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Immune / Infectious

HIV / AIDS

HIV Verified · Sep 2026

HIV (human immunodeficiency virus) is a retrovirus that targets CD4+ T-helper lymphocytes and integrates into the host genome, causing progressive immune suppression; AIDS is its final stage, defined by a CD4+ count below 200 cells/mm³ or by the presence of an AIDS-defining condition.

The disorder behind the CD4 count, the opportunistic-infection thresholds, the 4th-generation test and its window period, U=U, PrEP and the 72-hour PEP clock — and the reason adherence teaching is a life-or-death nursing intervention.

What’s going wrong in the body

The normal physiology, where it fails, and why the body’s compensation backfires.

01 A retrovirus that moves in permanently

HIV belongs to the Retroviridae family, Lentivirus genus, and it has one target above all others: the CD4+ antigen is "the primary host cellular receptor for HIV-1 and HIV-2." The viral envelope glycoprotein binds CD4 and then a chemokine coreceptor — CCR5 or CXCR4 — and that dual binding triggers a conformational change and "fusion of the viral and host cellular membranes." The cells that display CD4 — T-helper cells and macrophages — are therefore "the primary viral targets," which is why the virus dismantles precisely the cell that coordinates the rest of the immune response.

Once inside, the virus does something most pathogens cannot: the viral reverse transcriptase copies HIV RNA into DNA, and that DNA integrates into the host cell’s own genome. From that moment the infection is written into the patient’s cells. This single step explains the most important patient-teaching fact on the page — antiretroviral therapy suppresses the virus but does not cure it, and stopping treatment lets it come back.

The same enzyme creates the second defining problem. The error rate of HIV-1 group M reverse transcriptase is 100 to 1,000 times higher than that of human DNA polymerases. Every replication cycle throws off mutants, so any period of incomplete suppression — a missed week of doses, an antacid that blocked absorption — hands the virus a selection experiment and resistant strains win it. Adherence is not a compliance issue in HIV; it is the mechanism by which the drugs keep working. Even on fully suppressive therapy the virus persists in reservoirs, including T cells within B-cell follicles, which is why suppression must be maintained for life.

The HIV life cycle: CD4 plus coreceptor binding, membrane fusion, reverse transcription, and genomic integration — the step that makes infection lifelong — with the enzyme’s high error rate feeding drug resistance.

02 Three phases — and why the middle one is the dangerous one

HIV moves faster than most patients imagine. "Within 2 days of the initial mucosal exposure, HIV can be detected in the regional lymph node tissue. From here, the virus only requires 3 days to be detected in the plasma." What follows is peak viremia: "viral replication is rampant, with an exponential increase in the plasma HIV RNA level due to the large population of susceptible CD4+ T cells without any host immune response." This is the most infectious period of the entire disease, and it is also when the patient feels sick — the acute retroviral syndrome, arriving "approximately 2 to 4 weeks (with a range of 4 days to 8 weeks) after viral infection," with about 90% of patients experiencing at least one symptom within the first 4 weeks.

Then the immune system pushes back. "A significant decline from the peak viremia level occurs due to the HIV-specific immune response from the cytotoxic CD8+ T cells." Viral replication settles at a viral set point, the acute symptoms resolve over roughly 18 days, and the patient feels well again. That is the trap. "Most patients with chronic HIV remain asymptomatic before developing AIDS" — replication and CD4 destruction continue silently for years while nothing hurts. Clinical latency is why HIV is found by testing, not by symptoms, and why routine screening rather than symptom-driven testing is the policy.

The endpoint is defined two ways, and either one alone qualifies: a CD4+ count below 200 cells/mm³, or an AIDS-defining condition "regardless of the CD4+ count." The CDC surveillance ladder (as carried by StatPearls) runs stage 1 at 500 or more cells/µL, stage 2 at 200 to 499, and stage 3 below 200, with stage 0 reserved for primary infection identified by a positive test within 180 days of a negative or indeterminate one. Untreated, the trajectory has one ending: "Without therapy, HIV infections are invariably fatal."

The natural history of untreated HIV: dissemination within days, peak viremia and the acute retroviral syndrome, immune control down to a set point, then years of silent CD4 destruction before AIDS.

03 The CD4 count is a countdown, not a lab value

Losing CD4+ T-helper cells means losing cell-mediated immunity, and cell-mediated immunity is what holds intracellular organisms in check. Opportunistic infections typically emerge once the absolute CD4+ count falls below 200 cells/mm³, or the relative count below 14%. The pathogens are not exotic invaders; most are organisms a competent immune system meets and controls — Pneumocystis jirovecii, Toxoplasma gondii, Candida, Cryptococcus neoformans, Mycobacterium tuberculosis, Mycobacterium avium-intracellulare complex, herpes simplex, varicella-zoster, cytomegalovirus, and the JC virus behind progressive multifocal leukoencephalopathy.

Because each threshold opens a different door, prophylaxis is prescribed by CD4 number, and the number is a trend rather than a single reading. Below 200 cells/mm³, Pneumocystis prophylaxis with trimethoprim/sulfamethoxazole starts — and it covers more than one target: "in addition to preventing Pneumocystis pneumonia (PCP), it also protects against cerebral toxoplasmosis, bacterial infections, and malaria in endemic settings." Below 150, histoplasmosis prophylaxis is added for patients in hyperendemic areas or with occupational exposure. Below 100, toxoplasmosis prophylaxis is added only if the toxoplasma antibody is positive, and cryptococcal prophylaxis only if the serum cryptococcal antigen is positive — which is why that antigen "should be considered in patients with a CD4+ count of 100 cells/mm³ or less." Below 50, CMV retinitis becomes a real risk.

