After January's winter weather canceled multiple blood drives, the American Red Cross is urging donors to give this February.

There are several hundred thousand platelets in each drop of blood. Like red and white blood cells, platelets are made in bone marrow.

They are spread between hosts by mosquitoes, spend some time maturing in liver cells, and then eventually end up inside red blood cells. Once there, the parasites proliferate, feasting on hemoglobin.