Billionaire software baron turned philanthropist Bill Gates has warned that violence in Nigeria and Pakistan could set back his goal of eradicating polio by 2018.

Last year, The Bill and Melinda Gates Foundation -- a charity that funds medical research and vaccination drives -- made wiping out the crippling disease in the next six years its top priority.

Consumers may expect that medical treatments approved for the U.S. market are safe and thoroughly tested, but a study out Tuesday said that is not always the case.

Some drugs undergo more rigorous testing than others, while most are never compared to existing treatments to see if they are better or worse, said the study by researchers at Yale University.

Heart-attack patients admitted to hospital at night or on weekends run a five-percent higher risk of dying than those treated during regular hours, researchers said on Tuesday.

In the United States alone, this translates to an extra 6,000 deaths per year, they reported in the British Medical Journal (BMJ).

A United Nations envoy warned Wednesday that cholera deaths in Haiti will surge and spread to other countries unless more funds are found to battle the epidemic.

More than 8,330 people have already died from cholera, that started in 2010 and many blame on U.N. peacekeepers based in the impoverished Caribbean nation.

Sunlight may help to reduce high blood pressure, a danger factor for heart attacks and stroke, a study published in a specialist journal said on Monday.

British researchers found exposure to sunlight alters the level of nitric oxide in the skin, dilating blood vessels and thus easing hypertension.

More than 100 Nepalese doctors resigned on Tuesday as part of an ongoing strike to push for reform of medical education, while hospitals and clinics remained closed for a third day, the doctors' association said.

Doctors were still providing emergency and intensive care but all other services have been halted indefinitely since Sunday, despite a court order for their immediate return to work.

Vietnam has recorded its first death from bird flu in nine months, according to the country's Health Ministry, amid growing regional concerns over a potential resurgence of the deadly virus.

A 52-year-old man from southern Binh Phuoc province died Saturday after receiving treatment in Ho Chi Minh City, the ministry said in a statement issued late Monday.

It won't cure dementia or Alzheimer's disease, but music can nevertheless help sufferers "wake up" their memories, reveals a moving documentary presented at the Sundance Film Festival.

"Alive Inside: A Story of Music & Memory," the debut feature film by Michael Rossato-Bennett, follows the efforts of one man to convince Americans of the benefits of music on people with dementia or Alzheimer's.

Heart disease and stroke have replaced infectious disease as the top causes of early death in the Arab world, tracking the West in a trend towards lifestyle disorders, The Lancet reported Monday.

An international consortium of scientists compared the state of health in the 22 countries of the Arab League in 1990 and in 2010, using data from a vast study -- the 2010 Global Burden of Diseases report.

Thousands of people protested abortion in France in a Paris rally Sunday on the eve of a parliamentary debate on a bill that would make terminations of pregnancy easier.

Organizers, among them rightwing religious groups, anti-gay activists and associations for handicapped children, claimed 40,000 people took part. Police put their number at 16,000.