The risk of catching Ebola from a survivor is generally low since the virus disappears from the blood within weeks, but it may persist in semen for many months, researchers said Monday.

Until now, scientists have been uncertain of how to characterize the risk of catching the Ebola virus -- which killed more than 11,000 people in West Africa -- via social contact with survivors who have overcome their illness.

Scientists on Tuesday said they had confirmed that the Zika virus sweeping Latin America and blamed for severe birth defects can also trigger a dangerous neurological disorder.

In a study published in the medical journal The Lancet, a team probed Zika's suspected role in a 2013-2014 outbreak in French Polynesia of Guillain-Barre syndrome (GBS) -- a rare condition in which the body's immune system attacks a part of the nervous system that controls muscle strength.

Parents Monday withdrew all the children from a Sri Lankan school after false rumors spread that a new six-year-old pupil was HIV-positive, an official said.

Parents also protested outside Sambodi Primary School northeast of Colombo against the boy's admission after he turned up for his first day of class, the official said.

When doctors told Christophe Novou that his leg would have to be amputated at the hip due to a raging bacterial infection, the 47-year-old Frenchman thought about killing himself.

After surviving a crippling traffic accident and dozens of operations to repair the damage, to him life in a wheelchair just did not seem worth living.

A British nurse who contracted Ebola while working in Sierra Leone in 2014 was discharged from hospital in London on Sunday, five days after being admitted with complications, a statement said.

Pauline Cafferkey was successfully treated within weeks of her diagnosis but suffered a relapse in October 2015, when she became critically ill with meningitis linked to the deadly virus.

A first case of Zika spread through sexual transmission has been recorded in France after a woman was infected when her partner returned from Brazil, Heath Minister Marisol Touraine told Agence France Presse on Saturday. 

The case was detected several days ago in "a woman who is not pregnant," the minister told AFP during a visit to French Guiana, confirming information initially given to AFP by a medical source.

An ongoing yellow fever epidemic in Angola has killed 125 people out of 664 suspected cases since December 30, government statistics show, despite attempts to quell the outbreak.

The center of the health crisis remains the capital Luanda, where 92 people have died, the health ministry said on Friday.

The United States on Thursday announced a massive new medical study that will enroll one million people as part of a White House-led initiative to improve treatment of diseases and cancers.

President Barack Obama first unveiled the Precision Medicine Initiative (PMI) in January 2015, and funded it with $215 million to "accelerate a new era of medicine that delivers the right treatment at the right time to the right person, taking into account individuals' health history, genes, environments, and lifestyles," said a White House statement detailing the launch of a series of new programs.

The Zika virus, believed to be linked to the serious birth defect microcephaly, presents a "formidable" challenge that will be hard to stamp out, World Health Organization chief Margaret Chan warned Wednesday.

Calling mosquito-borne Zika a "bigger menace" than any other recent major health scare in terms of its geographical spread, Chan said tough times lie ahead.

A British nurse who was twice successfully treated after contracting Ebola in Sierra Leone in 2014 was on Tuesday admitted to hospital for a third time "for further investigations," the health service said.

Pauline Cafferkey, who voluntarily went to the west African country to treat Ebola patients, was being treated at Glasgow's Queen Elizabeth University Hospital, according to a spokesman from NHS Greater Glasgow and Clyde.