 The increase in MS in the Western world, along with other autoimmune inflammatory diseases and asthma may be attributed to decreased exposure to infections such as gut parasites due to improved hygiene the hygiene hypothesis. In animal models, controlled parasite infections including hookworms and related worms protect against MS-like disease. Parasites have evolved host-specific molecular mechanisms to dampen or condition the excessive immune responses against them and thus survive. These parasites induce regulatory mechanisms including Treg and a novel class of B cells that also dampen immune responses called Breg and were recently shown to improve MS in natural infection. They may suppress a class of lymphocytes that cause most damage in MS, Th17 cells. We will produce, with controlled exposure, a similar response to those associated with protective natural exposure in MS. We have the unique combination of expertise in hookworm biology, controlled parasite exposure and immunology of MS and MS trials and our data from our other human studies indicate this is a safe and tolerable intervention of significant potential. 