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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.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
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.
The use of salicylates dates back 2,500 years to Hippocrates's recommendation of willow bark (from which a salicylate is derived) as an aid to the pains of childbirth. However, overdosage of salicylates can harm body fluids, electrolytes, the CNS, the GI tract, the ears, the lungs, the blood, the liver, and the kidneys and cause coma or death.
Interferon was scarce and expensive until 1980, when the interferon gene was inserted into bacteria using recombinant DNA technology, allowing for mass cultivation and purification from bacterial cultures.