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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.
Of the estimated 2 million heroin users in the United States, 600,000–800,000 are considered hardcore addicts. Heroin addiction is considered to be one of the hardest addictions to recover from.
This year, an estimated 1.4 million Americans will have a new or recurrent heart attack.
HIV testing reach is still limited. An estimated 40% of people with HIV (more than 14 million) remain undiagnosed and do not know their infection status.