Menstruation, periodic discharge from the vagina of blood, secretions, and disintegrating mucous membrane that had lined the uterus. 1  The biological significance of the process in humans can best be explained by reference to the reproductive function in other mammals.
Chlamydial (kla-MID-ee-al) infections are caused by three species of microorganisms. Chlamydia trachomatis can cause eye or lung infections and can also infect the urinary and genital areas of both men and women. Chlamydia pneumoniae causes infections of the respiratory tract, and Chlamydia psittaci causes an illness, known as parrot fever, that is similar to the flu.
1 Humans are infected by handling sick birds. The chlamydia cause respiratory infection manifested with fever, malaise, cough, dyspnea, sore throat, photophobia and headaches.  Chlamydia is a common sexually transmitted disease caused by bacteria. You get it by having sex or sexual contact with someone who is infected.