Treponema sp.
* Fastidious
* No animal models available => difficult to research
* Several species human pathogens

Diseases caused by Treponema
Syphilis
* Caused by T. pallidum
* Major problem prior to introduction of antibiotics
- first mayor epidemic in Europe at the end of 15th century
- prior to antibiotics only treatment available: mercury
* Transmission
- by sexual contact
- congenital from infected mother to fetus
* More than 15,000 new cases reported in 1995
* Three stages with dramatically different clinical presentation:
- primary syphilis (2 - 10 weeks after infection):
    * chancre (skin lesion) at site of entry often unnoticed
    * disappears spontaneously
    * enlarged inguinal LN
    * organism multiplies in regional LN
- secondary syphilis (1 - 3 months after primary syphilis, lasts 2 - 6 weeks:
    * flue-like illnes, fever, rash
    * penetrates mucus membranes, enter blood-stream
- tertiary syphilis (3 - 30 years after secondary syphilis):
    * invade heart, musculoskeletal system, CNS, relatively noninfectious
    * heart damage, neurological symptoms, fatigue, skin lesions
    * cell mediated hypersensitivity and inflammation
    * treponemes are rare or absent
* Little known about pathogenic attributes
* Very sensitive to penicillin, no known resistance

Pinta
* Caused by T. carateum

Yaws
* Caused by T. pertenue
* Common in Africa
* Similar to syphilis but transmission by skin contact, typically childhood disease