Larval Ascaridoid Nematodes from Fishes near the Hawaiian Islands, with Comments on Pathogenicity Experiments!

Transcription

1 Pacific Science (1982), vol. 36, no by the University of Hawaii Press. All rights reserved Larval Ascaridoid Nematodes from Fishes near the Hawaiian Islands, with Comments on Pathogenicity Experiments! THOMAS L. DEARDORFF, MICHAEL M. KLIKS, MITCHEL E. ROSENFELD, ROBERT A. RYCHLINSKI, and ROBERT S. DESOWITZ 2 ABSTRACT: A total of 134 species of finfishes and 8 species of invertebrates, which were caught near the Hawaiian Islands over a 26-month period, were examined for larval nematodes. A total of 21,746 ascaridoid larvae were recovered. Larval nematodes ofthe genera Anisakis (two types), Hysterothylacium (three types), Raphidascaris (one type), and Terranova (two types) were identified. Descriptions and illustrations are provided for most larvae. A key is included. No anisakine larvae were found in the invertebrates. Inoculations of laboratory rats with various larvae demonstrated that at least Anisakis type II and Terranova type HA harm the host. SOME LARVAL MARINE ASCARIDOIDS can penetrate mechanically into or through the gastric or intestinal wall ofa host and elicit a variety of clinical conditions by the host (Oshima 1972). This zoonotic disease is called anisakiasis. Humans acquire these nematodes by ingesting raw or inadequately cooked seafood. Most cases of human anisakiasis have been reported from Japan and the Netherlands, but since 1950, cases of human anisakiasis have been reported in the United States. Some larval nematodes from Hawaiian fishes may be of public health significance. Deardorff et al. (in press) report that a larval Terranova sp., removed from fishes of Hawaii and gavaged into rats, possesses the ability to penetrate into the stomach and evoke pathological changes. I This study was conducted in part in cooperation with the U.S. Food and Drug Administration (contract no ), University of Hawaii Sea Grant College Program under Institutional Grant no. NA8IAA-D from NOAA, Office of Sea Grant, Department of Commerce, and by a grant from the Pacific Gamefish Foundation of Honolulu. Manuscript accepted 9 February John A. Burns School of Medicine, Department of Tropical Medicine and Medical Microbiology, University of Hawaii, Leahi Hospital, 3675 Kilauea Avenue, Honolulu, Hawaii While no cases of human anisakiasis have been identified in Hawaii to date, the consumption of large quantities of raw seafood dishes such as sashimi, poki, sushi, and lomi lomi salmon greatly increases the local consu'mer's exposure to this zoonotic infection. From a public health point ofview, the ability to predict which marine host may carry larval anisakids capable of infecting consumers would be valuable. Surveys for helminths of marine fishes and invertebrates, supported by the U.S. Food and Drug Administration, have been completed for the Atlantic coast (Cheng 1976, Jackson et al. 1978), the Gulfcoast (Deardorff and Overstreet 1981a, Norris and Overstreet 1976), and the Pacific coast (Myers 1979, Stern et al. 1976). Although surveys have been conducted to identify digenes (Yamaguti 1965, 1970) and monogenes (Yamaguti 1968) in or on fishes caught near Hawaii, no survey has been undertaken to examine the prevalance of larval anisakid nematodes. Therefore, during a 26-month period, we examined finfishes and shellfishes caught near the Hawaiian Islands for parasites. In this report, we present a host list ofexamined specimens, describe anisakid larvae col1ected (when necessary), and comment on experiments that involved larvae gavaged into laboratory rats.

