In a brief communiqu issued on Tuesday, the Health Ministry said the outbreak was first detected on January 6, and was being contained.
"Fifty-one cases have been confirmed to date," the statement read, without mentioning fatalities.
"Due to the measures adopted transmission is in the phase of extinction," it said.
But in off-the-record discussions with a ministry official and doctor directly involved in fighting the outbreak, a different picture emerged with hundreds of suspected cases.
They said the first cases were traced to a baseball game at the Latin American Stadium in the Cerro municipality of the Cuban capital, where fans come from all parts of the city to watch their team, the Industriales, play.
"We know what happened. Either the pork sandwiches or Tan Rico soda pop was contaminated at a game earlier this month," the official said.
"Even some of the baseball players became sick," she added.
The Health Ministry statement said the outbreak had begun in Cerro and "later spread to other municipalities in the capital."
Tens of thousands of tourists are visiting Havana, but there have been no reports of foreigners catching the illness.
Community clinics and family doctors are on high alert and giving out instructions to prevent the disease, transportation hubs have passengers sterilizing their shoes before leaving town and eateries are being systematically inspected and sometimes closed, residents say.
The official said Havana had been preparing to fight the disease since Cuba's first cholera outbreak in decades last year in eastern Granma province.
There have been scattered cases since then, but all were traced to the Granma area and quickly contained, she said.
"This time is different. There are many cases, but we are well prepared in terms of supplies and the protocol," she said, adding, "let's just hope we can stop this before it becomes much worse."
ARMY OF HEALTH PERSONNEL
Martica, a Culture Ministry employee, tells a tale typical of the stories circulating around the city.
"There is this young man who often buys a milkshake around the corner from the office building where I work. He comes to the cafeteria and eats lunch with his girlfriend," she said.
"Last week he was hospitalized with cholera and an army from the Health Ministry descended upon the area and my building, handing out penicillin, checking the water supply, closing snack shops and questioning residents and workers," she said.
The lack of official information until Tuesday has led to rumors that dozens have died in the Cuban capital, though the official and doctor said there had been only one fatality.
Three Havana hospitals have been designated to handle cholera cases - one for adults, another for children and a third for pregnant women.
Another doctor working at the designated adult hospital, the Center for Tropical Medicine, said they were swamped at the weekend with suspected cases.
Cholera is generally not fatal, but can kill in just a few hours when diarrhea and vomiting cause dehydration, especially among the elderly.
The illness runs its course within a week, making it relatively easy to track, but at the same time is highly contagious, spreading from hand to mouth, through contaminated food and the water supply.
"So far there is no indication it's in the water supply, but we are dumping more chlorine in the system," the Health Ministry official said.
Until 2012, there had been no cholera outbreaks reported in Cuba since well before the 1959 revolution and the creation of a national health system by the Communist government.
Hundreds of Cuban doctors and nurses have worked for over a decade in Haiti which has battled a cholera outbreak that has killed more than 7,000 people since that country's 2010 earthquake.
Cuba lies closer to Haiti than any other Caribbean country, with the exception of the Dominican Republic, which shares the island of Hispaniola with the crisis stricken country and has reported more than 20,000 cholera cases and 350 deaths since the Haiti epidemic began.
(Editing by Tom Brown and Mohammad Zargham)