But according to US microbiologists, it is the toilet itself and not the seat which is the offender. Sometimes we feel that this is all new knowledge, but in fact 285 years ago, Dr Charles Gerba of the Dept of Biology at the University of Arizona in Tuscan, wondered why gastro-intestinal illnesses spread so quickly.

Conventional wisdom of the time, held that the chef route for the spread of illness was in fact faecal contamination of the hands.

Dr Gerba believed that this notion could not always explain the rapid spread of many diseases such as diahorrea, gastroenteritis and others.

We at IHS could be mistaken for believing that we are the only practioners who have awareness of the hazards of airborne aerosols laden with bacteria.

In fact, 25 years ago Dr Gerba thought that bacteria might be spread through the air in water droplets when toilets are flushed. Dr then moved on to the practical application of his theory by carrying out controlled testing by stretching a moisture sensitive sheet over a toilet and flushing it.

Sure enough, he discovered that a vapour of water was blown upwards. He then went on to test the effectiveness of closing the toilet lid, finding that it was of no benefit as the bacteria laden aerosols were released upon opening.

Next Dr Gerba injected bacteria directly into the bowl water and found that the same bacteria were still present even after several days of flushing. Dr Gerba stressed the importance of regular disinfecting of the bowl, particularly when one or more users are suffering an illness.