One classic rule has changed and must be taught as changed. Mycobacterium avium complex prophylaxis is no longer automatic below CD4 50: it applies only to patients "not receiving ART, or who remain viremic on ART," and "if patients with HIV are rapidly initiated on ART, prophylaxis for Mycobacterium avium complex is not required." The prophylaxis ladder also runs in reverse — Pneumocystis prophylaxis "is often discontinued after the CD4+ count returns to >200 CD4+ cells/mm³ for 3 or more months in patients on antiretroviral therapy." The two numbers a nurse tracks answer different questions: viral load says whether the treatment is working; CD4 says how much immune damage exists and which prophylaxis is due.

The opportunistic-infection prophylaxis ladder: each CD4 threshold opens a different set of pathogens, two of the thresholds require a positive antibody or antigen first, and the MAC rule now depends on ART status.

04 Viral load is also the transmission dial — the mechanism behind U=U

Transmission risk is not a fixed property of being HIV-positive; it scales with how much virus is circulating. "Each log increase in viral load is estimated to increase the risk of HIV transmission 2.5-fold," and in the prevention literature there were "no viral transmission events noted from individuals who had a baseline viral load of less than 1500 copies/mL." Turn that relationship around and treatment becomes prevention.

That is U=U — undetectable equals untransmittable, and it has an exact boundary that must be taught alongside it. The sourced statement: "Treatment as prevention recognizes that HIV is not sexually transmitted if the viral load is undetectable (defined as <200 copies of HIV-1 RNA/mL of plasma)." The trials behind it — HPTN 052, PARTNER 1 and 2, and Opposites Attract — "showed 100% efficacy in preventing HIV transmission if antiretroviral therapy is taken as prescribed, and an undetectable viral load is achieved" At the population level, "every 10% increase in viral suppression on a population level is associated with a 4% decline in the incidence of HIV in the subsequent year."

The boundary is not a footnote: "Clinical data only support U=U for sexual transmission. Even with undetectable viral loads, HIV transmission still occurs perinatally and via breast milk." A nurse who teaches U=U without that sentence has taught a pregnant or breastfeeding patient something dangerous. Used correctly, U=U is a clinical intervention rather than reassurance — "clinical education and emphasis on undetectable equals untransmittable are crucial elements of HIV treatment," and "emphasis on U=U is a strong motivator for patient adherence to medication."

Causes & risk factors

Modifiable factors are teaching targets — the patient can act on them.

Receptive anal intercourse — approximately 138 infections per 10,000 exposures, the highest-risk sexual act by an order of magnitude modifiable Insertive anal intercourse (11 per 10,000) · receptive vaginal (8 per 10,000) · insertive vaginal (4 per 10,000) modifiable Sharing needles, syringes or other injection equipment — 63 infections per 10,000 exposures modifiable Inconsistent or absent condom use with a partner of unknown HIV status modifiable A partner living with HIV whose viral load is unknown or detectable modifiable A bacterial sexually transmitted infection within the past 6 months modifiable Pregnancy and delivery — 15% to 30% vertical transmission risk untreated modifiable Breastfeeding — an additional 10% to 20% risk on top of perinatal transmission modifiable Contact with the blood of a person with HIV; fomites such as reusable medical equipment or syringes Hepatitis B or hepatitis C coinfection — a named driver of higher morbidity and mortality modifiable Active injection drug use modifiable Populations disproportionately affected worldwide: men who have sex with men, sex workers, people in prisons and other closed settings, people who inject drugs, transgender people In the United States (2022), 67% of new infections were in men who have sex with men; Black, Hispanic and Latino patients and those in the US South are disproportionately affected Transfusion — now nearly eliminated by donor screening and testing of all blood products

Signs & symptoms

Each finding tied to the mechanism that produces it — and the triage it calls for.

