Health Highlights: March 3, 2009

Mar. 4 -- Here are some of the latest health and medical news developments, compiled by editors of HealthDay:

HIV Infection Among People 50 and Older Concerns WHO

A "surprisingly high" number of people over age 50 worldwide are infected with HIV and the number of cases in older adults may be growing, says a World Health Organization study released Tuesday.

For example, between 2003 and 2006, the rate of HIV infection among Americans 50 and older increased from 20 percent to 25 percent. Between 1996 and 2006, the rate of HIV infection among people 50 or older in Brazil increased from 7.5 to 15.7 per 100,000, Agence France Presse reported.

"The frequency of infection with HIV in older people is worrying. We need to understand why and when these people are becoming infected so that public health campaigns can be better targeted to prevent such infections," said WHO scientist George Schmid.

One problem is that HIV is widely regarded as a young people's disease, the WHO said. This leads to less HIV screening among older people, which results in delayed diagnosis. In addition, older people are less likely than younger people to practice safe sex, AFP reported.

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Scientists Identify Cause of Gray Hair

British and German scientists say they've identified the root cause of gray hair, a finding that may lead to new methods of treatment.

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In experiments with hair and follicle cells, the researchers found that gray hair is caused by a large build-up of hydrogen peroxide due to wear and tear of hair follicles. This build-up blocks hair's natural pigment, BBC News reported.

"This discovery is a major breakthrough in the understanding of hair graying and opens up some novel ideas to combat this scenario. These are being followed up at the current time in our laboratory," said lead researcher Karin Schallreuter.

The study appears in The FASEB Journal, published by the Federation of the American Societies for Experimental Biology.

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Doctor's Plan for Custom-Made Babies Condemned