Anthrax spreads

17 confirmed infections 3 deaths (2 in Washington DC, 1 in Florida) 7 ill with inhalation anthrax 7 cases skin anthrax 13,300 postal workers taking antibiotics as protective measure

Investigators are worried that the spores could be spreading from one piece of mail to another after the disease was detected in two women with no connection to the postal service, government or the media.

One of the victims, a 61-year-old New York hospital worker, is in a critical condition after contracting inhalation anthrax, the most serious form of the disease.

So far anthrax infections have killed three people - two postal workers and a journalist - and heavily disrupted the postal system and many government offices in which traces of the bacteria have been found.

Investigators still do not know who is behind the attacks. US-based extremists are now thought to be the chief suspects, rather than terrorists abroad.

Disruption

On Monday postal union leaders in Florida filed a lawsuit, demanding that 13 mail sorting offices which have been infected with anthrax be closed down.

The hospital has been closed

Other postal facilities in New Jersey, New York and Washington have also been hit by the bacteria. The Brentwood facility in Washington, where two of the victims worked, is closed.

Traces of anthrax in several federal buildings have also interrupted the work of America's executive, legislative and judicial powers:

• White House mail is in quarantine
• Congressional offices have been sealed with staff having to work from temporary offices around the city
• Supreme Court judges are convening elsewhere for the first time in the court's 66-year history
• The State Department has cut off mail to 240 embassies and consulates worldwide

Officials say the government has not been stopped from functioning, but James Thurber, a professor of government at American University says the terrorists seem to have succeeded "much beyond their own expectations".

"I can't think of anything that has disrupted government as much since the civil war," said Mr Thurber.

No connection

New York has been affected by the anthrax threat, with media companies NBC, CBS and the New York Post targeted. Several employees have contracted skin anthrax, a less serious form of the disease.

Post office accounts

Checking and sanitising equipment: $2.5bn Lost income so far: $300m Damage from the attacks: $60m

But Kathy Nyugen, the city's first victim of inhalation anthrax, has no direct link to any of the affected institutions. The only remote connection is that she worked near her hospital's mailroom.

She works in the basement stockroom of the Manhattan Eye, Ear and Throat hospital, where environmental tests are now being conducted.

Investigators in protective suits have also tested her apartment in the Bronx. So far, they say, no traces of anthrax have been found.

In a desperate attempt to discover how Ms Nyugen came into contact with the bacteria, they are trying to retrace her steps, interviewing more then 300 workers at the hospital and her neighbours.

She herself cannot be interviewed because she is sedated and connected to a respirator.

"We're not assuming anything. Like any detective, you have to look at all possibilities," a New York health official said.