New influenza A (H1N1) 2009 in Singapore: the first ten adult imported cases.

Introduction : Since late March 2009, a novel influenza H1N1 strain emerged in humans in Mexico and the United States. It has rapidly spread to many countries on different continents, prompting unprecedented activation of pandemic preparedness plans. Singapore has adopted a containment strategy with active screening of febrile travellers with respiratory symptoms from affected countries since April 27, 2009. Methods: All cases with new influenza A (H1N1) confirmed on polymerase chain reaction assay on combined nasal and throat swabs and who were admitted to the Communicable Disease Centre, were included in a prospective evaluation of clinical characteristics of new influenza A (H1N1).