(HealthDay News) -- More than 4.7 million people are bitten by dogs each year, the U.S. Centers for Disease Control and Prevention says.

(HealthDay News) -- Pneumonia is a bacterial or viral respiratory infection that's characterized by lung inflammation. It can be life-threatening, especially to the young, the elderly and to people with chronic health problems.

THURSDAY, Nov. 18 (HealthDay News) -- Depression may be linked to increased activity in the gene that regulates the body's 24-hour (circadian) clock, the results of a study suggest.

THURSDAY, Nov. 18 (HealthDay News) -- Poor children get the most benefit from preschool, but such programs also help children who aren't poor, particularly black youngsters, according to a new study.

THURSDAY, Nov. 18 (HealthDay News) -- Social networking platforms such as Twitter can increase university students' engagement in the learning process and improve their grades, a new study has found.

THURSDAY, Nov. 18 (HealthDay News) -- Cataract surgery, already an extremely safe and successful procedure, can be made more precise by combining a laser and three-dimensional imaging, a new study suggests.

THURSDAY, Nov. 18 (HealthDay News) -- New research supports the notion that patients who take cholesterol-lowering drugs known as statins may not have an increased risk for cancer, as some previous studies suggested.

WEDNESDAY, Nov. 17 (HealthDay News) -- Get ready, get set, quit! Thursday marks the annual Great American Smokeout, sponsored by the American Cancer Society, which urges all smokers to lay off the habit for at least 24 hours.

THURSDAY, Nov. 18 (HealthDay News) -- The spleen may be a major source of cells that cause inflammation and exacerbate the damage at the site of a spinal cord injury, a new animal study suggests.

THURSDAY, Nov. 18 (HealthDay News) -- The battle over menthol-flavored cigarettes heats up again Thursday as a U.S. Food and Drug Administration advisory panel continues a series of hearings on whether to ban the cigarettes.

THURSDAY, Nov. 18 (HealthDay News) -- A brain area that plays an important role in vision is divided into compartments that respond separately to different colors, a new animal study has found.

THURSDAY, Nov. 18 (HealthDay News) -- Patients in the United States are more likely to forgo medical care because of cost than residents of other developed countries, a new international survey finds.

THURSDAY, Nov. 18 (HealthDay News) -- Mammograms given to women under 50 with a moderate family history of breast cancer can spot cancers earlier and increase the odds for long-term survival, a new study shows.

THURSDAY, Nov. 18 (HealthDay News) -- Social networking might have triggered asthma attacks for one young Italian man, who experienced breathing troubles whenever he accessed an ex-girlfriend's Facebook page.

THURSDAY, Nov. 18 (HealthDay News) -- A new survey finds that 20 percent of U.S. adults -- over 45 million people -- experienced mental illness in the past year.

THURSDAY, Nov. 18 (HealthDay News) -- A large, new study provides more evidence that people infected with HIV, the virus that causes AIDS, do almost as well on the survival front as other patients when they undergo kidney transplants.

Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

(HealthDay News) -- Here are the latest clinical trials, courtesy of ClinicalConnection.com:

THURSDAY, Nov. 18 (HealthDay News) -- Knowing when to take antibiotics -- and when not to -- can help fight the rise of deadly "superbugs," say experts at the U.S. Centers for Disease Control and Prevention.

THURSDAY, Nov. 18 (HealthDay News) -- Millions of harried travelers must still put up with unhealthy fumes from indoor smoking at one in every four major U.S. airports, a new study finds.