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When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
Vaccines prevent between 2.5 and 4 million deaths every year.
Malaria mortality rates are falling. Increased malaria prevention and control measures have greatly improved these rates. Since 2000, malaria mortality rates have fallen globally by 60% among all age groups, and by 65% among children under age 5.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.