Yet another reason to keep your pants on.

Drudge: MALE INFERTILITY ALERT OVER HIDDEN BACTERIA...

Chlamydia, the sexually transmitted infection (STI) carried by one in ten sexually-active young British adults can make men infertile by damaging the quality of their sperm, new research has shown.

While the condition, which usually passes undetected, has long been known to threaten female fertility, scientists from Spain and Mexico have now established that it presents similar risks for men.

Men with chlamydia have three times the normal number of sperm with genetic damage that can impair their ability to father children, the study found.

Antibiotic treatment can reverse the effect, and preliminary results indicate that it may dramatically enhance pregnancy rates when couples are trying for a baby. But the discovery suggests that the prevalence of the disease may be contributing to infertility across an entire generation of young adults.

Britain’s national screening programme has found that 10.2 per cent of both men and women aged 18 to 25 carry the bacteria, and studies have found infection rates as high as 5 per cent among older groups with a lower risk.

The findings indicate that untreated chlamydia infections should not just concern women, who have long been warned that the condition can make them infertile, but has direct consequences for men.

This will create fresh pressure for chlamydia screening to be more effectively targeted at young men, who rarely seek testing and treatment unless they develop symptoms, which are often absent or quickly fade.

Doctors have already warned that the rise in the number of chlamydia cases in Britain may rob thousands of young women of the chance to have children. Figures from the Health Protection Agency reveal that cases of chlamydia have increased by more than 200 per cent in England in the past decade.