The shit you learn around here

The earliest known recorded uses of cooties in English date back to the First World War. It appeared in a 1917 service dictionary.[2] Albert Depew's World War I memoir, Gunner Depew (1918), includes: "Of course you know what the word "cooties" means ... When you get near the trenches you get a course in the natural history of bugs, lice, rats and every kind of pest that had ever been invented."[3] Similarly, Lieut. Pat O'Brien's memoir published March 1918, Outwitting the Hun: My Escape from a German Prison Camp refers to "cooties," on pages 61, 62 and 63, which in Lt. O'Brien's case had been caught in the prison camp in Courtrai. The infestation had originated from German soldiers who had become infested in the trenches. Cooties were treated by providing a pickle bath in some kind of solution. Lice were of course rife in the trenches on both sides of the conflict, and highly contagious.

The word is thought to originate from the Austronesian languages' Polynesian, Tagalog, and Malayan word kutu, meaning lice, or kudis (pronounced kuːdiːs), meaning scabies. The term presumably having been brought to the West by Western sailors and/or soldiers who had traveled to Polynesia, the Philippines, or Malaya.[1]

From its original meaning of head or body lice, the term seems to have evolved into a purely imaginary stand-in for anything contagious and repulsive.