UNLABELLED: OBJECTIVE To observe the characteristics of biology and pathogenicity of the third stage Anisakis simplex larvae (L3). METHODS: The survival time of the L3 in various conditions was observed and the pathological change after experimental infection in rats was examined. RESULTS: The results showed that the L3 frozen at -20 degrees C for 10 - 12 h can be killed. In the temperature range of 4 - 10 degrees C, the L3, can survive for over 8 months. The L3 was very active at 37 degrees C, and was killed at the high temperature over 40 degrees C in a very short time. The ingredients for sashimi cannot kill the L3. The experiment of rats infected by the L3 showed that about 15% -25% of the L3 penetrated into the gastrointestinal wall or migrated into the peritoneal cavity in 2 days. After 3d the L4 was not infectious, and died automatically in 7 - 10 days and could not develop into adults. The animals can be easily infected when the stomach was empty. The pathological study showed that the primary infection was a kind of reaction to foreign body, while that of the re - infection was allergic. CONCLUSION: The L3 has a strong resistance to low temperature and to ingredients, it can be killed by freezing at -20 degrees C in 24 hours. The L3 can not mature in the body of terrestrial mammals but causes pathological change in the stomach and allergy.
UNLABELLED: OBJECTIVE To observe the characteristics of biology and pathogenicity of the third stage Anisakis simplex larvae (L3). METHODS: The survival time of the L3 in various conditions was observed and the pathological change after experimental infection in rats was examined. RESULTS: The results showed that the L3 frozen at -20 degrees C for 10 - 12 h can be killed. In the temperature range of 4 - 10 degrees C, the L3, can survive for over 8 months. The L3 was very active at 37 degrees C, and was killed at the high temperature over 40 degrees C in a very short time. The ingredients for sashimi cannot kill the L3. The experiment of rats infected by the L3 showed that about 15% -25% of the L3 penetrated into the gastrointestinal wall or migrated into the peritoneal cavity in 2 days. After 3d the L4 was not infectious, and died automatically in 7 - 10 days and could not develop into adults. The animals can be easily infected when the stomach was empty. The pathological study showed that the primary infection was a kind of reaction to foreign body, while that of the re - infection was allergic. CONCLUSION: The L3 has a strong resistance to low temperature and to ingredients, it can be killed by freezing at -20 degrees C in 24 hours. The L3 can not mature in the body of terrestrial mammals but causes pathological change in the stomach and allergy.