No. 9 Vaccine for Dengue Fever
Several vaccines for dengue fever, a disease that strikes roughly 230 million people each year, showed promise in preliminary human trials. Larger scale tests began this year, and researchers should know just how effective they are by 2012.
The most promising experimental vaccine is made by combining a crippled yellow fever virus with proteins that are produced by each variety of dengue fever. In theory, those proteins can train the immune system to recognize and attack the deadly microbes. Four thousand children in Thailand will get the shot, which may offer protection from all four types of the virus.
No. 8 Breathalyzer Detects Lung Cancer
Researchers at the Israel Institute of Technology in Haifa built a sensor that can smell cancer. It uses gold nanoparticles to check for a telltale set of volatile organic chemicals that are emitted by malignant cells. The device could be used to give patients an early warning that they have the disease, which should increase their odds of survival.
No. 7 Computer Program Predicts Drug Side Effects
If you have a rare disease, don't count on big drug companies to find a cure. Your best shot is to find out whether drugs that are already approved by the FDA for other purposes might work as a remedy for your illness.
No. 6 Jellyfish Stir Oceans
Until recently, marine animals were thought to play but a small part in stirring Earth's waters. Scientists thought that hydrological friction would absorb the forces of flippers and fins, just as desk fans can't stir air in buildings across the street.
But geophysicists underestimated the power of induced fluid drift, or the tendency of liquid to stick to a body as it moves through water. In what is almost certainly the most poetic discovery of 2009, studies now suggest that jellyfish may stir the oceans with as much power as winds and tides.
No. 5 Bisphenol A in Plastics Harms Humans
In November, epidemiologists produced a study of BPA in humans. In 164 male Chinese factory workers exposed to high levels of BPA, severe sexual dysfunction was rampant. Their exposures were far higher than most people, but it can no longer be argued that BPA affects only lab animals, not people.