Ligula intestinalis (L.) (Cestoda: Pseudophyllidea): plerocercoid‐induced changes in the spleen and pronephros of roach, Rutilus rutilus (L.), and gudgeon, Gobio gobio (L.)

Abstract

The effects of the plerocercoid of Ligula intestinalis (L.) (Cestoda: Pseudophyllidea) on the major lymphoid organs, the spleen and pronephros, of roach, Rufilus rufilus (L.), and gudgeon, Gobio gobio (L.), are described. The spleen of ligulosed roach showed a significant decrease in weight. Differential cell counts suggested this was due to a reduction in erythrocytes, despite significant increases in macrophages and vacuolated granulocytes. The spleen of gudgeon, which consisted almost entirely of erythrocytes, showed a slight reduction in weight in ligulosed fish. In both roach and gudgeon this decrease was independent of parasite burden. Differential cell counts of the pronephros from ligulosed roach revealed a significant decrease in neutrophils and increase in vacuolated granulocytes. In the pronephros of gudgeon, however, cell counts were unaffected by ligulosis. Ultrastructural observations included an apparent disintegration of vacuolated granulocytes and increased pinocytic activity in specialized endothelial cells in the spleens of ligulosed roach. Also, melano-macrophage centres and melano-macrophages increased in the spleen of ligulosed roach and gudgeon, respectively. The marked changes in spleen weight and differential cell counts in ligulosed roach and lack of such changes in ligulosed gudgeon correlate with the differential response to the parasite by these two fish species.

Modulation of granulocyte responses in three-spined sticklebacks Gasterosteus aculeatus infected with the tapeworm Schistocephalus solidus

“…In another study by Barber et al (2001), elevated counts of total white blood cells were detected in S. solidus-infected G. aculeatus; however, their study did not distinguish between lymphocytes and granulocytes. Mobilisation of granulocytes is a common feature of the immune responses of fishes to helminth parasites (Taylor & Hoole 1989, Sharp et al 1992, Secombes & Chappell 1996. The initial increase in granulocyte proportions in the blood and head kidney of infected stickleback described here could be due to the mobilisation of granulocytes against S. solidus rather than to changes in lymphocyte frequencies.…”

Stimulation of carp Cyprinus carpio lymphocytes in vitro by the blood fluke Sanguinicola inermis (Trematoda:Sanguinicolidae)

“…This evasion strategy has previously been demonstrated by mammalian schistosomes (Capron & Camus 1979). Another evasion strategy used by parasites is the production of cytotoxic substances such as proteinase inhibitors, which suppress the effective functioning of the host immune system, and thus enhance parasite survival (Capron & Camus 1979, Hoole & Arme 1982, Pourreau et al 1987, Taylor & Hoole 1989. Previous studies by Richards et al (1994a) also found lysis of host cells around the eggs of S. inermis, but it is not known if this lysis occurred ds a consequence of substances released from the entrapped eggs, which were subsequently encapsulated within a granulomatous lesion.…”

Changes in the cellular composition of the spleen and pronephros of carp Cyprinus carpio infected with the blood fluke Sanguinicola inermis Trematoda: Sanguimcolidae)

“…Previous studies on tapeworm infections of fish (Taylor & Hoole 1989) have shown that parasitism alters the cellular composition of the pronephros and spleen of cyprinid fish. The present investigation has been undertaken to determine the effects of Sanguinicola inermis infection on the lymphoid organs of experimentally infected carp, and forms part of a more extensive study on the interaction between the parasite and carp leucocytes.…”