Senate to close after staff test positive for anthrax

The American House of Representatives is to close down after 29 workers tested positive for anthrax exposure.

Spores have been found in a ventilation system, so 200 more people are being prescribed antibiotics .

The Capitol and all its offices are to shut to allow a search for more anthrax.

Some has already been found in the ventilation systems and in a letter sent to the Senate.

At least 29 people, including staff and two police officers have tested positive for exposure to the potentially-deadly spores.

Anthrax can lead to a fatal infection of the respiratory system.

The workers affected are staff who were present when a letter was opened and then found to contain anthrax.

All are receiving antibiotics while more than 200 people who work in Congress, including some of its most senior politicians, are taking them as a preventative measure.

It's thought the type of spores found in the letter were a highly potent form of anthrax.