A small boy has taken the world by storm.

Over 66 million copies of J.K. Rowling's books about a teenage wizard have been sold around the world since the first edition was published in 1997. The books have been translated into 35 languages and their author, until recently an unemployed single mother, is now the third richest woman in Britain.

The first Harry Potter book arrived in Bulgaria last December and was an immediate success. Mariana Melnishka has just finished the Bulgarian translation of the third Harry Potter book, The Prisoner of Azkaban, and is about to start work on The Goblet of Fire. The book is 600 pages long and will take her at least six months of sleepless nights to complete. "God help me," she said. "By the end of the last one I was completely exhausted."

Her previous projects include translations of A Clockwork Orange and the French Lieutenant's Woman, and this is the first time in her 25-year career that she has worked with children's stories. "I was concerned that people would take me less seriously because of this," she said. "But it was a challenge I couldn't refuse and I have absolutely no regrets - Harry Potter is wonderful."

Melnishka's work has not been straightforward. "Rowling's writing has a subtly refined finesse and style that makes it very challenging to translate. It's not exactly street or school language and it's not exactly how students of Harry's age would talk in Bulgarian schools nowadays. You have to keep the scent of foreignness without making it too alien for the reader," she explained.

The use of made-up words in the books caused many headaches for the Bulgarian translator. Rowling invented the word "aperate" to describe a magical process of teleporting with your mind. "It seemed absolutely impossible to translate this," said Melnishka. "Bulgarian children know about teleportation but aperation is done only with the mind. After long discussions with my colleagues we came up with 'magiport.'" Rowling's agents made it clear that some of the invented words should not be changed, even if their imagery was lost. The Harry Potter phenomenon has spread worldwide and publishers want to ensure that children in any country can relate in some way to the original text. There will soon be a Harry Potter film and, although it will have subtitles in most countries, producers feel that foreign audiences will need to recognize key words for it to be successful. For this reason words such as "muggle" (non-magical human) are being introduced to the vocabularies of 35 languages.

Many of the newly coined words have their roots in Latin, a language unfamiliar to Bulgarian children. Melnishka based her equivalents on Roman and Greek mythology. "To connect Bulgarian children with the world of Harry Potter we have to retain clues to the original words when we translate," she said.

The Bulgarian publisher, Egmont, employs a team of specially trained children's fiction editors to help Melnishka. "I always consult younger people to get feedback on my work. They often come up with solutions for what seemed like unsolvable problems." Initially, she had her doubts about the popularity of the book in Bulgaria because of cultural differences, and the fact that the book is aimed at young children, but she has been amazed by its success. "People say that children don't read anymore, but give them Harry Potter and you'll see the sparks in their eyes - it makes all the hard work worthwhile."

The books are quite expensive for the Bulgarian market (seven to nine leva) and Melnishka expected them to only reach children from wealthier families. She was proved wrong on a recent trip to the coast where she encountered a family from a poor area of Bulgaria. They had saved up to buy a Harry Potter book for their daughter's birthday and had promised to buy her the next for Christmas. "I realized that they were rationing their expenses on the book. That was amazing for me," she said.

There has been much discussion about the secret of Harry Potter's success. Many put it down to skillful marketing strategies but Melnishka disagrees. "The books make children good. They are not about a magic world but about the real world seen through the eyes of magic. They show that in each bad person is something good and that in each good person there may be some weaknesses. Rowling shows children the things we meet in everyday life and gives them a colouring of magic to make them beautiful."

Melnishka was of the opinion that parents can happily spend a substantial amount on the books because they know their children will be in good hands. "Parents are often as eager to read the books as their children," she added.

And the Bulgarian translator is now looking forward to the challenge of the next Harry Potter book. "You need to be a little bit crazy to translate these books and even though I'm a grandmother, I'm still very much a child," she said.

Her translation of Harry Potter and the Prisoner of Azkaban will be available in bookshops from September 13. Bulgarian Harry Potter fans will have to wait until next spring to read The Goblet of Fire.