Hard to diagnose. Virulence factors come from Chlamydia's ability to hide from the immune system after stimulating it. Infertility is the ultimate result of chronic inflammation in the male or female genital tract. Chlamydia infections resemble gonococcal infections because they are both inflammatory diseases. The symptoms are the same because it is the immune system that is doing the damage not the microbe.
Blindness results from scaring in the eye.
Hardening of the arteries is only hypothesized as being caused by this species of bacteria. There is some evidence that Chlamydia is the cause of clogged arteries and the fatty plaques that lead to blocked coronary arteries and heart attacks. The infectious form is the elementary body form that is transmitted to humans. You can see that elementary bodies turn into reticulate bodies under certain environmental condions and vice versa. Therefore these 2 phases form a cycle.