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Some lesions in experimental fascioliasis
14
LABORATORY MEETING
HELMINTHOLOGY Mr. J. E. D. Keeling and Mr. G. D i c k e r s o n
The Wellcome Laboratories of Tropical Medicine, Beckenham, Kent Chemotherapy of helminthiases A large diagram of a generalized laboratory animal showed the location of helminth parasites which are used in screening substances for anthelmintic activity. Specimens or photographs were arranged to show the relationships of species used in primary and secondary screening tests and the objective parasites in man or in domestic livestock. Accompanying tables showed the performance, in various experimental host-parasite systems, of a number of anthelmintic substances which are widely used in human and veterinary medicine.
Professor Ben D a w e s
King's College, London S o m e lesions in e x p e r i m e n t a l fascioliasis Lesions revealed recently in experimental fasciollasis are due partly to the feeding activities of juvenile and adult stages of Fasciola hepatica, but also to some extent to the host's tissue reactions to its parasites. This demonstration of early-stage lesions indicates damage to various tissues during the migratory phase within the mammalian host, numerals indicating sections shown. During the first day of juvenile life after excystment, the young flukes break down various tissues within the intestinal wall progressively, causing damage to the villi of the mucosa, circular and longitudinal muscles and serosa. Tissue debris within the caeca of the flukes matches that seen in the burrows formed, but in all parts of the intestinal wall leucocyte infiltrations which inaugurate the first stages of tissue repair also extend the pathological effects. When young flukes are passing through the abdominal cavity they may penetrate various organs, causing similar damage to their tissues. Burrows of a sort are formed in lymph nodes, adipose tissue, pancreas and occasionally lungs and, although flukes may not remain long in such locations, damage is enhanced by widespread leucocyte infiltrations which are evoked. This is well seen in adipose tissue. Within the hepatic parenchyma the young flukes make extensive burrows, taking great and still greater toll of hepatic cells as they grow. Here also, damage is caused by leucocyte infiltrations and may become inordinate when flukes become unusually large as a result of tardy entry into the bile ducts. Especially heavy infiltrations of polymorphs may then shatter the walls of the burrows, converting these into large blood-filled spaces. T h e hyperplasia of the bile duct and underlying fibrosis of connective tissue are also related to the local tissue reactions of the host and may be moderate or intense, producing lesser or greater amounts of pathological tissue which is utilized by feeding adult flukes in the balanced host-parasite relationship which is set up and sustained for long periods of months and even years as these tissues are abraded by the flukes and renewed by the pathological condition which is finally established.
Dr. M. F. A. Saoud, Dr. H. S. EI-Nahal and Dr. G. S. Nelson
London School of Hygiene and Tropical Medicine Fluorescent antibody levels in m o n k e y s infected w i t h two strains o f Schistosoma monsoni
The fluorescent antibody technique ( F A T ) was used for the serological diagnosis of schistosomiasis by SADUN et al. (1960), and later the indirect method of staining was use). in the quantitative estimation of antibody titres in positive immune sera (SADuN et al., 1962d The demonstration illustrated fluorescent antibody titres, plasma protein levels and faecal egg counts in representative rhesus monkeys infected with 750 cercariae of the
LABORATORY MEETING
HELMINTHOLOGY Mr. J. E. D. Keeling and Mr. G. D i c k e r s o n
The Wellcome Laboratories of Tropical Medicine, Beckenham, Kent Chemotherapy of helminthiases A large diagram of a generalized laboratory animal showed the location of helminth parasites which are used in screening substances for anthelmintic activity. Specimens or photographs were arranged to show the relationships of species used in primary and secondary screening tests and the objective parasites in man or in domestic livestock. Accompanying tables showed the performance, in various experimental host-parasite systems, of a number of anthelmintic substances which are widely used in human and veterinary medicine.
Professor Ben D a w e s
King's College, London S o m e lesions in e x p e r i m e n t a l fascioliasis Lesions revealed recently in experimental fasciollasis are due partly to the feeding activities of juvenile and adult stages of Fasciola hepatica, but also to some extent to the host's tissue reactions to its parasites. This demonstration of early-stage lesions indicates damage to various tissues during the migratory phase within the mammalian host, numerals indicating sections shown. During the first day of juvenile life after excystment, the young flukes break down various tissues within the intestinal wall progressively, causing damage to the villi of the mucosa, circular and longitudinal muscles and serosa. Tissue debris within the caeca of the flukes matches that seen in the burrows formed, but in all parts of the intestinal wall leucocyte infiltrations which inaugurate the first stages of tissue repair also extend the pathological effects. When young flukes are passing through the abdominal cavity they may penetrate various organs, causing similar damage to their tissues. Burrows of a sort are formed in lymph nodes, adipose tissue, pancreas and occasionally lungs and, although flukes may not remain long in such locations, damage is enhanced by widespread leucocyte infiltrations which are evoked. This is well seen in adipose tissue. Within the hepatic parenchyma the young flukes make extensive burrows, taking great and still greater toll of hepatic cells as they grow. Here also, damage is caused by leucocyte infiltrations and may become inordinate when flukes become unusually large as a result of tardy entry into the bile ducts. Especially heavy infiltrations of polymorphs may then shatter the walls of the burrows, converting these into large blood-filled spaces. T h e hyperplasia of the bile duct and underlying fibrosis of connective tissue are also related to the local tissue reactions of the host and may be moderate or intense, producing lesser or greater amounts of pathological tissue which is utilized by feeding adult flukes in the balanced host-parasite relationship which is set up and sustained for long periods of months and even years as these tissues are abraded by the flukes and renewed by the pathological condition which is finally established.
Dr. M. F. A. Saoud, Dr. H. S. EI-Nahal and Dr. G. S. Nelson
London School of Hygiene and Tropical Medicine Fluorescent antibody levels in m o n k e y s infected w i t h two strains o f Schistosoma monsoni
The fluorescent antibody technique ( F A T ) was used for the serological diagnosis of schistosomiasis by SADUN et al. (1960), and later the indirect method of staining was use). in the quantitative estimation of antibody titres in positive immune sera (SADuN et al., 1962d The demonstration illustrated fluorescent antibody titres, plasma protein levels and faecal egg counts in representative rhesus monkeys infected with 750 cercariae of the