How Borrelia causes relapsing fever, why antigenic variation makes the fever return in waves, the difference between louse-borne and tick-borne types, and how a blood smear during...
How Treponema pallidum causes syphilis, the four stages of the disease from the painless chancre to tertiary syphilis, congenital syphilis, and the screen-then-confirm approach to...
What spirochetes are: long, thin, coiled bacteria that move with internal flagella and cannot be seen on ordinary stains. The three human pathogens, Treponema, Borrelia, and Leptos...
How Borrelia burgdorferi causes Lyme disease, the three stages from the erythema migrans rash to Lyme arthritis, why early Lyme is treated on the rash alone, and how two-tier serol...
The full dark-field procedure for detecting Treponema pallidum in a chancre, the 20-minute window that makes or breaks it, and why oral or rectal samples can give a false positive.
How Leptospira interrogans causes leptospirosis and Weil's disease, why the illness comes in two phases, and how it is diagnosed (dark-field microscopy, culture, and the MAT), with...
How dark-field microscopy makes spirochetes like Treponema pallidum visible without staining, by detecting scattered light rather than resolving fine detail.