2 188 MATERIAL AND METHODS From October 1979 through October 1981 specimens of fishes and shellfishes were obtained from commercial and sports fishermen, from fish auctions, and from wholesale and retail markets. Fishes and nematodes were examined following the method of Deardorff and OveJ;Street (1981a), and laboratory rats were oraily inoculated as described by Deardorff et al. (in press). Voucher specimens for all larval types have been deposited in the Bernice P. Bishop Museum, Honolulu (BPBM ). All measurements are in micrometers unless stated otherwise, and figures were drawn with the aid of a drawing tube. PACIFIC SCIENCE, Volume 36, April ) by having a mucron on the posterior extremity, an elongated ventriculus, and an oblique ventricular-intestinaljunction. Therefore, no figures or measurements are included. Numerous reports of this larval type infecting humans appear throughout the literature (e.g., Oshima 1972). Pippy and van Banning (1975) reared type I larva in vitro and identified the adult stage as Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878). Anisakis simplex parasitize many cetaceans and pinnipeds. The nematode has been reported worldwide but principally from colder temperate and polar waters (Davey 1971). We have not collected any adult specimens of A. simplex during this study. RESULTS The examination ofwhole fishes or viscera only of 1654 specimens representing 134 species offinfishes and 186 specimensofinvertebrates representing 8 species yielded 21,746 larval ascaridoid nematodes. A total of eight types of larval ascaridoids were collected and identified. Two types, Anisakis type I and Anisakis type II, have been previously reported from fishes throughout the world; however, the remaining six types, which we designate as Hysterothylacium type Hawaii A (HA), Hysterothylacium type Hawaii B (HB), Hysterothylacium type Hawaii C (HC), Raphidascaris type Hawaii A (HA), Terranova type Hawaii A (HA), and Terranova type Hawaii B (HB), are reported for the first time. Table 1 lists hosts positive for ascaridoid larvae and shows the host species, common name, number of hosts infected and examined, percentage of hosts infected, and total number ofeach larval type collected for each species. Hosts found to be negative for anisakine larvae are listed in Table 2. Anisakis type I REMARKS: Our specimens conform to the descriptions ofothers (Berland 1961, Cannon 1977, Grainger 1959, Oshima 1972, Punt Anisakis type II REMARKS: This larva is considered identical to Anisakis type II of Berland (1961), Koyama et al. (1969), and Kagei et al. (1978) by lacking a mucron on the posterior extremity, possessing a short ventriculus, and having a ventricular-intestinal junction that is horizontal. Each of 14 rats was inoculated with type II larva, with rats examined from 1 hr to 33 days PI (postinoculation); see Table 3. Two rats, 2 hr and 3 hr PI, demonstrated pathological changes. The stomach of the rat examined at 2 hr PI showed six small ulcers grossly; however, no worms were recovered or seen in tissue sections of the ulcers. Although the stomach ofthe rat sacrificed at 3 hr PI showed no abnormal pathology, a worm-induced perforation was observed in the small intestine. A larva was found in the peritoneal cavity encapsulated in the fatty tissue adjacent to the ovaries. Oshima (1972) stated that Anisakis type II larva possess almost no chance ofinvasion in humans. Kagei et al. (1978) reported the first case ofanisakis type II larva in the alimentary tract of a patient. They considered raw fish, Katsuwonus pelamis, orraw squid, Todarodes pacificus, as the source of infection. From edible portions of meat, we removed a single larva from K. pelamis and two larvae from C. hippurus.

3 TABLE 1 PREVALENCE OF LARVAL ASCARIDOID NEMATODES IN FINFISHES CAUGHT NEAR THE HAWAIIAN ISLANDS, Raphid- Anisakis Hysterothylacium ascaris Terranova NUMBER NUMBER PERCENT UNKNOWN HOST INFECTED EXAMINED INFECTED I II HA HB HC HA HA HB ASCARIDOIDS Acanthuridae (surgeonfishes) Acanthurus dussumieri Cuvier and Valenciennes A. mata Cuvier and Valenciennes A. nigrofuscus (Forsskal) A. triostegus Streets Manini Ctenochaetus strigosus (Bennett) Naso hexacanthus (Bleeker) Kala N. unicornis (ForsskAl) Zanclus cornutus Linnaeus Moorish idol Antigoniidae (boarfishes) Antigonia eos Gilbert '0 0 0 ;Q Aulostomidae (trumpetfishes) Aulostoma chinensis (Linnaeus) I '0 Balistidae (triggerfishes) Melichthys vidua (Solander) I Belonidae (needlefishes) Ablennes hians (Cuvier and Valenciennes) Carangidae (jacks) Carangoides ferdau (Forsskal) (!) Caranx cheilio (Snyder) (1)* (2) C. ignobilis (Forsskal) I I (1) (1) (1) C. mate Cuvier and Valenciennes 5 C. melampygus Cuvier and Valenciennes Carangoides sp (I) (I) (7)

4 TABLE I (cont.) PREVALENCE OF LARVAL ASCARIDOID NEMATODES IN FINFISHES CAUGHT NEAR THE HAWAIIAN ISLANDS, 1979~ 1981 Raphid- Anisakis Hysterothylacium ascaris Terranova NUMBER NUMBER PERCENT UNKNOWN HOST INFECTED EXAMINED INFECTED I II HA HB HC HA HA HB ASCARIDOIDS Decapterus macarellus (Cuvier) I (I) (5) (15) (4) Gnathanodon speciosus (Forsskiil) Pseudocaranx dentex (Schneider) (I) (2) Selar crumenophthalmus (Bloch) (39) (I) (I I) Seriola dumerili (Risso) I 0 0 I II (I) (I) (I) (2) Chaetodontidae (butterflyfishes) Chaetodon citrinellus Cuvier and Valenciennes I I C. ornatissimus Cuvier and Valenciennes I I I Heniochus diphreutes Jordan I I 0 0 Cirrhitidae (hawkfishes) Cirrhitus pinnulatus (Bloch and Schneider) (2) (I) Coryphaenidae (dolphinfishes) Coryphaena hippurus Linnaeus , ,899 Mahimahi (7) (29) (3) (18) (II) (19) (19) Exocoetidae (flyingfishes) Cypselurus simus (Cuvier and Valenciennes) I I Fistulariidae (cornetfishes Fistularia commersonii Riippell I Holocentridae (squirrelfishes) Myripristis amaenus (Castelnau) I I Myripristis spp I 0 0 (3) (I)

