One of the scientists who discovered Ebola said Tuesday he was not surprised a Spanish nurse contracted the deadly virus, stressing it was impossible to be too careful when dealing with the disease.

Doctors in Spain hospitalized four more people and rushed to identify dozens of others at risk on Tuesday after a nurse was infected with the deadly Ebola virus, raising fears of contagion in Europe.

The European Union demanded answers about how the disease spread in a specialized disease unit, while health staff protested over safety failures.

Cigarettes and other tobacco products increase the risk of contracting a sexually transmitted virus linked to mouth and throat cancer, according to a study released Tuesday.

Oral human papillomavirus type 16, or HPV16, is found in 80 percent of throat cancers and is transmitted by oral sex. Tumors related to the virus have increased by 225 percent in the United States in the past two decades.

Smoking rates have dropped among young Australians in recent years, and research released Tuesday suggests that banning tobacco displays from shops is a factor.

The parents of the first baby born to a woman who had a womb transplant say they hope they can be an inspiration to others struggling with infertility.

After what they describe as a rollercoaster of a journey, the unnamed Swedish couple finally became parents last month, when the mother gave birth to a healthy but premature baby boy. For the couple, making history was an afterthought.

A Liberian man diagnosed with Ebola in Texas was given an experimental drug for the first time, officials said Monday as the White House mulled tougher airport screening at home and abroad.

The EU said Tuesday it has asked Spain to explain how a nurse treating Ebola patients in Madrid contracted the deadly disease, the first known case of transmission outside Africa.

The European Commission "sent a letter Monday to the Spanish health minister to obtain some clarification" of how this had happened, despite all the precautions taken, a spokesman said.

African Union chief Nkosazana Dlamini-Zuma said Monday that Ebola-hit nations needed more doctors and health workers to help "break the cycle" of the virus, which was devastating their economies.

British-American researcher John O'Keefe on Monday won the Nobel Medicine Prize with a Norwegian couple, Edvard Moser and May-Britt Moser, for discovering how the brain navigates.

The annual hajj pilgrimage which drew two million Muslims from around the world has been epidemic-free, Saudi Arabia's acting health minister said on Monday.