When he first saw a map of malaria's range, Mann says it was as if the scales had fallen from my eyes. That range extends almost precisely to the Mason-Dixon Line, along which the American Civil War broke out in 1861, between the slave-holding states of the South and the Union soldiers of the North.
Opened yogurt will typically stay at peak quality for 5 to 7 days after opening, but will generally remain safe to consume for at least 1 to 2 weeks after the sell by date on the package, provided it has been properly stored- discard entire package if any sign of mold appears.
Yogurt usually lasts a good two to three weeks beyond the date on  the package, unless you notice signs of spoilage which would  indicate otherwise (such as an more than usual sour taste/smell, or  a bluish-green tinge on the surface of the yogurt) .