First came the flood, then came the disease.

Over the past three months, the tourism industry of Venice has had its share of plagues.

Flooding in November, prompted by exceptionally high tides, led to mass cancellations. Now as Italy experiences the biggest coronavirus outbreak outside Asia, a similar and unwelcome drop-off is occurring.

According to Associazione Venezia Albergatori, an association of local hotel owners, 50 percent of reservations in Venice have been canceled in the last week. “The situation is dramatic for the industry,” said Vittorio Bonacini, the chairman.

Mr. Bonacini estimates that since November, Venetian tourism, worth 3 billion euro or about $3.3 billion, “has probably lost 800 million euro.” Since the outbreak began on Feb. 21, he said, Venice hotels have lost almost 70 percent of their international visitors.