On 23 March 2007, Knut appeared in public for the first time. About 400 journalists visited Berlin Zoo on what was called "Knut Day" to make reports all over the world. Because Knut became famous when he was very young, many wrong stories about the cub's health were spread around during his first year. For example, on 16 April 2007, Knut took a break from his display because of teething pains, but reports said that he might have an unknown sickness. There were also many death threats, like the one sent on Wednesday 18 April 2007. The zoo received an anonymous letter by fax which said "Knut ist tot! Donnerstag Mittag." ("Knut is dead! Thursday noon.") The police increased the bear's security.