Chlamydia
Chlamydia damages male fertility
The common sexually transmitted infection chlamydia is found to damage the DNA quality of sperm.
Ref. https://news.bbc.co.uk/1/hi/health/7044602.stm
To halt spread of chlamydia and other STD/STIs, get tested before and after each partner. Some people may be embarrassed or nervous to get tested, but it is necessary for your health and the health of others. Some infections are treatable or even curable, but can damage the body if you don't get the problem taken care of soon. Think of your safety and the safety of those you care about and don't be afraid to let people know if you have been with them and tested positive for a disease.
How to control chlamydia: An ECDC guidance for Europe
They are young and mostly female: with more than 3.2 million cases between 2005 and 2014, chlamydia remains the most commonly reported sexually transmitted infection across Europe. An updated Guidance on chlamydia control in Europe from the European Centre for Disease Prevention and Control makes the case for national chlamydia control strategies in the European Union Member States and shows ways to develop, implement or improve national or local control activities. Ref. Source 5s.