5 TABLE I (cont.) PREVALENCE OF LARVAL ASCARIDOID NEMATODES IN FINFISHES CAUGHT NEAR THE HAWAIIAN ISLANDS, Raphid- Anisakis Hysterothylacium ascaris Terranova NUMBER NUMBER PERCENT UNKNOWN HOST INFECTED EXAMINED INFECTED I II HA HB HC HA HA HB ASCARIDOIDS Istiophoridae (billfishes) Makaira nigrieans Lacepede Blue marlin (3) (2) (I) (3) (3) Tetrapterus audax (Philippi) Striped marlin (I) (2) Kuhlidae (f1agtails or Aholehole) Kuhlia sandvieensis (Steindachner) Kyphosidae Kyphosus bigibbus Lacepede I 0 2 (3) (I) (I) (I) Labridae (wrasses or hinaleas) Bodianus bilunulatus (Lacepede) Lutjanidae (snappers or opakapakas) Aprion vireseens Cuvier and Valenciennes (9) (3) (2) (8) (4) (2) Etelis earbuneulus Cuvier (4) (I) (I) (12) (2) E. marshi (Jenkins) , (9) (4) (3) (7) (I) (14) Lutjanus kasmira (Forsskl'l1) I (2) (I) (I) (2) Pristipomoides filamentosus (Bleeker) I (12) (I) (4) (25) (3) (2) P. sieboldi (Bleeker) I 2 50 I P. zonatus (Cuvier and Valenciennes) (2) (2) Mullidae (goatfishes) Mulloides vanieolensis (Cuvier and Valenciennes) Parupeneus eye/ostomus (Lacepede) I I

6 TABLE 1 (cont.) PREVALENCE OF LARVAL ASCARIDOID NEMATODES IN FINFISHES CAUGHT NEAR THE HAWAIIAN ISLANDS, Raphid- Anisakis Hyslerolhylacium ascaris Terranova NUMBER NUMBER PERCENT UNKNOWN HOST INFECTED EXAMINED INFECTED I 11 HA HB HC HA HA HB ASCARIDOIDS P.muhifascwtw(Quoyand Gaimard) Muraenidae (moray eels or pubis) Gymnollwrax meleagris (Shaw and Nodder) Ophidiidae (cusk-eels and brotulas) Brotula multibarbala Temminck and Schlegel Pomacentridae (damselfishes) Chromis ovalis (Steindachner) C. veraler Jordan and Metz Slegastes fasciolatus (Ogilby) Priacanthidae (bigeyes) Priacanthus cruentatus (Lacepede) Priacanthus sp I Scaridae (parrotfishes) Scarus perspicillatus Steindachner Scombridae (tunas and mackerels) Acanthocybium solandri (Cuvier and Valenciennes) Wahoo (8) (5) (4) (7) Euthynnus affinis (Cantor) Kawakawa (2) (1) (3) Katsuwonus pelamis (Linnaeus) , Skipjack tuna (7) (14) (1) (22) (10) (4) (2) Thunnus albacares (Bonnaterre) Yellowfin tuna (6) (6) (4) (5) (4) (2) (11) T. obesus Lowe Bigeye tuna (3) (1) Scorpaenidae (scorpionfishes) Scorpaenopis cacopsis Jenkins

7 TABLE I (cont.) PREVALENCE OF LARVAL ASCARIDOID NEMATODES IN FINFISHES CAUGHT NEAR THE HAWAllAN ISLANDS, Raphid- Anisakis Hysterothylacium ascaris Terranova NUMBER NUMBER PERCENT UNKNOWN HOST INFECTED EXAMINED INFECTED I II HA HB HC HA HA HB ASCARIDOIDS Serranidae (sea basses) Cephalopholis argus Bloch and Schneider Sphyraenidae (barracudas) Sphyraena barracuda (Walbaum) I I I S. helleri Jenkins , (10) (10) Tetraodontidae (puffers) Lagocephalus lagocephalus (Linnaeus) II (I) (10) (I) Xiphiidae (swordfishes) Xiphias gladius Linnaeus I I (I) Totals 518 1, ,847 8,552 1, , ,152 In cases where multiple infections occur, the number within parentheses indicates the number ofhosts infected with a specific larval type.

