Description and surface topography of the cercaria of Austrobilharzia sp. (Digenea: Schistosomatidae).

The cercaria of Austrobilharzia sp. from the marine prosobranch gastropod Planaxis sulcatus in Kuwait Bay is described. The surface microtopography and pattern of the tegumentary sensory receptors are examined using scanning electron microscopy. The general microtopography of the surface of the cercaria is similar to that previously observed in cercariae of mammalian schistosomes, although differences are recorded in the types, numbers and distribution of the sensory receptors. The study identified more than 13 types of receptors comprising aciliated, uniciliated and for the first time a multiciliated receptor in a strigeid cercaria. The ciliated receptor types differ in the cilium length and structure of the surrounding collar and tegumentary base. The receptor types are site specific: (1) the aciliated and pitlike on the anterior organ-neck region and ventral sucker; (2) the uniciliated with a long flexible cilium with or without collar or a tegumentary base on the body and tail; and (3) the uniciliated with a short rigid cilium and a robust collar and tegumentary base, and the multiciliated with 6 flexible cilia and a high cylindrical collar on the anterior organ tip. The reported SEM information on the sensory receptors may contribute to elucidating their functional role and to establishing morphological characters for the phylogeny of the family Schistosomatidae.

Temporal variations in the infection of a population of Cerithidea cingulata by larval trematodes in Kuwait Bay.

The prosobranch gastropod Cerithidea cingulata (Gastropoda: Potamididae) in Kuwait Bay was examined for larval trematode infections over a 17-month period. A total of 2537 snails were examined and 1265 (49.9%) found to be infected with one or more species of trematodes. The component community in the snail comprised 12 species representing the families Cyathocotylidae (2), Echinostomatidae (2), Haplosplanchnidae (1), Heterophyidae (2), Microphallidae (1), Philophthalmidae (2), Plagiorchiidae (1) and Schistosomatidae (1). Cyathocotylid II (41.6%) was by far the most prevalent species followed by the microphallid (3.9%), the two species comprised 90% of the total trematode fauna. The prevalence of infection increased with shell size and was significantly higher in male (47%) than female (33%) snails. Multiple infections were observed in only 15 (1.2%) of the infected snails; cyathocotylid I and cyathocotylid II combination occurred 14 times and heterophyid I and the microphallid occurred once. Trematode species were more diverse and prevalent in winter, and cercarial shedding peaked in summer. Behaviour of the definitive host and snail population dynamics were probably the major contributors to the detected temporal pattern in the infections.

Surface morphology of Probolocoryphe uca (Sarkisian, 1957) (Digenea: Microphallidae) from Kuwait bay.

The surface ultrastructure of Probolocoryphe uca (Digenea: Microphallidae), recovered from a rat experimentally fed on crabs, Nanosesarma minutum (Brachyura: Grapsidae), naturally infected with the metacercariae, was studied by scanning electron microscopy. The flukes were leaf-like, ventrally concave and pyriform or ovoid in outline. The anterior end was modified into a sucker-like organ, comprising a protrusible disc-shaped structure surrounded by single-pointed spines. This organ is probably involved in the attachment and feeding process in a manner similar to the action of the oral suckers. Apart from the sucker-like organ, the entire tegumental surface was covered with triangular spines with multi-pointed tips. Ciliated, dome-shaped papillae were observed, singly or in groups, arranged symmetrically on the sucker-like organ and around the oral and ventral suckers. Kuwait Bay constitutes a new geographical record and the crab N. minutum is a new second intermediate host record for P. uca.

Surface ultrastructure of Stictodora tridactyla (Trematoda: Heterophyidae) from Kuwait Bay.

The surface morphology of Stictodora tridactyla recovered from a kitten that was fed the killifish, Aphanius dispar, naturally infected with the metacercariae was studied using scanning electron microscopy. The body comprised a rounded head, elongate neck, and widely pyriform hind-body. The head bore a circular oral sucker on the ventral side, and concentric rows of peg-like cephalic spines on the dorsal side. The oral sucker was armed with pre-oral spines similar in shape and size to the cephalic spines. The neck and hind-body were densely covered with scale-like multipointed spines, the size and density of which decreased from anterior to posterior parts of the body. Ciliated dome-shaped papillae were found solitarily or as conjugated groups on the head apex and lips of the oral sucker. Non-ciliated dome-shaped papillae were restricted to the lower lip of the oral sucker. The body was devoid of a ventral sucker. The genital opening appeared as a round depression of the tegument at about the anterior third of the body. This is the first record of the occurrence of S. tridactyla in the Arabian Gulf region and A. dispar is a new second intermediate host.

