Recurrence of Pelecypod-associated cholera in Sardinia

From Oct. 30 to Nov. 7, 1979, 10 people in the Sardinian province of Cagliari had onset of bacteriologically confirmed cholera. Two symptom-free excretors of Vibrio cholerae O:1 were detected in household contacts of the patients. There were no deaths. All but 1 of the 12 people with V. cholerae O:1 infection gave a history of recent consumption of marine bivalves known locally as arselle (pelecypods). Triplicate matched neighbourhood controls for each of the first 7 cases identified were also interviewed; none had recently eaten arselle. V. cholerae O:1 was also recovered from samples of water and bivalves obtained from a lagoon on the outskirts of the city of Cagliari. Arselle had also been implicated as the vehicle of transmission in 1973 in the last outbreak of cholera in Sardinia. It seems unlikely that cholera transmission had persisted locally in the interim.