Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Knowledge on the factors involved in the parasite transmission and course of infection in Sparus aurata

The direct fish-to-fish transmission of E. leei by the three assayed routes, cohabitation (CH), oral (OR) and contaminated effluent (EF) was confirmed in the present project, although differences in the onset and course of infection were observed. Several factors, such as parasite availability, entry route, differences in fish susceptibility and temperature could be involved.

According to the obtained results, the main entry route in CH and EF transmission [which reproduce the mode of contagion in natural (spontaneous) infections], is probably the anus, although the oral port of entry might also play an important role, considering the success of OR infections. The rectum and pyloric caeca are the main target organs in CH and OR, respectively. Parasite stages were only found in the different parts of the intestinal tract. Other parts of the digestive (stomach, gall bladder), haematopoietic organs, liver and blood were never found infected.

The earliest stage observed was a primary (P) cell harbouring one secondary (S) cell. As the infection progressed, parasite maturation also occurred, and proliferative and sporogonic stages were present in fish with mild or severe infections. Parasites were mainly found in small patches, in which initial stages were usually located in the periphery and more mature stages (sporoblasts and spores) in the central area. These observations were confirmed by ultrastructural studies.

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Universitat Autònoma de Barcelona (UAB)
Universitat Autònoma de Barcelona (UAB),Dept. Biologia Animal, Biologia Vegetal i Ecologia, Facultat de Veterinaria, Edifici V
08193 Bellaterra
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