View Record

Yeast and Hematodinium

Stentiford, G.D., Evans M., Bateman, K., Feist, S.W. (2003). Co-infection by a yeast-like organism in Hematodinium-infected European edible crabs (Cancer pagurus) and velvet swimming crabs (Necora puber) from the English Channel. Diseases of Aquatic Organisms 54, 195-202.

Opportunistic pathogen, Hematodinium infected crabs have been shown to exhibit haemocytopenia (decline in haemocytes) enabling opportunistic pathogens to exploit the weakened immune system and cause secondary infections. Infected crabs did not display external symptoms of yeast-like infection but did show signs of hyperpigmentation of carapace and showed opaque to creamy colouration of haemolymph, symptoms characteristic of Hematodinium infection.

No obvious host reaction to Hematodinium sp. parasite cells. Host reaction associated with large numbers of small ovoid yeast-like cells, 4.14 ± 0.06 x 2.68 ± 0.03 µm, some of which may be in state of division (budding). Stain positively with both PAS stain and Grocott-Gomori silver stain.. Yeast-like cells can be seen as free cells, some of which may appear to be budding in the haemolymph surrounding hepatopancreatic (hp) tubules and in sinuses of other tissues. Under phase contrast microscopy cells appear refractile and can be easily distinguished from other cell types. Haemal sinuses may be congested with large haemocytic encapsulations of yeast-like cells. Abundant secretory packets within the B-cells of hp tubules may be seen, granuloma-like inflammatory reactions, melanised encapsulation responses within gill lamellae and connective tissues and hp tubule degeneration.