In Germany with its population of 82 million, some 3,000 people became infected with HIV in 2008, nearly double the number registered in 2001, according to the Robert Koch Institute, the federal institution in Germany responsible for disease control and prevention.

"At greatest risk are men who have sex with men," noted Joerg Litwinschuh, spokesman for Deutsche AIDS-Hilfe (German AIDS Help), an HIV/AIDS self-help association in Berlin. He said that about a third of the approximately 65,000 HIV-infected people in Germany were unaware of their infection and could unwittingly transmit the virus to others.

"You can't tell outwardly that someone's infected," pointed out Elisabeth Pott, director of the Federal Centre for Health Education (BZgA) in Cologne.

So having safe sex means using a condom. Other contraceptives can "prevent pregnancies but not HIV," Litwinschuh said.

But what constitutes sex? Does sex include petting? It depends, Pott said. "If caressing is what you mean, there's no risk of infection," she said. Pott added that a risk existed if ejaculated semen entered the vagina, however.

People in a long-term, mutually monogamous relationship who do not always want to use a condom can be tested for HIV. Anyone can have the test, which is done by doctors and, anonymously, by public health authorities. "One should definitely get counselling first, though," Pott said.

Someone who has the test needs to know that the body takes about three months after infection with HIV to develop detectable antibodies against the virus. So to be virtually certain that a negative HIV result is true, individuals must avoid unprotected sex for three months before testing.

Those who have an HIV test in order to forgo condoms must be sure that their partner is also sexually faithful, since a partner who has unprotected sex with another person can become infected. Ulrich Gerth, chairman of Germany's Federal Child Guidance Association (BKE), advised caution: 'People relying on an HIV test need to be aware that unfaithfulness can occur unexpectedly."

Condoms, consequently, remain the best defence. Before going out, you should always have one in your wallet or trousers pocket. But how do you tell your boyfriend or girlfriend that you always use a condom during sex?

"For quite a lot of adolescents, condoms are a matter of course nowadays," Litwinschuh remarked. Gerth was more sceptical, and recommended bringing up the subject beforehand. - dpa

Internet: www.worldaidsday.org.