3. How is it transmitted?
The Human Immunodeficiency Virus (HIV) is transmitted through body fluids such as blood, semen, vaginal secretions, and breast milk. It enters the body through some small cut or break in the skin or mucous membranes. This can occur during vaginal, oral, and anal sexual contact. Generally speaking, male-to-female transmission is more likely than female-to-male transmission. It occurs all the more easily if other sexually diseases such as syphilis, herpes, or chancroid are already present and have caused sores or ulcers through which the virus can enter. Transfusions with infected blood or organ transplants can also transmit the virus. However, this danger is now remote, since in most countries today all blood and organ donations are screened for HIV. A major source of infection is the sharing of injection needles among intravenous drug users. If only one of them is infected, all the others are at risk, because some infected blood may still be left in the needle. The virus can also be transmitted from an infected mother to her fetus through their shared blood circulation and, through her breast milk, to her baby. In all of these cases, the infected person may have no symptoms and, indeed, may be unaware of the infection.  
HIV is not transmitted through saliva, sweat and tears, and it is therefore safe to shake the hands of infected persons, drink from their cup or glass, or give them a simple kiss. Kissing could pose a risk only if it were a prolonged “deep” tongue kiss and there were open sores or bleeding cuts somewhere inside the mouth. Even then, the risk would be remote. Finally: The virus cannot exist outside the human body and its fluids. Therefore, it is not transmitted through clothes, towels, plates or utensils or through toilet seats. HIV is also not transmitted through mosquitoes.