8 TABLE 2 FINFISHES AND INVERTEBRATES NEGATIVE FOR ANISAKINE LARVAE OSTEICHTHYES Acanthuridae Acanthurus achilles Shaw (3) A. glaucopareius Cuvier (2) A. nigroris Cuvier and Valenciennes (I) A. olivaceus (Bloch and Schneider) (3) A. xanthopterus Cuvier and Valenciennes (I) Zebrasomaflavescens (Bennett) (2) Albulidae Albula sp. (Linnaeus) (5) Apogonidae Apogon taeniopterus Bennett (I) Balistidae Melichthys niger (Bloch) (I) Belonidae Tylosurus crocodilus (Peron and Lesueur) (I) Bothidae Bothus mancus (Broussonet) (2) Carangidae Alectis ciliaris (Bloch) (I) A. indica (Ruppell) (2) Carangoides equula (Schlegel) (3) Uraspis helvolus (Forster) (I) Chaetodontidae Chaetodon auriga ForsskAI (2) C.fremblii Bennett (I) C. miliaris Quoy and Gaimard (5) C. multicinctus Garrett (I) C. quadrimaculatus Gray (I) C. trifasciatus Park (I) C. unimaculatus Bloch (I) Forcipiger jl.avissimus Jordan and McGregor (1) Chanidae Chanos chanos (ForsskAI) (12) Cichlidae Sarotherodon mossambicus (Peters) (15) Cirrhitidae Cin'hitus pinnulatus (Bloch and Schneider) (I) Elopidae Elops hawaiiensis Regan (2) Holocentridae Adioryx lacteoguttatus (Cuvier and Valenciennes) (2) Myripristis kuntee Cuvier and Valenciennes (3) M. murdjan (Forsskol) (2) Istiophoridae Makaira indica (Cuvier) (3) Tetrapterus angustirostris Tanaka (6) Labridae Cheilinus rhodochrous Gunther (1) Coris ballieu (Vaillant and Sauvage) (I) C.flavovittata (Bennett) (I) Xyrichtys pavo Cuvier and Valenciennes (10) Lethrinidae Monotaxis grandoculus (ForsskAI) (5) Lutjanidae Aphareusfurcatus (Lacepede) (I) A. rutilans Cuvier and Valenciennes (3) Lutjanusfulvus (Bloch and Schneider) (2) Mugilidae Mugil cephalus Linnaeus (10) NOTE: Numbers within parentheses indicate the number of hosts examined. Mullidae Mulloidesjl.avolineatus (Lacepede) (I) Parupeneus chrysonemus (Jordan and Evermann) (1) P. pleurostigma (Bennett) (1) P. porphyreus (Jenkins) (6) Muraenidae Gymnothoraxflavimarginatus (Ruppell) (3) G. steindachneri Jordan and Evermann (2) G. undulatus (Lacepede) (3) Ostracidae Lactoriafornasini (Bianconi) (I) Pomacanthidae Centropyge potteri (Jordan and Metz) (1) Priacanthus sp. (I) Pomacentridae Abudefdufabdominalis (Quoy and Gaimard) (8) Scorpaenidae Dendrochirus barberi (Steindachner) (1) Taenianotus triacanthus Lacepede (1) Serranidae Anthias thompsoni (Fowler) (I) Epinephelus sp. (3) CHONDRICHTHYES Carcharhinidae Carcharhinus amblyrhynchos (Bleeker) (1) C. longimanus (Poey) (3) C. milberti (Muller and Henle) (I) Prionace glauca (Linnaeus) (I) Triaenodon obesus (Ruppell) (I) Dalatiidae Isistius brasiliensis (Quoy and Gaimard) (I) Dasyatidae Dasyatis latus (Garman) (3) Dasyatis sp. (I) Urotrygon daviesi Wallace (2) Isuridae Isurus oxyrhyncus Rafinesque (I) Isurus sp. (I) Odontaspidae Odontaspis ferox (Risso) (I) Sphyrnidae Sphyrna lewini (Griffith and Smith) (4) INVERTEBRATES Euphausiacea Miscellaneous shrimp (46) Palaemonidae Macrobrachium rosenbergii (De Man) (47) Palinuridae Panulirus spp. (29) Pandalidae Heterocarpus spp. (40) Portunidae Portunus sp. (4) Scylla serrata (ForsskAl) (2) Raninidae Ranina ranina (Linnaeus) (17) Scyllaridae Scyllarides haanii (De Haan) (I)

