This book is great fun, but also you can learn a bit about cells and the immune system, but in a humorous, laid back sort of style. I think this is more for 6- 10 year old boys and girls. I really liked the whole plot, but it could have had a bit more detail and been a bit longer, to incorporate some more of the (thoroughly entertaining) adventures! Please, please write more! I also really liked the illustrations, they were great!