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Studies on the pathology of experimental sparganosis
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LABORATORY MEETING
type response became increasingly important after this, characterized by proliferation of cells in rapidly enlarging germinal centres and the production of large numbers of plasma cells in the cortico-medullary junction and medullary cords of the nodes. Repeat infections were more complex, with both types of immunological response occurring throughoUt the infection. Cats yielding high worm loads produced little antibody response, both histologically and serologically, as well as developing a good cell-mediated response. Thus in both single and repeat infections, a combination of cell-mediated and antibodytype immunological responses occurred. Effect o f c o n t i n u a l r e i n f e c t i o n on B. pahangi i n f e c t i o n s in cats D. A. D E N H A M , T. P O N N U D U R A I AND G. S. N E L S O N
Medical Helminthology Department, London School of Hygiene and Tropical Medicine Cats given a single infection with Brugia pahangi show very stable microfilarial counts. We have studied the effect of repeatedly challenging these cats arid have observed 3 different responses. 1. There is no change in microfilarial levels for at least 8 months. 2. The microfilarial level increases and then levels off to form a new stable count which is also maintained for at least 8 months. 3. The microfilarial count goes on increasing for as long as we have observed. I n cats with responses 1 and 2 there has been a sudden decline in the n u m b e r of microfilariae and the blood has been completely negative. This does not happen with type 3. It was also shown that the adult worm population continues to increase for at least 15 challenges with 50 larvae but after 20 challenges there was no development of adult worms. The most advanced pathology was seen in cats which became microfilaria negative. Those in group 3 showed no oedema or skin thickening. S t u d i e s on the p a t h o l o g y o f e x p e r i m e n t a l s p a r g a n o s i s E. K. O P U N I , R. L. M U L L E R AND G. S. N E L S O N
Department of Medical Helminthology, London School of Hygiene and Tropical Medicine The demonstration presented some effects of the early pathology associated with infection with plerocercoids of a spirometrid tapeworm (MULLER et al., 1968). Studies have been made using hairless and T.O. strain mice, rats and rhesus monkeys. The use of hairless mice makes it possible to observe some of the effects of the tissue migration of the plerocercoid in the live animal. Infection was initiated by either intraperitoneal injection of infected Cyclops, by subcutaneous injection of plerocercoid scoleces or by feeding whole plerocercoids. The pathology may be divided into two phases : - -
i.
Intestinal phase
I n orally infected mice and rats penetration took place mainly in the duodenum. Migration took a direct route and the process was over in 30-45 minutes. Apart from haemorrhagic patches marking the sites of penetration, tissue damage was minimal. When the intraperitoneal route was used, extensive haemorrhage, tissue damage to submucosa and villi were observed. Intestinal ulcer, haemorrhagic ascites and peritonitis resulting from larval migration from the peritoneum to the subcutaneous tissues have been observed in a rhesus monkey and several mice and rats. A high mortality occurred in infected mice between day 21 and 28 as a result of haemorrhage and peritonitis.
ii.
Tissue or subcutaneous phase
Characteristic feature of the histology of this phase include tissue damage, encapsulation of worms, tunnelling, scarring, necrosis and chronic inflammation. Infiltration by plasma cells, lymphocytes, eosinophils and mast cells has been noted. REFERENCE
MULLER, R. L., WEEKS, n. & NELSON, G. S. (1068). Trans. R. Soc. trop. Med. Hyg., 62, 467.
LABORATORY MEETING
type response became increasingly important after this, characterized by proliferation of cells in rapidly enlarging germinal centres and the production of large numbers of plasma cells in the cortico-medullary junction and medullary cords of the nodes. Repeat infections were more complex, with both types of immunological response occurring throughoUt the infection. Cats yielding high worm loads produced little antibody response, both histologically and serologically, as well as developing a good cell-mediated response. Thus in both single and repeat infections, a combination of cell-mediated and antibodytype immunological responses occurred. Effect o f c o n t i n u a l r e i n f e c t i o n on B. pahangi i n f e c t i o n s in cats D. A. D E N H A M , T. P O N N U D U R A I AND G. S. N E L S O N
Medical Helminthology Department, London School of Hygiene and Tropical Medicine Cats given a single infection with Brugia pahangi show very stable microfilarial counts. We have studied the effect of repeatedly challenging these cats arid have observed 3 different responses. 1. There is no change in microfilarial levels for at least 8 months. 2. The microfilarial level increases and then levels off to form a new stable count which is also maintained for at least 8 months. 3. The microfilarial count goes on increasing for as long as we have observed. I n cats with responses 1 and 2 there has been a sudden decline in the n u m b e r of microfilariae and the blood has been completely negative. This does not happen with type 3. It was also shown that the adult worm population continues to increase for at least 15 challenges with 50 larvae but after 20 challenges there was no development of adult worms. The most advanced pathology was seen in cats which became microfilaria negative. Those in group 3 showed no oedema or skin thickening. S t u d i e s on the p a t h o l o g y o f e x p e r i m e n t a l s p a r g a n o s i s E. K. O P U N I , R. L. M U L L E R AND G. S. N E L S O N
Department of Medical Helminthology, London School of Hygiene and Tropical Medicine The demonstration presented some effects of the early pathology associated with infection with plerocercoids of a spirometrid tapeworm (MULLER et al., 1968). Studies have been made using hairless and T.O. strain mice, rats and rhesus monkeys. The use of hairless mice makes it possible to observe some of the effects of the tissue migration of the plerocercoid in the live animal. Infection was initiated by either intraperitoneal injection of infected Cyclops, by subcutaneous injection of plerocercoid scoleces or by feeding whole plerocercoids. The pathology may be divided into two phases : - -
i.
Intestinal phase
I n orally infected mice and rats penetration took place mainly in the duodenum. Migration took a direct route and the process was over in 30-45 minutes. Apart from haemorrhagic patches marking the sites of penetration, tissue damage was minimal. When the intraperitoneal route was used, extensive haemorrhage, tissue damage to submucosa and villi were observed. Intestinal ulcer, haemorrhagic ascites and peritonitis resulting from larval migration from the peritoneum to the subcutaneous tissues have been observed in a rhesus monkey and several mice and rats. A high mortality occurred in infected mice between day 21 and 28 as a result of haemorrhage and peritonitis.
ii.
Tissue or subcutaneous phase
Characteristic feature of the histology of this phase include tissue damage, encapsulation of worms, tunnelling, scarring, necrosis and chronic inflammation. Infiltration by plasma cells, lymphocytes, eosinophils and mast cells has been noted. REFERENCE
MULLER, R. L., WEEKS, n. & NELSON, G. S. (1068). Trans. R. Soc. trop. Med. Hyg., 62, 467.