Biomedical Ephemera, or: A Frog for Your Boils

The Life-Cycle of Spirochaeta duttoni, as elucidated by William Boog Leishman

Fig 1-6. General character of organism
Fig 6-8. Transverse division
Fig 9. Longitudinal division
Fig 10-11. Unknown method reproduction, thought to be conjugation
Fig 12. Coiled form in peripheral blood
Fig 13. Swollen form in liver
Fig 14-15. Skein-like forms in the spleen
Fig 16. Encysted form

Spirochetes such as Spirochaeta duttoni and Trepanoma pallidum pallidum (syphilis) were originally grouped with other eukaryotic parasitic organisms such as protozoa, because their methods of reproduction (both longitudinal and transverse division) made discerning their true nature confusing at first.

All spirochetes are now known to be Gram-negative helically-coiled bacteria. The species “Spirochaeta duttoni” (now Borrelia duttoni) causes African tick fever, which causes general muscle pain, fever, chills, nausea, and a generalized rash. The bacteria has the ability to change its surface proteins to evade the immune system for some time, and as such often relapses after initial treatment. 

[Human Parasitology. Damaso Rivas, 1920.]