Japanese shares tumble, Topix posts biggest fall in 6 1/2 months

* Slow global growth adds to economy concerns * End of QE in U.S. also adds to market gloom * First Ebola case in U.S. hurt airline shares * Exporters hit, Honda falls 4.2 pct By Hideyuki Sano TOKYO, Oct 2 (Reuters) - Japanese shares tumbled to one-month lows on Thursday as disappointing global manufacturing activity surveys stoked concerns over global growth, while the first confirmed case of Ebola in the United States fed into a risk-averse mood. Japan's Nikkei shar