Acute retroviral syndrome — fever, fatigue, muscle pain, rash, headache, sore throat, swollen lymph nodes, joint pain, night sweats, diarrhea early Hold & notify
Why: Peak viremia with no established immune response yet. Onset is 2 to 4 weeks after infection (range 4 days to 8 weeks), and about 90% of patients have at least one symptom in the first 4 weeks. It looks like influenza — and it is the most infectious period of the entire disease.
Mucocutaneous ulceration — shallow, sharply demarcated ulcers with a white base ringed by thin erythema early Hold & notify
Why: Described as "a characteristic feature of acute HIV" — this is the finding that separates acute HIV from an ordinary viral illness. Paired with fever, rash and adenopathy after a recent exposure, it is acute HIV until tested.
Nothing at all — years of asymptomatic clinical latency Expected
Why: After the viral set point is established the acute symptoms resolve while replication and CD4 destruction continue. "Most patients with chronic HIV remain asymptomatic before developing AIDS," which is exactly why HIV is found by routine testing rather than by symptoms.
Persistent generalized lymphadenopathy and nonspecific fatigue Expected
Why: Defined as at least 2 noncontiguous sites other than inguinal nodes with enlarged nodes for more than 3 to 6 months, not explained by another lymphoproliferative or infectious cause — chronic immune activation made palpable.
Progressive exertional dyspnea with a non-productive dry cough and low-grade fever — Pneumocystis jirovecii pneumonia late Report immediately
Why: The classic late presentation, with "a more indolent and subtle onset of symptoms … over several weeks": dyspnea in 95%, dry cough in 95%, low-grade fever in over 80%. Hypoxemia is already present at diagnosis, and 10% to 20% of patients with PJP die — escalate before the hypoxemia becomes severe.
Any new visual symptom in a patient with a low CD4 count — CMV retinitis late Report immediately
Why: CMV retinitis usually occurs below CD4 50 cells/µL; the retina shows full-thickness intraretinal opacification with hemorrhages, minimal anterior-chamber reaction and a clear vitreous. Vision is lost to macular or optic-nerve involvement, retinal detachment, and immune-recovery uveitis, and delay risks "irreversible damage to vision" — the source calls for immediate ophthalmological evaluation.
Cotton-wool spots and retinal hemorrhages found on a routine eye exam — HIV retinopathy Expected
Why: The most common ophthalmic manifestation of HIV, in up to 70% of patients, tracking with low CD4 counts and high plasma HIV RNA. It is a microangiopathy that typically does not threaten vision — the teaching point is not to confuse it with CMV retinitis, which does.
Oropharyngeal or esophageal candidiasis late Hold & notify
Why: Candida is a commensal the immune system normally contains; once cell-mediated immunity fails it becomes invasive. Esophageal and pulmonary candidiasis are AIDS-defining conditions — their presence establishes AIDS regardless of the CD4+ count.
Kaposi sarcoma and other AIDS-defining malignancies late Hold & notify
Why: Loss of immune surveillance lets virally driven tumors emerge. Kaposi sarcoma, invasive cervical cancer, primary brain lymphoma, non-Hodgkin and Burkitt lymphoma all appear on the AIDS-defining list, and Kaposi sarcoma can be complicated by HIV-associated Kaposi sarcoma inflammatory cytokine syndrome and multicentric Castleman disease.
HIV-associated wasting syndrome — progressive involuntary weight loss late Hold & notify
Why: An AIDS-defining condition in its own right, driven by chronic infection, malabsorption and the metabolic cost of unchecked viral replication. It is the reason weight and nutrition monitoring are named nursing responsibilities rather than routine paperwork.
Cognitive change, and burning or numbness in a stocking-glove distribution late Hold & notify
Why: HIV-associated neurocognitive disorders, psychiatric complications, HIV-associated distal symmetric polyneuropathy, and HIV encephalitis — which is itself an AIDS-defining condition. The virus reaches the nervous system directly, and some antiretrovirals add their own neuropathy.
Getting worse days to weeks after starting antiretroviral therapy — immune reconstitution inflammatory syndrome Hold & notify
Why: IRIS occurs "particularly in HIV-infected patients who start treatment with a low CD4+ cell count and have an underlying opportunistic infection or malignancy." The deterioration is the recovering immune system attacking a pathogen it could not previously see — not treatment failure, and not a reason to stop ART. "In many cases, IRIS is self-limiting and only symptomatic treatment is required."
Fat redistribution, new dyslipidemia, glucose intolerance or weight gain on therapy Expected
Why: HIV-associated lipodystrophy and the mitochondrial toxicity of NRTIs, compounded by regimen effects: "multiple ART regimens are associated with weight gain," with integrase inhibitors causing more than protease inhibitors or NNRTIs. Guidelines therefore pair ART initiation with lifestyle counselling and routine metabolic screening.

Diagnostics

Test In this disorder Normal
4th-generation HIV antigen/antibody immunoassay Routine screening is recommended for everyone aged 13 to 64 in healthcare settings, once for most people at low risk and as often as every 3 to 6 months for higher-risk patients; pregnant patients are screened early in pregnancy. Opt-out screening is used — "no U.S. state requires signed consent," but the patient must be verbally informed and given the chance to decline The standard first test — detects antibodies to HIV-1 and HIV-2 plus the p24 antigen, "enabling earlier identification of infection following exposure" CDC, as reported by StatPearls —
Window period & retest timing Most people test positive within 3 weeks on a 4th-generation assay, but "some may not seroconvert for up to 3 months." After an exposure, retest during the 4- to 6-week period with a final test at 12 weeks. If the exposure was within 14 days, an HIV RNA test is the initial diagnostic test — a negative antibody result does not rule out acute HIV The eclipse period lasts about 10 days (no test can detect HIV); the window phase runs up to 20–25 days. HIV RNA becomes detectable about a week after infection (assay-dependent), p24 antigen at 13 to 20 days, IgM near 20 days and IgG near 30 days StatPearls A negative test more than 3 months after the last at-risk exposure is considered conclusive
Confirmatory testing Antigen positive with antibody negative → reflex HIV RNA test to confirm or exclude infection. Both positive → a confirmatory test differentiates HIV-1 from HIV-2 antibodies. Acute HIV is diagnosed by a positive nucleic acid amplification test or p24 antigen with a negative or indeterminate antibody result A second, different, preferably laboratory-based test is required — a confirmed HIV case means a second, different test confirms the first. One positive screen is never a diagnosis —
Plasma HIV-1 RNA (viral load) Recheck 4 to 8 weeks after starting ART; suppression below 200 copies/mL "may take up to 24 weeks of continuous therapy"; once suppressed, monitor every 3 to 4 months. Virologic failure is defined as inability to suppress below 200 copies/mL (NIH) or above 1,000 copies/mL on two consecutive measurements over 3 months after 6 months of therapy (WHO) The indicator of whether treatment is working — "the most important indicator of initial and sustained response to ART." Therapeutic goal: sustained suppression below 50 copies/mL NIH and WHO definitions, as reported by StatPearls —
CD4+ T-lymphocyte count Monitored every 3 to 6 months for the first 2 years or if viremia develops; after 2 years, every 12 months if the count is 300–500, and above 500 "monitoring is optional." Track the trend, not a single value — each falling threshold opens a new set of pathogens The indicator of how much immune damage exists — CD4+ counts are "the best indicators of immune function, disease progression, and survival, and they determine the need to initiate prophylaxis for opportunistic infections." CDC staging: stage 1 ≥ 500 cells/µL · stage 2 200–499 · stage 3 < 200 CDC staging, as reported by StatPearls —
Genotypic drug-resistance testing Timing is a nursing-relevant rule: draw the sample while the patient is still taking the ART, or as soon as possible after discontinuation — resistant strains fade from the sample once drug pressure is removed. Baseline work-up also includes CBC, glucose, renal and liver panels, urinalysis, lipids, hepatitis A/B/C serology, and pregnancy testing when appropriate Baseline testing of reverse transcriptase and protease genes in treatment-naive patients, adding integrase strand transfer inhibitor genes for anyone previously treated with ART or long-acting cabotegravir PrEP —
Serum cryptococcal antigen This is an antigen-triggered decision, not a CD4-alone decision. The same logic applies to toxoplasmosis prophylaxis, which requires a positive toxoplasma antibody in addition to a CD4 below 100 Screened when the CD4+ count is 100 cells/mm³ or less — a positive result is what triggers cryptococcal prophylaxis —
Pneumocystis pneumonia work-up Definitive diagnosis is by PCR, dye staining or fluorescein antibody staining of induced sputum or bronchoalveolar lavage fluid — the imaging and LDH build the case, the respiratory specimen closes it. Do not wait for confirmation to escalate a hypoxemic patient Chest x-ray shows diffuse bilateral peri-hilar interstitial infiltrates; CT shows ground-glass attenuation or cystic lesions with high sensitivity; serum LDH is elevated, as is serum beta-D-glucan in the right clinical setting —

