False. Most infections — chlamydia, gonorrhoea, HIV — often give no sign at all. You can have them and pass them on without noticing: that is why testing happens even when everything seems fine.
They protect very well against HIV and genital chlamydia and gonorrhoea. They protect less against what passes by skin-to-skin contact (HPV, herpes, syphilis) and against gonorrhoea in the throat, which can also pass through saliva and deep kissing.
There is a window period. The lab blood test () is reliable at 6 weeks (the CDC says 45 days: three days’ difference); rapid finger-prick or oral-fluid tests need confirmation at 3 months.
No. They are imbalances of the normal flora, not transmitted infections: no STI testing is needed and there is no partner to notify.
Without symptoms neither is recommended. Herpes serology generates anxiety and almost one positive in two may be false; Ureaplasma is an ordinary inhabitant of the body, and looking for it leads only to pointless treatment.
reduces syphilis and chlamydia in selected groups, but in Europe it works poorly against gonorrhoea (resistance) and is not recommended as routine. It does not replace testing: on medical advice only.
For HIV, yes. But deep kissing can transmit gonorrhoea in the throat (emerging evidence) and cold sores.
STIs also concern sexually active older people, and people in steady relationships when the arrangements change. What counts is what you do, not how old you are.
Testing is health maintenance, like going to the dentist. Almost every STI can be cured or well controlled. Telling partners is an act of care, not an admission of guilt: an untreated partner is the leading cause of reinfection. A person with HIV on effective treatment, with an undetectable viral load, does not transmit the virus sexually ().