Pre - existing conditions contributed to deaths of U.S. victims , report said . The WHO reports 642 confirmed cases of H1N1 infection . Brazil 's health minister told reporters Thursday that four cases of H1N1 infection have been confirmed in Brazil . Most hospitalized patients have recovered , report says . WHO reports four cases of pneumonia .
Pre - existing conditions contributed to deaths of U.S. victims , report said . The WHO reports 642 confirmed cases of H1N1 infection . Most hospitalized patients have recovered , report says . WHO reports four cases of pneumonia .