Complications

Warning: Opportunistic infections — the CD4 cliff Report immediately
Emerge once the absolute CD4+ count falls below 200 cells/mm³, or the relative count below 14%: Pneumocystis, toxoplasmosis, candidiasis, cryptococcosis, tuberculosis, MAC, HSV, VZV, CMV, and JC virus (progressive multifocal leukoencephalopathy).
These are organisms a competent immune system contains — the infection is the immune failure made visible. Prophylaxis is prescribed by CD4 threshold and stopped by CD4 recovery (Pneumocystis prophylaxis is discontinued once CD4 exceeds 200 for 3 or more months on ART). A new fever, cough, headache, visual change or swallowing difficulty in a patient below 200 is escalated, not observed.
Warning: Pneumocystis jirovecii pneumonia Report immediately
Weeks of progressive exertional dyspnea, a non-productive dry cough, and low-grade fever in a patient with CD4 below 200 — with hypoxemia already present when the diagnosis is made.
10% to 20% of patients with PJP will die, and mortality reaches as high as 84% once mechanical ventilation is required. That gradient is the argument for escalating on the dry cough rather than on the desaturation. Per the NIH/HHS opportunistic-infection guideline, TMP-SMX "is the treatment of choice for PCP" and "The recommended duration of therapy for PCP (irrespective of regimen) is 21 days," with adjunctive corticosteroids when the room-air PaO₂ is < 70 mm Hg or the A–a gradient is ≥ 35 mm Hg.
Caution: Immune reconstitution inflammatory syndrome (IRIS) Hold & notify
The patient starts ART with a low CD4 count and an underlying opportunistic infection or malignancy — then gets clinically worse over the following days to weeks.
The recovering immune system mounts the inflammatory response it was previously too depleted to mount. The prevention rule is a timing rule: "The opportunistic infection should be treated before initiating ART to decrease the risk" — start ART within 2 weeks of treating most acute opportunistic infections, but wait 4 to 6 weeks after antifungal therapy in acute cryptococcal meningitis and 4 to 8 weeks in tuberculous meningitis. IRIS "is self-limiting" in many cases and is not a reason to stop therapy.
Caution: AIDS-defining malignancies
Kaposi sarcoma, invasive cervical cancer, primary brain lymphoma, non-Hodgkin and Burkitt lymphoma, plus primary effusion, follicular and diffuse large B-cell lymphomas.
Loss of immune surveillance permits virally driven tumors to grow. Any one of these establishes AIDS regardless of the CD4+ count — the diagnosis does not require the number to be below 200. Cancer screening is part of the baseline work-up at diagnosis, not a later add-on.
Caution: Cardiometabolic disease and incomplete immune recovery
Long-term HIV and ART raise cardiovascular morbidity and mortality, with high rates of dyslipidemia, glucose intolerance and diabetes, and weight gain on several regimens.
Guidelines therefore "recommend lifestyle modification counseling from the onset of ART" plus routine screening for glucose intolerance, diabetes and hyperlipidemia. The separate, permanent cost of late diagnosis: starting ART only after CD4 falls below 200 reduces the chance the count ever normalizes, and patients suppressed 3 or more years without recovering above 200 carry 2.6 times greater all-cause mortality.

Medications for this condition

Why each class is prescribed here — every card links to its full pharmacology page.

Antivirals First-line
Immune / Anti-infective · acyclovir

Antiretroviral therapy is the disorder — it is started for everyone with confirmed HIV regardless of CD4 count or clinical stage, preferably within 7 days of diagnosis (per the DHHS, WHO and IAS-USA Panel 2024 recommendations, as reported by StatPearls), because early treatment reduces AIDS- and non-AIDS events, death from any cause, and onward transmission. A regimen combines 3 drugs from at least 2 classes, most often an integrase inhibitor with a dual NRTI backbone, chosen for speed of suppression and a low propensity to develop resistance. The one exception to starting immediately is a severe opportunistic infection, which is treated first to reduce the risk of IRIS. Adherence is the drug’s mechanism of durability: viral load rebounds within weeks of stopping, and the very high reverse-transcriptase error rate converts any gap into selected resistance — which is why nurses screen for the named barriers (pill-swallowing difficulty, shift work, unstable housing, substance use, fear of disclosure, lack of insurance) and offer pillboxes, blister packs, apps and alarms rather than simply restating the instructions. Two safety rules belong at the bedside: abacavir requires HLA-B*5701 pretesting and is contraindicated if positive, and magnesium, aluminum, calcium and iron supplements reduce absorption of dolutegravir, bictegravir and raltegravir — every antacid, supplement and new medication needs pharmacist review.
Vaccines & Immunizations
Immune / Anti-infective

Immunization replaces some of the protection the CD4 compartment can no longer provide, so the recommended list is broad: COVID-19, hepatitis A, hepatitis B, meningococcal ACWY, pneumococcal and HPV vaccines, plus annual inactivated or recombinant influenza vaccine. The safety rule is the CD4-dependent one: live attenuated vaccines are restricted, and MMR is contraindicated in patients with a CD4+ count below 200 cells/mm³ — a weakened live organism given to a depleted immune system can cause the disease it was meant to prevent. An immunization history is taken at diagnosis specifically to "determine which vaccines could offer future protection," and hepatitis serology at baseline identifies who needs hepatitis A and B coverage.

