line drawing of treponema pallidum the pathogen of syphilis bacterias external anatomy.

bacteria treponema vector medical bacterium biological design epidemic health illness illustration infection macro micro microbe microbiology microorganism microscopic organism pallidum pathogen protection scientific sex syphilis sexually transmitted spirochaete sickness genital infect hygienic syphilitic quarantine scattered genitals element organ sample structure bejel yaws spiral outline contour