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Diseases of Aquatic Organisms

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DAO 62:227-232 (2004)  -  doi:10.3354/dao062227

Anguillicolosis: dynamics of the infection over two decades

F. S. Lefebvre1, A. J. Crivelli2,*

1Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand
2Station Biologique de la Tour du Valat, Le Sambuc, 13200 Arles, France
*Corresponding author. Email:

ABSTRACT: The dynamics of the infection of the European eel Anguilla anguilla L. by the Asian nematode Anguillicola crassus Kuwahara, Niimi and Itagaki, 1974 (i.e. anguillicolosis) was monitored over 2 decades in an oligohaline canal in southern France (Camargue, Mediterranean coast). Since the first mention of the parasite in this canal in 1985, which was also the first record in France, prevalence of pre-adult and adult forms has risen from 32 to 73%. However, during the last 7 yr (1997 to 2003), prevalence seems to have stabilized around values of 60 to 70% and parasite load, though inter-annual variation is substantial, shows no sign of increase (intensity for the last 5 yr: min. = 3.70, max. = 9.66, mean = 6.01). Our results thus confirm the dynamic pattern observed elsewhere in Europe, i.e. a rapid spread following the introduction of the parasite in a water system and then stabilization around ceiling levels. We review possible mechanisms that may explain such a leveling off in the infection spread. We particularly document the possibility that repetitive infections may render the infected organ, i.e. the swimbladder, unsuitable for further A. crassus establishment. In support of this hypothesis, we showed that the infection rate is lower among eels with severely damaged swimbladders.

KEY WORDS: Epidemiology · Anguilla anguilla · Anguillicola crassus · Host-parasite system · Regulation process

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