Beyond medications

  • Treatment as prevention (U=U) — HIV "is not sexually transmitted if the viral load is undetectable," defined as below 200 copies of HIV-1 RNA/mL; HPTN 052, PARTNER 1 and 2, and Opposites Attract showed 100% efficacy when ART is taken as prescribed and suppression is achieved. Teach it with its boundary: the data cover sexual transmission only — perinatal and breast-milk transmission still occur at an undetectable viral load.
  • Pre-exposure prophylaxis (PrEP) — for people who in the past 6 months had anal or vaginal sex with a partner with HIV, had a bacterial STI, used condoms inconsistently with partners of unknown status, or shared injection equipment — and for "all patients who request it, regardless of known risk factors." Oral PrEP cuts risk by 86% when taken consistently; long-acting injectables are more effective. It is not fire-and-forget: a negative antigen/antibody test no more than 1 week before starting, then a negative HIV test every 3 months for oral PrEP or before each injection (cabotegravir every 2 months; lenacapavir, FDA-approved for PrEP in 2025, every 6 months), because starting PrEP during undiagnosed acute HIV selects resistance. Injectable PrEP additionally needs HIV RNA testing alongside the 4th-generation test at every visit.
  • Post-exposure prophylaxis (PEP) — the clock rule: antiretrovirals started as soon as possible and within 72 hours of exposure to potentially infected blood, semen or vaginal fluid, and continued for 4 weeks. Occupational exposures use the same regimen with the added opportunity to test the source person. Anyone who has needed PEP more than once in 12 months, or who remains at repeated risk, is referred for PrEP instead.
  • Perinatal prevention — the number that shows what treatment achieves: ART with viral suppression through pregnancy and childbirth, plus 4 to 6 weeks of antiretroviral therapy for the infant, drops transmission from 15–30% (plus 10–20% with breastfeeding) to 0.1% to 0.5%. Components: universal testing before conception and as early as possible in pregnancy, repeat third-trimester testing in high-prevalence areas, intrapartum zidovudine for anyone with a high viral load, and infant antiretrovirals started preferably within 6 hours of birth. Feeding: formula or donor human milk eliminates the milk route; breastfeeding by a virally suppressed mother carries a risk "less than 1% but not zero."
  • Barrier and harm-reduction prevention — consistent condom use at every encounter produced an 80% decrease in HIV incidence in a Cochrane review, and over 70% reduction among serodiscordant heterosexual couples; male condoms remain "the mainstay of barrier HIV prevention" and also cover other STIs. Sterile syringe programs roughly halve the incidence of HIV and hepatitis C, are cost-saving, and "do not increase illegal drug use or crime."
  • Standard precautions and a screened blood supply — "universal precautions for healthcare workers effectively decreased occupational exposure," and between 2000 and 2010 the global share of HIV transmissions attributed to unsafe medical injections fell by 87%, from 5–9% to under 1.3%. Donor screening and testing of all blood products have "nearly eliminated" transfusion-related transmission.
  • Opportunistic-infection prophylaxis and treatment — trimethoprim/sulfamethoxazole below CD4 200 (alternatives: inhaled pentamidine, dapsone, atovaquone), with the antibody- and antigen-conditional additions below 100 and the ART-status-conditional MAC rule below 50. Established Pneumocystis pneumonia is treated with 21 days of trimethoprim-sulfamethoxazole, adding corticosteroids when the room-air PaO₂ is < 70 mm Hg or the A-a gradient is ≥ 35 mm Hg.

Nursing considerations

The RN-specific layer — each action paired with the reason it matters.

