Hepatitis B is a viral [[disease]] transmitted by infected blood or blood products, or thorugh unprotected sex with someone who is infected.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#h</ref>
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Hepatitis B is a viral [[disease]] transmitted by infected [[blood]] or [[blood]] products, such as [[blood transfusions]], or through unprotected sex with someone who is infected.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#h</ref>
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As with [[AIDS]], Hepatitis B is not contagious from casual contact (as in the school environment).