Studies on Cercariae from Kuwait Bay. XI. Description and surface topography of Cercaria kuwaitae XI sp.n. (Digenea: Echinostomatidae).

A new echinostome cercaria, Cercaria kuwaitae XI sp.n., from the prosobranch gastropod Cerithidea cingulata (Gmelin) from Kuwait Bay is described. The new cercaria is characterized by 23 collar spines and primary excretory tubules with distinct diverticula. The cercaria encysts in the snail host and is similar to those of Acanthoparyphium sp. The surface topography of the redia, cercaria and metacercarial cyst wall is studied by scanning electron microscopy. This is the first echinostome cercaria to be recorded in a gastropod from the Arabian Gulf region.

Temporal variations in the infection of a population of Clypeomorus bifasciata (Gastropoda: Prosobranchia) by a digenean microphallid larva in Kuwait Bay.

The prosobranch snail Clypeomorus bifasciata in Kuwait Bay was examined for digenean infections over a one year period during 1994/1995. A total of 1500 snails was examined and 567 (37.8%) were found to harbour nine digenean species. The prevalence of a microphallid species was 33.9% while each of the others occurred in less than 1.2% of the snails. The prevalence of infection increased with shell size. Multiple infections were observed in only five of the infected snails and the microphallid was involved in all of them. Snails were infected with the microphallid throughout the year and there appeared to be two peaks in the proportion of infected snails shedding cercariae, a winter peak from November to January and a summer peak from June to August. The crab Xantho exaratus collected from snail sampling sites was heavily parasitized by microphallid metacercariae of the genera Longiductotrema and Microphallus. This is the first report on microphallid metacercariae in crabs in the Arabian Gulf region.

Studies on Cercariae from Kuwait Bay. X. Description and surface topography of Cercaria kuwaitae X sp. n. (Digenea: Renicolidae).

A new renicolid cercaria, Cercaria kuwaitae X sp. n., from the prosobranch gastropod Cerithium scabridum from Kuwait Bay is described. The new cercaria is nonstyleted gymnocephalous with voluminous Y-shaped excretory vesicle, flame cell formula 2[(3 + 3 + 3) + (3 + 3 + 3)] = 36, and without caudal fins. Surface topography of the new cercaria is studied by scanning electron microscopy. Domed papillae are abundant on the anterior and lateral aspects of the body, ciliated papillae are sparse dorsally. The ventral sucker bears nine domed papillae. Domed papillae form two circles around the oral sucker with three circles of spines in between. This is the first renicolid cercaria to be recorded in a gastropod from the Arabian Gulf region.

Studies on cercariae from the Kuwait Bay. VI. Description and surface topography of Cercaria kuwaitae VI sp. n. (Trematoda: Haplosplanchnidae).

A new haplosphlanchnid cercaria, Cercaria kuwaitae VI sp. n., was found in the prosobranch snail Cerithidea cingulata in the Kuwait Bay. Details are presented on the morphology and behavior of the cercaria and the encystment process. The new cercaria is a biocellate, distome, with a prominent single sac-like intestinal cecum extending well posterior to the ventral sucker and develops in simple sporocysts. It differ from known haplosplanchnid cercariae in the absence of finger-like processes on the tail, and the presence of V-shaped excretory vesicle extending beyond ventral sucker and the presence of cervical glands. The surface topography of the cercaria and its sporocyst is examined by scanning electron microscopy. This is the first haplosplanchnid cercaria to be described from a Cerithidea species.

Descriptions of two new didymozoids from the barracuda Sphyraena obtusata in Kuwait Bay.

Two new species of didymozoid trematodes, belonging to the subfamily Didymozoinae (Ishii, 1935), genus Allodidymozoon Yamaguti, 1959, are described from the barracuda Sphyraena obtusata caught in Kuwait Bay. Allodidymozoon pharyngi n. sp. from cysts in the pharyngeal muscles is distinguished from its congeners by the posteriorly extended testes, glandular cells surrounding the esophagus, and the distribution of the ovarian and vitelline branches in the dorsal side of the hindbody. Allodidymozoon trilobata n. sp. from cysts in the muscles on the inner surface of the operculum is distinguished by the trilobed hindbody and distally curved testes.

Seasonal prevalence of Onchocerca-like microfilaria in camels in Kuwait.