Assessment & monitoring
Take the sexual, drug-use and transfusion history in a nonjudgmental manner — number of partners, sexual practices, frequency and type of barrier protection, and any previous sexually transmitted infections.
Why: The wording is the source’s own. An accurate risk history determines screening frequency, PrEP eligibility and partner-notification needs — and a judgmental tone reliably produces an inaccurate history.
Track the two numbers separately and know what each answers: viral load = is the treatment working; CD4 = how much immune damage and which prophylaxis is due.
Why: Viral load is "the most important indicator of initial and sustained response to ART"; CD4 counts are "the best indicators of immune function, disease progression, and survival" and determine prophylaxis. Confusing them leads to reassuring a patient about the wrong thing.
Monitor for the opportunistic-infection cues below CD4 200: new or progressive dyspnea, a dry non-productive cough, fever, headache, painful swallowing, and any new visual symptom.
Why: These organisms are only dangerous because cell-mediated immunity has failed. A new visual symptom below CD4 50 needs immediate ophthalmology — delay in CMV retinitis risks irreversible vision loss.
Assess mental health, substance use, housing and social support as part of the HIV assessment — not as an optional add-on.
Why: A mental-health assessment "is essential for identifying conditions such as depression, other mental illnesses, or substance use that may result in barriers to care," and the social history predicts ability to adhere. Neither mental illness nor substance use is a contraindication to starting ART.
Monitor weight and nutritional status at every visit, and watch for the metabolic effects of therapy: dyslipidemia, glucose intolerance and weight gain.
Why: Nurses and nutritionists "monitor weight and promote adequate nutrition and hydration… and minimize the risk of HIV wasting syndrome," and guidelines pair ART initiation with routine screening for glucose intolerance, diabetes and hyperlipidemia.
Watch for the patient who gets worse in the days to weeks after starting ART, and report it as possible IRIS rather than treatment failure.
Why: The deterioration is a recovering immune system attacking a pathogen it previously could not see. It is often self-limiting and needs symptomatic treatment — stopping ART is the wrong reflex.
Interventions & safety
Deliver a positive result in person, in a nonjudgmental, calm and confidential environment with enough time for counseling and emotional support.
Why: The source is explicit: "Positive test results should be given to patients in person," though results "may be provided by phone when delays arise." How the diagnosis is delivered shapes whether the patient returns for care.
Screen emotional and physical safety at the results visit — ensure the presence of at least one trusted person for support and assess the risk of domestic violence.
Why: Disclosure of an HIV diagnosis can put a patient at risk in their own home. Assessing safety at the results visit is named as essential, not optional.
Protect confidentiality absolutely: document accurately, and do not disclose to anyone unless the patient requests their presence. Partner notification services exist in most states and may be conducted anonymously.
Why: "Accurate documentation and strict confidentiality are essential for both clinical diagnosis and public health surveillance," and fear of disclosure is a named barrier to adherence — a breach costs both trust and treatment.
Expect ART to start within 7 days of diagnosis regardless of CD4 count — but anticipate deliberate delay when a severe opportunistic infection is present.
Why: Rapid start reduces AIDS events, death and onward transmission. The exception exists because starting ART into an untreated severe opportunistic infection is what precipitates IRIS.
Route every new medication, antacid and supplement through pharmacy review before it is given.
Why: Magnesium, aluminum, calcium and iron reduce absorption of dolutegravir, bictegravir and raltegravir; boosted protease inhibitors strongly inhibit CYP3A4 and raise levels of benzodiazepines, statins, direct oral anticoagulants and calcineurin inhibitors; efavirenz induces CYP3A4 and cuts methadone and hormonal-contraceptive levels. A subtherapeutic ART level is a resistance event.
Draw genotypic resistance testing while the patient is still on ART, or as soon as possible after it stops — and confirm HLA-B*5701 status before abacavir is given.
Why: Resistant strains recede from the sample once drug pressure is removed, so late sampling can miss them. Abacavir is contraindicated in HLA-B*5701–positive patients because of hypersensitivity, and pretesting is required.
Patient teaching
Teach that HIV is a chronic, manageable condition, and explain the distinction between HIV and AIDS explicitly.
Why: The source names both as part of the basic education given at diagnosis. Patients who believe a positive test means imminent AIDS disengage from the care they need to prevent exactly that.
Teach U=U with its boundary: sustained suppression below 200 copies/mL means HIV is not transmitted sexually — but transmission still occurs perinatally and through breast milk.
Why: "Emphasis on U=U is a strong motivator for patient adherence to medication," so teaching it is a clinical intervention. Teaching it without the perinatal and breastfeeding exception hands a pregnant patient a false reassurance.
Build adherence with tools, not lectures: 7-day pillboxes, phone apps and alarms, blister packs, automated reminders, home nurse visits, and navigator or telehealth check-ins.
Why: Viral load rises within weeks of stopping, raising the risk of resistance, complications and transmission. The named barriers — pill-swallowing difficulty, shift work, unstable housing, substance use, fear of disclosure, lack of insurance — are solved with logistics, not with willpower.
Teach the patient to recognize the signs of ART toxicity and what to do about them, rather than to stop the medication and wait for the next visit.
Why: The source names identifying "the signs and symptoms that indicate toxicity from ART and the recommended next steps" as a teaching deliverable. Silent self-discontinuation is how resistance develops.
Teach ongoing prevention: correct and consistent condom use, lower-risk sexual activities, encouraging partners to take PrEP, and never sharing needles, syringes or other injection equipment.
Why: A person living with HIV can still acquire other infections and can still transmit if suppression lapses. Condoms cut incidence by roughly 80% with consistent use and also cover other sexually transmitted infections.
Name stigma out loud and refer for support — psychology, social work, specialized nursing, public health, or peer support groups.
Why: Patients "face further difficulties due to stigma and discrimination, including self-stigma" — internalizing the belief that they deserved the diagnosis. Stigma is a clinical problem because it drives people out of care, and only 54% of US patients diagnosed in 2021 were retained in care.

How a real nurse thinks

The clinical-judgment loop, worked for a typical presentation — reasoning, not reference.

  1. 1
    Recognize cues

    The cues that matter cluster fast: three weeks of progressive exertional dyspnea with a non-productive dry cough and low-grade fever, a respiratory rate of 26, and SpO₂ 90% on room air in a patient whose CD4+ count is 150 cells/mm³ — below the 200 threshold — with no Pneumocystis prophylaxis started. Supporting cues: elevated LDH, oral thrush, and a viral load of 210,000. The deceptive cue is the chest exam: lungs clear to auscultation. Pneumocystis pneumonia is an interstitial process, so a normal-sounding chest does not reassure — the hypoxemia does the talking.

  2. 2
    Analyze cues

    A CD4+ of 150 means two things at once. First, it is CDC stage 3 — AIDS by count, independent of any symptom. Second, it is below the CD4 200 threshold at which Pneumocystis jirovecii prophylaxis is indicated — and it has not been started, so it is due now. Note the timeline before drawing a causal conclusion: his symptoms began about three weeks ago and he was diagnosed nine days ago, so this pneumonia was already established before anyone knew he had HIV. Prophylaxis is overdue, not the reason he is sick. The symptom profile matches the sourced description of PJP almost item for item: indolent onset over several weeks, dyspnea in 95%, dry cough in 95%, low-grade fever in over 80%, with hypoxemia present at diagnosis. The elevated LDH supports it. At CD4 150 he has not yet crossed the toxoplasmosis and cryptococcal thresholds at 100 or the CMV and MAC thresholds at 50 — but those are the next lines, and the trend is what matters.

  3. 3
    Prioritize

    Oxygenation and escalation come first, and the mortality gradient is why: 10% to 20% of patients with PJP die, and mortality reaches as high as 84% once mechanical ventilation is required. Every hour spent treating this as allergies is spent on the wrong side of that curve. Second priority is the diagnostic pathway — chest imaging and a respiratory specimen — but it does not gate treatment of a hypoxemic patient. Third, and deliberately not first: starting antiretroviral therapy. The temptation is strong, because ART is recommended for everyone regardless of CD4 — but the one stated exception is a severe opportunistic infection.

