Immunomodulatory effects of helminths and protozoa in multiple sclerosis and experimental autoimmune encephalomyelitis.

Multiple sclerosis is a chronic inflammatory CNS disease, which affects about 1 in 1000 individuals in the western world. During the last couple of decades, epidemiological data have accumulated, pointing towards increases in incidence. This has been suggested to be linked to the relatively high hygiene standards that exist in the western world, with reduced exposure to various pathogens, including parasites, as a consequence. Parasites are known to employ various immunomodulatory and anti-inflammatory strategies, which enable them to evade destruction by the immune system. This is most likely one of the reasons for the disease-dampening effects, reported in numerous studies investigating parasite infections and autoimmunity. This review will focus on recent advances in the field of parasites as beneficial immunomodulators, in multiple sclerosis and the animal model experimental autoimmune encephalomyelitis.