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Credit: CDC/ Dr. Stan Erlandsen; Dr. Dennis Feely
Being tiny doesn't stop viruses, bacteria, certain insects and other microscopic critters from causing all sorts of misery. But under the microscope, we can see them for what they truly are. This image, made using a scanning electron microscope, shows the free-swimming protozoan Giardia, which causes diarrhea and other symptoms when it infects the small intestine, often as a result of contaminated drinking water.