Infection of the camel (Camelus dromedarius) with Onchocerca-like microfilaria is recorded for the first time in Kuwait. Throughout a period of 14 months, the blood of 284 camels were examined, of these 32 (11%) were found infected with the microfilaria. Infections were recorded in all months except during summer, July to September, and in February. The highest monthly incidence (27%) was detected in June at the end of spring. It is suggested that harsh environmental conditions in Kuwait during summer either arrest development of microfilariae or influence their diurnal distribution in tissues of the camel.

A survey of didymozoid trematodes of the barracuda Sphyraena obtusata from Kuwait Bay.

Examination of 120 yellow-finned barracudas, Sphyraena obtusata, from Kuwait Bay revealed 8 species of didymozoid trematodes encapsulated in pairs in the tissues. Four species of the didymozoids, Allodidymozoon operculare, Didymocylindrus sp., Didymocystis sp., and Didymocystoides sp., were found in the head region, 3 species, Didymozoon tetragynae, Lepidodidymozoon sinicum and Platocystoides polyaster, in external surfaces and 1 species, Allodidymozoon sp., in stomach wall. The didymozoid species collected constitute new geographic distribution records and occurrence of D. tetragynae and L. sinicum are new host records.

Studies on cercariae from Kuwait Bay. V. Description and surface topography of Cercaria kuwaitae V sp. n. (Digenea: Heterophyidae).

A parapleurolophocercous cercaria, Cercaria kuwaitae V sp. n., was resembles closely larvae of the family Heterophyidae. Details are presented on the morphology, swimming activity and behavior of the cercaria. The surface topography of the cercaria and the redia was examined by scanning electron microscopy.

Seasonal fluctuations of gastrointestinal helminths of camels in Kuwait.

Over a period of 1 year, from May 1982 to April 1983, the gastrointestinal tracts of 240 camels were examined for the presence of parasitic helminths. The study quantifies the prevalence of gastrointestinal helminths and the seasonal fluctuations in intestinal worm burdens and faecal worm egg counts. Among the three species of cestodes and eight species of nematodes which were recorded for the first time from Kuwait, Trichostrongylus probolurus (93.8%), T. colubriformis (34.2%) and Stilesia vittata (30.0%) were the most prevalent in the small intestine and Camelostrongylus mentulatus (59.6%) in the abomasum. Estimation of the intestinal worm burdens and faecal worm egg counts showed that Trichostrongylus infections were by far the most predominant. The highest worm and egg counts were recorded in June and August, during the hot dry season. This rise is attributed to infections acquired from February to April, during the cool wet season. Possibly the most effective control can be achieved by a critical treatment at the end of the wet season coinciding with the first rise in nematode population.

Hydatidosis in camels in Kuwait.

Infection of indigenous camels, Camelus dromedarius, with hydatid cysts has been recorded for the first time in Kuwait. From February 1982 to April 1983, 293 camels slaughtered for human consumption were examined. The overall rate of infection was 39.6%: 18.5% in animals less than 6 years old, and between 40.1% and 45.2% in older animals. The infection rate in females (44.9%) was significantly higher than in males (24.7%). Females also showed higher susceptibility to infections in multiple organs (22.7%) than males (10.5%). The lung was the most predominant site infected (63.0%). Pulmonary cysts showed a higher fertility rate than hepatic cysts (71.7% vs 29.2%) and were smaller and more numerous. The high infection rate recorded for this animal is probably related to recent shifts in animal maintenance from the traditional free-grazing to the corralling system.

Schistosoma mansoni: immunofluorescent detection of its antigen reacting with Biomphalaria glabrata amoebocytes.

The reaction of amoebocytes in the hemolymph of the infected intermediate host, Biomphalaria glabrata, to Schistosoma mansoni antigens has been investigated using the indirect immunofluorescence antibody test. Monolayers of amoebocytes, prepared from hemolymph of infected and normal snails, were first fixed and then reacted with antisera obtained from mice infected for 7 to 9 weeks. Nonspecific and cross-reactions between the antisera and monolayers of amoebocytes were eliminated by absorbing the antisera with tissues from uninfected snails. The liberation of detectable schistosomal antigens in the hemolymph in soluble and particulate forms coincided with completion of the infection cycle 3 to 4 weeks after exposure to miracidia. The schistosomal antigens were demonstrable in the cytoplasm of amoebocytes and in the center of amoebocyte aggregates.