GENEVA (Reuters) - Post-election violence in Kenya and unrest in Gaza showed how political turmoil can threaten public health, the head of the World Health Organisation (WHO) said yesterday.

Margaret Chan, in an address to the United Nations agency's executive board, said she was concerned that upheaval in Kenya after a disputed election would cause setbacks in the fight against HIV/AIDS, malaria, tuberculosis, and other diseases that required monitoring and action.

In Gaza, Israeli blockades and road closures were taking a heavy toll on sufferers of cancer, heart disease, diabetes and those needing emergency care in the occupied Palestinian territory, the WHO Director-General said.

"We are seeing right now some stark evidence of the threat arising from instability and civil unrest," Chan told the preparatory meeting for the WHO's World Health Assembly in May.

The 34-member board will this week consider advances in international efforts to combat pandemic influenza, eradicate polio and guinea worm disease, and prepare for health risks associated with climate change.

It will also assess campaigns aimed at combating female genital mutilation, improving global immunisation coverage, and reinforcing health care systems in poorer countries.

Though tuberculosis prevalence appears to have stabilised globally, the spread of drug-resistant strains in Eastern Europe, parts of Central Asia, and China was a serious concern, Chan said.

Extremely drug-resistant varieties of tuberculosis, which are virtually immune to all treatments, represented another serious threat, she said.

"Its emergence reminds us to be prepared for setbacks arising from the constantly changing microbial world," she said.

Although Chan repeated her view that H5N1 bird flu remains a threat, she spoke only briefly about the virus which previously dominated the WHO chief's public statements.

"This season has again given us some stark reminders that the threat of an influenza pandemic has by no means diminished," she told the meeting.

Both Pakistan and Myanmar reported their first human infections with H5N1 bird flu late in 2007. The virus is known to have infected 343 people since 2003, killing 212. Most cases have been in Vietnam and Indonesia.

On the issue of climate change, Chan cited findings that Africa could be severely affected by shifting patterns of droughts, floods, storms and heat waves as early as 2020.

"This is just a dozen years away," she told the meeting, stressing that international health experts needed to address the expected impacts of "droughts, floods, storms, heat-waves, air pollution, malnutrition, displaced populations, and water-borne and vector-borne disease."