Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 7 3 2012 09 15 73 81 EN W Saksirisampant Dept. of Microbiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand AND Dept. of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand N Choomchuay Dept. of Pathology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand K Kraivichian Dept. of Pathology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand B Wongsatayanon Thanomsub Dept. of Microbiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand 2015 10 03 Background: Gnathostoma spinigerum causes larva migran in human which is endemic in Southeast Asia. Information regarding larva migration is limited. In this study, we investigated the parasite migra­tion by recovery of worms from the whole body of mouse after oral infection with advanced third stage larvae (AL3). The percentage of blood eosinophils was examined in parallel. Methods: Mice were orally infected with AL3 and histological study of organs was investigated in order to study the migration of AL3, along with blood eosinophilia. Results: At 1 hr post infection (PI), the larvae remained in the stomach, thereafter at 3, 5, 7, 10 and 24 hr PI; they were recovered from various organs including liver, mesentery, esophagus, diaphragm, lung, heart and dorsal fat. At day 15 PI, they were mostly found in muscles (76.47%). The average worm recovery (5 months) was 78.03%. The worms were found in the liver at every time point. Larva encystment was detected. There was a significant difference in blood eosinophils between the 8 larvae- (average 9.33% + 6.25%) and the 15 larvae-infected groups (average 22.66% + 11.03%). Surprisingly, the blood eosinophils (average 19.00% + 2.92%) were not higher in the higher infective dose- group (25 larvae). Conclusion: Liver was involved by G. spinigerum throughout the study. We detected larva encyst­ment which had never been reported in human gnathostomiasis. The highest percentage of eosino­phil occurred during the invasive stage. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/255 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/255/254