OBJECTIVEThe aim of this research was to investigate the third phase Anisakis simplex larvae (Anisakis L₃) infection in marine fish caught in Zhoushan Fishery and to find out its physicochemical and biological characteristics.

METHODSA total of 444 fish belonging to 29 species were dissected to isolate anisakis larvae which were then morphologically identified. The survival tolerance of Anisakis L₃ were observed in various conditions, such as in different temperature and medium.

RESULTSA total of 218 fish from 21 species were infected by Anisakis simplex larvae, yielding an overall infection rate of 49.10% (218/444). Trichiurus haumela, pneumatophorus japonicus, miichthys miiuy, argyrosomus argentatus and anguilliformes had high infection rate and had an average infection intensity of 15.28 per fish. 3332 Anisakis larvae were detected in 218 fish, among which Anisakis L₃ and Pseudoterranova larvae accounted for 99.46% (3314/3332) and 0.54% (18/3332) respectively. Anisakis L₃ was highly resistant to common condiment. We found the liquor with high concentration of alcohol showed better insecticidal effect than that with low concentration of alcohol (t = 4.105, P < 0.05) and low concentration mebendazole composite was not only more effective than high concentration mebendazole composite (F = 45.198, P < 0.01) but also more effective than other drugs, such as albendazole and mebendazole. Anisakis L₃ could live up to 9 h and 12 h at -20°C, -10°C respectively, however they were very sensitive to high temperature. It has been shown that they could only survive for less than 11 s and 1 s at 50°C and 60°C respectively.

CONCLUSIONThe observed Anisakis L₃ infection rate in the marine fish found in Zhoushan Fishery was very high. Anisakis L₃ showed high resistance to low temperature but not to high temperature.

Animals ; Anisakiasis ; parasitology ; veterinary ; Anisakis ; Fish Diseases ; parasitology ; physiopathology ; Fisheries ; Fishes ; parasitology ; Larva ; Temperature

A parasitological investigation on trematode metacercariae was made on 62 freshwater fishes of 13 species in northern Thailand; Cyclocheilichthys apogon, Puntioplites proctozysron, Labiobarbus siamensis, Barbodes gonionotus, Barbodes altus, Henicorhynchus siamensis, Osteochilus hasselti, Notopterus notopterus, Mystacoleucus marginatus, Anabas testudineus, Systomus orphoides, Morulius chrysophykadian, and Hampala macrolepidota. The fish were caught over the summer period (February-May 2007) from 2 Chiang Mai water reservoirs, i.e., the Mae Ngad (UTM 47Q E 503200, 47Q N 2119300) and the Mae Kuang Udomtara (UTM 47Q E 513000, 47Q N 2092600) Reservoirs in Chiang Mai province, Thailand. The prevalence of heterophyid (Haplorchis taichui and Haplorchoides sp.) metacercariae in these fish was 83.9% and 74.2% in the Mae Ngad and Mae Kuang Udomtara Reservoirs, respectively. The highest intensity of heterophyid metacercariae in H. siamensis in the Mae Ngad was 120.4 and that in P. proctozysron in the Mae Kuang Udomtara was 180.0. The fish, A. testudineus, C. apogon, and M. chrysophykadian, were not found to be infected with H. taichui metacercariae. The results show that the freshwater fish in Chiang Mai water reservoirs are heavily infected with H. taichui and Haplorchoides sp. metacercariae.
Animals ; Fish Diseases/*epidemiology/*parasitology ; Fishes/*parasitology ; Fresh Water/*parasitology ; Heterophyidae/*isolation & purification ; Thailand/epidemiology ; Trematode Infections/epidemiology/parasitology/*veterinary

The metacercariae of Centrocestus formosanus, a minute intestinal trematode of mammals and birds, were detected in the freshwater fish, Puntius brevis, from Vientiane Municipality, Lao PDR. The metacercariae were experimentally fed to mice, and adult flukes were recovered in their small intestines 7 days later. The adult flukes were morphologically characterized by having 32 (rarely 34) circumoral spines arranged in 2 alternative rows, a large bipartite seminal vesicle, an oval-shaped ovary, and an X-shaped excretory bladder. Based on these characters, the adults were identified as Centrocestus formosanus (Nishigori, 1924). The taxonomic significance of C. formosanus, in relation to a closely related species, C. caninus (Leiper, 1913), is briefly discussed. It has been first verified by adult worm recovery that C. formosanus is prevalent in Vientiane areas of Lao PDR, taking the freshwater fish, P. brevis, as a second intermediate host.
Animals ; Fish Diseases/*parasitology ; Fishes ; Laos ; Trematoda/*classification/ultrastructure ; Trematode Infections/parasitology/*veterinary

