Identification, isolation, and characterization of a species-specific 30-kDa antigen of Oesophagostomum dentatum

In the search for a serology tool for the diagnosis of nonpatent as well as patent infections with Oesophagostomum dentatum in pigs a water-soluble, unglycosilated antigen of about 30 kDa specific for the third-stage larvae of the parasite was purified by ion-exchange chromatography. In Western blots, the antigen was first detected by antibodies at day 7 postinfection. Cross-reactivity with O. quadrispinulatum, Ascaris suum, or Trichuris suis was not detected. It is suggested that this protein is a suitable tool for the species-specific serodiagnosis of O. dentatum infection in pigs. Received: 15 June 1998 / Accepted: 28 September 1998     

Quantitative proteomic studies in resistance mechanisms of Eimeria tenella against polyether ionophores

Polyether ionophores are widely used to treat and control coccidiosis in chickens. Widespread use of anticoccidials resulted in worldwide resistance. Mechanisms of resistance development and expansion are complex and poorly understood. Relative proteomic quantification using LC-MS/MS was used to compare sensitive reference strains (Ref-1, Ref-2) with putatively resistant and moderately sensitive field strains (FS-R, FS-mS) of Eimeria tenella after isotopic labelling with tandem mass tags (TMT). Ninety-seven proteins were identified, and 25 of them were regulated. Actin was significantly upregulated in resistant strains in comparison with their sensitive counterparts. On the other hand, microneme protein (MIC4) was downregulated in resistant strains. Optimization of labelling E. tenella sporozoites by TMT might identify further proteins that play a role in the obvious complex mechanism leading to resistance against Monensin.     

Comments on potential efficacy of monthly administrations of spot-on moxidectin 2.5 %/imidacloprid 10 % in the simultaneous prevention of major canine filarioses

Information on the efficacy of pharmaceutical protocols for the prevention of the major canine filarioses (i.e., Dirofilaria immitis, Dirofilaria repens, and Acanthocheilonema reconditum) under natural conditions is scant. Chemoprophylaxis for canine filarioses under field conditions deserves to be studied more fully and information about vector biology, ecology, and seasonality has to be well appreciated to correctly set control protocols. It is advisable that researchers planning field trials to assess the efficacy of any product for the prevention of canine vector-borne diseases should consider different eco-epidemiological aspects of diseases, including their dynamics of transmission, which are driven by complex interactions between animals, pathogens, and vectors.     

Inactivation of exogenous endoparasite stages by chemical disinfectants: current state and perspectives

Chemical disinfection is common practice and inevitable to achieve sufficient control over parasites particularly in intensive animal housing systems. To identify suitable chemicals, reliable data on antiparasitic efficacy of disinfectants are required. This review summarizes recently published experience with procedures applied to evaluate the viability of a variety of endoparasites following physical or chemical stress. It is concluded that laboratory models used to assess antiparasitic efficacy of e.g. commercial disinfectants should consider the most resistant stages of both helminths and protozoa, i.e. ascarid eggs and coccidia oocysts. To ensure reproducibility and transparency, standardized protocols are pivotal. Such protocols are established on a national level (e.g. DVG guidelines in Germany); however, internationally accepted certification procedures are currently lacking.     

Efficacy of early treatment with toltrazuril in prevention of coccidiosis and necrotic enteritis in chickens

In the present study, efficacy of the toltrazuril treatment for prevention of coccidiosis and necrotic enteritis was tested. Ninety-six 14-day-old commercial broiler chickens were caged and divided into eight groups (n=12), designated groups 1 to 8. Chickens of groups 1 to 6 were inoculated orally at 18 days of age with 25,000 oocysts of Eimeria tenella and 75,000 oocysts of Eimeria brunetti. At 22 days of age, chickens of groups 1 to 6 were infected with 10⁹ colony-forming unit Clostridium perfringens. Chickens of group 1 were treated with 75 parts/10⁶ toltrazuril in drinking water for 8 h on two consecutive days up to 12 h before Eimeria infection, while chickens of groups 2 to 5 were treated with the same dose of toltrazuril at 12 h, 36 h, 60 h and 84 h after Eimeria infection, respectively. The non-treated group 6 served as a positive control. Chickens in group 7 were treated with toltrazuril at 17 and 18 days of age, and those of group 8 remained uninfected and non-treated as a negative control. The feed conversion ratio was higher in the positive control compared with other groups. The mortality rates were 16.8% and 41.7% in the late toltrazuril-treated (at 84 h) and infected non-treated chickens, respectively. Lesions scores of necrotic enteritis or coccidiosis in infected, non-treated chickens were significantly more severe compared with negative controls (P<0.01) and late toltrazuril-treated (at 84 h) chickens (P<0.05). In conclusion, application of toltrazuril before Eimeria challenge protected chickens from coccidiosis and indirectly from successive necrotic enteritis caused by C. perfringens infection.     

