Geneva - Turning sixty is usually a time to start winding down and think of retirement, but the World Health Organisation is using this milestone as a spur to its greatest challenge yet - climate change.

The WHO already warned three years ago that global warming was a key cause of up to 150 000 deaths and 5 million illnesses each year, be it from heat waves or the higher risk of natural disasters such as floods, droughts and typhoons.

Similarly, the Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC) warned last year that malaria, cholera, malnutrition, heatstroke and pollen allergies are all set to worsen as the world's temperatures rise.

Climate change has already extended the range of mosquitoes and ticks, helped spread diarrhoeal disease, boosted the length and location of pollen seasons and pumped up the intensity of dangerous heat waves, the IPCC said in a report.

"Adverse health impacts will be greatest in low-income countries," the report said.

"Those at greater risk include, in all countries, the urban poor, the elderly and children, traditional societies, subsistence farmers and coastal populations." Chan, a former director of public health in Hong Kong and the first Chinese national to head a UN institution, said the organisation was well placed to meet its future challenges.

The WHO was born in the shadow of the Second World War on April 7, 1948 at a time when infectious diseases such as cholera threatened a world weakened by six bloody years of conflict.

Sixty years later and numbering 193 member states, the Geneva-based WHO is concerned with a whole host of health issues, from smoking to road safety, as well as the threats of Aids, Sars and bird flu.

This would appear more than enough for any organisation but WHO Director General Margaret Chan has chosen this anniversary year to address the issue of climate change and its implications for public health the world over.

"Sixty years ago, when WHO was founded, public health faced the daunting task of restoring basic health services in a world badly damaged by war," she said in a statement.

Since then, "the challenges confronting public health have changed in profound ways. In today's closely interdependent and interconnected world, health problems are increasingly shaped by the same powerful forces, creating universal threats," Chan said.

"As a mature institution, WHO enters its seventh decade fully aware of the challenges, yet bolstered by the optimism that has characterised this Organisation since its inception," she said.

- Sapa