Blow-in-the-bag test for terrorism

Scientists in America are developing a way of testing the breath to see if someone has been exposed to a biological warfare agent during a terrorist attack.

Dr Joany Jackman of Johns Hopkins University in Baltimore said the aim was to detect infection rapidly after potential exposure by simply sampling exhaled breath rather than taking blood.

"We want to have a tool that can help in the emergency room or ... on site so that people who are infected can get treatment first. It's not so hard to sample breath from many people very quickly as it is to draw blood."

The test exploits the fact that when the body is exposed to disease-causing organisms the immune system generates the release of proteins called cytokines which help to identify and fight the infection.

The researchers believe that cytokines may work their way up through the tissues until eventually they are breathed out with water vapour in exhaled breath.

If so, it should in theory be possible to detect the chemicals with a specially adapted breathalyser.

"Old medical texts, in the days long before sophisticated diagnostics, would recommend that a doctor check a patient by checking his or her breath, so we knew there must be something to it,"

Dr Jackman says.

Studies on pigs exposed to different infectious agents have demonstrated that the technique may work in humans.

Dr Jackman and her colleagues collected breath samples from the pigs, and put them through an instrument called a mass spectrometer which could test for the presence of cytokines and other proteins.

The scientists detected a strong surge in cytokines in exhaled breath in as little as an hour after exposure, and long before any visible symptoms appeared.

They also tested breath samples from disease-free pigs and found that the markers of infection were at or below the limits of detection, showing that it was possible to use the test to distinguish healthy animals from those that had recently been exposed to an infection.

The next step is to carry out tests on humans.

- INDEPENDENT