Tests have confirmed an outbreak of avian flu in chickens at a farm in southern England but officials described it as a "low severity" strain of the disease on Monday.

Britain's Department for Environment, Food and Rural Affairs (Defra) said there was no link with a separate outbreak of bird flu detected at a duck breeding farm in November.

Parents have long suspected it, but now doctors have proof: the more time teenagers spend on computers or mobile phones, the less they sleep -- especially if the gadget is used just before bedtime.

The evidence is so strong, the experts said, that health watchdogs should overhaul guidelines for electronic device use by youngsters.

The first large-scale trials of two Ebola vaccines were due to begin in Liberia on Monday, the partnership conducting the research said.

The vaccines contain harmless fragments of the virus that trigger an immune response, according to the Partnership for Research on Ebola Vaccines in Liberia (PREVAIL), a collaboration between the United States and Liberia.

Many packaged meals and snacks for toddlers contain worrisome amounts of salt and sugar, potentially creating an early taste for foods that may contribute to obesity and other health risks, according to a new government study.

About seven in 10 toddler dinners studied contained too much salt, and most cereal bars, breakfast pastries and snacks for infants and toddlers contained extra sugars, according to the study by researchers at the federal Centers for Disease Control and Prevention. They advise parents to read food labels carefully and select healthier choices.

As Africa's leaders meet in Ethiopia to discuss the Ebola crisis, expectations of firm action will be tempered by criticism over the continent's poor record in the early stages of the epidemic.

The outbreak is a priority on the agenda of the 54-nation African Union (AU) summit in Addis Ababa on Saturday, yet the bloc is still smarting from criticism that it reacted too slowly to the outbreak.

Embattled milk producers in the U.S. launched a social media campaign this week to rebuild public confidence in the health benefits of their product.

But how healthy is it?

The husband of a Canadian who was diagnosed earlier this week with bird flu after returning from a trip to China has also tested positive for the virus, health officials said Friday.

The couple in their 50s began feeling sick days after returning home in westernmost British Columbia province.

A Spanish hospital has successfully used stem cells culled from healthy donors to treat seven heart attack victims, in what officials said was a world first. 

Madrid's Gregorio Maranon hospital plans to treat 55 patients in all with the technique in a clinical trial, the regional Madrid government which runs the hospital said in a statement.

A British company's plan to unleash hordes of genetically modified mosquitoes in Florida to reduce the threat of dengue fever and other diseases has sparked an outcry from fearful residents.

As of Friday, more than 145,000 people had signed a petition at change.org urging regulators to "say no" to allowing the tourist-friendly fishing and diving haven to become "a testing ground for these mutant bugs."

With California gripped by a measles outbreak, Dr. Charles Goodman posted a clear notice in his waiting room and on Facebook: His practice will no longer see children whose parents won't get them vaccinated.

"Parents who choose not to give measles shots, they're not just putting their kids at risk, but they're also putting other kids at risk — especially kids in my waiting room," the Los Angeles pediatrician said.