Animals from Z-Z.

THIS column has been running for ages now. After a few hundred articles it is easy to run out of new topics, so a few weeks ago I decided that when I was stuck for an idea I would work my way alphabetically through diseases.

I hope you enjoyed athletes foot and actinic keratoses (the articles not the diseases). But then Brian sportingly turned up with a zoonosis from the other end of the alphabet, so we are going to do it backwards. Brian was really quite ill. He was hot, miserable and his joints were aching. He also had a dry cough and chest pains. His chest was making some creaky noises, which gave me a diagnosis of pleurisy. I prescribed some painkillers and antibiotics but over the next few days he got worse. The second time I listened into his chest there was less creaking but very little air was getting to the bottom of his left lung, so I revised the diagnosis to pneumonia, ordered a chest x-ray and gave him more antibiotics with steroids. Still, he got no better. The x-ray showed me I was right about the pneumonia. Listening to Brian's chest again showed that the antibiotics and steroids were still not working.

Blood tests were invented to give doctors something to do when they are stuck, so I did some. The tests showed Brian had pneumonia caused by chlamydia psittaci, a bacteria that laughs at our normal antibiotics but is killed by tetracycline. He recovered quickly once he was given the correct drugs. This infection is most often caught from birds. I had asked Brian if he kept pigeons, parrots or a budgie. He didn't.

But he was a heating engineer and had cleared some dead birds and their droppings from an airconditioning system. This was the source of his unusual infection. Zoonoses are defined by the World Health Organisation as "Diseases and infections which are naturally transmitted between vertebrate animals and man". A zoonotic agent may be a bacterium, virus, fungus, parasite, or other communicable agent. Or, if you like, illnesses you can catch from your pet, you can catch from cats or dogs: Campylobacter infection, cat scratch disease, hookworm, lyme disease and toxoplasmosis are but a few.

If you keep a pet you must ensure it is kept healthy in order to protect your own health. If your doctor asks you if you keep animals and you don't, but have been pulling dead ones from drains let him know about that too.