Human and experimental anisakiasis in the United States

In the past 13 years, 24 cases of anisakiasis have been reported in the United States. Of these, 14 were infections by Phocanema sp. and found in California and Alaska, and most were of the tissue non-invasive type. The remaining 10 cases were infections by larvae of anisakis type I (L3 and L4). Of these 10 cases, 4 were found on the west coast, 5 were on the east coast and one was in Hawaii. In 3 of the 10 cases, the parasite invaded the digestive tract. A characteristic symptom of the throat named "tingling throat" was manifested in 16 of the 24 cases, and this symptom was found to be due to larvae of Phocanema in most cases. As a method for immunological diagnosis of anisakiasis, the radioallergosorbent test (RAST) is being investigated as a cooperative study with Ishikura. As a result, IgE obtained from the sera of 4 patients who had been parasitologically diagnosed as having the disease and one patient in whom the parasite had not been confirmed but was clinically diagnosed as having the disease reacted strongly with anisakis larva antigens, and this reaction was able to be distinguished from the immune response to antigens of other Ascaris. On the other hand, when RAST was applied to child bronchial asthma patients in Hawaii, they showed a strong response to the anisakis larva antigens. Because the causative factors of child bronchial asthma in Hawaii are few and the environmental conditions are also good (i.e., do not cause asthma), their asthma is surmised to be helminth-associated asthma. In view of this background, as well, the results of RAST are interesting. When anisakis larva antigens were analyzed, a strong immunosuppressive effect was confirmed in the high molecular weight fraction (MW: greater than 10,000), while the presence of a substance having mutagenicity was confirmed in the low molecular weight fraction (MW: less than 10,000). In addition, in the sea near Hawaii, we discovered a novel species of Phocanema, which were named Terranova HA.