Symptoms include bumps in and around the genitals. Spreads through any sexual contact (anal, oral, and vaginal), and also by skin to skin contact. A vaccine exists to help prevent this disease. Which of the following STIs is this?

Choice A reason: CD4 counts are not used to detect HIV, but to monitor the progression of the infection and the immune system status. CD4 cells are a type of white blood cell that HIV targets and destroys. A normal CD4 count ranges from 500 to 1,500 cells per microliter of blood. A low CD4 count indicates a high risk of opportunistic infections and AIDS.

Choice B reason: Virus is a vague term that does not specify what kind of virus is being detected. HIV is a type of virus that belongs to the retrovirus family. It is difficult to detect the virus itself, as it hides inside the host cells and has a low concentration in the blood. Therefore, most laboratory tests focus on the antibodies that the body produces in response to the virus.

Choice C reason: HIV antibodies are the most common way to detect HIV, as they are produced by the immune system to fight the virus. Antibodies are proteins that bind to specific antigens (foreign substances) and mark them for destruction. HIV antibodies can be detected by a blood test, a saliva test, or a rapid test. However, antibodies may take several weeks to develop after exposure, so a negative test does not rule out the possibility of infection.

Choice D reason: CD8 counts are not used to detect HIV, but to monitor the immune system response and the viral load. CD8 cells are a type of white blood cell that kill infected cells and secrete antiviral substances. A high CD8 count indicates a strong immune response and a low viral load. A low CD8 count indicates a weak immune response and a high viral load.

Choice A reason: The incidence of hepatitis C is not decreasing, but rather increasing, especially among young people who inject drugs. Hepatitis C is a chronic infection that can lead to liver damage and cancer.

Choice B reason: Hepatitis B is more contagious than HIV, as it can be transmitted by blood, semen, vaginal fluids, and other body fluids. Hepatitis B can also cause chronic infection and liver problems.

Choice C reason: A vaccine exists for hepatitis B but not for hepatitis C. Hepatitis B vaccine is recommended for all infants, children, and adults who are at risk of exposure. Hepatitis C vaccine is still under development.

Choice D reason: Hepatitis A is caused by eating contaminated food or drinking polluted water. It is an acute infection that usually resolves on its own. Hepatitis A vaccine is available for travelers and people who live in areas with poor sanitation.