Epizootic Ulcerative Syndrome (EUS) Technical Handbook

Public healthPrior to the initial EUS outbreaks, most countries in the region had notexperienced a fish disease epizootic on such a large scale and, not surprisingly,there has been a great deal of local apprehension as to the consequences ofconsuming diseased fish or using affected waters for domestic or agriculturalpurposes. The concurrent deaths of ducks, cattle and other animals wereattributed to the occurrence of EUS. There is however, no scientific evidencethat the disease itself causes any human or animal illness. Rahman et al.(1988) were unable to induce any disease symptoms in ducks fed EUSinfectedfish or even injected with Aeromonas hydrophila cultures. Thereforeit is important to take public educational measures and allay the naturalfears of farmers, fishers and consumers about any wider effects of EUS.However, it must be stressed that good hygiene practices should be adheredto. In particular, dead fish should not be collected for sale or consumption, notbecause of ulcerative disease as such, but because bacteria or toxins presentin decomposing, EUS-affected fish may cause human illness.The uncontrolled use of chemotherapeutants to treat EUS or other diseasesin intensive culture systems is also a matter of public health concern.Chloramphenicol for instance, is used in treating typhoid in humans andthere is a risk that the build up of bacterial resistance in treated fish(Poonsuk et al., 1983) may be transferred to humans. Of greater concern tofarmers is the possibility of severe allergic reactions affecting farm workersin contact with the drug. There is also the danger that consumers may beexposed to drug residues in marketed fish that had been hurriedly harvestedbefore the recommended withdrawal period had been completed. Althoughthese are issues that affect aquaculture in general, the occurrence of EUShas underlined the need to develop appropriate guidelines and legislation toprotect farmers and consumers against the indiscriminate use ofchemotherapeutants.15