Molecular characterization of Ancylostoma inhibitors of coagulation factor Xa. Hookworm anticoagulant activity in vitro predicts parasite bloodfeeding in vivo.
(1/17)
Bloodfeeding hookworms, which currently infect over a billion people in the developing world, are a leading cause of gastrointestinal hemorrhage and iron deficiency anemia. The major anticoagulant inhibitor of coagulation factor Xa has been identified from the hookworm parasite Ancylostoma ceylanicum using reverse transcription PCR and 3'-rapid amplification of cDNA ends. This is the first anticoagulant cloned from a hookworm species for which humans are recognized permissive hosts. Despite approximately 50% amino acid similarity, A. ceylanicum anticoagulant peptide 1 (AceAP1) is both immunologically and mechanistically distinct from AcAP5, its homologue isolated from the dog hookworm Ancylostoma caninum. Studies using plasma clotting times and single stage chromogenic assays of factor Xa activity have demonstrated that the recombinant AceAP1 protein is substantially less potent than AcAP5 and that soluble whole worm protein extracts of adult A. ceylanicum possess less anticoagulant activity than extracts of A. caninum. These values correlate with previously reported differences in bloodfeeding capabilities between these two species of hookworm, suggesting that factor Xa inhibitory activity is predictive of hookworm bloodfeeding capabilities in vivo. These fundamental differences in the mechanism of action and immunoreactivity of the major anticoagulant virulence factors from related Ancylostoma hookworm species may have significant implications for human vaccine development. (+info)
Mortality of Creole kids during infection with gastrointestinal strongyles: a survival analysis.
(2/17)
Mortality due to strongyles infection in small ruminants is a critical component of flock productivity in a tropical climate. In goat production, few experiments have been conducted to estimate the variability of this trait. A survival analysis study was carried out in the Creole experimental flock of INRA-Gardel (Moule, Guadeloupe) to identify management and genetic factors influencing mortality of kids reared at pasture and infected with gastrointestinal strongyles, predominantly Haemonchus contortus and Trichostrongylus colubriformis. Survival curves from 3 and 11 mo of age were analyzed for 837 kids sired by 48 bucks and 250 does. The causes of death were recorded. Mortality due to gastrointestinal strongyles was the variable considered. The flock management included drenchings with levamisole every 8 wk. Fecal egg counts and packed cell volume were regularly measured after 7 wk of natural infection. All but 6.7% of the records were uncensored, with an average failure time of 165 d. The probability of death following gastrointestinal infection was more than three times greater in males than in females. Kids raised by their mother before weaning had a lower (P < 0.05) relative risk of dying than those reared in nursery (0.40 vs. 1). Parity of the dam and litter size effects were not significant. The risk of death was reduced by approximately 80% during the 3 wk that followed a drenching (P < 0.01). Risk decreased by about 25% for each additional kilogram of body weight at weaning. Live weight, fecal egg counts, and packed cell volume all had significant effects on risk of death when introduced as time-dependent covariates in the model (P < 0.0001 for live weight and packed cell volume, and P < 0.01 for fecal egg counts). The estimated genetic variability was small and inaccurate. These results demonstrated that risk of death from gastrointestinal infection could be reduced with appropriate flock management. High infection levels increased the risk of death, but they were not the direct cause. The important mediation of reduced body weight and anemia in likelihood of death is highlighted. More data are needed to better assess the possibility for genetic improvement of viability in Creole kids during gastrointestinal strongyle infection. (+info)
Global warming is changing the dynamics of Arctic host-parasite systems.
(3/17)
Global climate change is altering the ecology of infectious agents and driving the emergence of disease in people, domestic animals, and wildlife. We present a novel, empirically based, predictive model for the impact of climate warming on development rates and availability of an important parasitic nematode of muskoxen in the Canadian Arctic, a region that is particularly vulnerable to climate change. Using this model, we show that warming in the Arctic may have already radically altered the transmission dynamics of this parasite, escalating infection pressure for muskoxen, and that this trend is expected to continue. This work establishes a foundation for understanding responses to climate change of other host-parasite systems, in the Arctic and globally. (+info)
New method for simultaneous species-specific identification of equine strongyles (nematoda, strongylida) by reverse line blot hybridization.
(4/17)
The ability of a reverse line blot (RLB) assay to identify 13 common species of equine small strongyles (cyathostomins) and to discriminate them from three Strongylus spp. (large strongyles) was demonstrated. The assay relied on the specific hybridization of PCR-amplified intergenic spacer DNA fragments of the nuclear ribosomal DNA to membrane-bound species-specific probes. All cyathostomins examined were unequivocally identified and simultaneously discriminated from each other and from three large strongyles (Strongylus edentatus, Strongylus equinus, and Strongylus vulgaris). This assay will enable the accurate and rapid identification of equine cyathostomins irrespective of their life cycle stage, opening important avenues for a better understanding of their biology and epidemiology and of the pathogenesis of cyathostomin-associated disease. In particular, this RLB method promises to be a powerful diagnostic tool to determine the roles of individual species in the pathogenesis of mixed infections and to elucidate some aspects of cyathostominosis. Also, it could represent a basic step toward the development of a rapid and simple molecular test for the early detection of drug-resistant genotypes of horse strongyle species. (+info)
Diagnostic and clinical implications of a nested PCR specific for ribosomal DNA of the feline lungworm Aelurostrongylus abstrusus (Nematoda, Strongylida).
(5/17)
Aelurostrongylus abstrusus larvae in the colon of two cats.
(8/17)
A 12-year-old male domestic shorthair cat with a history of depression, aggression, and fever was presented for necropsy, and formalin-fixed tissues from a second male domestic shorthair cat of unknown age were submitted for histopathologic examination to the Athens Veterinary Diagnostic Laboratory. Both cats had granulomatous pneumonia associated with large numbers of parasite eggs and larvae, consistent with Aelurostrongylus abstrusus. Both cats also had larvae within glands in the colon that were identified morphologically as A. abstrusus first-stage larvae. (+info)