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.
Postage stamps are miniature works of art designed to reflect the American experience and highlight heroes, history, milestones, achievements and natural wonders. 1  19 billion U.S. postage stamps were printed in 2015. 2  12 billion postage stamps were sold in 2015 â 77 percent of them in the popular Forever format.