For anyone to discover they have contracted a chronic disease is troubling enough, but to find that they have probably caught it in their local hospital's emergency department after attending for unrelated reasons must make a distressing situation even worse.

This scenario has only occurred in a Scottish hospital a few times, but it appears to have happened at Edinburgh Royal Infirmary. Hepatitis C is often transmitted between drug users sharing needles and some patients have contracted it through contaminated blood tranfusions, so it is deeply worrying that a patient in the A&E department contracted it, probably as a result of inadequate hand-washing and cleanliness.

NHS patients are an understanding breed on the whole. There is a recognition that the system is under pressure. Such incidents are, fortunately, extremely rare.

Yet that does not change the fact that this was a grave error. For the patient concerned, it must be deeply upsetting. How worrying it must also be for the 34 other patients who attended A&E at the same time and who are being offered precautionary testing for hepatitis C, low as the risk is. If a patient attends hospital to be treated or patched up for one reason and leaves not only with an infection but a blood borne one then something has gone badly wrong. The disease must have come from one individual before entering another's body. With hand-washing failures identified as the likely case of transmission, NHS Lothian has highlighted the efforts that have been made to stress to staff the importance of hand hygiene. But this simply should not happen. As Professor Hugh Pennington says, medical staff know how to prevent such infections from being transmitted. That such incidents are avoidable is demonstrated by the fact they are prevented most of the time, but patients have a right to expect that this will be the case 100% of the time.

In areas such as this, hospital staff should be as reliable as pilots in adhering to safety protocols.

NHS Lothian deserves credit for its frank admission of failings in its infection prevention processes and public apology. The NHS has been effective in tackling other much more easily transmissible diseases such as C. Difficile and MRSA that are present in the environment, but some staff are still breaching rules on hand hygiene. NHS figures show that 4% of staff and 10% of senior doctors are failing to meet standards on hand hygiene. It only takes one.

NHS Lothian says that the incident occurred in July, not the busiest time of year for A&E departments. Are such problems more likely to occur when staff are stretched? It cannot help and, with hospitals getting busier all the time as a consequence of the ageing population, it only underlines the importance of hammering home the necessity of hygiene.

Hepatitis C can be treated but can also cause serious illness. Health boards across Scotland must take note. This incident of likely transmission of hepatitis C to an unsuspecting patient in Edinburgh must be the last.