[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Immunology](https://durgical.com/en/immunology/) › [Immunodeficiencies](https://durgical.com/en/immunology/#a-immunodeficiency) › Secondary immunodeficiency: HIV, malnutrition, drugs, asplenia [Immunology](https://durgical.com/en/immunology/) · [Immunodeficiencies](https://durgical.com/en/immunology/#a-immunodeficiency) # Secondary immunodeficiency: HIV, malnutrition, drugs, asplenia - Topic Most weak immune systems are acquired, from HIV, poor nutrition, medicines, cancer or losing the spleen, not inherited. Updated 2026-11-01 **See it in 3D:** [Spleen](https://durgical.com/en/anatomy/spleen/) ## Key points - HIV destroys CD4 T cells; AIDS is defined by a CD4 count below 200 cells per microliter or an AIDS-defining illness. - Protein-energy malnutrition mainly impairs T-cell function and the thymus; it is the leading cause of immunodeficiency in the world. - Asplenia (surgical, or functional as in sickle cell disease) raises the risk of overwhelming sepsis by encapsulated bacteria; Howell-Jolly bodies on the smear. - Corticosteroids lower lymphocytes and eosinophils, raise neutrophils and blunt fever; they can trigger Strongyloides hyperinfection and Pneumocystis pneumonia. - Anti-TNF biologics reactivate latent tuberculosis: TB screening (tuberculin skin test or IGRA) comes before starting them. - CLL and multiple myeloma lower functional antibodies; diabetes, kidney failure, cirrhosis and old age also weaken defenses. ## What it is A secondary immunodeficiency is acquired during life. Worldwide, malnutrition is the most common cause and HIV the best known; in hospitals, corticosteroids, chemotherapy, transplant drugs and biologics are frequent causes. Recognizing the cause predicts the infections to expect and the vaccines and prophylaxis that apply. ## Main causes of acquired immunodeficiency | Cause | What fails | Typical infections | Clue or key test | | --- | --- | --- | --- | | [HIV infection](https://durgical.com/en/conditions/hiv-infection-and-aids/) | CD4 T cells (cell-mediated immunity) | Pneumocystis, tuberculosis, Cryptococcus, Histoplasma, Toxoplasma, CMV, candidiasis | HIV test; CD4 count; viral load | | Protein-energy malnutrition | T cells, thymus, phagocytes, complement, barriers | Severe measles, diarrhea, pneumonia, tuberculosis | Weight for height, albumin; often with micronutrient lack (zinc, vitamin A) | | Drugs (corticosteroids, chemotherapy, transplant drugs, biologics) | Depends on the drug: neutrophils, T cells, B cells | Bacterial and fungal infections in neutropenia; Pneumocystis; TB reactivation with anti-TNF | Drug history; blood count | | [Asplenia (splenectomy, sickle cell disease)](https://durgical.com/en/conditions/sickle-cell-disease/) | Clearance of opsonized bacteria; IgM memory B cells | Overwhelming sepsis by pneumococcus, meningococcus, Haemophilus; severe malaria and babesiosis | Howell-Jolly bodies on the blood smear | | [Blood cancers (CLL, multiple myeloma)](https://durgical.com/en/conditions/multiple-myeloma/) | Functional antibodies (hypogammaglobulinemia) | Recurrent pneumonia by encapsulated bacteria | Immunoglobulins; protein electrophoresis | | Diabetes, kidney failure, cirrhosis, old age | Neutrophil function, barriers, complement | Skin and urinary infections, mucormycosis in ketoacidosis, spontaneous bacterial peritonitis | Glucose and HbA1c; kidney and liver tests | ## Clinical notes - In Colombia, tuberculosis and histoplasmosis are frequent opportunistic infections in people with advanced HIV. - People without a functioning spleen receive pneumococcal, meningococcal and Haemophilus influenzae type b vaccines, ideally before a planned splenectomy. - Before high-dose or long courses of corticosteroids, people who lived in tropical areas are often