Although Chinese government officials claim that the outbreak of severe acute respiratory syndrome (SARS) has been effectively contained in Beijing, the rapid decline in the number of cases there has raised suspicions that China may be under-reporting by excluding mild cases.

“They fit the case definition, but because they get better in a few days they are not seen as probable cases. Clinicians are making this decision because there's an assumption that SARS patients must be very sick, but there's a spectrum of severity for SARS,” said Dr Daniel Chin, team leader of the World Health Organization's Beijing SARS experts.

Outbreaks in some of China's poorer provinces, such as Guangxi and Hebei, have been tackled with vigour by local authorities and health workers, keeping numbers below the worst fears of WHO. In Guangxi, a major feeder province for the factories of neighbouring Guangdong, an estimated 260 000 migrant workers returned home between 1 April and 8 …