(Repeats to add UPDATE 1 to headline.)
(Updates with details of outbreak)
WASHINGTON, April 26 (Reuters) - Twenty cases of swine flu have been confirmed in the United States as the White House stepped up efforts to monitor the outbreak, U.S. officials said on Sunday.
Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, said at a White House briefing that all of the U.S. cases have been mild. U.S. officials said President Barack Obama is being briefed regularly on the potential spread of the new strain of flu, which has taken as many as 81 lives in Mexico.
"At this point, a top priority is to ensure that communication is robust and that medical surveillance efforts are fully activated," John Brennan, assistant to the president for Homeland Security, said at a White House news conference.
He said beefed up monitoring would enable rapid identification and notification of any new cases that might occur in the United States and Mexico.
Besser said the CDC has confirmed one case of swine flu in Ohio, two in Kansas and eight in New York. There were already seven confirmed cases in California and two in Texas. Officials emphasized that the U.S. cases are not as severe as the cases that have been identified in Mexico.
Nevertheless, the officials recommended planning for potential U.S. school closures and Homeland Security Secretary Janet Napolitano said the United States would release some of its stockpiles of anti-flu drugs Tamiflu and Relenza. She also said the United States would declare a public health emergency to start the flow of aid to states and communities that might be affected by the outbreak.
(Writing by Donna Smith, editing by Patricia Zengerle)
3D Model of an influenza virus Officials in Mexico are asking citizens to take actions in order to minimize the spread of the swine flu outbreak. Citizens are urged to stay away from large crowds, avoid kissing people and stay at least 6 feet (1.8 meters) away from one another. Additionally, all schools and universities in Mexico City have been closed indefinitely. In addition, at least twenty people in the United States have been infected with the disease, causing the government to issue a "national public health emergency."

On Monday, Mexican officials reported that at least 100 deaths in their country were "likely linked" to the swine flu. Dr. Jose A. Cordova Villalobos, the health secretary of Mexico, said that at least 20 of the deaths have been confirmed as swine flu related deaths while the World Health Organization (WHO) says that 71 people have died from complications caused by the disease. Meanwhile, over 1,300 people in Mexico have been hospitalized because of flu-like symptoms since April 13.

In New Zealand, 26 students and teachers might have been infected by the flu during their trip to Mexico. Dr. Julia Peters, the clinical director of Auckland Regional Public Health Service, said that at least 22 have shown flu-like symptoms. All of the students and teachers are being quarantined pending test results. Similar health scares occurred in Israel. France, Spain and the United Kingdom, where people with flu-like symptoms have been tested for the swine flu. In the UK, test results came back negative for the deadly strain, while results from Israel, France and Spain are still pending.

In the United States, there have been twenty confirmed cases of swine-flu in the states of Kansas, Texas and California. Today, New York Mayor Michael Bloomberg reported that at least 8 students from a New York preparatory school have contracted the mutated flu strain. The White House also said today that there was at least one confirmed case of the disease in Ohio, prompting the federal government to declare a "public health emergency." 

Robert Gibbs, a White House spokesman, said that the swine flu outbreak "is of great concern to the White House," and that President Obama is now receiving briefings on the issue on a regular basis. Gibbs added, "I would tell people it's certainly not a time to panic ... The government is taking all the steps it needs to and must do to take the precautions to deal with whatever size and scope we may be facing."

The WHO is taking the outbreak very seriously, calling it a "public health emergency of international concern" that has a "pandemic potential." The WHO's emergency council met on Saturday for the first time since its creation. If the committee decides that the swine flu outbreak is an international public health emergency, WHO could recommend travel warnings and restrictions and possible border closures.

The Center for Disease Control says that swine flu symptoms include a fever above 100º Fahrenheit, diarrhea, nausea, vomiting, coughing, sore throat, lack of appetite, runny nose, breathing problems and fatigue. However, not all symptoms are present in each case of swine flu.