Fewer teenagers know about the risks of catching HIV, putting them in increased danger, experts have warned.
Fewer teenagers are worried about HIV
Surveys of more than 140,000 young people aged 12 to 15 across the UK found a decline in the level of knowledge about HIV and Aids.
The research by the Schools Health Education Unit shows fewer teenagers understand the risks of having unprotected sex and sharing needles when taking drugs.
The latest statistics showed cases of
HIV rose by 20% in a year.
In 2002 there were 4,204 new cases of HIV infection reported in the UK, rising to more than 5,000 in 2003.
The Health Protection Agency said unsafe sex was the "driving force" behind the rise.
For its analysis, the Schools Health Education Unit (SHEU) compared survey data from 1995 and 2001.
It found that in 1995, 77% of boys aged 12 to 13 knew that HIV could be passed on by having sex without a condom. By 2001 this figure had dropped to 63%.
In 1995, 82% of girls aged 12 to 13 knew that the HIV infection could be passed on by sharing needles when taking drugs.
But six years later, this had dropped to just 59% in the same age group.
Being in control
The proportion of teenagers in that age group who knew HIV could be passed on when coming into contact with blood when giving first aid, fell from 49 to 36%.
Overall knowledge about the dangers of HIV/Aid were greatest among girls, with those aged 14-15 the most knowledgeable.
There was little change in the number of young people who said they would take care not to get infected with HIV, falling from 89% to 86%.
Previous research from SHEU showed the number of 12-15-year-olds who were worried about HIV and Aids had fallen over the last decade.
A survey of over 225,000 teenagers, carried out over the last decade, found that in 1993 34% were worried "quite a lot" or "a lot", dropping to 7% in 2003.
The SHEU researchers said: "The more that young people feel in control of their health, the less likely they are to worry about HIV/Aids."
SHEU said having the appropriate information and skills helped young people to choose contraception, and to protect themselves against sexually transmitted infections.
A spokeswoman for the Terrence Higgins Trust said it was shocked at the research findings.
"With rates of sexually transmitted infections at an all time high, it's appalling that young people are becoming less aware of the risks of unprotected sex, or how HIV is passed on."
She added: "Good sex education works, but too many young people are not aware of the genuine risks of HIV and other sexually transmitted infections.
"Teachers must be given the support they need to tackle this dreadful information gap, and to deliver co-ordinated and appropriate sex education in our schools."