tested or treated for Strongyloides. ## Memory aid Think HANDS: HIV, Asplenia, Nutrition, Drugs, Sugar and other systemic disease (diabetes, kidney, liver). ## Test yourself Think of the answer, then tap the question to see it. ## What is the most common cause of immunodeficiency worldwide? Protein-energy malnutrition, which mainly impairs T-cell immunity. ## Which CD4 count defines AIDS in a person with HIV? A CD4 count below 200 cells per microliter, or the presence of an AIDS-defining illness. ## What finding on the blood smear suggests asplenia? Howell-Jolly bodies, nuclear remnants in red cells that the spleen would normally remove. ## Which infection must be ruled out before starting an anti-TNF biologic? Latent tuberculosis, with a tuberculin skin test or interferon-gamma release assay (IGRA). [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/immunology/secondary-immunodeficiency-hiv-malnutrition-drugs-asplenia/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Spleen](https://durgical.com/en/anatomy/spleen/) ## Related - [CD4⁺ helper T cell](https://durgical.com/en/immunology/cd4-helper-t-cell/) - [Spleen: white pulp, red pulp, asplenia](https://durgical.com/en/immunology/spleen-white-pulp-red-pulp-asplenia/) - [Immunodeficiency: warning signs and the infection pattern by defect](https://durgical.com/en/immunology/immunodeficiency-warning-signs-and-the-infection-pattern-by-defect/) - [The neutropenic and immunosuppressed patient (nursing)](https://durgical.com/en/immunology/the-neutropenic-and-immunosuppressed-patient/) - [Immunosuppressants by mechanism (classes)](https://durgical.com/en/immunology/immunosuppressants-by-mechanism/) - [Monoclonal antibodies and biologics: naming and targets](https://durgical.com/en/immunology/monoclonal-antibodies-and-biologics-naming-and-targets/) ## Related conditions - [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/) - [Tuberculosis](https://durgical.com/en/conditions/tuberculosis/) - [Sickle cell disease](https://durgical.com/en/conditions/sickle-cell-disease/) - [Multiple myeloma](https://durgical.com/en/conditions/multiple-myeloma/) - [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/) ## Microorganisms - [Human immunodeficiency virus](https://durgical.com/en/microbiology/human-immunodeficiency-virus/) - [Pneumocystis jirovecii](https://durgical.com/en/microbiology/pneumocystis-jirovecii/) - [Mycobacterium tuberculosis](https://durgical.com/en/microbiology/mycobacterium-tuberculosis/) - [Cryptococcus neoformans](https://durgical.com/en/microbiology/cryptococcus-neoformans/) - [Histoplasma capsulatum](https://durgical.com/en/microbiology/histoplasma-capsulatum/) - [Toxoplasma gondii](https://durgical.com/en/microbiology/toxoplasma-gondii/) - [Streptococcus pneumoniae](https://durgical.com/en/microbiology/streptococcus-pneumoniae/) - [Strongyloides stercoralis](https://durgical.com/en/microbiology/strongyloides-stercoralis/) [← All of immunology](https://durgical.com/en/immunology/) Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given. Sources: [Immunodeficiency diseases](https://medlineplus.gov/ency/article/000818.htm) (MedlinePlus, U.S. National Library of Medicine, 2026); [About HIV](https://www.cdc.gov/hiv/about/index.html) (Centers for Disease Control and Prevention (CDC), 2026); [Spleen removal](https://medlineplus.gov/ency/article/002944.htm) (MedlinePlus, U.S. National Library of Medicine, 2026); [Risk Factors for Meningococcal Disease](https://www.cdc.gov/meningococcal/risk-factors/index.html) (Centers for Disease Control and Prevention (CDC), 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/immunology/secondary-immunodeficiency-hiv-malnutrition-drugs-asplenia/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/secondary-immunodeficiency-hiv-malnutrition-drugs-asplenia/