9 Larval Ascaridoid Nematodes from Fishes-DEARDORFF ET AL. 195 TABLE 3 LARVAL TYPE, INOCULUM, NUMBER OF HOSTS, AND INTERVAL OF NECROPSY OF RATS WITH LARVAL ANISAKINE NEMATODES REMOVEiJ FROM LoCAL FINFISHES LARVAL TYPE INOCULUM NUMBER OF HOSTS EXAMINED INTERVAL OF EXAMINATION (PI) Anisakis I Anisakis II Hysterothy/acium HA Hysterothy/acium HB Hysterothy/acium He Raphidascaris HA Terranova HA hr-22 days I hr-33 days 1 hr-13 days I hr- 1 day 5 hr-io days 2-13 days See Deardorffet a!., in press Terranova type HA DESCRIPTION: Terranova type HA is mm long, has an esophagus approximately percent of the length of the body, a ratio of intestinal cecal to esophageal lengths of 1: , and a ratio of cecal to ventriculus lengths of 1: Terranova HA was found principally encapsulated in the viscera of lutjanids. More detailed descriptions and illustrations of this larval type are reported elsewhere. REMARKS: Terranova type HA is easily distinguished from other described larval Terranova sp. (Cannon 1977, Chandler 1935) by possessing a cecum that is shorter than the ventriculus. A total of37 rats were exposed to this larva. Larva penetrated the mucosa of the stomach within 1 hr PI. Granulomatous tissue reactions occurred by 28 hr PI. Acute, focal, hemorrhagic areas or ulcers were associated with worm penetration. An account of histopathological changes as a direct result of single infections is reported elsewhere. Terranova type HB Figures 1, 6, 11 DESCRIPTION: Based on 10 specimens from Aprion virescens: body mm long by wide at greatest width; ratio of greatest width to length 1: Cuticle with annules weakly defined. Cuticular alae lacking. Boring tooth projecting anterioventrad. Esophagus long or 9-12 percent of body length. Ventriculus longer than wide, mm long by wide; ratio for lengths ofventriculus to esophagus I : Intestinal cecum mm long by wide; ratio of cecal to ventricular lengths 1: ; ratio ofcecal to esophageal lengths 1: Nerve ring located within anterior percent of esophagus, in breadth. Excretory pore opening at anterior extremity. Rectal glands spherical, numbering 4. Tail conically shaped, blunted at posterior extremity, long or 1-2 percent of body length. REMARKS: Type HB larva differs from Terranova type HA in the ratio of the lengths of the intestinal cecum to the v.entriculus and in the length of body. Type HB larva most closely resembles Terranova (as Porrocaecum) secundum of Chandler (1935) in the cutlassfish, Trichiurus lepturus Linnaeus, from Galveston Bay, Texas, and Terranova (type I) described by Cannon (1977) from various marine fishes in Southeastern Queensland. Cannon (1977) suggested that his larval type was most similar to T. chiloscylli Johnston and Mawson, 1951, which parasitized a shark, Chiloscyllium punctatum Muller and Henle, based on similar relationships of the cecum and ventriculus. We collected an adult species of Terranova from the scalloped hammerhead, Sphyrnea lewini, caught in Kaneohe Bay, Hawaii, that exhibits a ratio oflengths of cecum to ventriculus similar to Terranova HB.

10 196 PACIFIC SCIENCE, Volume 36, April 1982 II o oco FIGURES Larvalascaridoidsfrom Hawaiianfishes showinglateral views ofanteriorextremities. 1, Terranova type HB; 2, Raphidascaris type HA; 3, Hysterothy/acium type HA; 4, Hysterothy/acium type HB; 5, Hysterothy/acium type HC, the relationship between various appendages of the digestive tract; 6, Terranova type HB; 7, Raphidascaris type HA; 8, Hysterothy/acium type HA; 9, Hysterothy/acium type HB; 10, Hysterothy/acium type HC, the posterior extremities; 11, Terranova type HB; 12, Raphidascaris type HA; 13, Hysterothy/acium type HA; 14, Hysterothy/acium type HB; 15, Hysterothy/acium type He.

