The result is a five to twenty percent drop in the amount of oxygen in the blood.

VOA: special.2009.07.14

Another doctor believes that Ernest Shackletons vision was caused by a drop in blood sugar.

VOA: special.2010.02.24

That means they take a drop of blood and they look at it under a microscope, and they can confirm that this was an actual case of malaria.

VOA: standard.2010.06.17