Inflammatory mechanisms have been implicated in autism. Treatments that modulate the immune system and inflammatory response, such as Trichuris suis ova (TSO), a parasitic worm called whipworm helminth, may be an experimental therapeutic option. Individuals with autism may have an increased immune response due to excess type 1 T-helper cells, which increases chronic inflammation. Individuals with autism may also have less of anti-inflammatory cytokines released by type 2 T-helper cells, which decreases chronic inflammation. It has been noted that some individuals with autism have improvements in behavioral symptoms when they have a fever, which further suggests that factors that influence the immune system and inflammation may have a role in autism etiology and potential treatments.

Helminth worms, specifically TSO, have been studied in autoimmune disorders in relation to the hygiene hypothesis, which suggests that a rise in hygiene is associated with fewer protective microbes in humans and an increase in autoimmune inflammatory disorders. It further suggests that stimulation of the immune system by microbes protects against the development of inflammatory diseases.

Eric Hollander and his team at Albert Einstein College of Medicine, Montefiore Medical Center in New York assessed the effect of TSO and a placebo on repetitive behaviors, irritability and global functioning in adults with autism.

This exploratory safety and efficacy study included young, high-functioning adults with autism, normal intelligence and good verbal skills. Irritability scores on the Aberrant Behavior Checklist-Irritability Subscale were low at baseline. Measures of rigidity, need for sameness and repetitive behaviors improved in individuals on TSO versus placebo. Participants also showed less discomfort and protest associated with interruption of restricted interests or deviation from expectations. As in previous studies of TSO the side-effect profile is low^1-6. Flatulence, stomach cramping and nausea or vomiting were more common with TSO, while loose stool, weight loss and knee pain were more common with the placebo.

This is the first placebo-controlled trial of TSO in a population of individuals with autism. The preliminary interim analyses from this exploratory pilot study demonstrate the feasibility of completing a 28-week study of TSO in an autism population. They also demonstrate the safety of TSO in this population and its potential efficacy for rigidity, insistence of sameness, and repetitive or restricted behaviors.

Future studies are needed to replicate these preliminary findings in a younger population stratified for higher baseline irritability. Further exploration of target engagement with the immune system and TSO’s relationship to clinical improvement in autism is also needed.

1. Fleming J.O. et al. Mult. Scler. 17, 743-754 (2011) PubMed
2. Sandborn W.J. et al. Aliment Pharmacol. Ther. 38, 255-263 (2013) PubMed
3. Summers R.W. et al. Am. J. Gastroenterol. 98, 2034-2041 (2003) PubMed
4. Summers R.W. et al. Gut 54, 87-90 (2005) PubMed
5. Summers R.W. et al. Gastroenterology 128, 825-832 (2005) PubMed
6. Hollander E. et al. (2013, December). Trichuris suis ova (TSO) as an immune-inflammatory treatment for repetitive behaviors in autism spectrum disorder (ASD). Poster presented at the meeting of the American College of Neuropsychopharmacology. Hollywood, Florida.