Fish tapeworm infections (diphyllobothriasis) in Canada,particularly British Columbia.

Although the risk of diphyllobothriasis is generally low in Canada, fish tapeworm infections seem to have become more frequent in recent years. This increase is probably a consequence of the growing popularity of raw or inadequately cooked ethnic fish dishes or of a preference for lightly cooked fish, especially salmon. Only freshwater fish become infected with the larvae, but not everyone may realize that salmon can acquire the parasites before they leave their native lakes and rivers for the sea. If fish known to be sources of the tapeworms are to be eaten raw they should first be well frozen or salted to kill the larvae. Physicians should regard fish tapeworm infection as a notifiable disease. In Canada niclosamide, the drug of choice, is available from the manufacturer on a patient-by-patient basis.     

Parasites of lake sturgeon, Acipenser fulvescens (Chondrostei: Acipenseridae), from central Canada

Nineteen species of parasites were recovered from lake sturgeon, Acipenser fulvescens, from four major waterways of Central Canada; the Saskatchewan, Nelson, Winnipeg and Rainy River systems, Twelve of these are new host records. Host specific parasites, Crepidostomum auriculatum , Diclybothrium armatum , Spinitectus acipenseri and Truttaedacnitis clitellarius , forming the core parasite species, were recovered with the highest prevalence (≥70%) and were most widely distributed. Polypodium hydriforme was recovered from only stage IV sturgeon oocytes. With the exception of Pomphorhynchus bulbocolli , prevalence and intensity of endohelminth infections were not correlated with sex or age of host but the distribution of non host-specific parasites among sampling sites was determined by the type and relative abundance of food items consumed. The parasites of lake sturgeon are closely correlated to its diet and the species of parasites recovered are more similar to those of freshwater sturgeon in Eurasia than to other species of Acipenser in North America. The present parasite community of lake sturgeon appears to have been shaped by three major factors; the presence of core parasite species which predates geographic isolation, a benthic freshwater diet which has reshaped the parasite community to one comprising freshwater species and a long association with freshwater habitats which is reflected in the reproductive isolation of the lake sturgeon and lastly, the establishment of a host-specific parasite, Spinitectus acipenseri .     

Discrimination among Fish Models by Hawaiian Eleotris sandwicensis (Eleotridae)1

I examined behavioral responses of the benthic fish Eleotris sandwicensis to painted models (dummies) of fish that Eleotris typically encounter in Hawaii. Eleotris sandwicensis were associated with coarse substrates where their mean (±SE) density was 1.5 (±0.30) fish/m². I hypothesised that Eleotris would retreat from all models in open areas, but not when they were present in shelters. The five models represented Stenogobius hawaiiensis, Awaous guamensis, E. sandwicensis (female coloration), a male E. sandwicensis in breeding colors (black), and a 12 cm block of wood (control). Whether or not Eleotris held its position or retreated was not a function of body size. Differences among the responses of Eleotris to models depended on whether or not the fish was hidden or exposed on substrates. More retreats in response to models occurred when Eleotris were exposed on substrates than when fish were hidden. There were no significant differences in the response of E. sandwicensis to models when fish were exposed on substrates. In contrast, responses of E. sandwicensis to the models were not random for fish that were hidden, indicating that Eleotris discriminated among the models. The basis for discrimination among models was most likely visual. Although Eleotris are typically secretive, their presence on exposed substrates at this study site may be attributed to die lack of benthivorous fishes and few avian predators. The ability of Eleotris to distinguish among fishes when hidden as well as their tendency to retreat in response to all intruders whenever exposed on substrate surfaces could reduce potential interactions between Eleotris and other native and nonindigenous fishes.     

Coccidian Parasites (Apicomplexa: Eimeriidae) from Insectivores: New Species from Shrew Moles (Talpidae) in the United States1

