Travel in the Saada region of northern Yemen is strongly discouraged because of the risk of violent civil unrest. Travel to the eastern parts of the country (Ma'rib, Shabwah, Hadramawt) and the south (Aden, Abyan, Al-Bayda') is also inadvisable because Al-Qaeda is active in some of these areas.
Your doctor will not test for illegal drugs unless you ask him to. A CBC stands for complete blood count which has to do with your blood cells not drugs.
A complete blood count (CBC) is a test that measures the cells that make up your blood: red blood cells, white blood cells, and platelets. You might get a CBC as part of your yearly check-up. Your doctor might also order it to: Check for anemia or leukemia.