Nematocidal Effect of Japanese Traditional Intestinal Medicine ‘Seirogan’ on Larval Anisakid and Raphidascaridid Nematodes

Seirogan is a well-known Japanese traditional herbal medicine for stomachache or diarrhea due to digestive disorders. In addition, the administration of Seirogan alleviates the severe abdominal pain and other symptoms of gastric anisakiasis [1], a parasitic disease caused by eating raw or undercooked fish or other seafoods that harbor larvae of anisakid nematodes such as Anisakis simplex, A. pegreffii and Pseudoterranova decipiens [2,3]. This disease typically requires hospitalization and in the worst case, can result in perforation of the stomach wall due to the penetration of the organisms. When Anisakis larvae are exposed to Seirogan solution, they quickly become immobile [1]. The medicine’s ability to alleviate abdominal pain due to anisakiasis may be partly related to suppression of the motility of the Anisakis larvae. However, the symptoms of anisakiasis are mainly caused by allergens secreted from the nematodes or substances on the surface of the nematodes [3]. If anisakid nematodes can be killed, not only production and secretion of allergens from the nematodes would halt, but also the nematodes would be disrupted by digestive enzymes in the stomach.