All of 18 shrew moles, Neurotrichus gibbsii, collected in Oregon and Washington were infected with one or more species of coccidia. Three eimerians and one isosporan were identified and described as new species. Sporulated oocysts of Eimeria heterocapita n. sp. were subspheroid to ellipsoid, 25.5 times 21.4 (23–27 times 18–23) μm. A membranous, cap-like structure was present at one pole of the oocyst, but a micropyle, oocyst residuum, and polar body were absent. Ovoid sporocysts were 13.6 times 10.0 (12–15 times 9–11) μm; a compact sporocyst residuum was present, but Stieda, sub-, and parastieda bodies were absent. This species was found in 2 of 18 (11%) hosts. Sporulated oocysts of Eimeria neurotrichi n. sp. were avoid, 17.6 times 13.6 (16–20 times 11–16) μm; micropyle and oocyst residuum were absent, but a polar body was present. Ovoid sporocysts were 10.7 times 5.5 (9–12 times 5–6) μm; Stieda body and sporocyst residuum were present, but sub- and parastieda bodies were absent. This species was found in 2 of 18 (11%) hosts. Sporulated oocysts of Eimeria parastiedica n. sp. were subspheroid, 27.4 times 25.5 (25–30 times 22–28) μm; micropyle, oocyst residuum, and polar body were absent. Ovoid sporocysts, pointed at both ends, were 18.3 times 10.4 (16–20 times 9–11) μm; Stieda, sub-, and parastieda bodies were present as was a sporocyst residuum. This species was found in 2 of 18 (11%) hosts. Sporulated oocysts of Isospora neurotrichi n. sp. were subspheroid, 13.9 times 12.0 (11–16 times 10–15) μm; micropyle and oocyst residuum were absent, but 1–3 polar bodies were present. Ellipsoid sporocysts were 9.2 times 6.1 (8–11 times 5–8) μm; sub- and parastieda bodies were absent, but a Stieda body and sporocyst residuum were present. This species was found in 17 of 18 (94%) hosts. Ten of 18 (56%) hosts were seen to be naturally infected with only one coccidium.     

Fish Communities of the Lower Fraser River (Canada) and a 21-year Contrast

Fish communities were sampled at 14 sites along the lower 120km of the Fraser River, British Columbia by beach seine four times in 1972–1973 and three times in 1993–1994. Of the 37 species collected, peamouth chub, largescale sucker, starry flounder, and northern squawfish were predominant in either density or biomass. Densities and biomass of most species and all fish combined were higher in 1993–1994. Strong rank correlations of species abundance or biomass indicated that the overall fish community structure was very similar in both periods. At smaller spatial scales (reaches of 2–3 sites) and shorter time scales (by season), less than half the comparisons showed any significant correlation indicating changes in community composition. Largescale sucker, one of the largest contributors to biomass in both periods, showed decreased abundance, i.e., lower density, lower biomass, and large differences in the size-frequency distribution, specifically very low representation of small size classes. Other species, especially small-bodied forms, generally increased in numbers. Despite large changes in the lower Fraser River ecosystem in the past 21 years, the overall fish community has shown remarkably little change over that interval.     

Studies on the Coccidian Parasites (Apicomplexa: Eimeriidae and Pfeifferinellidae) of Pulmonate Gastropods1

Pulmonate and prosobranch gastropods collected in Minnesota and Washington were examined for the presence of coccidian parasites. Typical coccidian oocysts were recovered from the feces of 89 of 543 (16%) pulmonate snails representing the families Lymnaeidae, Physidae, Planorbidae, and Succineidae. No coccidial infections were apparent in 104 specimens representing the prosobranch families Viviparidae and Pleuroceridae. Oocysts identified as Pfeifferinella ellipsoides were recovered from 21 of 101 (21%) Stagnicola elodes, 2 of 94 (2%) Physa gyrina, and 4 of 67 (6%) Aplexa hypnorum although incidence of infection differed greatly (2–40%) dependent upon the locality sample. This coccidian has not been described previously from North America and is reported here from members of the families Lymnaeidae and Physidae for the first time. Twenty percent of Oxyloma retusa from one habitat were shedding oocysts slightly smaller than, but otherwise identical with, those of Alveocystis gugleri. A third as yet unidentified oocyst was recovered from up to 54% of Helisoma trivolvis. As a group, the coccidia of pulmonate molluscs have been poorly studied. The findings of this survey, however, suggest that these parasites may be more common and widely distributed in both the Basommatophora and Stylommatophora than previously believed.     

Parasites and diseases of bison in Canada IV. Serologic survey for brucellosis in bison in northern Canada

Serum samples collected from 2,365 free-roaming hybrid bison (Bison bison bison x Bison bison athabascae) in Wood Buffalo National Park and adjacent areas in the Northwest Territories were tested for brucellosis during the period 1959 to 1974. A positive reaction was obtained in 739 (31.2%) of the animals tested. The overall effect of brucellosis on this free-roaming bison population is unknown. The authors also dealt with some of the actual and possible consequences of the disease in this population.     

