Born in Penang, Malaysia, on 10 March 1879 and educated in the UK, Wu was recruited to work on a deadly disease outbreak in north-eastern China in December 1910. The first people to be affected were marmot trappers and fur traders, who were part of a flourishing trade in marmot pelts in the region.
From a postmortem examination – the first performed in China – Wu succeeded in isolating and culturing the bacterium responsible for the disease, identifying it as Yersinia pestis, which was known from earlier bubonic plague epidemics.
Wu understood that the disease could be spread by respiratory droplets and wasn’t just caught from rats or fleas, as many believed at the time.
Wu produced a mask made from cotton and gauze, with extra layers of cloth and more secure ties to improve on previous designs. He encouraged medical staff and others to wear these masks to protect themselves, the first time widespread mask use had been part of an epidemic control strategy. It was met with some resistance, however: a French colleague died of the plague after refusing to wear a mask.
Wu advised authorities to impose restrictions on movement, including stopping trains, to limit the spread of the disease, and to instruct sick people to self-isolate. He also persuaded officials to authorise the cremation of dead bodies, which wasn’t normally accepted in China.
The last case of the disease, which killed an estimated 60,000 people, was recorded in March 1911. It came to be known as the Manchurian plague.