The Group of Eight summit is a prime opportunity for world leaders to show they are seriously committed to fight the spread of infectious diseases, the acting head of the World Health Organization said Tuesday.

"I'm quite optimistic," said Dr. Anders Nordstrom, acting director-general of the U.N. agency. "There have been G-8 meetings for 30 years, and that we are now able to have health issues (on the agenda) for the last six, seven years, it's a good sign that there is a political interest."

Infectious diseases, education and energy security are on the agenda for the G-8 summit starting Saturday in St. Petersburg, Russia.

The big question is whether lofty statements by G-8 leaders will translate into more money to fight scourges such as HIV/ AIDS, malaria and tuberculosis.

Nordstrom said the WHO has only collected about one-third of the US$100 million that donor countries pledged to the organization in January as a part of a US$1.9 billion package to the U.N.

"It's still quite low, but I think now there has been some progress," Nordstrom told The Associated Press in a phone interview. "I think we're closer to US$30 million now. There is still a big gap, but we are still managing and surviving with the resources we have."

Nordstrom said outbreaks of mad cow disease, SARS and other epidemics have helped decision-makers realize that the infections diseases don't only have a human toll — they hurt the economy, too.

"The link between disease outbreaks, security and economic development is quite strong on the agenda now," said Nordstrom, who will travel to St. Petersburg to attend the G-8 summit on Monday.

Nordstrom said he hoped leaders would address the risk of new disease outbreaks and the scaling up of health services to fight the spread of diseases such as HIV/AIDS, malaria and polio.

He also called for discussions on how to stem the brain drain of health workers from poor countries.

"It's not enough with money, new drugs and vaccines," he said. "But you need also staff in health centers and hospitals, and I think there is quite a keen interest in that issue as well, which will require ... political support in order to be able to do something."

Nordstrom praised the improvement of preparedness plans for an influenza pandemic that experts say is long overdue. Today, 170 countries have such plans compared with only 30 a few years ago, he said.

"Whether they are able to implement them or not is a big question mark," he added.

There have been three pandemics in the past century, the most deadly being the 1918 Spanish flu that killed millions around the world.

Experts have warned that bird flu, which has spread to dozens of countries since 2003, could mutate into a form easily transmitted among humans and spark a pandemic.

So far that has not happened, but Nordstrom warned against complacency.

"The threat is definitely still there. If we look back to 2004, we had outbreaks of humans in two countries, in 2005 in five countries. Now we have outbreaks in 10 countries," he said.

"We have been able to decrease the risk of transmission between animals and humans and that is one of the key strategies. But the threat is very much still real."

Nordstrom has been the acting head of the WHO since Director-General Lee Jong-wook died in May. A permanent replacement is set to be elected in November.