Is HIV a Primary or Secondary Immunodeficiency? What To Know

You’ve probably heard of the human immunodeficiency virus (HIV) before, but how does it compare to primary immunodeficiency (PI)? If you or a loved one is living with PI, it’s natural to wonder how other immune conditions such as HIV are related.

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One key difference is that HIV is a secondary immunodeficiency. Most primary immunodeficiency conditions are inherited from parents through the genes a person is born with. HIV, on the other hand, usually develops later in life after coming into contact with the virus. A baby can be born with HIV if their mother has the virus during pregnancy, childbirth, or breastfeeding, but this is rare.

In this article, we’ll break down the important differences between primary and secondary immunodeficiency conditions. We’ll also explain how HIV affects the immune system, and why early blood testing and treatment are so important.

Primary vs. Secondary Immunodeficiency

Your immune system’s job is to protect you from outside invaders, like viruses, bacteria, fungi, and parasites. Think of it as your body’s security team — always on patrol, spotting trouble, and calling in reinforcements when needed. When certain parts don’t work well, it means you may have an immune deficiency. Not all immune deficiencies are the same, though. They can differ in their causes, how serious they are, and how they affect the body.

Primary Immunodeficiency

Primary immunodeficiency conditions are caused by mutations (changes) in a person’s genes. These changes affect how the immune system works from birth. For some people, a diagnosis may not come until they are adults, often after years of repeated infections.

There are more than 500 known PI diseases. Most conditions are rare on their own, but together, they affect between 1 in 1,000 to 1 in 5,000 people. These conditions target distinct parts of the immune system, including:

• White blood cells — These are the body’s main defenders against infection.
• T cells — This type of white blood cell finds and destroys infected cells.
• B cells — These help make antibodies (immune proteins) to fight viruses and bacteria.
• Antibodies (immunoglobulins) — These are special proteins that “tag” germs so your body can destroy them.
• Bone marrow — Blood cells, including immune cells, are made in the bone marrow.

Some more common types of PI include:

• Primary T-cell immunodeficiency — T cells are missing or don’t work properly, making it harder to fight infections.
• Hypogammaglobulinemia — The body doesn’t make enough antibodies, leading to frequent bacterial infections.
• Severe combined immunodeficiency — In this serious condition, both T cells and B cells are badly damaged or missing, leaving the immune system almost unable to fight infections.

Symptoms of PI vary depending on the specific disease. However, prolonged or recurrent infections are common among most of them. People with PI may need lifelong care to manage their condition. This treatment can include prophylaxis (medication to prevent infections) and regular vaccines. Sometimes, it may also involve immunoglobulin therapy to help boost immune defenses.

PI is a lifelong condition, but with proper treatment started early, many people can live long and healthy lives.

Secondary Immunodeficiency

Secondary immunodeficiency conditons happen when something outside the body harms the immune system. Unlike PI conditions, they aren’t inherited, so they can’t be passed down from your parents, except in rare cases when HIV passes from mother to baby. They develop later in life because of another condition, certain treatments, infections, or exposure to harmful chemicals or radiation.

HIV is one of the most common examples of a secondary immunodeficiency. Other causes of secondary immunodeficiency include:

• Severe malnutrition — This condition weakens the body’s defenses.
• Cancer treatments like chemotherapy — These treatments lower the number of healthy immune cells.
• Medications that suppress the immune system, such as steroids — These drugs reduce the body’s ability to fight infections.
• Serious infections — These can damage the immune response over time.

Symptoms of secondary immunodeficiency are often similar to those of PI. These can include frequent or long-lasting infections — especially those that are hard to treat or keep returning.

Doctors use blood tests to figure out what’s going on. Some people have low levels of neutrophils (a type of white blood cell). Others may not make enough antibodies. Depending on the symptoms, your doctor might order more specialized tests to check how well your immune system is working. These tests usually only require a few small blood samples.

Why Is HIV Considered a Secondary Immunodeficiency?

HIV is considered a secondary immunodeficiency because it develops after birth — it’s not inherited or present from birth. That’s why it’s known as acquired. HIV is spread through certain body fluids. This can happen by:

• Having unprotected sex
• Sharing needles or syringes
• Being exposed during pregnancy, childbirth, or breastfeeding

You can’t get HIV from touching, hugging, or shaking hands with someone.

