HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases. It is spread by contact with certain bodily fluids of a person with HIV, most commonly during unprotected sex (sex without a condom or HIV medicine to prevent or treat HIV), or through sharing injection drug equipment.
Child abuse is not just physical violence directed at a child. It is any form of maltreatment by an adult, which is violent or threatening for the child. This includes neglect.
Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere.
Vaccines train your immune system to create antibodies, just as it does when it's exposed to a disease. However, because vaccines contain only killed or weakened forms of germs like viruses or bacteria, they do not cause the disease or put you at risk of its complications.
There are many types of liver disease. Some of the most common types are treatable with diet and lifestyle changes, while others may require lifelong medication to manage. If you begin treatment early enough, you can often prevent permanent damage. But you may not have symptoms in the early stages. Late-stage liver disease is more complicated to treat.