Chronic disease is a condition that lasts for a very long time and usually cannot be completely cured, although there are some diseases that can be controlled through lifestyle (diet and exercise) and medication. Some of the chronic diseases that many people know about are diabetes, heart disease, arthritis, HIV/AIDS, lupus erythematosus, etc.

The CD4 T-cell count is a measure of how well your immune system is working. These are the white blood cells that fight infection and are the target of the virus that causes HIV. Therefore, monitoring the CD4 T-cell count is essential in deciding on treatment and monitoring treatment in patients with HIV.