Once HIV enters the body, it begins to damage the immune system. In some people, early symptoms may appear within two to four weeks after infection. However, not everyone develops noticeable symptoms during this early stage. In fact, HIV may stay in the body for years before symptoms appear. Over time, though, the virus weakens your ability to fight infections and certain types of cancer.

If HIV infection isn’t treated, it can lead to acquired immunodeficiency syndrome (AIDS). AIDS is considered the final stage of HIV infection. It happens when the immune system becomes so weak that it can no longer protect the body. With early HIV testing and treatment, most people with an HIV infection never develop AIDS.

How Does HIV Harm the Immune System?

HIV attacks the immune system by targeting CD4 T cells, a type of white blood cell that protects the body from germs. You can think of CD4 T cells as the commanders of your immune army — they direct other immune cells on when and how to fight. When HIV destroys these commanders, the rest of the immune system becomes less able to defend the body.

Over time, as more of these cells are lost, T-cell counts drop to dangerously low levels. The immune system becomes so weak that it can’t fight off infections, leading to immunosuppression and a higher risk of serious illness.

In the early stage of an HIV infection, about half of the people don’t feel sick at all. Others may notice flu-like symptoms within weeks of the infection. These may include:

• Fever or chills
• Swollen lymph nodes
• Skin rash or sore throat
• Muscle or joint aches
• Nausea, vomiting, or diarrhea

When the CD4 T-cell count falls below 200, a person is considered to have AIDS. At this stage, they’re more likely to develop opportunistic infections — certain fungal, viral, or bacterial infections that usually don’t affect people with healthy immune systems.

People diagnosed with AIDS also more likely to get certain types of cancer, such as:

• Kaposi sarcoma (a type of cancer that causes patches or tumors to form in the skin, mouth, lungs, or other organs)
• Cervical cancer
• Lymphoma (a type of cancer that starts in the lymphatic system, which is part of your body’s defense system)

Can HIV Be Treated or Cured?

There’s no cure for HIV yet, but the available treatments work very well. The main treatment option is antiretroviral therapy (ART). These medicines stop the virus from making copies of itself. ART usually consists of two or three different drugs, and can help:

• Lower the viral load (amount of HIV in the blood)
• Raise CD4 T-cell count
• Prevent infections
• Reduce the risk of passing HIV to others

People with HIV may need other treatments to stay healthy, too. These might include:

• Antifungal medications — These are used to treat fungal infections like thrush, which are more common when the immune system is weak.
• Antibiotics — These treat bacterial infections such as pneumonia or prevent them from returning.
• Pneumococcal vaccine — This vaccine protects against certain types of pneumonia, which can be serious in people with HIV.

What Happens Without Proper Treatment?

Without proper HIV treatment, the virus will continue to damage the immune system and can potentially lead to AIDS. However, this is avoidable. Don’t let fear or stigma prevent you from seeking care. HIV is just like any other medical condition, and with proper treatment, it won’t hold you back from living a full and meaningful life.

Preventing HIV Infection

One of the most effective tools for preventing HIV infection is pre-exposure prophylaxis (PrEP). PrEP is a medication that lowers the risk of getting HIV from sex or sharing of syringes. It works by stopping the virus from taking hold in your body if you’re exposed.

PrEP is recommended for people at high risk of getting HIV. This includes those with HIV-positive partners, people who inject drugs, or anyone who has unprotected sex.

Other ways to prevent HIV infection include using condoms, not sharing needles, and getting tested for HIV regularly. There’s also post-exposure prophylaxis (PEP) — a medicine you can take within 72 hours after a possible exposure.

Getting Tested for HIV

The Centers for Disease Control and Prevention (CDC) recommends that everyone between the ages of 13 and 64 get tested for HIV at least once in their life. People at higher risk — such as those with new or multiple partners, or who inject drugs — should test more often.

For more info or to find free testing near you, visit gettested.cdc.gov.

Ask Your Doctor

HIV treatment has come a long way in the past few decades. With the right care, people living with HIV can live longer and healthier lives than ever before. If you have questions about HIV or other types of secondary immunodeficiency, don’t be afraid to talk to your doctor for the information and care you need to stay healthy.

Talk With Others Who Understand

On myPIteam, people come together to learn more about life with primary immunodeficiency disorders.

Have you or someone in your family been diagnosed with a primary immunodeficiency? What tips or insights would you like to share with someone newly diagnosed? Join the conversation and share your insights in the comments below.