Cuban dissident Walter Clavel says that when he took his 2-year-old son to a hospital Wednesday with a case of diarrhea, the boy was tested for a sometimes fatal disease that the government is stubbornly refusing to acknowledge — cholera.

Nurses told him the test was negative, and the boy was not quarantined in the three wards reserved for cholera patients at the North Pediatric Hospital in the eastern city of Santiago de Cuba, Clavel said.

Cuba, especially the eastern third of the island, is suffering through an alarming outbreak of cholera — as well as the mosquito-borne dengue fever — brewed in its decrepit water and sewer systems and fueled by Hurricane Sandy’s floods, according to residents.

More than a dozen deaths have been reliably reported. Hospitals and prisons have been quarantined at times. Schools have been shut down, and so have restaurants and street kiosks selling juices and other products made with water.

Government buildings have established hand and shoe disinfection stands at their entrances. Some public health officials have gone door to door asking if anyone is suffering from diarrhea, vomiting or fevers, and others distributed water purification tablets.

Cuba’s government has said nothing publicly about cholera since Aug. 28, when it announced that an outbreak in the eastern city of Manzanillo — the first in a century — had ended after three deaths and 417 confirmed cases.

Spread by bacteria that cause severe diarrhea and vomiting, the disease killed millions in the Middle Ages.

Police in uniform and plainclothes stationed at hospitals are telling visitors to keep quiet about cholera and other diseases, Clavel told El Nuevo Herald — apparently to avoid upsetting the Caribbean island’s $2.5 billion-a-year tourism industry.

“We have to question whether the Cuban government today prioritizes their need for tourism … more than local public health demands,” wrote Sherri Porcelain, a public health expert at the University of Miami and researcher at its Institute for Cuban and Cuban American Studies.

Worst hit by the cholera has been eastern Cuba, where Sandy came ashore last month halfway between Manzanillo and Santiago, the island’s second-largest city and capital of a province with the same name.

It damaged water, electricity and sewer systems, flooded latrines and left behind puddles where dengue-carrying mosquitoes easily bred.

“There is tremendous worry in Santiago,” said Clavel, one of a dozen Cubans contacted for this story. Many were dissidents, unafraid to talk about the epidemics. Their versions coincided in many ways, but could not be individually confirmed.

In the only independent report, a Nov. 2 announcement by the Pan American Health Organization in Washington, a branch of the U.N.’s World Health Organization, noted that “suspected cholera cases detected in several areas of the country continue to be investigated.”

Two Cubans said the cholera spread rapidly in Sandy’s wake in part because infected inmates at the Mar Verde prison were transferred to the Boniato prison, both in Santiago province, and later to another prison in the neighboring province of Camaguey.

Mar Verde was quarantined as of Monday, said city of Santiago dissident Eunices Madaula. More than 100 cholera cases were reportedly being treated at the Boniato prison’s infirmary and 80 more at the nearby Ambrosio Grillo Hospital.