Best-selling British fantasy author Terry Pratchett has officially announced that he has been diagnosed with a rare form of early onset Alzheimer’s disease, through an open letter to his fans, entitled “An Embuggerance,” posted on Paul Kidby’s Discworld News site:

Folks,

I would have liked to keep this one quiet for a little while, but because of upcoming conventions and of course the need to keep my publishers informed, it seems to me unfair to withhold the news. I have been diagnosed with a very rare form of early onset Alzheimer's, which lay behind this year's phantom "stroke".

We are taking it fairly philosophically down here and possibly with a mild optimism. For now work is continuing on the completion of Nation and the basic notes are already being laid down for Unseen Academicals. All other things being equal, I expect to meet most current and, as far as possible, future commitments but will discuss things with the various organisers. Frankly, I would prefer it if people kept things cheerful, because I think there's time for at least a few more books yet :o)

Terry Pratchett

PS I would just like to draw attention to everyone reading the above that this should be interpreted as 'I am not dead'. I will, of course, be dead at some future point, as will everybody else. For me, this maybe further off than you think - it's too soon to tell. I know it's a very human thing to say "Is there anything I can do", but in this case I would only entertain offers from very high-end experts in brain chemistry.

Pratchett is the author of the beloved satirical series Discworld, about a flat planet that rides on the backs of four elephants on the back of a giant sea turtle swimming through space. The first Discworld novel, The Colour of Magic, was published in 1983. Making Money, the 36^th and most recent Discworld novel, was published in 2007.

He is also the author of numerous other fantasy and science fiction novels, including series for children’s and YA fiction, some of them Discworld novels. His work has been adapted for radio plays, computer and role-playing games, graphic novels, and television, with Pratchett frequently writing the adaptations.

His books have sold 55 million copies worldwide and been translated into 33 languages, making him the second highest selling fiction writer in Britain, after fellow fantasy writer J.K. Rowling, and among the top ten bestselling fiction writers in the world. His first professional publication occurred when he was only fifteen-years-old. His first novel, The Carpet People, was published in 1971.

His first Discworld novel for children, The Amazing Maurice and His Educated Rodents, was awarded the 2001 Carnegie Medal. His novel Night Watch won the Prometheus Award for Best Novel. His Tiffany Aching novels have won the Locus Award for Best Young Adult Novel in 2004, 2005 and 2007. In 1994, he was named the British Book Awards Best Fantasy and Science Fiction Author of the Year. In 1998, he was made an OBE for services to British literature.

Currently, HarperCollins Children is still planning to publish his novel Nation in 2008. A television production of The Colour of Magic, for which Pratchett wrote the adaptation, is in production and Pratchett will appear in it in a cameo. In 2006, Discworld novel Hogfather was adapted for television, with Pratchett also doing screenwriting duties. His novel The Wee Free Men is scheduled to be turned into a feature film by director-producer Sam Raimi, for release in 2010.