A nosode is a homeopathic therapy that could be described as an 'oral vaccine'. Nosodes are derived from pathological substances; i.e. tissue, blood, pus, mucus, sweat, urine, feces from a diseased human or animal but may also include fungi.
For example, a rabies nosode could be prepared from the saliva of a rabid dog which is then "potentized" through homeopathic succussion/dilution techniques. Ben Goldacre's Bad Science blog reported that Malaria Nosode 30 was made from rotting vegetation from marsh areas where the mosquito breeds.
The opposite of a nosode is a "sarcode" which is prepared from a healthy specimen.