The germ theory of disease has an interesting history in Tricin.
Ancient Talman rituals
Ancient Talman religion had a practice of hand-washing with clean water after coming into contact with bodily fluids or soil, or with water contaminated with such unclean material. Observing that not following this ritual caused outbreaks of disease probably motivated people to keep this practice, even after the religious motive was gone.
Trician historians recognize this religious ritual as a lucky coincidence that helped make Talma different from other premodern Trician civilizations. In particular, it helped greatly reduce infant mortality in ancient Talma. Combined with the ready availability of silphium on Talma, this contributed to premodern Talman society being relatively gender-egalitarian for an agricultural society: women needed to spend less time being pregnant even though they had to raise many children.
Rith Ătsa's contributions to germ theory
Yachef rith Ătsa was a Gweats dynasty Windermere physician who originated and verified germ theory scientifically.
Rith Ătsa proposed that transmissible diseases were caused by pests that were too small to see. His insight came from seeing an aphid infestation of crops. In order to test his theory, rith Ătsa used experiments on animals.