Helminth Collection and Identification from Wildlife

Wild animals are commonly parasitized by a wide range of helminths. The four major types of helminths are "roundworms" (nematodes), "thorny-headed worms" (acanthocephalans), "flukes" (trematodes), and "tapeworms" (cestodes). The optimum method for collecting helminths is to examine a host that has been dead less than 4-6 hr since most helminths will still be alive. A thorough necropsy should be conducted and all major organs examined. Organs are washed over a 106 μm sieve under running water and contents examined under a stereo microscope. All helminths are counted and a representative number are fixed (either in 70% ethanol, 10% buffered formalin, or alcohol-formalin-acetic acid). For species identification, helminths are either cleared in lactophenol (nematodes and small acanthocephalans) or stained (trematodes, cestodes, and large acanthocephalans) using Harris'' hematoxylin or Semichon''s carmine. Helminths are keyed to species by examining different structures (e.g. male spicules in nematodes or the rostellum in cestodes). The protocols outlined here can be applied to any vertebrate animal. They require some expertise on recognizing the different organs and being able to differentiate helminths from other tissue debris or gut contents. Collection, preservation, and staining are straightforward techniques that require minimal equipment and reagents. Taxonomic identification, especially to species, can be very time consuming and might require the submission of specimens to an expert or DNA analysis.     

Oochoristica novaezealandae n. sp. (Cestoda: Anoplocephalidae) from a New Zealand skink,Leiolopisma nigriplantare maccanni Hardy, 1977

Abstract

Oochoristica novaezealandae n. sp. is described from the small intestine of a skink, Leiolopisma nigriplantare maccanni (Hardy 1977) from Birdling's Flat, Banks Peninsula, South Island, New Zealand. In having fewer than 20 testes it differs from all other species in the genus except O. chinensis Jensen, Schmidt & Kuntz, 1983; O. vacuolata Hickman, 1954; O. lygosomae Burt, 1933; and O. lygosomatis Skinker, 1935. Of these, it most resembles O. chinensis, but differs from it in the ovary, which consists of 2 rounded lobes; they are subdivided into finger-like lobules in O. chinensis. Further, O. novaezealandae has a conspicuous, encapsulated, sac-like mass of glands surrounding the genital atrium; these are not present in O. chinensis.     

Differences in pyloric caeca morphology between Arctic charr Salvelinus alpinus ecotypes: adaptation to trophic specialization or parasite‐induced phenotypic modifications?

Gut-tract morphology differed between benthivorous and zooplanktivorous Arctic charr Salvelinus alpinus caught in the littoral and pelagic zones of a sub-Arctic lake. The differences were related to trophic niche and infection with the cestodes Cyathocephalus truncatus and Eubothrium salvelini . Measurements that were unrelated to cestode infection, including intestinal length, numbers of pyloric caeca and posterior pyloric caeca morphology, differed between S. alpinus that had consumed different prey types, suggesting an adaptive response to divergent trophic niches. The anterior pyloric caeca of S. alpinus with high numbers of cestodes were significantly wider and shorter than those in fish with lower levels of infection. The differences were strongly associated with infection by C. truncatus , which was site-selective and attached to the anterior caeca with a large scolex. Differences in caecal measurements were probably the result of mechanical damage caused by scolex attachment and host responses to infection with C. truncatus . The differences in anterior caeca were also an indirect indicator of trophic specialization. Benthivorous S. alpinus were more exposed to, and more heavily infected with C. truncatus than were pelagic zooplanktivorous fish, because this cestode had Gammarus lacustris as its intermediate host. Nevertheless, care should be exercized when using gut measurements for making inferences about the trophic ecology of fish because a history of infection with cestodes may have profound effects on caecal morphology.     

The effect of development of Taenia hydatigena larvae in the peritoneal cavity of dogs on resistance to a challenge infection with Echinococcus granulosus

Activated oncospheres of T. hydatigena within filtration membrane diffusion chambers implanted intraperitoneally into dogs developed into larvae 3 mm in dia possessing a scolex anlage without hooks. Exogenous antigens released by developing T. hydatigena larvae failed to stimulate any measurable resistance in the dogs to challenge infection with E. granulosus protoscolices.     

Isolation and partial characterization of a Taenia taeniaeformis metacestode proteinase inhibitor

Suquet C., Green-Edwards C. and Wes Leid R. 1984. Isolation and partial characterization of a Taenia taeniaeformis metacestode proteinase inhibitor. International Journal for Parasitology14: 165–172. A proteinase inhibitor from the metacestode of Taenia taeniaeformis was purified 136-fold to apparent homogeneity as evidenced by one Coomassie Blue protein staining band on 10% SDS slab gels under both reducing and non-reducing conditions. The apparent molecular weight under dissociating conditions was 19,500. This parasite protein inhibited esterolysis of TAME and BTEE by bovine pancreatic trypsin and chymotrypsin respectively in a time and dose-dependent manner. Proteolysis of casein by both enzymes was also inhibited in a time and dose-dependent manner. The parasite inhibitor was stable from pH 2.2 to 10.5 and was fully active after heating at 56 °C for 3 h. The proteases pronase and thermolysin, at concentrations of 1 mg ml^?1, completely inactivated the metacestode inhibitor. Two sulfhydryl proteases, papain and chymopapain, used at concentrations of 1 mg ml^?1 were without effect. The irreversible proteinase inhibitors TLCK, TPCK and PMSF at concentrations up to 10 mM had no effect on the parasite inhibitor.     

