Germ warfare

Anthrax fatality rate is 80-90% Scientists say an entire city could be knocked out Smallpox can spread like wildfire 90% of the US population lacks smallpox immunity

Public health experts in the United States have warned for several years that bio-terrorism, the release of deadly bacteria or viruses, is an increasingly real threat.

These warnings follow the discovery of Iraq's biological and chemical weapons stockpile and the Sarin nerve gas attack on the Tokyo subway in 1995.

The four-day Atlanta conference, which started on Sunday, is being sponsored by the US Centres for Disease Control and Prevention (CDC).

The CDC recently joined with law enforcement, intelligence and defence agencies to address what is viewed as a national security threat.

Officials have been working on a report suggesting that speedy identification of any infectious agents would prove vital, if a nation were to respond effectively to an attack.

Bio-terror in Japan

Sarin gas attack carried out by cult Aum Shinrikyo in 1995 Gas was released on crowded trains Tokyo's subway system 12 people died, thousands were injured US troops reportedly among other Aum targets Botulism and anthrax said to be in cult's deadly arsenal

Dr Jim Hughes, director of the CDC said health officials needed better surveillance, greater diagnostic capacity and more communication between scientific disciplines, to respond to emerging threats.

"We feel it is prudent to be prepared to deal with the unexpected, whether it's a naturally occurring infectious disease or an episode that is a result of a purposeful release of an infectious agent," he said.

The CDC has emphasised the need to educate those who would have to deal with such attacks - doctors, hospital staff, firefighters and police.

It says they need to be able to recognise the symptoms caused by the viruses most likely to be used - such as anthrax or smallpox.

Aum leader Shoko Asakara

Last month, a US congressional report warned that an outbreak of West Nile virus, which killed seven people in New York last year, exposed gaping holes in the nation's preparedness to deal with bio-warfare.

Senator Charles E. Schumer said the mosquito-borne virus was "the closest example of a dry run for a bio-terrorist attack that we could possibly face."

Professor Leonard Cole, for Rutgers University in New Jersey, says that, although most scientists acknowledge bio-terrorism as a threat, they are divided on how much of a problem it really is.

Mad scientist

"Is it likely someone, some day will try it?" he asked.

"It has been tried in the past and has failed, to the extent that we can get the message out that maybe bioterrorism is not that easy an enterprise to engage in.

"That may discourage the potential terrorist or mad scientist, who would like to disperse these materials."

The Atlanta conference will also discuss the growing resistance of bacteria to antibiotics commonly used to treat them.