The metacercariae of Centrocestus formosanus, a minute intestinal trematode of mammals and birds, were detected in the freshwater fish, Puntius brevis, from Vientiane Municipality, Lao PDR. The metacercariae were experimentally fed to mice, and adult flukes were recovered in their small intestines 7 days later. The adult flukes were morphologically characterized by having 32 (rarely 34) circumoral spines arranged in 2 alternative rows, a large bipartite seminal vesicle, an oval-shaped ovary, and an X-shaped excretory bladder. Based on these characters, the adults were identified as Centrocestus formosanus (Nishigori, 1924). The taxonomic significance of C. formosanus, in relation to a closely related species, C. caninus (Leiper, 1913), is briefly discussed. It has been first verified by adult worm recovery that C. formosanus is prevalent in Vientiane areas of Lao PDR, taking the freshwater fish, P. brevis, as a second intermediate host.
Animals ; Fish Diseases/*parasitology ; Fishes ; Laos ; Trematoda/*classification/ultrastructure ; Trematode Infections/parasitology/*veterinary

The surface ultrastructure of Acanthotrema felis (Trematoda: Heterophyidae) adults, recovered from a kitten experimentally infected with the metacercariae, was observed using a scanning electron microscope. The worm was leaf-like, ventrally concave and covered with scale-like multi-pointed tegumental spines. The spines on the anterior surface were short but broad, and had 10-12 pointed tips. The cytoplasmic processes protruded around the spines, like pockets for the spines. The ventrogenital opening was crescent, or kidney-shaped, and had protuberances with minute spines on its surrounding tegument. The spines on the posterior surface were long, but narrow, with 6-8 pointed tips. The cytoplasmic processes on this tegument were ridge-like, and elevated along the row of the spines. The surface ultrastructure of A. felis is generally similar to that of other heterophyid flukes, but some features are characteristic, and may be of taxonomic and bio-ecological significance.
Animals ; Cats/*parasitology ; Fishes/parasitology ; Microscopy, Electron, Scanning ; Trematoda/growth & development/*ultrastructure

To identify acanthocephala found in 'Changran-pickles' and 'Myungran-pickles' each organ was measured in permanent slides. In the present report, the results obtained were as follows: 1. Morphology of male worms: Worms possessed 18-19 longitudinal rows, with 4 hooks per row, which became smaller towards the base of proboscis. Each worm contained two testis and six cement glands arranged linearly. Body 22.0 by 0.8-0.6 mm and 15.0 by 0.6-0.4 mm, proboscis 284.8 by 227.6 microgram and 524.9 by 151.4 microgram, proboscis sheath 1570.7 by 72.7 microgram and 751.9 by 280.4 microgram, lemnisci length 2566.7 and 1085.6, testis 2202.9-1860.5 by 737.0-575.7 microgram and 1033.8-981.1 by 463.1-351.6 microgram, cement glands 940.2 by 441.2 microgram and 610.0 by 369.1 microgram. 2. Morphology of female worms: Worms possessed 14-18 longitudinal rows, with 6-10 hooks per row and become smaller toward the base of proboscis. Each worm contained an uterine bell and uterus in the posterior portion and the eggs filled the body cavity. Body 14.0~51.0 mm by 0.7-0.5~2.2-1.4 mm, proboscis 466.1-268.9 microgram by 259.9-252.0 microgram, proboscis sheath 1550.7-506.0 by 298.8-231.1 microgram, lemnisci length 1325.7-473.1 microgram, eggs 112.4 by 28.5 microgram~51.7 by 14.0 microgram. In this present study, the acanthocephala collected in 'Changran-pickles' and 'Myungran-pickles' were identified as Echinorhynchus gadi by morphological features.
Acanthocephala/anatomy & histology/classification/*isolation & purification ; Animals ; Female ; Fish Diseases/*parasitology ; Fishes ; Helminthiasis, Animal/*parasitology ; Korea ; Male ; Seafood/*parasitology

The infection status of marine fish and cephalopods with Anisakis simplex third stage larva (L3) was studied over a period of 1 year. A total of 2,537 specimens, which consisted of 40 species of fish and 3 species of cephalopods, were purchased from the Cooperative Fish Market in Busan, Korea, from August 2006 to July 2007. They were examined for A. simplex L3 from the whole body cavity, viscera, and muscles. A. simplex L3 were confirmed by light microscopy. The overall infection rate reached 34.3%, and average 17.1 larvae were parasitized per infected fish. Fish that recorded the highest infection rate was Lophiomus setigerus (100%), followed by Liparis tessellates (90%), Pleurogrammus azonus (90%), and Scomber japonicus (88.7%). The intensity of infection was the highest in Gadus macrocephalus (117.7 larvae per fish), followed by S. japonicus (103.9 larvae) and L. setigerus (54.2 larvae). Although abundance of A. simplex L3 was not seasonal in most of the fish species, 10 of the 16 selected species showed the highest abundance in February and April. A positive correlation between the intensity of L3 infection and the fish length was obvious in S. japonicus and G. macrocephalus. It was likely that A. simplex L3 are more frequently infected during the spring season in some species of fish. Our study revealed that eating raw or undercooked fish or cephalopods could still be a source of human infection with A. simplex L3 in Korea.
Animals ; Anisakiasis/*parasitology ; Anisakis/growth & development/isolation & purification/*physiology ; Cephalopoda/*parasitology ; Disease Reservoirs/parasitology ; Fishes/*parasitology ; Food Contamination/analysis ; Humans ; Korea ; Larva/growth & development/physiology ; Seafood/*parasitology ; Seasons

