Cases of sexually transmitted diseases increased sharply in Quebec's Outaouais region between 1996 and 2006, alarming public health officials.

Provincial statistics for the western Quebec region that includes Gatineau show that over 10 years, chlamydia infections more than doubled, from 275 cases in 1996 to 590 cases in 2006 (about 170 cases per 100,000).

Gonorrhea infections are also on the rise and syphilis, which had almost disappeared from the region, is making a comeback. There was only one case of syphilis in 2001, but around a dozen in 2006.

In the case of hepatitis C, there were 95 cases in 2006, up from 49 in 1996, but down from a high of 118 in 2003.

The growth in sexually transmitted diseases was particularly large among 15- to 35-year-olds, said Denis Carrier, a spokesman for the Outaouais public health agency.

He blames the growth on young people failing to use protection such as condoms.

"Because there's some new pills or new treatments, people consider there's no big risk anymore," he said.

However, he warned that unprotected sex can have serious health consequences, and he said the health agency is launching a campaign to send home that message.

According to Health Canada's website, even chlamydia and gonorrhea, which can be treated with antibiotics, can potentially have serious effects such as pelvic inflammatory disease in women, which can cause internal abscesses and long-lasting pain. They can also lead to infertility among both men and women, and in some cases, a type of arthritis that affects joints throughout the body.

Sores associated with syphilis greatly increase the chance of contracting HIV. And if left untreated, syphilis can cause a wide range of symptoms ranging from fever to joint pain to hair loss, Health Canada said.

The agency also warns that AIDS is still incurable and fatal, and hepatitis C, which is also incurable, can lead to serious liver damage or liver cancer.