What is the difference between primary and secondary immunodeficiencies?

What is the difference between primary and secondary immunodeficiencies?

• A. Primary immunodeficiencies are inherited or genetic; secondary immunodeficiencies are caused by environmental factors
• B. Primary immunodeficiencies are inherited or genetic; secondary are caused by environmental factors
• C. Primary immunodeficiencies are caused by infections; secondary by malnutrition
• D. Primary and secondary immunodeficiencies are the same

Answer: (B)

The key idea is how the immune deficiency arises. Primary immunodeficiencies are inherited or genetic disorders present from birth due to congenital defects in the immune system. Secondary immunodeficiencies are acquired after birth as a result of environmental or external factors that dampen immune function, such as infections (like HIV), malnutrition, chemotherapy or radiotherapy, or immunosuppressive drugs. So the best statement captures that distinction: the deficiency is genetic and present from birth when it’s primary, whereas it’s acquired later from outside factors when it’s secondary. For example, SCID is a primary immunodeficiency from gene defects, while HIV infection causes a secondary immunodeficiency by targeting CD4 T cells. The idea that infections cause primary immunodeficiencies or that both types are the same doesn’t fit the established classification.

The key idea is how the immune deficiency arises. Primary immunodeficiencies are inherited or genetic disorders present from birth due to congenital defects in the immune system. Secondary immunodeficiencies are acquired after birth as a result of environmental or external factors that dampen immune function, such as infections (like HIV), malnutrition, chemotherapy or radiotherapy, or immunosuppressive drugs.

So the best statement captures that distinction: the deficiency is genetic and present from birth when it’s primary, whereas it’s acquired later from outside factors when it’s secondary. For example, SCID is a primary immunodeficiency from gene defects, while HIV infection causes a secondary immunodeficiency by targeting CD4 T cells. The idea that infections cause primary immunodeficiencies or that both types are the same doesn’t fit the established classification.