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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Pink eye is a term that refers to conjunctivitis, which is inflammation of the thin, clear membrane (conjunctiva) over the white part of the eye (sclera). It may be triggered by a virus, bacteria, or foreign body in the eye. Antibiotic eye drops alleviate bacterial conjunctivitis, and antihistamine allergy pills or eye drops help control allergic conjunctivitis symptoms.
The most common childhood diseases include croup, chickenpox, ear infections, flu, pneumonia, ringworm, respiratory syncytial virus, scabies, head lice, and asthma.
The term pharmacology is derived from the Greek words pharmakon("claim, medicine, poison, or remedy") and logos ("study").
Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.