This subtype is termed minor aphthous ulceration (MiAU), or minor recurrent aphthous stomatitis (MiRAS). It is termed major aphthous ulceration (MaAU) or major recurrent aphthous stomatitis (MaRAS). Others include generalized stomatitis, angular cheilitis and gingivitis. T cells in the peripheral blood of individuals with aphthous stomatitis is decreased. When used without qualification, "aphthae" commonly refers to lesions of recurrent aphthous stomatitis. The important differentiation is with acute leukemia or herpetic stomatitis. For a discussion of the epidemiology of aphthous stomatitis, see the epidemiology of aphthous stomatitis. The thickness of the mucosa may be an important factor in aphthous stomatitis. However, other studies report no correlation between aphthous stomatitis and menstrual period, pregnancy or menopause. Smokeless tobacco products also seem to protect against aphthous stomatitis. As with all types of aphthous stomatitis, it is not contagious. It may describe many different conditions apart from aphthous stomatitis such as angular stomatitis. Aphthous stomatitis (canker sores) is the recurrent appearance of mouth ulcers in otherwise healthy individuals. The current most widely used medical term is "recurrent aphthous stomatitis" or simply "aphthous stomatitis". Angular cheilitis generally occurs in elderly people and is associated with denture related stomatitis.