Researchers impressed by Google's medical diagnoses

It may prove to be a better diagnostic tool than the stethoscope or the thermometer. Next time your doctor appears baffled over what is wrong with you, you could suggest he "google for a diagnosis".

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Researchers have found that a simple Google search can solve diagnostic problems which mystify even the best GPs.

Modern medicine is so complex that the average doctor, estimated to carry around two million medical facts in his head, does not have a big enough brain to be capable of identifying every ailment presented to the surgery or clinic.

But Google gives access to more than three billion medical articles on the web and may be the most powerful diagnostic aid available to doctors. To test Google's value as a clinical tool, researchers from Brisbane University selected 26 of the hardest cases and found the search engine got the correct diagnosis in more than half of them (58 per cent) - with just a few keystrokes.

Google successfully diagnosed conditions ranging from Creutzfeldt-Jakob disease, the degenerative brain disorder, to cat scratch disease, an infection causing lymph node swelling after an animal wound.

Writing in the online version of the British Medical Journal, they say: "Search engines allow quick access to an ever increasing knowledge base.

"Our study suggests that in difficult diagnostic cases, it is often useful to "google for a diagnosis". Doctors in training need to become proficientin [its] use."

The cases were taken from the New England Journal of Medicine which tests the diagnostic skills of its readers each week by asking them to judge what is wrong with a patient whose brief medical history and symptoms are given.

The researchers, unaware of the correct diagnosis, entered between three and five search terms and selected Google's three most prominent results that seemed to fit the symptoms.

In some cases they rejected the Google diagnosis as not being accurate enough. For example it correctly diagnosed extrinsic allergic alveolitis in a patient with breathing problems but did not specify it was "hot tub lung" caused by Mycobacterium avium, a bug that thrives in hot tubs, which are becoming increasingly popular.