Perilobular fibrosis in chronic bovine fascioliasis

Summary The character, extent, and localization of perilobular fibrosis were studied in cattle experimentally infected with Fasciola hepatica. Such fibrosis is indirectly due to the liver flukes. The regionally localized fibrosis results from cholestasis due to transient occlusion of branches of the biliary tree. In perilobular fibrosis it is possible to distinguish a florid, an intermediate, and an uncomplicated form. The florid phase is marked by proliferation of the biliary epithelium and is followed by infiltration of inflammatory cells.     

Diagnosis of ovine fascioliasis by a dot enzyme-linked immunosorbent assay: a rapid microdiagnostic technique

A microenzyme-linked immunosorbent assay (dot-ELISA) was modified for making an immunodiagnosis of Fasciola hepatica infections in sheep. Sheep were alloted as follows: group I-3 controls and 4 principals, each inoculated with 500 metacercariae; group II-3 controls and 7 principals, each inoculated with 250 metacercariae; and group III-3 controls and 7 principals, each inoculated with 500 metacercariae. Blood and fecal samples were collected from each animal every 2 weeks for 16 weeks. Presence (or absence) of flukes was confirmed by fecal examinations and examination of dissected livers at necropsy of the sheep. The dot-ELISA incubations were done at ambient room temperature. Nitrocellulose disks dotted with 1 microliter (50 ng of protein) of F hepatica excretory/secretory products were placed in 96-well tissue culture plates. After nonspecific binding sites on the disks were bound with bovine serum albumin-triethanolamine-buffered saline solution, dilutions (1:2) of positive- and negative-control serum samples or experimental serum samples were placed in appropriate wells for a 30-minute incubation. Wells were washed (3 times), and 50 microliters of horseradish peroxidase conjugated rabbit anti-sheep immunoglobulin G was added to each well for a 30-minute incubation and then aspirated. Substrate solution (4-chloro-1-naphthol, methanol, triethanolamine-buffered saline solution, and H2O2; 50 microliters) was added for a 30-minute incubation and then aspirated. Disks were air dried for visualization: solid purple dot = positive sample, or no dot = negative sample.(ABSTRACT TRUNCATED AT 250 WORDS)     

Albumin metabolism in chronic fasciola hepatica infections of cattle

The metabolism of I¹³¹-albumin was examined in chronically fluke- infected animals in which anaemia and hypoalbuminaemia were prominent features. Animals with high fluke-burdens exhibited increased turnover rates of albumin, presumably due to a loss of blood into the bile ducts. Despite pronounced hepatic fibrosis the animals had a normal or only slightly decreased synthetic rate of albumin. This was in keeping with results from liver-function tests and is presumably explained by enlargement of the liver, resulting in maintenance of a near-normal parenchymal cell mass.     

Chronic subclinical ovine fascioliasis: plasma glutamate dehydrogenase, gamma-glutamyl transpeptidase and aspartate aminotransferase activities and their significance as diagnostic aids

The effect of low grade chronic Fasciola hepatica infection on the concentration of plasma glutamate dehydrogenase (GD), gamma-glutamyl transpeptidase (gamma-GT) and aspartate aminotransferase (AST) was investigated in sheep dosed daily with three (AL3), eight (AL8) or 14 (AL14) metacercariae over 22 weeks or given a single dose of 200 metacercariae. Significant increases in plasma GD activity first occurred after nine, 12 and 23 weeks and in gamma-GT activity after 12, 24 and 32 weeks for groups AL14, AL8 and AL3 respectively. Changes in AST activity were not as clearly related to dose level. In sheep with single infection, both GD and gamma-GT were capable of detecting liver damage resulting from the migration of 10 or more flukes. Plasma GD and gamma-GT activities are more sensitive indicators of liver cell damage in chronic subclinical fascioliasis than AST activity and gamma-GT may be more suitable as a diagnostic aid on account of its greater stability.