A louse-feeder was a job in interwar and Nazi-occupied Poland, at the Lviv Institute for Study of Typhus and Virology and the associated Institute in Kraków, Poland. Louse-feeders were human sources of blood for lice infected with typhus, which were then used to research possible vaccines against the disease.
Research into a typhus vaccine was started in 1920 by parasitologist Rudolf Weigl. Weigl and his wife Zofia Weigl were some of the earliest lice feeders. During the Nazi occupation of the city, louse-feeding became the primary means of support and protection for many of the city's Polish intellectuals, including the mathematician Stefan Banach and the poet Zbigniew Herbert. While the profession carried a significant risk of infection, louse-feeders were given additional food rations, were protected from being shipped to slave labour camps and German concentration camps, and were permitted to move around the occupied city.
Typhus research involving human subjects, who were purposely infected with the disease, was also carried out in various Nazi concentration camps, in particular at Buchenwald and Sachsenhausen and to a lesser extent at Auschwitz.