Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

HIV · Human Immunodeficiency Virus

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In one line

·HIV is a virus that gets inside CD4 cells — the white blood cells that direct your immune system — copies itself, and kills those cells one by one until your body can't fight off germs anymore.

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Normal physiology

·Your immune system is a team of white blood cells that patrol your body looking for germs. CD4 T cells are the coordinators — they recognize the invader, decide what kind of threat it is, and send signals that wake up other immune cells (B cells that make antibodies, CD8 killer T cells, and scavenger cells called macrophages). Without CD4 cells running the show, the whole defense falls apart.

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What goes wrong

·HIV is a retrovirus (a virus that writes its genetic code backward into your DNA). It infects CD4 T cells, hijacks the cell's machinery to copy itself thousands of times, then bursts the cell open and kills it. Every day, billions of new virus particles are made and billions of CD4 cells die. Your body tries to make new CD4 cells to replace them, but eventually it can't keep up. When the CD4 count drops below 200 (normal is 500–1,200), you have AIDS, and your immune system is too weak to fight off infections that healthy people never worry about.

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Hallmark signs

·Fever and flu-like illness 2–4 weeks after exposure (acute retroviral syndrome)
·Widespread rash (trunk, face, arms, legs)
·Sore throat and painful mouth sores
·Swollen lymph nodes in the neck, armpits, or groin
·Night sweats and muscle aches
·Diarrhea
·Headache and confusion (less common, serious)
·No symptoms for years (chronic HIV without treatment)

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Red flags · escalate now

·Fever, rash, and sore throat 2–4 weeks after unprotected sex or needle sharing — do not dismiss as 'just a virus'; test for acute HIV with HIV RNA or combination antigen/antibody test.
·Sudden confusion, severe headache, or stiff neck in someone with HIV — may be meningitis or brain infection from the virus or an opportunistic germ.
·CD4 count below 200 or unusual infections (thrush in the mouth, pneumonia from Pneumocystis, vision changes) — signals AIDS and needs urgent treatment and infection prevention.

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Workup

·HIV-1/2 antigen/antibody combination immunoassay (4th-generation test)
·HIV-1 RNA viral load (quantitative PCR)
·CD4 cell count (absolute count and percentage)
·Hepatitis B surface antigen (HBsAg) and hepatitis C antibody
·HLA-B5701 genetic test
·Tuberculosis screening (interferon-gamma release assay or tuberculin skin test)
·Sexually transmitted infection panel (gonorrhea, chlamydia, syphilis)

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Treatment

·Start antiretroviral therapy (ART) immediately—recommended regimen is an integrase inhibitor (bictegravir or dolutegravir) plus two nucleoside reverse transcriptase inhibitors (tenofovir alafenamide and emtricitabine)
·Give prevention (prophylaxis) for opportunistic infections when CD4 is below 200 cells per microliter—trimethoprim-sulfamethoxazole (one double-strength tablet daily) prevents Pneumocystis pneumonia and toxoplasmosis
·Screen for and treat hepatitis B and hepatitis C; vaccinate against hepatitis B if the person is negative
·Prescribe post-exposure prevention (prophylaxis) (PEP) within 72 hours to anyone with recent high-risk exposure (needlestick, condomless sex with someone who has HIV, sexual assault)
·Offer pre-exposure prevention (prophylaxis) (PrEP) to HIV-negative people with ongoing high-risk behavior—daily tenofovir/emtricitabine or long-acting injectable cabotegravir every 2 months
·Screen for cancers that are more common with HIV—cervical cancer (Pap smear and HPV test), anal cancer (anal Pap smear in high-risk groups), lung cancer (low-dose CT in smokers)—and treat them early
·Screen for and treat mental health disorders (depression, anxiety, PTSD) and substance use disorders; offer counseling, antidepressants, or addiction treatment as needed

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NCLEX trap

·Start antiretroviral therapy (ART, the medicines that block HIV) immediately in every person with HIV, no matter what the CD4 count is. Early treatment stops HIV from killing more CD4 cells (the immune cells that protect you from infection) and prevents AIDS (the stage when your immune system is too weak to fight off infections).
·Fever plus rash plus recent exposure is acute HIV until proven otherwise. Right now the virus is making millions of copies and destroying CD4 cells. Test for HIV RNA (the virus itself) and start treatment immediately. The antibody test may still be negative this early, so order the RNA test.
·Undetectable means untransmittable. When HIV RNA is undetectable (below 50 copies/mL) on treatment, the virus is not replicating and the person cannot pass HIV to others through sex. This is proven science (U=U).
·HIV is the upstream problem that destroyed the CD4 cells and left the door open for these infections. Start ART to rebuild the immune system, and the body will be able to fight off the infections on its own. Treat the infections AND the HIV together.
·HIV is a chronic disease—it never leaves the body. Stop ART and the virus comes roaring back, CD4 cells drop again, and AIDS returns. ART must continue every single day for life to keep the virus suppressed.
·Drug resistance is a real danger if the patient misses doses or does not take the right combination. Resistant HIV destroys CD4 cells even faster and limits future treatment options. Use single-tablet regimens (one pill once a day) to make it easier to stay on track and prevent resistance.

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