Tokyo has shown that mass-transit systems need not be a poor or dirty option.

ECONOMIST: Driving

Poor piercing hygiene practices such as reusing dirty equipment or not washing ones hands or changing gloves may also enable infections to be spread.

CNN: What could be causing my jaundice?

The global burden of illness owing to dirty water, bad or non-existent sanitation and poor standards of hygiene is remarkable, according to the studies cited by Mr Rijsberman.

ECONOMIST: Economics focus