Casimir-Joseph Davaine (19 March 1812 – 14 October 1882) was a French physician known for his work in the field of microbiology.

In 1850, Davaine along with French pathologist Pierre François Olive Rayer, discovered a certain microorganism in the blood of diseased and dying sheep.

Soon afterwards, Rayer published a description of the bacillus in a paper titled, Inoculation du sang de rate (1850).

[5][6] Later on, German microbiologist Robert Koch investigated the etiology of Bacillus anthracis, and discovered its ability to produce "resting spores" that could stay alive in the soil for a long period of time to serve as a future source of infection.

[7] Casimir Davaine is also credited for pioneer work in the study of sepsis (blood poisoning).