More US health workers vaccinated for smallpox

Health workers in the US are being vaccinated against smallpox, amid fears the virus may be used in a terrorist attack.

The Centres for Disease Control and Prevention in Atlanta has vaccinated some staff as a precaution in case they need to investigate the virus.

The agency says there is no evidence anyone is readying an attack but the say the virus, which was eradicated outside laboratories 21 years ago, is so dangerous it is important to be prepared.

"We are putting together several teams that could be quickly dispatched to the field if we did see a suspected case of smallpox," CDC spokesman Tom Skinner said.

The agency expects a number of false alarms as doctors heighten their suspicion of anthrax, smallpox and other diseases, according to Dr. Jeffrey Koplan, the CDC director.

Last week, the CDC vaccinated several dozen members of epidemiological teams that can be sent at a moment's notice to examine suspected cases of smallpox. This week, the CDC will begin a series of training courses on the disease for some employees and state and local health workers.

The contagious virus is known to survive only in laboratories in the United States and Russia. However, germ warfare experts suspect that other countries, including North Korea and Iraq, may have secretly obtained stocks.

Health experts worry about smallpox because it can spread quickly from person to person and has a high death rate. The infection is characterized by a rash and a fever of at least 102 degrees Fahrenheit (39 degrees Celsius).