Experimentation with human growth hormones by America's teens more than doubled in the past year, as more young people looked to drugs to boost their athletic performance and improve their looks, according to a new, large-scale national survey.

In a confidential 2013 survey of 3,705 high school students, being released Wednesday by the Partnership for Drug-Free Kids, 11 percent reported using synthetic HGH at least once — up from about 5 percent in the four preceding annual surveys. Teen use of steroids increased from 5 percent to 7 percent over the same period, the survey found.

There is more good news about HIV treatment pills used to prevent infection in people at high risk of getting the AIDS virus: Follow-up from a landmark study that proved the drug works now shows that it does not encourage risky sex and is effective even if people skip some doses.

The research was discussed Tuesday at the International AIDS Conference in Melbourne, Australia, and was published by the British journal Lancet Infectious Diseases.

A German court ruled for the first time Tuesday that seriously ill patients may grow their own marijuana for medical purposes in certain cases.

The administrative court in the western city of Cologne said that while cannabis remained illegal for general use in Germany, it may be cultivated at home by some patients with medical permits for the drug.

A massive gene trawl has linked over 100 DNA coding mutations to schizophrenia, yielding critical clues about what causes the illness and possibly how to treat it, scientists said Tuesday. 

Using more than 80,000 genetic samples from schizophrenia patients and healthy volunteers, an international team of researchers found 128 variants -- 83 of them new -- associated with a higher risk for people who carry them.

Researchers in Saudi Arabia said Tuesday they have found genetic traces of the dangerous Middle East respiratory virus, MERS-CoV, in the air of a barn that housed a sick camel.

The study in mBio, the journal of the American Society for Microbiology, calls for further research to determine if the potentially fatal virus can be transmitted through the air.

An outbreak of encephalitis has killed 60 people in two weeks in the eastern Indian state of West Bengal, a top health official has said, calling the situation "alarming'.

Hundreds of mainly children die across India each year from the mosquito-borne virus, but West Bengal is not normally one of the worst-hit states.

The elusive quest for an HIV cure received a boost at the world AIDS conference Tuesday as scientists said they had forced the virus out of a hiding place where it had lurked after being suppressed by drugs.

The experiment, carried out with six HIV-infected volunteers, is an important advance in the so-called "kick-and-kill" approach for a cure, they said.

An experimental cocktail of three drugs can dramatically shorten the time it takes to treat patients infected with TB strains that are hard to cure with conventional antibiotics, according to research presented Monday at the world AIDS forum.

Dubbed the PaMZ regimen, the drugs killed more TB bacteria than standard therapy and at a faster rate in a so-called Phase IIb trial, usually the penultimate step in vetting new treatments for safety and effectiveness, investigators said.

The monkey version of HIV can take refuge from anti-AIDS drugs within days of entering the body, a study said Sunday, dampening hopes for a human cure.

In the heart of Gaza City, as its citizens again find themselves under fire from Israeli airstrikes and artillery, the wounded and their wailing families stream into Shifa Hospital without end.

Shifa, Gaza's largest hospital, only has an 11-bed emergency room and six operating theaters. Yet amid power cuts and among the screams of the bereaved, doctors at the 600-bed facility have become masters of improvisation, forced by the seemingly unending conflict engulfing the coastal strip to care for the wounded.