The prevalence of fish-borne trematodes (FBT), including Clonorchis sinensis, is still high in riverside areas of the Republic of Korea. The author reviewed the detection and identification methods, differential keys, fish intermediate hosts, and morphological characteristics of FBT metacercariae. FBT metacercariae found in freshwater fish are classified mainly into 4 families, i.e., Opisthorchiidae, Heterophyidae, Echinostomatidae, and Clinostomidae. The metacercariae of C. sinensis, found in 40 species of freshwater fish, are elliptical and 0.15-0.17 x 0.13-0.15 mm in size, have nearly equal sized oral and ventral suckers, brownish pigment granules, and an O-shaped excretory bladder. Their general morphologies are similar to those of Metorchis orientalis (except in the thickness of the cyst wall). Metagonimus spp. (M. yokogawai, M. takahashii, and M. miyatai) metacercariae are subglobular or disc-shaped, and 0.14-0.16 mm in diameter. They have yellow-brownish pigment granules, a ventral sucker deflectively located from median, and a V-shaped excretory bladder. The metacercariae and fish intermediate hosts of Centrocestus armatus, Clinostomum complanatum, and 3 echinostomatid flukes (Echinostoma hortense, E. cinetorchis, and Echinochasmus japonicus) were summarized. FBT metacercariae detected in brackish water fish are mainly members of the Heterophyidae. The morphological characters, identification keys, and fish intermediate hosts of 7 species (Heterophyes nocens, Heterophyopsis continua, Pygidiopsis summa, Stellantchasmus falcatus, Stictodora fuscata, Stictodora lari, and Acanthotrema felis) were also reviewed. The contents treated in this study will provide assistance at the laboratory bench level to those working on recovery of metacercariae from fish hosts and identifying them.
Animals ; Fishes/anatomy & histology/*parasitology ; Fresh Water/parasitology ; Host-Parasite Interactions ; Humans ; Republic of Korea ; Trematoda/anatomy & histology/classification/*isolation & purification ; Trematode Infections/*parasitology ; Zoonoses/*parasitology

The metacercariae of Acanthotrema felis Sohn et al., 2003 (Digenea: Heterophyidae) were discovered in a species of the brackish water fish, Acanthogobius flavimanus, in the Republic of Korea. They were experimentally fed to kittens, and adult flukes were harvested 7 days later. The adults were morphologically characterized by the presence of a bipartite seminal vesicle, the ventral sucker associated with a ventrogenital sac enclosing 3 sclerites (2 long and pointed, and 1 short and thumb-like), and an unarmed gonotyl. The adult flukes were identified as A. felis Sohn et al., 2003, and the brackish water fish A. flavimanus has been verified as one of its second intermediate hosts.
Animals ; Cats/parasitology ; Fishes/*parasitology ; Histocytochemistry/veterinary ; Intestinal Diseases, Parasitic/parasitology/pathology/veterinary ; Korea ; Trematoda/anatomy & histology/*growth & development ; Trematode Infections/parasitology/pathology/veterinary

Freshwater fish from Vientiane Municipality and Savannakhet Province, Lao PDR were examined by the muscle compression and artificial digestion methods to know the infection status with trematode metacercariae. In the fish from Savannakhet, 2 species of metacercariae, Opisthorchis viverrini and Haplorchis taichui, were detected. O. viverrini metacercariae were found in 6 species of fish, Puntius brevis, Hampala dispar, Esomus metallicus, Mystacoleucus marginatus, Puntioplites falcifer, and Cyclocheilichthys armatus. H. taichui metacercariae were detected in 3 species of fish, P. brevis, P. falcifer, and M. marginatus. In the fish from Vientiane, 4 species of metacercariae, O. viverrini, H. taichui, Haplorchis yokogawai, and Centrocestus formosanus, were detected. Among them, O. viverrini metacercariae were found in 7 species of fish, Onychostoma elongatum, C. armatus, H. dispar, P. brevis, Cyclocheilichthys repasson, Osteochilus hasseltii, and Hypsibarbus lagleri. The metacercariae of H. taichui were detected in 6 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, and Cirrhinus molitorella. The metacercariae of H. yokogawai were found in 9 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, O. hasseltii. C. molitorella, Hypsibarbus wetmorei, and H. lagleri. The metacercariae of C. formosanus were detected in 4 species of fish, C. repasson, P. brevis, O. hasseltii, and C. molitorella. From these results, it is confirmed that fishborne trematode metacercariae, i.e. O. viverrini, H. taichui, H. yokogawai and C. formosanus, are prevalent in various species of freshwater fish from Savannakhet Province and Vientiane Municipality, Lao PDR.
Animals ; Fish Diseases/epidemiology/*parasitology ; Fishes ; Fresh Water ; Laos/epidemiology ; Trematoda/anatomy & histology/classification ; Trematode Infections/epidemiology/parasitology/*veterinary