LONDON — Best-selling fantasy author Terry Pratchett has been diagnosed with a rare form of early onset Alzheimer's, he said in a message posted to his illustrator's Web site.
In a brief note to fans entitled "An Embuggerance," Pratchett, 59, said he was taking the news "fairly philosophically" and "possibly with a mild optimism."
"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," he wrote on the Web site of Paul Kidby, who has illustrated many of his books.
Pratchett is best known for his Discworld series, which explores the residents of very flat, very weird and almost invariably hilarious planet dominated by the sprawling, chaotic city of Ankh-Morpork. Pratchett wrote his first Discworld novel, "The Color of Magic," in 1983, and 35 more books followed, many of which topped the best seller charts.
Pratchett's Web site said his novels have sold more than 45 million copies and have been translated into 33 languages worldwide.
His latest work, "Making Money," was published in September and Harper Children's was due publish a non-Discworld novel, "Nation," in 2008.
Pratchett said he would continue completing "Nation" and that he had already begun working on "Unseen Academicals" _ another writing project.
"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)" he wrote in his message. "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."