By Emma FargeGENEVA, March 6 (Reuters) - The World Health Organization said on Friday that medical supplies in Gaza were running critically low despite Israel's reopening of a key crossing this week.Supplies of some items such as gauze and needles have already run out, said WHO's regional director Hanan Balkhy, citing information from the Health Ministry in Gaza, devastated by the two-year Israel-Hamas war."Stocks of essential medicines, trauma supplies and surgical consumables are critically lo...