PARIS (Reuters) – France will tighten measures to contain bird flu after a resurgence of the virus that swept through poultry flocks last winter, said the agriculture ministry, adding that the nationwide alert level on bird flu had been raised to ‘moderate’ from ‘low’. France experienced its worst-ever bird flu crisis between November and May, with over 19 million animals being culled to stem a severe strain of the disease that spread in major poultry breeding regions in western France. The government scaled back restrictions in June after a lull in outbreaks, before an unusual upturn in cases…