Singapore has ordered schoolchildren to stay at home, Hong Kong has invoked a little used quarantine law and with their mandatory masks its residents look like actors in a sci-fi film, and in the rest of the world overseas travellers are being kept at an arm’s length. The emergence of an unidentifiable pathogen has always qualified as health workers’ biggest nightmare, and by all appearances they could be wading into it. In terms of casualties, the severe acute respiratory syndrome (Sars) has claimed a relatively moderate number of victims—over 1,400 infected, and about 50 dead. But the World Health Organisation has already termed the influenza-like disease a “worldwide health threat”—and comparisons are being drawn to the 1918 flu pandemic that killed 50 million around the globe, with Samoa said to the only spot on earth escaping the virus.That comparison is unduly alarmist, but the unprecedented precautions are definitely warranted. In brief, Sars is believed to be connected with the outbreak of a rare form of pneumonia in China’s Guangdong region this winter. In recent weeks increasing numbers of cases have been reported — mostly in Hong Kong and Singapore, but also in nearby Taiwan as well as in Europe and the US. The syndrome begins with flu symptoms like high fever and cough, but rapidly develops into acute pneumonia. According to early estimates, four out five infected persons recover, while 5 per cent die. With doctors still unable to isolate the infection, antibiotics and antivirals are of no use. There is, as yet, no cure.Till the microbe is isolated, awareness and quarantines are the most prudent prescriptions. For an infection that’s taking flight on international air routes, airports have become hubs for health workers. Sars has highlighted how interconnected the global village really is. Pathogens cannot be made to respect regional and national boundaries. On the one hand, this points to the futility of travel advisories. On the other, it indicts local authorities who hush up health scares — as the Chinese did, choosing to put their “mysterious pneumonia” death toll at five before suddenly admitting it was far higher. Each day, international teams of doctors say they are on the brink of a cure; till they announce one, strict monitoring is imperative.