(S (S (S (BASENP (DT The) (JJ current) (NN polio) (NN epidemic)) (VP (VBZ has) (VP (VBN been) (VP (VP (VBG going) (PRT (RP on))) (PP (IN for) (BASENP (DT a) (NN year))))))) (CC and) (S (BASENP (EX there)) (VP (VBP have) (VP (VBN been) (NP (BASENP (NNS outbreaks)) (PP (IN in) (NP (BASENP (DT the) (JJ last) (NN six) (NNS months)) (PP (IN in) (NP (NP (NP (NP (NP (NP (NP (NP (BASENP (NNP Burkina) (NNP Faso)) (COMMA ,) (BASENP (NNP Cameroon))) (COMMA ,) (BASENP (NNP Chad))) (COMMA ,) (BASENP (NNP Guinea))) (COMMA ,) (BASENP (NNP Liberia))) (COMMA ,) (BASENP (NNP Mali))) (COMMA ,) (BASENP (NNP Mauritania))) (COMMA ,) (BASENP (NNP Senegal))) (CC and) (BASENP (NNP Sierra) (NNP Leone))))))))))) (PERIOD .))