Search

Abstract: Mercury (Hg) bioaccumulates in the tissues of organisms and biomagnifies within food-webs. Gray wolves (Canis lupus) in Alaska primarily acquire Hg through diet; therefore, comparing the extent of Hg exposure in wolves, in conjunction with stable isotopes, from interior and coastal regions of Alaska offers important insight into their feeding ecology. Liver, kidney, and skeletal muscle samples from 162 gray wolves were analyzed for total mercury (THg) concentrations and stable isotopic signatures (δ13C, δ15N, and δ34S). Median hepatic THg concentrations were significantly higher in wolves with coastal access compared to wolves from interior Alaska. Stable isotope ratios, in conjunction with THg concentrations, provide strong evidence that coastal wolves are utilizing marine prey representing several trophic levels. The utilization of cross-ecosystem food resources by coastal wolves is clearly contributing to increased THg exposure, and may ultimately have negative health implications for these animals. [Copyright &y& Elsevier]

Molecular data have defined seven genetic Assemblages of Giardia duodenalis, named A–G. Humans are infected with Assemblages A and B, dogs primarily with C and D, and cats with F. Assemblage A has been subclassified into subtypes A-I to A-IV: A-I has been reported in humans and animals, A-II in humans, and A-III and IV exclusively in animals. Assemblage B has broad host specificity infecting humans and animals. Recently, small numbers of dogs and cats have been reported to also carry Assemblages A-I or B. Because these genotypes are found primarily in humans, and no comprehensive studies to address zoonotic transmission of G. duodenalis are yet available, the potential role of dogs and cats cannot be conclusively excluded. [Copyright &y& Elsevier]

Abstract: The prevalence of and risk factors associated with the shedding of cryptosporidial oocysts were determined for domestic cats in northeastern Mississippi and northwestern Alabama. Cryptosporidial oocysts were found in a single fecal samples from 30 of 250 cats using a centrifugal concentration technique followed by an immunofluorescent assay. The odds of a cat shedding oocysts were increased when another cat shedding oocysts was present in the household. Logistic regression analysis showed only concurrent shedding of Giardia cysts to be significantly associated with the presence of Cryptosporidium oocysts in the feces. Oocysts from 12 cats were successfully genotyped, based on sequencing of a fragment of the 18S rRNA gene, all isolates were Cryptosporidium felis. [Copyright &y& Elsevier]

Acanthocephalans, cestodes, and some species of nematodes acquire nutrients from the lumen contents in the gastrointestinal (GI) tract of their definitive host. These parasites are exposed to toxicants, such as mercury (Hg), through passive or active feeding mechanisms; therefore, the focus of this study was to determine if there is an effect of parasites on the dietary availability of total mercury (THg) within piscivorous pinniped hosts. THg concentrations ([THg]) in selected host tissues, parasites, and GI lumen contents from 22 California sea lions ( Zalophus californianus ), 15 ringed seals ( Phoca hispida ), and 4 spotted seals ( Phoca largha ) were determined. Among all pinnipeds, [THg] in acanthocephalans of the large intestine were significantly higher than concentrations in other samples (host lumen contents, other parasites and host intestinal wall), irrespective of location within the host GI tract. δ 15 N values of parasites depended both on parasite group and location within the GI tract. δ 15 N values were consistently higher in parasites inhabiting the large intestine, compared to elsewhere in the GI tract, for both sea lions and seals. δ 13 C values in parasites did not differ significantly from host GI tissues. Based on both [THg] and stable isotope values, parasites are likely affecting the Hg bioavailability within the GI lumen contents and host tissues, and toxicant-parasite interactions appear to depend on both parasitic taxon as well as their location within the host intestine. [ABSTRACT FROM AUTHOR]

Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves ( Canis lupus ) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to be Toxascaris leonina . Taenia species present included T. krabbei and T. hydatigena . Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from < 1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ 13 C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host. [ABSTRACT FROM AUTHOR]