  4. 4
    Generate solutions

    Apply oxygen and reassess. Escalate to the provider with the full picture, anticipating a chest x-ray looking for diffuse bilateral peri-hilar interstitial infiltrates, a CT if needed, and induced sputum or bronchoalveolar lavage for PCR or staining. Anticipate 21 days of trimethoprim-sulfamethoxazole, and anticipate that adjunctive corticosteroids will be ordered if the room-air arterial PaO₂ is < 70 mm Hg or the alveolar-arterial gradient is ≥ 35 mm Hg — so an arterial blood gas is likely. Plan ART to start after the opportunistic infection is being treated, typically within about 2 weeks, and prepare the patient and the team to expect possible IRIS.

  5. 5
    Take action

    Oxygen on, patient positioned upright, continuous pulse oximetry, and the provider called now rather than at the end of the visit. The SBAR: "41-year-old man, HIV diagnosed nine days ago, no ART and no prophylaxis started. CD4 150, viral load 210,000, LDH elevated. Three weeks of progressive exertional dyspnea and dry cough, now RR 26 and SpO₂ 90% on room air with a clear chest exam. I am concerned about Pneumocystis pneumonia and have started oxygen. Requesting urgent evaluation — anticipating chest imaging, an ABG, induced sputum or BAL, and TMP-SMX." The trap to avoid is reflexively starting ART today because "everyone gets ART regardless of CD4." Here, the opportunistic infection is treated first: "the opportunistic infection should be treated before initiating ART to decrease the risk" of immune reconstitution inflammatory syndrome.

  6. 6
    Evaluate

    Success over the next days: oxygen saturation improving on therapy, respiratory rate falling, fever settling, and a 21-day TMP-SMX course under way with corticosteroids added if the gas criteria were met. Prophylaxis is now on the problem list permanently — and it will be stopped only after the CD4 count exceeds 200 for 3 or more months on ART, not sooner. ART is scheduled to start within about 2 weeks, with the team briefed that clinical worsening after ART begins may be IRIS rather than failure. The re-escalation trigger is set in advance: rising oxygen requirement, rising respiratory rate, or altered mental status means the patient is heading toward the ventilated end of that mortality range.

Scenario — you’re the nurse

Work each question before revealing the answer. Rationales explain the wrong options too.

Infectious disease clinic, escalating to the emergency department · 1030

A 41-year-old man diagnosed with HIV nine days ago after a routine opt-out screen during an urgent-care visit. He has not yet started antiretroviral therapy — baseline labs were drawn at diagnosis and today is his first follow-up. He tells you he has been "winded going up the stairs" for about three weeks and has a dry cough that will not clear: "I keep thinking it is allergies, but it is getting worse."

