As the US grapples with the worst coronavirus outbreak in the world, Florida hit a grim milestone on Sunday when it shattered the national record for a state’s largest single-day increase in positive cases. The state recorded 15,299 positive cases in only 24 hours to Sunday. Deaths from the virus have also been rising in the United States, especially in the south and west, though still well below the highs recorded in April. “I really do think we could control this, and it’s the human element that is so critical. It should be an effort of our country. We should be pulling together when we’re in a crisis, and we’re definitely not doing it,” said University of Florida epidemiologist Dr Cindy Prins. Admiral Brett Giroir, a member of the White House coronavirus task force, said it was "absolutely essential" to wear a mask in public after resistance in some US states. Admiral Giroir, the assistant secretary at the Health and Human Services Department, told <em>ABC's</em> <em>This Week</em> on Sunday that "if we don't have that, we will not get control of the virus". President Donald Trump wore a mask in public for the first time on Saturday, something Democratic House Speaker Nancy Pelosi said on Sunday showed he had “crossed a bridge”. Ms Pelosi told<em> CNN's</em> <em>State of the Union</em> that she hoped it meant the president "will change his attitude, which will be helpful in stopping the spread of the coronavirus". In Texas' hard-hit Houston, two top Democratic officials called for the nation’s fourth-largest city to be placed again under lockdown as area hospitals strained to accommodate the onslaught of sick patients. In Florida, where parts of Walt Disney World reopened on Saturday, 15,299 people tested positive, for a tally of 269,811 cases. Forty-five deaths were recorded, according to the state's Department of Health statistics on Sunday. California held the previous record of daily positive cases with 11,694 set last Wednesday. The numbers come at the end of a record-breaking week as Florida reported 514 fatalities – an average of 73 a day. Three weeks ago, the state was averaging 30 deaths a day. Researchers expect deaths to rise in the US for at least several weeks, but some think the count probably will not go up as dramatically as it did in the spring because of several factors, including increased testing. The World Health Organisation, meanwhile, reported another record increase in the global number of confirmed cases over a 24-hour period, at more than 230,000 new infections. The UN health agency said the US again topped the list among countries, with more than 66,000 cases. The figures don’t necessarily account for delays in reporting cases and are believed to far underestimate actual scale of the outbreak.