Water temperature, time of exposure and population density are key parameters in Enteromyxum leei fish‐to‐fish experimental transmission

• Published in: Journal of fish diseases Vol. 43; no. 4; pp. 491 - 502
• Main Authors: Picard‐Sánchez, Amparo, Estensoro, Itziar, Pozo, Raquel, Palenzuela, Oswaldo R., Piazzon, Maria Carla, Sitjà‐Bobadilla, Ariadna
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-04-2020
• Subjects: Anorexia; Antibodies; antibody; Aquaculture; Aquaculture facilities; Bream; Chronic illnesses; Cohabitation; Defence mechanisms; Disease control; Effluents; Enteromyxum leei; Exposure; Fish; Fish culture; Fish parasites; growth delay; High temperature; host–parasite interaction; Immune response; Immunity; Infections; Intestine; Intestines; Low temperature; Marine fishes; Marketability; Population density; temperature; time of exposure; Water temperature; host-parasite interaction; temperature; antibody; growth delay; time of exposure
• ISSN: 0140-7775; 1365-2761
• DOI: 10.1111/jfd.13147

Enteromyxum leei is a myxozoan histozoic parasite that infects the intestine of several teleost fish species. In gilthead sea bream (Sparus aurata), it provokes a chronic disease, entailing anorexia, delayed growth, reduced marketability and mortality. Direct fish‐to‐fish transmission, relevant in aquaculture conditions, has been demonstrated for E. leei via effluent, cohabitation, and oral and anal routes. However, the minimum time of exposure for infection has not been established, nor the possible effect on the fish immune response. Two effluent trials were performed at different temperatures (high: average of 25.6°C; and low: constant at 18°C), different times of exposure to the effluent (1, 3, 5 and 7 weeks) and different population densities. The results showed that 1 week was enough to infect 100% of fish at high temperature and 58.3% at low temperature. High temperature not only increased the prevalence of infection in posterior intestine, but also induced a higher production of specific antibodies, limiting the progression of the infection along the intestine. Longer time of exposure to the parasite and higher fish densities facilitated E. leei infection. These results show that effective diagnosis, lowering animal density and removal of infected fish are key aspects to manage this disease in aquaculture facilities.