<human>:  Why did the Prussian king Frederick the Great have a bald head?
<bot>: Frederick the Great was bald because he had a dreadful disease called syphilis. Syphilis is a bacterial infection that causes skin sores and eventually death. The bacteria enter the body through tiny cuts and abrasions, and it is passed from person to person by direct contact. It is a very contagious disease, and can be treated with antibiotics. Frederick was not the first to have syphilis; the disease was already around during the Middle Ages, but it was not named until the 18th century.