But the WHO is happy with the city's reporting method, even though the Department of Health uses a stringent definition of infection A medical watchdog yesterday accused the government of manipulating the Sars figures and distorting the picture of new infections in Hong Kong. The accusation came from Kwok Ka-ki, of the Action Group on Medical Policy, following a significant drop in the official number of new severe acute respiratory syndrome cases since April 26. However, the World Health Organisation (WHO) has said it is happy with Hong Kong's reporting of infections. Dr Kwok said the Department of Health had failed to adopt the standard set out by the WHO in defining Sars cases. Instead, Hong Kong used more stringent criteria that, he said, might have lowered the number of reported infections. Dr Kwok said it would become more difficult for Hong Kong to persuade the WHO to lift its travel warning to potential visitors if the government continued using different criteria. 'Also, people may tend to loosen their precautions against the infection after [seeing] only a few new cases every day. 'Hong Kong may end up facing an even bigger financial loss and health threat if Sars continues to hit Hong Kong,' he warned. Director of Health Margaret Chan Fung Fu-chun rejected the criticism, saying the definition by the WHO 'may be too broad, making everyone a Sars patient'. Dr Chan said Hong Kong might have actually over-reported the number of Sars cases as the laboratory tests used earlier were not well-developed enough to identify Sars patients accurately. 'When the laboratory tests become more mature, we would like to carry out serum tests on all 1,637 patients. The serum test is a more accurate test, so part of the [reported total] may not have Sars,' she explained. Dr Chan also said some patients might have been 'over-diagnosed', in the sense that they were treated as having Sars when they were actually not infected. Asked whether this over-diagnosis would leave some patients suffering from the unnecessary side-effects of the antiviral treatment, Dr Chan said: 'We should not think it this way. 'Under these circumstances, doctors have to give the best possible treatment to the patients - despite the risks [of over-diagnosis].' According to the WHO, suspect cases are people with symptoms of high fever and cough or breathing difficulty. Other reasons for suspecting Sars are if the patient has had close contact with Sars patients or recently travelled to infected places. Sars becomes probable, or highly likely, after a positive finding from chest X-rays or laboratory tests. In Hong Kong, patients are defined as suspect once given antiviral drugs. Sars is confirmed based on their symptoms, test results and clinical diagnosis.