11 Larval Ascaridoid Nematodes from Fishes-DEARDORFF ET AL. 197 Raphidascaris type HA Figures 2, 7, 12 DESCRIPTION: Based on 4 specimens each from Kyphosus bigibbus, Decapterus macarel Ius, and Caranx cheilio: body mm long by wide at greatest width; ratio of greatest width to length 1: Cuticle with inconspicuous annules becoming more obvious at posterior extremity. Cuticular alae lacking. Esophagus long or percent of body length. Ventriculus in diameter; ventricular appendage long by wide; ratio for length of ventricular appendage to esophagus 1: Nerve ring located within anterior percent of esophagus, in breadth. Excretory pore opening posterior to nerve ring. Rectal glands spherical, numbering 4. Tail conically shaped, blunted at posterior extremity, long or 2-6 percent of body length. By possessing a ventricular ap REMARKS: pendage and no intestinal cecum, type HA larva differs from all other larvae collected. Similar to larval Raphidascaris in the Gulf of Mexico (Deardorff and Overstreet 1981a); when compared with other ascaridoid taxa, nematodes ofthis genus occurred infrequently in fishes of Hawaii. Hysterothylacium type HA Figures 3, 8, 13 DESCRIPTION: Based on 10 specimens from Sphyraena helleri: body mm long by wide at greatest width; ratio of greatest width to length I : Cuticle with inconspicuous annules. Cuticular alae lacking. Boring tooth projecting anterioventrad. Esophagus long or 5-7 percent of body length. Ventriculus in diameter; ventricular appendage long by wide; ratio for length of ventricular appendage to esophagus 1: Intestinal cecum long by wide; ratio of cecal to ventricular appendage lengths 1: ; ratio of cecal to esophageal lengths 1: Nerve ring located within anterior percent ofesophagus, 13-24in breadth. Excretory pore opening just below nerve ring. Rectal glands spherical, numbering 4. Tail conically shaped, blunted at posteriorextremity, long or 1-3 percent of body length including single spinous structure 2-4 long. REMARKS: Type HA is distinguished from all other larvae studied by possessing a blunt tail tipped with a single spine. This type is most similar to type MD (Mississippi type D) of Deardorff and Overstreet (l981a) from the northern GulfofMexico. No adult species of Hysterothylacium collected from local fishes during our survey possessed a single spine; however, it is possible that this spine may be lost during the worm's final molt. Hysterothylacium type HA differs from H. (as Thynnascaris) (type III) of Cannon (1977) from Queensland, Australia, which also possesses a, single tail spine, by having a blunt posterior extremity as compared with the fine tapered extremity of (type III). Each of 18 rats was inoculated with HA larva, and hosts were examined at intervals from 1 hr to 13 days PI. No abnormal pathology was noted in any experimental animal. Hysterothylacium type HB Figures 4, 9, 14 DESCRIPTION: Based on 10 specimens from Thunnus albacares: body mm long by wide at greatest width; ratio ofgreatest width to length 1: Cuticle with inconspicuous annules. Cuticular alae lacking. Boring cap at anterior extremity, with 7-9 posteriorly directed spinous projections on margin; longest spine ventrad, long. Esophagus long or percent of body length. Ventriculus in diameter; ventricular appendage long by wide; ratio for lengths of ventricular appendage to esophagus 1: Intestinal cecum long by wide; ratio of cecal to ventricular appendage lengths 1: ; ratio ofcecal to esophageal lengths 1: Nerve ring located within anterior percent ofesophagus, 9-11 in breadth. Excretory pore opening just below nerve ring. Rectal

12 198 PACIFIC SCIENCE, Volume 36, April 1982 glands oblong, numbering 4. Tail conically shaped, tapering to fine point long or 4-6 percent of body length. REMARKS: Hysterothylacium type HB is readily distinguished from all other larvae studied from waters near the Hawaiian Islands by its multispined boring cap and the ratio of the length of the intestinal cecum to ventricular appendage. No sympatric adult forms have been found with such a long ventricular appendage. Perhaps this ratio ofcecal to ventricular appendage lengths is dependent on the length ofthe worm, diminishing as the larva matures. Six rats were gavaged 6-58 larva and necropsied at various intervals. A small ulcerated area was grossly observed in the stomach at 1 hr PI. Histologically, the entire thickness of the stomach mucosa was necrotic with scattered neutrophils found within the submucosa adjacent to this zone. Examination of the corpus of the stomach at 2 hr PI revealed an intact but hyperemic mucosa. Extravasated blood cells, neutrophils, and aggregations of fibrin were observed in the lam-ina propria. The submucosa contained distended capillaries. No worms were seen in stomach sections ofeither case. At 24 hr PI, the stomach of the rat showed no evidence of lesions or mucosal hemorrhage. Hysterothylacium type HC Figures 5, 10, 15 DESCRIPTION: Based on 10 specimens from Caranx cheilo: body mm long by wide at greatest width; ratio ofgreatest width to length 1: Cuticle with inconspicuous annules. Cuticular alae lacking. Boring tooth projecting anterioventrad. Esophagus long or percent of body length. Ventriculus wide; ratio for length ofventricular appendage to esophagus 1: Intestinal cecum long by wide; ratio of cecal to ventricular appendage lengths 1: ; ratio ofcecal to esophageal lengths 1: Nerve ring located within anterior percent ofesophagus, 4-6 in breadth. Excretory pore just below nerve ring. Rectal glands spherical, numbering 4. Tail long or percent of body length including tuft ofapproximately 6-8 spinous structures 4-6 long. REMARKS: Type HC, by possessing a tuft of 6-8 spinelike projections distally on the tail, differs from other larvae in this study. It is, on the basis of the tuft on the tail, similar to type MC ofdeardorffand Overstreet (l981a), which they considered to be Hysterothylacium fortalezae (Klein, 1973). However, our specimens differ from type MC in the ratio of the intestinal cecum to ventricular appendage lengths, 1: as compared with 1: for type Me. We did not find adult specimens of H. fortalezae during our survey; unfortunately, we were not able to examine many known hosts for H.fortalezae. A discussion ofhosts for H.fortalezae was reported by Deardorff and Overstreet (l981b). Two rats inoculated with type HC were negative. DISCUSSION In this study, we have identified eight types of third-stage anisakine larvae from 518 (31 percent) of the finfishes caught in waters near the Hawaiian Islands. Larval worms were found encapsulated within theviscera offishes with the exception of an Anisakis type I, an Anisakis type II, and a Terranova type HB collected from edible flesh of Coryphaena hippurus, Katsuwonus pelamis, and Carangoides ferdau, respectively. Because nearly all anisakine larvae we recovered were found in nonedible tissues, the risk of infection to humans is probably slight. Oneofthe mostcommonly consumedfishes in Hawaii, Coryphaena hippurus, was infected with every larval type but Raphidascaris HA and Terranova HB. Other predator fishes displayed a similar wide variety of parasites. The most prevalent larvae belong to the genus Hysterothylacium. Third-stage larvae from this genus were found in 50 different species and at least 19 percent of the fishes sampled. Considering the three larval types of Hysterothylacium collected, type HB was most prevalent, followed by type HA and type

