Normally this column looks at some kind of condition or illness and talks about ways to prevent or treat it. However, this week I want to look at a special condition that few people would consider an illness. But handled the wrong way it puts the victim's health, well-being and very life in danger. I'm talking about celebrity. The appalling way the popular singer Anita Mui Yim-fong has been hounded by the media ever since rumours she may have a serious illness began circulating is a classic example of how toxic celebrity status can be. Anyone with major illness, especially something like cancer where they need to marshal their entire immune system to fight rogue cells, needs to have stress reduced not increased. Yet the hordes of photographers and reporters camped outside Mui's home paid no heed to that; they were merely intent on getting the first pictures of the star looking ill. I am not saying celebrities are entitled to pick and choose the level of publicity they receive. There is nothing more hollow about the celebrity who cooks up publicity stunts just before a film or concert, then complains bitterly about having no privacy when she is chased by fans or the media at other times. But there are areas of their lives that should indeed be off-limits, as in anyone's life. And that is really the central issue: when is someone else's health your business? The simple answer: never. Unless you are managing their health or have been invited by them to share in their health problems, health, good, bad or indifferent, is their business and theirs alone. And that is why confidentiality: the unspoken promise your doctor makes every time you see him or her that whatever happens during a medical consultation remains private is so crucial to medical care. There are times, when, by law this promise has to be broken. If your illness turns out to be one of the highly infectious 'notifiable diseases' - such as cholera, tuberculosis, measles, dengue fever - your doctor is obliged to inform the department of health. And if your illness is considered so infectious and dangerous that you and any of your close contacts are likely to be spreading it, your doctor is not only obliged to tell the department, he or she has to make sure you are quarantined. We are all now experts on this particular reason for breaching confidentiality, thanks to Sars. But this requirement - that outsiders be notified of serious infectious illness can cause problems as well. Some people are so afraid of the reaction they will get from the authorities, their employers, friends, neighbours, even insurance companies that they do anything to avoid being tested if they think they have a serous infectious disease. When Aids first appeared on the scene, some activists were advising people in the risk groups not to take the test to avoid the social consequences of being HIV-positive. During the Sars outbreak we saw the same thing , with people lying about being from Amoy Gardens to avoid being put in quarantine. At least one of them kept on working, with all the symptoms of Sars and left it so late to get to hospital, she died soon after being admitted. These people were 'ordinary' people, but the fear of suffering brought on by others' reaction to their disease made them avoid getting the right medical care. When people are celebrities with illnesses that no-one beyond their doctors have any need or right to know about, the media's constant monitoring of their homes prevents them from getting the treatment and care they need. A very important part of that treatment is rest from public duties. To be fair, much of the blame lies with the media, including those of us who write about health. Celebrities with rare or hitherto unglamorous diseases have done a lot to raise awareness of those conditions and to educate the public who are only too willing to listen and learn if the information is coming from a much loved singer or actress. But doing that is a choice the celebrity makes. Being ill and famous does not oblige a celebrity to discuss their disease. So make this the last discussion you read of Mui's condition. If her illness doesn't sell papers and the latest picture doesn't fetch a big price, her tormenters will soon stop bothering her. And if the effect is really dramatic, the next celebrity to fall ill may have the rest and care he or she is entitled to.