Immunodeficiency
A weakened immune system that struggles to fight infection
Quick Facts
- Type: Immune system disorder
- Two main types: Primary (inherited), secondary (acquired)
- Key feature: Frequent, severe, or unusual infections
- Common causes: Infections, medications, chronic illness
Overview
Immunodeficiency means that the immune system, the body's defense against infection, is weakened or not working as it should. As a result, a person catches infections more easily, has infections that are more severe or last longer, or develops unusual infections that rarely affect people with healthy immune systems.
Immunodeficiency can be present from birth, called primary immunodeficiency, or develop later in life, called secondary or acquired immunodeficiency. The acquired forms are far more common and can result from infections such as HIV, certain medications, or other illnesses. Understanding the type guides treatment, and many people can be protected with the right care and precautions.
Symptoms
The hallmark of immunodeficiency is a pattern of infections, often summarized by warning signs:
- Frequent or recurrent infections, such as ear, sinus, or lung infections
- Infections that are severe, slow to clear, or keep coming back
- Unusual infections, or infections by organisms that rarely cause illness in healthy people
- Poor response to standard treatment, sometimes needing intravenous antibiotics
- Failure to gain weight or grow normally in children
- Other signs such as swollen lymph nodes, persistent fatigue, or recurrent skin infections
A family history of immune problems can also be a clue to an inherited form.
Causes
Causes fall into two broad groups:
- Primary immunodeficiency: Inherited conditions present from birth in which part of the immune system is missing or faulty. There are many types, ranging from mild to severe.
- Secondary (acquired) immunodeficiency: Far more common, caused by something that affects an immune system that started out normal. Causes include HIV infection, certain cancers, chemotherapy and immune-suppressing medications, malnutrition, diabetes, and removal of the spleen.
Risk Factors
- A family history of primary immunodeficiency
- HIV infection
- Cancer treatment such as chemotherapy or radiation
- Long-term use of corticosteroids or other immunosuppressant drugs
- Organ or stem cell transplant
- Poorly controlled diabetes, malnutrition, or severe chronic illness
- Absent or non-functioning spleen
Diagnosis
Diagnosis focuses on the pattern of infections and on testing immune function:
- History and exam: Reviewing the frequency, type, and severity of infections and any family history.
- Blood tests: Counting and measuring immune cells and antibody (immunoglobulin) levels.
- Specialized testing: Assessing how the immune system responds to vaccines or specific challenges, and genetic testing for inherited forms.
Treatment
Treatment depends on the type and cause of the immunodeficiency.
- Preventing and treating infections: Prompt treatment of infections and, in some cases, preventive antibiotics.
- Immunoglobulin replacement: For people who cannot make enough antibodies, regular infusions can supply protective antibodies.
- Treating the cause: Managing HIV with antiviral therapy, adjusting immune-suppressing drugs when possible, or improving nutrition.
- Vaccination: Keeping vaccines up to date as advised, with special guidance about live vaccines.
- Advanced treatments: For some severe inherited forms, stem cell transplant or specialized therapies may be options.
Prevention and Self-Care
- Practice good hand hygiene and food safety
- Stay up to date with recommended vaccines, following your doctor's advice
- Avoid close contact with people who are sick when possible
- Treat infections early and complete prescribed courses of medicine
- Manage underlying conditions such as diabetes or HIV
- Carry information about your condition in case of emergencies
When to See a Doctor
See a doctor if you or your child have frequent, severe, or unusual infections, infections that do not respond to standard treatment, or a family history of immune problems. Seek emergency care for signs of a serious infection, such as a high fever with confusion, difficulty breathing, a stiff neck, or signs of sepsis like rapid breathing, a fast heartbeat, and feeling very unwell. People with weakened immune systems can become seriously ill quickly.
Frequently Asked Questions
What is the difference between primary and secondary immunodeficiency?
Primary immunodeficiency is inherited and present from birth, caused by a part of the immune system being missing or faulty. Secondary, or acquired, immunodeficiency develops later from causes such as HIV, cancer treatment, or immune-suppressing medications, and is far more common.
What are the warning signs of immunodeficiency?
Key signs include frequent, severe, or unusual infections, infections that are slow to clear or keep returning, and poor response to standard treatment. In children, failure to grow normally can also be a clue, as can a family history of immune problems.
Can immunodeficiency be treated?
Yes. Treatment depends on the cause and may include prompt treatment of infections, preventive antibiotics, antibody (immunoglobulin) replacement, treating the underlying cause, and tailored vaccination. Some severe inherited forms may be treated with stem cell transplant.
Are vaccines safe for people with immunodeficiency?
Many vaccines are recommended and helpful, but some live vaccines may not be safe for people with weakened immune systems. It is important to follow a doctor's specific advice about which vaccines are appropriate.
When should someone with a weak immune system seek emergency care?
Seek emergency care for high fever with confusion, difficulty breathing, a stiff neck, or signs of sepsis such as rapid breathing, a racing heartbeat, and feeling very unwell. People who are immunocompromised can become seriously ill quickly.
References
- National Institute of Allergy and Infectious Diseases (NIAID). Primary Immune Deficiency Diseases.
- MedlinePlus, U.S. National Library of Medicine. Immunodeficiency disorders.
- Mayo Clinic. Primary immunodeficiency — Symptoms and causes.
- Centers for Disease Control and Prevention (CDC). Immunocompromised People and Infections.