(S (S (S (NP (BASENP (DT Some) (NN flu) (NNS viruses)) (PP (IN in) (NP (BASENP (DT the) (NNP United) (NNPS States)) (CC and) (BASENP (NNP Canada))))) (VP (VBP have) (VP (VBN shown) (NP (BASENP (JJ increased) (NNS levels)) (PP (IN of) (NP (BASENP (NN resistance)) (PP (TO to) (NP (BASENP (DT the) (JJ antiviral) (NN drug) (NNP Tamiflu)) (PRN (LRB -LRB-) (BASENP (NN oseltamivir)) (RRB -RRB-)))))))))) (COMMA ,) (S (NP (BASENP (DT the) (NNP World) (NNP Health) (NNP Organization)) (PRN (LRB -LRB-) (BASENP (NNP WHO)) (RRB -RRB-))) (VP (VBD said) (PP (IN on) (BASENP (NNP Friday)))))) (PERIOD .))