Fifteen teenage girls report a mysterious outbreak of spasms, tics and seizures in upstate New York. But tests find nothing physically wrong.

Scores of adults in Northern California report crawling skin sensations and other bizarre symptoms. Government doctors find no physical cause after an extensive study.

Malaria kills more than 1.2 million people a year, nearly 50 percent more than previously thought, and inflicts a high toll among adults and older children and not just toddlers, a new investigation says.

But there is also good news: deaths from the mosquito-borne disease have in fact been falling sharply thanks to access to better drugs and insecticide-treated nets.

Drug addicts have inherited abnormalities in some parts of the brain which interfere with impulse control, said a British study published in the United States on Thursday.

Previous research has pointed to these differences, but it was unclear if they resulted from the ravages of addiction or if they were there beforehand to predispose a person to drug abuse.

Measles outbreaks in parts of Europe and Africa led to some 60,000 more cases worldwide in 2010 over the previous year, after nearly a decade of declines, U.S. health authorities said on Thursday.

Due to a boost in global efforts to vaccinate people against measles, total cases declined from more than 853,000 in 2000 to nearly 278,000 in 2008, and remained stable in 2009.

Sugar should be identified alongside alcohol and tobacco as a health danger, and governments should tax sweetened drinks and food as part of their efforts to combat it.

So says a commentary, published on Thursday in the journal Nature as part of a widening debate among doctors and policymakers about food fiscality and health.

India has the worst air quality in the world, beating even its neighbor China, according to an annual survey based at Yale and Columbia universities in the United States.

Of all the countries surveyed in the Environmental Performance Index (EPI), which measures the effects of polluted air on human health, India ranked the lowest at 132.

A woman in southern Vietnam has died after contracting the bird flu virus, health authorities said Thursday, in the country's second human death from the virulent disease in less than a month.

Concerns about avian influenza have risen in the region with China, Cambodia and Indonesia all reporting deaths from the H5N1 virus this year.

A new U.S. study has found that Alzheimer's disease spreads from one part of the brain to another like an infection, a discovery that could aid the development of treatments to slow its progress.

The Columbia University Medical Center (CUMC) study on transgenic mice found that the abnormal tau protein linked to the disease travels along brain circuits, "jumping" from neuron to neuron.

Bhagyalaxmi Dairy Farm lies tucked away up a rutted country track, among the patchwork of dusty brown scrub and lush green parcels of farmland to the northeast of the Indian city of Pune.

With a herd of more than 3,000 cows, a state-of-the-art milking parlor and on-site bottling plant using French technology, it's a world away from traditional Indian village farming.

A warning to men considering a pricey new treatment for prostate cancer called proton therapy: Research suggests it might have more side effects than traditional radiation does.

A study of Medicare records found that men treated with proton beams later had one-third more bowel problems, such as bleeding and blockages, than similar men given conventional radiation.