GORAKHPUR, May 17 -- The presence of the H5N1 avian influenza has been confirmed in two more Gorakhpur zoo animals - a tiger and a leopard - which died in March and April, officials said on Friday. While the tiger died on March 30, the leopard succumbed on April 5. This is in addition to the tigress Shakti which died at the Gorakhpur zoo on May 7 due to bird flu. District forest officer and Gorakhpur zoo director Vikas Yadav said the National Institute of High Security Animal Diseases (NIHSAD) Bhopal confirmed the presence of the bird flu virus in samples taken from two tigers (including Shakti) and a leopard that died at the Gorakhpur zoo between March 30 and May 7. A wolf that also died during this period did not test positive for the virus. Initially, experts had attributed the death of the leopard and the tiger to cancer and meningitis respectively. But samples of these animals were sent to Bhopal for lab tests later....