1 Although any individual may develop a case of pinworms, the infection occurs most frequently in school children between 5 to 10 years of age.  Pinworm infections occur in all socioeconomic groups; however, human-to-human spread is favored by close, crowded living conditions. Spread among family members is common.
Before they start collecting, stamp collectors try to identify the types of stamps. These will help them segregate and sort stamps according to their classification. On its basic concept, there are three main classifications of stamps â special, commemorative, and definitive.
1 The First Washington postage stamp. 2  The 5-cent Franklin and the 10-cent Washington postage stamps issued in 1847 were the first postage stamps issued and authorized for nationwide postal duty by the U.S. Post Office.or more than 160 years the one subject that has appeared most frequently on the face of U.S. Postage stamps is that of American Presidents. When the U.S. Post Office released its first two postage stamps in 1847, George Washington, along with Benjamin Franklin, were the two subjects depicted on these premier issues.