Chancre

A chancre (/ˈʃæŋkər/ SHANG-kər) is a painless ulceration (sore) most commonly formed during the primary stage of syphilis. This infectious lesion forms approximately 21 days after the initial exposure to Treponema pallidum, the gram-negative spirochaete bacterium yielding syphilis. Chancres transmit the sexually transmissible disease of syphilis through direct physical contact. These ulcers usually form on or around the anus, mouth, penis, and vagina. Chancres may diminish between four and eight weeks without the application of medication.

Chancres, as well as being painless ulcerations formed during the primary stage of syphilis, are associated with the African trypanosomiasis sleeping sickness, surrounding the area of the tsetse fly bite.

The word "chancre" (French pronunciation: ​[ʃɑ̃kʁ]) means "little ulcer" in Old French. Related to the English "canker", they both come from the Latin cancer, meaning "crab", which is a translation from the Greek word καρκίνος (karkínos), also meaning "crab".

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