Jan. 18 (HealthDay News) -- Parasitic infections may actually benefit people with multiple sclerosis (MS), suggests a study by researchers in Argentina.

These infections may affect the body's immune response in a way that changes the course of the disease.

Previous studies found that parasite infection could affect the course of autoimmune diseases in animals. This is the first study to examine the relationship between parasite infections and MS in humans.

The study included 12 MS patients with a parasite infection and 12 MS patients who were parasite-free. The patients in both groups had a similar disease course. The patients were followed for an average of 4.6 years.

During the study period, there were three clinical relapses of MS among patients infected with a parasite, compared to 56 relapses in the group of uninfected MS patients. Patients in the infected group were less likely to suffer increased disability due to MS.

The researchers also found that infected patients had much higher numbers of cells that produce cytokine suppressants. MS involves an inflammatory response associated with the production of cytokines, which are regulatory proteins.

The findings provide evidence to support the idea that an autoimmune response caused by a parasite infection can decrease the normal inflammatory response associated with MS, the study authors suggested.

The study appears in the January issue of the Annals of Neurology.