What Are Viral Load and CD4 Counts in HIV/AIDS Patients?


Quick Answer

Viral load refers to the amount of HIV in a sample of a patient’s blood, while a CD4 count is a lab test that determines the amount of CD4 cells in a sample of the patient’s blood, according to AIDS.gov. A high viral load indicates that the patient’s immune system is not fighting the virus efficiently, while a high CD4 count indicates that the person has a strong immune system.

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Full Answer

CD4 or T-helper cells are a type of white blood cell that fights infection. They are made in the spleen, thymus gland and lymph nodes, explains WebMD. When a person is exposed to HIV, the virus binds to the surface of CD4 cells and enters them. As the cells replicate to fight the infection, they also make more copies of the virus. Consequently, as the CD4 cells continue to replicate, their level in the blood keeps declining. The reduced immunity then opens the body up to attack by opportunistic infections.

The CD4 count test determines a patient’s immunity by measuring the number of T-helper cells in a cubic millimeter of his blood. A normal count ranges from 500 to 1,500 cells per cubic millimeter of blood and keeps lowering as the HIV disease progresses, notes WebMD.

HIV stands for human immunodeficiency virus. It is sexually transmitted, but can also be spread via contact with infected blood or from mother to child during pregnancy, birth or breast-feeding, says Mayo Clinic. HIV damages the patient’s immune system, weakening the body’s ability to fight disease. It has no cure as of 2015, but there are drugs that can slow the progression of the illness. If HIV is left untreated, it leads to acquired immunodeficiency syndrome.

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