Life history, ecology and parasite community structure in Soviet birds

The paper describes an investigation of parasite richness in relation to host life history and ecology using data from an extensive survey of helminth parasites (cestodes, trematodes and nematodes) in Soviet birds. Correlates of parasite richness (number of parasite species per host species) were sought among 13 life-history variables, 13 ecological variables and one non-biological variable (number of host individuals examined) across a sample of 158 species of host. A statistical method to control for the effects of phylogenetic association was adopted throughout. Parasite richness correlates positively with the number of hosts examined (sample size) in all three parasite groups. Positive correlations (after controlling for the effects of sample size) were also found between host body weight and parasite richness for trematodes and nematodes, but not for cestodes.
A number of ecological variables were associated with parasite richness. However, when the effects of sample size and body weight were controlled for, only a single significant correlation (an association between trematode richness and aquatic habitat) remained. Similarly, a number of significant correlates of parasite richness were found among the life-history variables examined. Though several of these were robust to the confounding effects of sample size, all could be explained by the co-variation between life-history traits and body weight among the host species under investigation.     

Diapause of copepods as an element for stabilizing the parasite system of some fish helminths

The analysis of infection dynamics of copepods, which are the intermediate hosts of three helminth species of freshwater fishes (Triaenophorus crassus, Proteocephalus exiguus and P. percae), has shown that diapause in the life cycle of the copepods is favourable for preserving the infection in the waterbody until physiological prerequisites for successful infection of the final host are acquired. The peculiarity of a copepod's life cycle may determine the strategy of a parasite in its preimaginal phase as a waiting stage, and the duration of the residence of helminth larvae in copepods that have an obligatory diapause, is one of the elements the provide stability in parasite systems.     

Occurrence of Tetracampos ciliotheca (Cestoda: Bothriocephalidea) in the gall bladder of Clarias anguillaris in Burkina Faso

The presence of the bothriocephalidean cestode Tetracampos ciliotheca Wedl, 1861 is reported from the gall bladders of the catfish Clarias anguillaris from Loumbila and Ziga reservoirs, Burkina Faso, in 2010–2011. Of the 159 specimens examined, 47 were infected. Mean intensity of infection was 4.3 parasites per infected host, the maximum was 22 tapeworms in the gall bladder and the mean abundance was 1.3 parasites. There was no significant difference between males and females or between the two localities. There was a positive relationship between fish size and the number of parasites in the gall bladder. This study provides further evidence of the presence of T. ciliotheca in the gall bladder, in which most tapeworms found were localised. Tapeworms were also found in the stomach and intestine, with prevalences of 1% and 16%, and mean infection intensities of 1 and 5.3, respectively.     

Intestinal helminths infection of rats (Ratus norvegicus) in the Belgrade area (Serbia): the effect of sex, age and habitat

SUMMARY: Gastrointestinal helminths of Norway rat (Rattus norvegicus) from the Belgrade area were studied as a part of a wider ecological research of rats in Serbia (data on the distribution, population ecology, economic and epizoothiological-epidemiological importance, and density control). Rats were captured from May 2005 to July 2009 at both urban and suburban-rural sites. Of a total of 302 trapped rats 48% were males and 52% females, with 36.5% and 38.8% of juvenile-subadult individuals, per sex respectively. Intestinal helminth infection was noted in 68.5% of rats, with a higher prevalence in male hosts and in adult individuals. Higher numbers of infected juveniles-subadults were noted in suburban-rural habitats, while an opposite tendency was noted in adult rats. Seven helminth species were recovered, of which five were nematode (Heterakis spumosa, Nippostrongylus brasiliensis, Capillaria sp., Trichuris muns and Syphacia muris) and two cestode species (Hymenolepis diminuta and Rodentolepis fraterna). The most prevalent parasites were Heterakis spumosa (36.7%) and Hymenolepis diminuta (30.5 %). Sex and habitat-related differences were noted in the prevalence of infection with Capillaria sp. and Trichuris muris, while there were no age-related differences in the prevalence of infection with any individual helminth species. Significantly higher prevalence of infection was noted in summer as compared to spring or winter, with a tendency to be higher in autumn as compared to spring. The only significant difference in the prevalence of infection between habitat-related was noted during spring. H. spumosa was most prevalent in summer, while H. diminuta and N. brasiliensis in autumn. The mean intensity of infection with H. spumosa, R. fraterna, S. muris and T muris was higher in autumn than in the other seasons, while N. brasiliensis and Capillaria sp. occured in winter. No more than four helminth species were found in one host.     

Parasites and the avian spleen: helminths

A comparative analysis of the relationship between the spleen–a major organ of immunity and helminths was undertaken with bird species, using the phylogenetic regression technique. Species in which many individuals are infected with nematodes relative to the number of individuals examined for the presence of helminths (termed 'relative nematode presence') have significantly larger spleens, for a given body weight, in females (though not in males). There was little indication that this relationship depends on incidental ecological indices, the weights of other organs, or the 'relative presences' of trematodes, cestodes or haematozoa. Combined with previous, experimental, work it suggests that the avian spleen is important in resisting nematodes. Body weight is correlated with the relative presence of helminths; but even after removing body size effects, bird species which tend to be infected with trematodes are also more likely to be infected with cestodes. This paper indicates that the spleens of wild bird species are associated with macroparasites in the natural environment.