text: These H5N1 infections may be quite common : in a survey of 10 apparently healthy pigs housed near poultry farms in West Java , where avian flu had broken out , five of the pig samples contained the H5N1 virus .
simplified: Chairul Nidom , a virologist at Airlangga University 's tropical disease center in Surabaya , East Java , did some independent research : he tested the blood of 10 apparently healthy pigs housed near poultry farms in West Java where avian flu had broken out , Nature reported . Five of the pig samples contained the H5N1 virus .