Last April, WHO director general Margaret Chan returned from an official visit to North Korea to describe the health system there as the envy of many developing nations, with no shortage of doctors or nurses. Nevertheless, the WHO admits great challenges remain in North Korea, but a spokesman said improving health for people there would not be achieved by turning the issue into a political football.

Scientists in the US have created a new strain of mosquito that's resistant to malaria, meaning it can't then pass the disease onto humans. But their release into the wild is several years away, as Victoria Gill reports.