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.
Washington stamp, the first U.S. postage stamp to specifically honor a woman. Women Subjects on United States Postage Stamps Although Queen Isabella appeared in the first commemorative stamps issued in 1893, the first stamp specifically to honor a woman was the eight-cent Martha Washington stamp issued in 1902. The many stamps issued in honor of women since then are listed below. The Postal Service Guide to U.S. Stamps lists all United States postage stamps