, "Bah! Humbug!", cover your mouth until it passes. Infection takes place mainly through the eye, and young people are particularly susceptible. The active element is often found on ceilings, pine trees or draped over electronic equipment. It is generally harmless and will not last long into the New Year.