Light micrograph of the anaerobic spirochaete bacteria, Treponema pallidum (black spirals), the causative agent of syphilis in man. The bacterium enters the body during sexual intercourse through the mucous membranes of the vagina or urethra. It may be transmitted by an infected pregnant woman across the placenta to her unborn child (congenital syphilis). The disease passes through three stages, the third, or tertiary syphilis, may cause severe damage to the heart, blood vessels, brain & spinal cord. Blindness & insanity may result. Penicillin is effective if administered in the early stages. Mag: X400.