<div><p>WASHINGTON (Reuters) - The new pandemic H1N1 influenza was circulating undetected in pigs for at least a decade before it jumped to people, and much better surveillance is needed among both pigs and people, an expert said on Tuesday.</p><p>Molecular tests show the swine flu virus made a mutational ...

<div id="subtitle">New study says AIDS virus started circulating 100 years ago in Africa; rise of cities blamed</div><div><p>The AIDS virus has been circulating among people for about 100 years, decades longer than scientists had thought, a new study suggests. Genetic analysis pushes the estimated origin of HIV ...