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.

A common treatment for irregular heartbeats may have a serious side effect: a new study out Tuesday showed it could increase the risk for certain cancers, especially among men.

The research, published in the U.S. journal CANCER, found that individuals taking a high dose of amiodarone for a long time had twice the risk of developing cancer as those taking a low amount of the drug.

Constantly beeping alarms in hospitals are being linked to patient deaths and other dangers in a new alert from the Joint Commission.

The alarms can lead to "noise fatigue," and doctors and nurses sometimes inadvertently ignore the sounds when there's a real patient emergency, possibly resulting in treatment delays that endanger patients.

The biggest thing in operating rooms these days is a million-dollar, multi-armed robot named da Vinci, used in nearly 400,000 surgeries nationwide last year — triple the number just four years earlier.

But now the high-tech helper is under scrutiny over reports of problems, including several deaths that may be linked with it and the high cost of using the robotic system.

After nine friends and relatives were killed in a U.S. drone strike four years ago, Mohammed Fahim took tranquilizers to blot out the nightmares.

The 19 year-old is one of a growing number of Pakistanis living in the tribal areas on the Afghan border who has suffered from conditions related to depression, anxiety and mental health problems because of war.

China's deadly bird flu outbreak has dealt a "devastating" blow to the nation's poultry sector, an industry group said Tuesday, with sales reportedly plunging amid concerns over food safety.

Chinese authorities say they do not know how the H7N9 avian influenza -- which has killed seven people and sickened 24 -- is spreading, though it is believed the infection is passing from birds to humans.