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Can infection be prevented?
from What you need to know about epizootic ulcerative syndrome (EUS) – An extension brochure for Africa
How is epizootic ulcerative syndrome (EUS) spread? What factors cause the fish to become infected with EUS?
Successful invasion and establishment of EUS in fish requires epithelial tissue damage, a susceptible fish species and environmental conditions which favour sporulation of A. invadans.
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In some countries, outbreaks occur in wild fish first and then spread into fish ponds.
A number of risk factors are associated with EUS occurrence; some are predisposing factors, others are environmental conditions and biological factors that contribute to the occurrence of EUS.
Shipping movements, ballast water, fish migrations and ocean currents are potential pathways by which the pathogen can spread between water bodies.
Cross border movement of fish for aquaculture and the ornamental fish trade are proven pathways by which the disease spreads.
Some EUS outbreaks follow heavy rainfall and flood events; reductions in water temperature, alkalinity and salinity; and acidified run-off water from acid sulphate soil areas have been associated with outbreaks of disease.
Parasites and rhabdoviruses have also been associated with particular outbreaks, and secondary gram-negative bacteria invariably infect EUS lesions.
©FAO/D. Huchzermeyer, Rhodes University
Figure 32. Fishing nets may be infected with spores of Aphanomyces invadans and should be dried immediately after use, and not be left where they remain wet as in this picture, Bangweulu swamps, north Zambia, 2014 outbreak of epizootic ulcerative syndrome (EUS).
Figure 33. The ornamental variety of the common carp (koi) is a popular and often valuable fish that is imported into many countries for ornamental purposes. Some varieties of koi have been shown to be susceptible to epizootic ulcerative syndrome (EUS).
Figure 34. Gold fish, Carassius auratus, is a popular and widely traded ornamental fish that is known to be susceptible to epizootic ulcerative syndrome (EUS).
©FAO/D. Huchzermeyer, Rhodes University
©D. K. Hatai ©D. K. Hatai
©D. K. Hatai
Gold fish, Carassius carassius auratus is the susceptibility to Aphanomyces piscicida. (Hatai, 1980) Gold fish, Carassius carassius auratus is the susceptibility to Aphanomyces piscicida. (Hatai, 1980) Gold fish, Carassius carassius auratus is the susceptibility to Aphanomyces piscicida. (Hatai, 1980)
