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When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).