Disseminated Neoplasia in Cerastoderma edule: Geographic Distribution
Disseminated neoplasia in the common cockle (Cerastoderma edule) occurs primarily along the Atlantic coasts of Europe, with documented cases in Galicia (NW Spain), France (Arcachon Bay and Normandy), Ireland, and Portugal (Algarve region), extending along the northwest African coast.
Geographic Distribution Pattern
The disease shows a clear Atlantic European distribution:
Spain (Galicia): This region has documented hyperendemic disease since 1997, with DN present year-round at high prevalence in adult cockles 1. Multiple cockle beds in different Galician Rías show persistent infection 1.
France: DN was first detected in Arcachon Bay with prevalences ranging from 2.2% to 13.6% throughout the year 2. More recently, the disease was detected for the first time in Normandy along the western coast 3.
Portugal: The Algarve region (southern coast) has documented cases, though interestingly showing a decline in prevalence between 2017 and 2024 3.
Ireland: Historical reports document DN in Irish cockle populations 4.
Key Epidemiological Features
The disease affects cockles inhabiting the Atlantic coasts of Europe and northwest Africa 5. Two distinct transmissible cancer lineages (BTN lineages) have been identified in C. edule populations, both with hemocytic origins 5.
Species Specificity
Importantly, DN appears species-restricted to cockles. Surveys of cohabiting bivalve species (Ruditapes spp. and Scrobicularia plana) in the same geographic areas found no cases of haemic neoplasia, suggesting cockle cancer transmission does not cross species barriers 3.
Temporal Patterns
The disease shows temporal variation with annual prevalence minima typically occurring in spring, likely due to death of heavily affected cockles concurrent with gonad ripeness and spawning 1. In Arcachon Bay, prevalences showed unexplained oscillations throughout the year not correlated with seawater temperature 2.
Clinical Significance
This is a transmissible cancer—clonal neoplastic cells that spread between individual cockles as an infectious disease 5. The disease causes leukemia-like pathology and is associated with massive mortalities in affected populations 4. Cockles at the sediment surface show higher prevalence (11.8%) and intensity (53.0%) compared to normally buried cockles (6.7% and 40.6% respectively) 2, suggesting DN may impair normal burrowing behavior.
The identification of these geographic patterns is critical for fisheries management, particularly for populations important to traditional fisheries and cultural practices along European Atlantic coasts.