There are tiny bugs closely related to spiders living in the pores of your face. They have long been considered mere passengers, doing no harm beyond upsetting the squeamish. But they may be causing an ancient skin disease that is estimated to affect between 5 and 20 per cent of people worldwide, and 16 million in the US alone.
People aged between 30 and 60, especially women, sometimes develop rosacea: red inflamed skin, with swelling, roughness and fine, visible blood vessels, usually in the central zone of the face. Severe cases can resemble acne, irritate the eyes and lead to the bulbous red nose seen in caricatures of the elderly.