Salt and lime with tequila. Salt with your iced "michelada" beer. Salt and chili on fruit and even candy. Mexicans love salt, so much so that some estimates show them eating nearly three times the recommended amount and significantly more than what Americans put down.

Add this to rising obesity and a hypertension epidemic, and you have a potential health nightmare that has spurred Mexico's massive capital city to try to get residents to shun the salt shaker.

A tiny magnetic bracelet implanted at the base of the throat is greatly improving life for some people with chronic heartburn who get limited relief from medicines. It's a novel way to treat severe acid reflux, which plagues millions of Americans and can raise their risk for more serious health problems.

It happens when a weak muscle doesn't close after swallowing as it should. That lets stomach juices splash back into the throat. Drugs like Nexium and Prilosec reduce acid. But they don't fix the underlying problem, called GERD, or gastroesophageal reflux disease.

U.S. scientists on Wednesday said they had used baker's yeast to make a key ingredient of malaria drugs, a feat that could iron out fluctuations in supply caused by sourcing the chemical from a Chinese herb.

One of the revolutions in malaria treatment in recent decades has been the advent of artemisinin drugs, whose active ingredient comes from a traditional Chinese herb, Artemisia annua.

Health officials in Costa Rica said an outbreak of dengue fever has sickened 7,000 people, with many cases occurring in some of this Central American country's most popular tourist areas.

The incidence of illness represents a three-fold increase over this time a year ago, according to Maria Villalta, medical director of national Social Security office, which has been tracking the outbreak.

Scientists said Wednesday they have figured out how to recognize pain in brain scans, possibly paving the way for future tests that could accurately gauge its severity.

"Right now, there's no clinically acceptable way to measure pain and other emotions other than to ask a person how they feel," said Tor Wager, lead author of the paper, published in the New England Journal of Medicine.

Residents of a Chinese city were ordered to cull all their poultry as authorities stepped up attempts to halt the spread of the deadly H7N9 bird flu, state media reported Thursday.

Thousands of birds and livestock were slaughtered by the Tuesday midnight deadline in Nanjing, in the eastern province of Jiangsu, the China Daily said.

Health officials in Costa Rica said an outbreak of dengue fever has sickened 7,000 people, with many cases occurring in some of this Central American country's most popular tourist areas.

The incidence of illness represents a three-fold increase over this time a year ago, according to Maria Villalta, medical director of national Social Security office, which has been tracking the outbreak.

China has detained at least a dozen people for spreading false rumors about bird flu, police statements showed Wednesday, with authorities seeking to control "panic" as the number of cases rose to 33.

There have been nine deaths since China announced over a week ago that the H7N9 strain of avian influenza had been found in humans for the first time.

The Vatican on Thursday will organise a conference to promote adult stem cell research as an alternative to research using destroyed human embryos, which is considered by the Roman Catholic Church as deeply unethical and less effective.

Cardinal Gianfranco Ravasi, head of the Vatican's Pontifical Council for Culture, at a briefing on Tuesday said several leading world scientists would attend including Britain's John Gurdon, winner of the Nobel Prize for Medicine last year.

African-Americans with a certain gene variant have nearly double the risk of developing late-onset Alzheimer's disease than those without it, a new study out Tuesday found.

But the gene doesn't seem to be affiliated with higher incidence of Alzheimer's among white populations, the scientists said in the report in the Journal of the American Medical Association.