13 Larval Ascaridoid Nematodes from Fishes-DEARDORFF ET AL. 199 He. Hysterothylacium HB had the highest intensity of infection. Habitats appear to influence the prevalence and intensity ofsome types oflarvae in fishes. Seven species of fishes, all caught offshore, were infected with Hysterothylacium HB. Hysterothylacium HA infected a wider variety of species of fishes, mainly from shallow reef habitats. The relative increase in prevalence of Hysterothylacium HA in inshore fishes suggests that transmission probably occurs in these areas. Infections with Hysterothylacium HA in fishes from offshore areas may represent fishes that previously occupied inshore areas prior to capture. For example, both larval types infect Sphyraena helleri, which when small, frequents the shoreline but, as it grows, migrates offshore. Anisakis types I and II were found mainly in pelagic fishes. This distribution of worms by host habitat may be related to the occurrence of the parasites' definitive host. The numbers ofrecovered larval Anisakis sp. reported by Jackson et al. (1978) from fishes along the eastern seaboard of the United States, for example, are extremely low when compared with similar surveys conducted along the Pacific coast of the United States (Dailey, Jensen, and Hill 1981, Myers 1979). These results are indicative ofthe larger numbers ofmarine mammals along the Pacific coast compared with the Atlantic coast. Hawaii's marine mammal population is less than that ofthe Pacific coast and greater than that ofthe Atlantic coast ofthe United States, and the 546 larval Anisakis spp. we collected reflect this fact. Water temperatures may playa role in the natural transmission of some larvae. Deardorff and Overstreet (1981a) report that second-stage larvae of two different anisakine genera tolerate various temperatures differently. They suggest that this feature may accommodate the behavior of the definitive host. Considering the numerous surveys reporting larval Anisakis spp. from fishes in waters throughout the world, cold water fishes appear to be infected at a higher intensity and prevalence with Anisakis larvae when compared with fishes inhabiting warmer waters. When snapper of different sizes were compared, the rate and number of Terranova HA larva increased with advancing size. We speculate that this increase in larva may be due to the fact that snapper are continually infected throughout their lives and the longevity of larva may exceed the lives of the intermediate hosts. Our results are similar to other surveys in that larval Terranova spp. are found mainly in bottom-dwelling marine fishes. The use ofsome ofthese anisakine larvae as biological tags to assess various aspects ofthe marine fisheries in Hawaii may be possible because some of the larvae appear to be confined to specific habitats. Certainly, these larvae could be useful to supplement other existing methods of fisheries management. KEY TO THIRD-STAGE LARVAE OF ASCARIDOID NEMATODES PARASITIZING FINFISHES NEAR THE HAWAIIAN ISLANDS 1. a. Intestinal cecum (IC) lacking 2 b. IC present 4 2. a. Ventricular appendage (VA) lacking; excretory pore (EP) at anterior extremity 3 b. VA present; EP near nerve ring; ratio of VA to esophagus 1: ; body length mm Raphidascaris type HA 3. a. Tip of tail lacking mucron; ventricular-intestinal junction transverse.. Anisakis type II b. Tip of tail with mucron; ventricular-intestinal junction oblique Anisakis type I 4. a. VA lacking; EP at anterior extremity b. VA present; EP near nerve ring 5 5. a. Tip of tail with ornamentation b. Tip of tail lacking ornamentation, conical; boring cap covering anterior extremity, with 7-9 spinous like projections; ratio of cecal to VA lengths 1: ; body length mm Hysterothylacium type HB

