The sexually transmitted disease chlamydia has long been recognized as a threat to female fertility, but new research suggests it may also impair men's ability to father children.
Chlamydia is caused by the bacterium Chlamydia trachomatis. The infection can lead to discharge from the penis or a burning sensation when urinating, but about half of infected men, and three-quarters of infected women, have no symptoms.
Dr. José Luis Fernández of Juan Canalejo University Hospital in Coruña, Spain, led a study of 143 men who were attending a male infertility clinic, and who had been diagnosed with chlamydia infection. A group of 50 fertile men was used as a comparison group.
The infected men had significantly more DNA fragmentation, or damage to the genetic material in their sperm, with 35 per cent of sperm cells affected versus 11 per cent in the comparison group.
Traditional semen test results were also abnormal, but to a lesser degree: Sperm concentration was 1.7 times lower in the infected group and sperm motility, or swimming ability, was 1.8 times lower compared with the fertile controls.
Further analysis suggested antibiotic treatment lessened DNA fragmentation but did not improve the other sperm test results in affected men. In a subgroup of 30 couples, the pregnancy rate was only 13 per cent among couples in which the male partner was still undergoing treatment for chlamydia infection, but jumped to 86 per cent among couples who attempted to conceive three to six months after the man completed therapy.
"We must be very cautious and emphasize that although there seems to be a clear improvement in pregnancies, the real magnitude of the improvement needs more extensive research in wider groups," says Fernández.
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