Biochemical Aspects of Parasitism by the Angiosperm Parasites: Phenolics in Parasites and Hosts

the contents of total phenolics in three parasitic angiosperms, Cuscuta species, Orobanche aegyptiaca and Dendrophthoe falcata and their respective hosts, were colorimetrieally determined. A biochemical comparison was made of the phenolics on the basis of the ability of alcoholic extracts of the tissues to inhibit amylose phosphorylase in vitro. High concentration of phenolics seemed to be a general feature of parasitic angiosperms. An increase in the concentration of the phenolics occurred in the tissues of infected hosts, in comparison with controls. the phenolics of Orobanche and mistletoe had inhibitory activity against amylose phosphorylase, but those of Cuscuta developed the inhibitory ability only when growing on hosts which themselves possessed inhibitory phenolics. the inhibitory activity of host phenolics was sometimes altered as a result of infection by parasite. Although the hosts often exerted some influence on the concentration and the inhibitory activity of phenolics in the parasites, there was no direct relationship between host and parasite phenolics. the sum of the phenolics in the tissues of parasite and the infected bost generally exceeded the phenolics in the tissues of the control host. The content of phenolics and their inhibitory activity did not appear to be directly related to the resistance of a host or to the extent of its susceptibility to parasite infection.     

Parasites of rice stemborers in Sarawak (Malaysian Borneo)

Observations on parasites were made during a study of the following rice stem-borers in Sarawak (Malaysian Borneo):Tryporyza incertulas (Walker),T. innotata (Walker),Chilo suppressalis (Walker)C. auricilia (Dudgeon), andSeamia inferens (Walker). Egg-parasitism was often high, but that of the larval and pupal stages generally very low. Between 40–80% of theTryporyza eggs were parasitised byTelenomus rowani (Gahan), while 30–50% were attacked byTetrastichus schoenobii Ferrière. About 40–90% of the eggs ofChilo were parasitised byTrichogramma? japonicum Ashmead and 5–26% byTelenomus dignus (Gahan). Only 0.4–3% of theTryporyza larvae were parasitised by a Braconid,Rhaconotus schoenobivorus (Rohwer), whileBracon chinensis Szepligeti attacked 0.2–0.7% of the larvae ofC. suppressalis. Parasitism ofSesamia larvae byApanteles flavipes Cameron was equally low, never exceeding 2%. Pupal parasitism was somewhat higher.Tetrastichus israeli (Mani & Kurian) attacked 8% and 18% of the pupae ofC. suppressalis andS. inferens, respectively, while the Ichneumonid,Xanthopimpla stemmator (Thunberg) attacked up to 3% of the pupae of the former species. The immature stages of some of these parasites are described.     

Coccidian Parasites (Apicomplexa: Eimeriidae) from Insectivores. II. Six New Species from Japanese Shrew Moles (Talpidae)1

ABSTRACT. Thirty-eight of 51 (74.5%) shrew moles collected in Japan were infected with from one to four species of Eimeria and/or Isospora including six of six Dymecodon pilirostris and 32 of 45 (71.1%) Urotrichus talpoides. Four eimerians and two isosporans were identified and all are described as new species. Sporulated oocysts of Eimeria amorphospora n. sp. were subspheroid/ellipsoid, 21.1 × 17.9(18-25 × 16-21) μm. Sporocysts were amorphous, gelatinoid envelopes 20.3 × 7.5 (17–24 × 7–9) μm. Sporozoites were enclosed together within a membrane in each sporocyst. This species was found in 9 of 45 (20%) U. talpoides. Sporulated oocysts of Eimeria gonocilia n. sp. were subspheroid/ellipsoid, 28.8 × 24.4 (25–30 × 21–28) μm; a highly ornate outer oocyst wall gave the appearance of a ciliated ball. Sporocysts ovoid, pointed at both ends, were 17.0 × 9.0 (15–19 × 7–11) μm; this species was found in 4 of 45 (8.9%) U. talpoides. Sporulated oocysts of Eimeria talpoidei n. sp. were asymmetrical ovoid, 20.6 × 13.3 (18–23 × 12–15) μm, with sporocysts lacrimiform, 12.0 × 5.8 (10–14 × 5–7) μm. This species was found in 7 of 45 (15.6%) U. talpoides. Sporulated oocysts of Eimeria honshuensis n. sp. were ellipsoid, 15.5 × 11.4 (13–18 × 10–13) μm, with sporocysts ovoid, 9.1 × 5.2 (8–10 × 4–6) μm. This species was found in 10 of 45 (22.2%) U. talpoides and in 5 of 6 (83.3%) D. pilirostris. Sporulated oocysts of Isospora dymecodi n. sp. were subspheroid/ellipsoid, 15.8 × 12.6 (13–17 × 11–13) μm, with sporocysts ellipsoid, 10.9 × 6.9 (10–13 × 6–8). This species was found in six of six D. pilirostris. Sporulated oocysts of Isospora urotrichi n. sp. were spheroid/subspheroid, 13.4 × 12.4 (11–16 × 9–14) μm, with sporocysts ovoid, 9.2 × 6.3 (8–11 × 5–7) μm. This species was found in 27 of 45 (60%) U. talpoides. Only 14 of 38 (36.8%) infected hosts (one D. pilirostris, 13 U. talpoides) were seen to be naturally infected with only one coccidian species when sampled.