The average adult is made up of 100 trillion cells. But only one-tenth of those are human. The rest are bacteria, fungi, parasites, and “miscellaneous riff-raff.” That is one of the astonishing facts in Dr. Robert Buckman’s book, Human Wildlife, the companion volume to his television series. The premise of the show is that the human body is a planet with its own ecosystem of creepy-crawlies. Some of these organisms are benign, such as the eyebrow mite Demodex. Others are more of the Cronenberg variety.

Perhaps the vilest is the guinea worm. The larvae hatch in the gastrointestinal tract. The adult worms – two feet in length! – bore their way to the skin. But don’t scratch: if the worm’s body breaks, you will die of toxic shock. The only treatment, which takes days, is to wind the end of the worm on a small piece of wood, easing it out inch by inch. This ancient cure gave the medical profession its symbol – the staff encircled by a snake (or worm).

Human Wildlife is a fascinating look at the critters that cohabit our bodies, with occasional stunning colour photographs and micrographs. However, many shots are recycled scans and only serve to remind you that you could be watching TV instead of reading. More research and detailed explanations would have made the book worthwhile in its own right. Buckman’s laboured puns – the origin of feces – also detract from the hard science.

Biology buffs will already know about house dust mites, sleeping sickness, and the fascinating life cycle of the tapeworm. The merely curious will probably wait for the TV series to air again. Which begs the question: who are left as readers? Nasty boys, obsessive-compulsive types, and people looking for a reason to wash their hands.