14 200 PACIFIC SCIENCE, Volume 36, April a. Tip of tail with single spinous structure; ratio of cecal to VA lengths of 1: ; body length mm Hysterothylacium type HA b. Tip of tail with about six spinouslike projections in tuft; ratio of cecal to VA lengths 1: ; body length mm Hysterothylacium type HC 7. a. Ratio ofic to ventriculus 1: ; body length mm Terranova type HA b. Ratio ofic to ventriculus 1: ; body length mm Terranova type HB ACKNOWLEDGMENTS We wish to acknowledge R. L. Edmundson and K. C. Hagen, then at the University of Hawaii, S. H. Deardorff, Honolulu, and R. E. Brock of the Hawaii Institute of Marine Biology for aid in collecting parasites; J. E. Randall of the Bernice P. Bishop Museum, Honolulu, for permission to remove worms from stomachs of several museum hosts and for assistance with the taxonomy of fishes; W. Steffan ofthe Bernice P. Bishop Museum, Honolulu, for use ofequipment; M. D. Dailey of California State University, Long Beach, for his advice during this project; the staff and management of Fishland Market Ltd., Honolulu; R. W. Brill then of the Pacific Gamefish Foundation, Honolulu; the Hawaiian International Billfish Association, Kailua-Kona, for cooperation, space, and permission to examine fishes collected by fishermen; and Sheila K. Kawamoto of Leahi Hospital for technical assistance. This constitutes UNIHI-Sea Grant-JC LITERATURE CITED BERLAND, B Nematodes from some Norwegian marine fishes. Sarsia 2: CANNON, L. R. G Some larval ascaridoids from south-eastern Queensland marine fishes. InternatI. J. ParasitoI. 7: CHANDLER, A. C Parasites of fishes in Galveston Bay. Proc. U.S. NatI. Mus. 83: CHENG, T. C The natural history of anisakiasis in animals. J. Milk Food Techn. 39: DAILEY, M. D., L. A. JENSEN, and B. W. HILL Larval anisakine roundworms of marine fishes from southern and central California, with comments on public health significance. Ca. Fish Game 67: DAVEY, J. T A revision of the genus Anisakis (Dujardin, 1845) (Nematoda: Ascaridata). J. HelminthoI. 45: DEARDORFF, T L., and R. M. OVERSTREET. 1981a. Larval Hysterothylacium (= Thynnascaris) (Nematoda: Anisakidae) from the Gulf of Mexico. Proc. Helminth. Soc. Wash. 48: b (1980). Review of Hysterothylacium and Iheringascaris (both previously = Thynnascaris) (Nematoda:Anisakidae) from the northern Gulf of Mexico. Proc. BioI. Soc. Wash. 93: DEARDORFF, T. L., M. M. KLIKS, and R. S. DESOWITZ. In press. Histopathology induced by larval Terranova (type HA) (Nematoda: Anisakinae) in experimentally infected rats. J. ParasitoI. GRAINGER, J. H. R The identity of the larval nematodes found in the body muscles ofthe cod (Gadus callarias L.). Parasitology 49: JACKSON, G. J., J. W. BIER, W. L. PAYNE, T. A. GERDING, and W. G. KNOLLENBERG Nematodes in fresh market fish ofwashington, D.C. area. J. Food Protection 41: KAGEl, N., M. SANO, Y. TAKAHASHI, Y. TAMURA, and M. SAKAMOTO A case of acute abdominal syndrome caused by Anisakis type II larva. Japan. J. ParasitoI. 27: KOYAMA, T, A. KOBAYASHI, M. KUMADA, Y. KOMIYA, T OSHIMA, N. KAGEl, T ISHII, and M. MACHIDA Morphological and taxonomical studies on anisakidae larvae found in marine fishes and squids. Japan. J. ParasitoI. 18: MYERS, B. J Anisakine nematodes in fresh commercial fish from waters along the

15 Larval Ascaridoid Nematodes from Fishes-DEARDORFF ET AL. 201 Washington, Oregon and California coasts. J. Food Protection 42: NORRIS, D. E., and R. M. OVERSTREET The public health implications of larval Thynnascaris nematodes from shellfish. J. Milk Food Techn. 39: OSHIMA, T Anisakis and anisakiasis in Japan and adjacent area. Pages in Progress of medical parasitology in Japan. Vol. 4. Meguro Parasitological Museum, Tokyo. PIPPY, J. H. c., and P. VAN BANNING Identification of Anisakis larva (1) as Anisakis simplex (Rudolphi, 1809, det. Krabbe, 1879) (Nematoda:Ascaridata). J. Fish. Res. Bd. Canada 32: PUNT, A Recherches sur quelques nematodes parasites de poissons de la Mer du Nord. Mem. Mus. R. Hist. Nat. Belg. 98: STERN, L., B. J. MYERS, R. A. AMISH, W. G. KNOLLENBERG, and K. CHEW Anisakine nematodes in commercial marine fish from Washington State. Trans. Amer. Microsc. Soc. 95: 264. YAMAGUTI, S New digenetic trematodes from Hawaiian fishes. Part I. Pac. Sci. 19: Monogenetic trematodes of Hawaiian fishes. University of Hawaii Press, Honolulu. 287 pp Digenetic trematodes of Hawaiian fishes. Keigaku Publishing Co., Tokyo. 436 pp.