Fasciola hepatica alters coagulation parameters in sheep plasma in vivo and in vitro

The blood-sucking activities of the liver fluke, Fasciola hepatica, are likely to cause alterations in coagulation during the course of infection; and the effect of F. hepatica on various coagulation parameters was studied during the course of acute and chronic fasciolosis of sheep over a period of 17 weeks. Whole blood and plasma samples from infected sheep (with 800 metacercariae each) and uninfected controls were collected weekly until 17 weeks post-infection (w.p.i.) and the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) were determined. Additionally, adult F. hepatica were recovered from bile ducts, incubated for the production of excretory/secretory products (ESP) or homogenised and the effect of fluke products on APTT, PT and TT was determined. Anaemia was evident in infected sheep from 8 w.p.i. until 17 w.p.i. Plasma APTT was accelerated during 8, 9, 12, 14, 16 and 17 w.p.i., while PT was prolonged at 8-11 w.p.i. and TT at 10, 14 and 17 w.p.i. Addition of worm ESP or homogenate to plasma resulted in an enhancement of the intrinsic pathway (APTT) together with a prolongation of the extrinsic and common pathways (PT, TT) of coagulation. It was concluded that F. hepatica contains and releases substances that may contribute to coagulation changes in vivo. Further characterisation of the active substance(s) in vitro revealed heat inactivation, a size >30 kDa and inhibition by the proteinase inhibitors Complete and EDTA for the APTT-accelerating substance(s). The TT-deceleration, in contrast, was increased after heating.     

Autofluorescence microscopy for the detection of nematode eggs and protozoa, in particular Isospora suis, in swine faeces

Parasites from swine faeces were examined for autofluorescence. Oocysts of Eimeria polita, E. scabra and Isospora suis, cysts of Balantidium coli and eggs of Oesophagostomum dentatum, Strongyloides ransomi and Trichuris suis (but not those of Ascaris suum) emitted light after excitation with UV light. I. suis oocyst counts in McMaster chambers utilising autofluorescence were compared to those from conventional bright field microscopy. Similarly, faecal smears containing I. suis were examined using the same techniques. Autofluorescence was superior to bright field microscopy in detecting oocysts after flotation and was highly significantly more sensitive when direct smears were examined.     

Effects of curcumin (diferuloylmethane) on Eimeria tenella sporozoites in vitro

The negative effects of coccidiosis on poultry health and productivity and increasing problems related to drug resistance have stimulated the search for novel and alternative methods of control. The present study evaluates the anticoccidial activity of curcumin (diferuloylmethane), a natural polyphenolic compound abundant in the rhizome of the perennial herb turmeric (Curcuma longa) which is a spice and food colourant commonly used in curries and also used as medicinal herb. Its effects were evaluated on Eimeria tenella sporozoites, including morphological alterations, sporozoite viability and infectivity to Madin–Darby bovine kidney (MDBK) cells. Morphological alterations of the sporozoites were recorded as deformation due to swelling and cell membrane corrugations. Curcumin at concentrations of 25, 50, 100, 200 and 400 μM showed considerable effects on sporozoite morphology and viability in a dose-dependent manner after incubation over 3, 6, 18 and 24 h while lower curcumin concentrations (6.25 and 12.5 μM) were not effective. In comparison to the untreated control, sporozoite infectivity was reduced at curcumin concentrations of 100 and 200 μM by 41.6% and 72.8%, respectively. Negative effects of curcumin on MDBK cells were not seen at these concentrations; however, curcumin at concentrations of 1,800, 600 and 400 μM was toxic to MDBK cells and affected cell proliferation. In conclusion, curcumin exhibited a marked inhibitory effect in vitro on E. tenella sporozoites inducing morphological changes and reducing sporozoite viability and infectivity.