1030 vitals — HR 104 · BP 128/76 · RR 26 · SpO₂ 90% on room air · T 37.8 °C
Assessment — speaks in short phrases, accessory muscle use climbing to the exam table; lungs clear to auscultation; no chest pain; oral thrush on the buccal mucosa
Baseline labs (drawn at diagnosis, resulted since) — CD4+ 150 cells/mm³ · HIV-1 RNA 210,000 copies/mL · LDH elevated
Chart — antigen/antibody screen reactive, confirmed by a second laboratory-based test · no prophylaxis started · no ART started · genotypic resistance testing pending
Patient report — three weeks of progressive exertional dyspnea, non-productive cough, low-grade fevers, no sputum
Q1 Select all that apply
Which findings require immediate follow-up? Select all that apply.
  1. A. SpO₂ 90% on room air with a respiratory rate of 26
  2. B. Three weeks of progressive exertional dyspnea with a non-productive cough
  3. C. CD4+ count 150 cells/mm³ with no Pneumocystis prophylaxis started
  4. D. Lungs clear to auscultation
  5. E. Temperature 37.8 °C
Reveal answer & rationale
Answer: A, B, C
Hypoxemia with tachypnea (A) is the finding that establishes urgency — in Pneumocystis pneumonia hypoxemia is already present at diagnosis. The indolent three-week course of exertional dyspnea and dry cough (B) matches the sourced presentation, where dyspnea and dry cough each occur in about 95% of cases. A CD4+ of 150 with no prophylaxis (C) is an intervention that is now overdue, since prophylaxis begins below 200 — though note it could not have prevented this particular pneumonia, which began about twelve days before he was diagnosed. Clear lungs (D) is a distractor that must not reassure — Pneumocystis is interstitial and the chest can auscultate normally while the patient desaturates. A temperature of 37.8 °C (E) is consistent with the low-grade fever described in over 80% of cases, but it is not itself the actionable finding.
Q2 Multiple choice
The nurse understands that this patient meets criteria for AIDS because:
  1. A. His viral load exceeds 200,000 copies/mL
  2. B. His CD4+ count is below 200 cells/mm³
  3. C. He has been HIV-positive for more than nine days without treatment
  4. D. He has a respiratory infection
Reveal answer & rationale
Answer: B
AIDS is defined two ways, and either one alone qualifies: a CD4+ count below 200 cells/mm³ — CDC stage 3 — or the presence of an AIDS-defining condition regardless of the count (B). Viral load (A) measures whether treatment is working and drives transmission risk, but it plays no part in the AIDS definition. Duration of infection (C) is not a criterion; the staging ladder is built on CD4 counts, with stage 1 at 500 or more and stage 2 at 200 to 499. Having "a respiratory infection" (D) is too vague — Pneumocystis jirovecii pneumonia specifically is on the AIDS-defining list, but an ordinary respiratory infection is not.
Q3 Put in order
Put the nurse’s first four actions in priority order:
  1. A. Notify the provider with an SBAR, anticipating chest imaging, an arterial blood gas, and a respiratory specimen
  2. B. Apply oxygen, position the patient upright, and begin continuous pulse oximetry
  3. C. Reinforce teaching on antiretroviral adherence and U=U
  4. D. Document the respiratory assessment and the oxygen therapy initiated
Reveal answer & rationale
Correct order: B → A → D → C
Oxygenation comes first (B) — it needs no order, it addresses the immediate physiologic threat, and the mortality of Pneumocystis pneumonia climbs steeply once respiratory failure sets in. Escalation follows immediately (A), because imaging, an arterial blood gas and a respiratory specimen all require provider orders and the corticosteroid decision depends on the PaO₂ or A-a gradient. Documentation (D) records what was done but never precedes doing it. Adherence and U=U teaching (C) is genuinely important and will matter enormously to this patient — but it is a stable-visit conversation, not something to deliver to a hypoxemic man speaking in short phrases.
Q4 Multiple choice
The provider plans to treat the pneumonia now and begin antiretroviral therapy in about two weeks. A new nurse asks why ART is not started today, since "everyone with HIV starts ART regardless of CD4." The best explanation is:
  1. A. Antiretroviral therapy cannot be given at the same time as trimethoprim-sulfamethoxazole
  2. B. Starting ART into an untreated severe opportunistic infection raises the risk of immune reconstitution inflammatory syndrome, so the infection is treated first
  3. C. Antiretroviral therapy is withheld until the CD4 count rises above 200
  4. D. Genotypic resistance testing must result before any antiretroviral can be started
Reveal answer & rationale
Answer: B
ART is recommended for everyone regardless of CD4 count or clinical stage, and the single stated exception is exactly this one: "The opportunistic infection should be treated before initiating ART to decrease the risk" of IRIS, with ART then started within about 2 weeks for most acute opportunistic infections (B). There is no stated prohibition on giving ART alongside TMP-SMX (A). Waiting for CD4 to rise above 200 (C) inverts the rule — delaying ART until CD4 falls below 200 actually reduces the chance the count ever normalizes, and carries 2.6 times greater all-cause mortality in patients who never recover above 200. Resistance testing (D) guides regimen choice and should be drawn while the patient is on therapy or soon after stopping, but current guidance is to initiate integrase-inhibitor-based therapy with a dual NRTI backbone before further laboratory testing results for most patients.
Q5 Multiple choice
Three months later the patient is on ART with a viral load of 40 copies/mL. He asks, "Does this mean I cannot give HIV to anyone now?" The best response is:
  1. A. "Yes — once you are undetectable you cannot transmit HIV by any route."
  2. B. "No — an undetectable viral load does not change transmission risk at all."
  3. C. "With a sustained undetectable viral load you will not transmit HIV sexually — but transmission can still occur perinatally and through breast milk."
  4. D. "You should keep using condoms because the viral load test is not accurate enough to rely on."
Reveal answer & rationale
Answer: C
U=U is real and it is quantified: HIV "is not sexually transmitted if the viral load is undetectable," defined as below 200 copies/mL, and four named trials showed 100% efficacy when therapy is taken as prescribed. But the evidence has an explicit boundary — "clinical data only support U=U for sexual transmission. Even with undetectable viral loads, HIV transmission still occurs perinatally and via breast milk" (C). Option A over-promises across every route and is the answer that could harm a pregnant or breastfeeding patient. Option B is simply wrong and discards a documented result that is also "a strong motivator for patient adherence." Option D undermines a valid test rather than teaching its actual limits; condoms remain valuable for other sexually transmitted infections, but that is a different reason than the one offered.

Common questions

What causes hiv / aids?
Common causes and risk factors include receptive anal intercourse — approximately 138 infections per 10,000 exposures, the highest-risk sexual act by an order of magnitude, insertive anal intercourse (11 per 10,000) · receptive vaginal (8 per 10,000) · insertive vaginal (4 per 10,000), sharing needles, syringes or other injection equipment — 63 infections per 10,000 exposures, inconsistent or absent condom use with a partner of unknown hiv status, a partner living with hiv whose viral load is unknown or detectable, and others.
What are the early signs of hiv / aids?
Early findings include Acute retroviral syndrome — fever, fatigue, muscle pain, rash, headache, sore throat, swollen lymph nodes, joint pain, night sweats, diarrhea, Mucocutaneous ulceration — shallow, sharply demarcated ulcers with a white base ringed by thin erythema.
Which findings should a nurse report immediately in hiv / aids?
Report immediately: Progressive exertional dyspnea with a non-productive dry cough and low-grade fever — Pneumocystis jirovecii pneumonia, Any new visual symptom in a patient with a low CD4 count — CMV retinitis, Opportunistic infections — the CD4 cliff, Pneumocystis jirovecii pneumonia. These signal deterioration that needs rapid intervention.
What is the difference between HIV and AIDS?
HIV is the virus; AIDS is the final stage of HIV infection. A patient has AIDS when either of two things is true — the CD4+ count falls below 200 cells/mm³ (CDC surveillance stage 3), or an AIDS-defining condition is present "regardless of the CD4+ count." That second route is why someone with a CD4 of 300 and Pneumocystis jirovecii pneumonia, esophageal candidiasis, Kaposi sarcoma, CMV retinitis, tuberculosis or HIV wasting syndrome still has AIDS. Explaining this distinction clearly is named as part of the basic education given at diagnosis.
At what CD4 count does prophylaxis start, and when does it stop?
Below 200 cells/mm³, Pneumocystis prophylaxis with trimethoprim/sulfamethoxazole begins — and it also covers cerebral toxoplasmosis and bacterial infections. Below 150, histoplasmosis prophylaxis is added for patients in hyperendemic areas or with occupational exposure. Below 100, toxoplasmosis prophylaxis is added only if the toxoplasma antibody is positive, and cryptococcal prophylaxis only if the serum cryptococcal antigen is positive. Below 50, CMV retinitis becomes a real risk — and MAC prophylaxis applies only to patients not on ART or still viremic on it, since "if patients with HIV are rapidly initiated on ART, prophylaxis for Mycobacterium avium complex is not required." Prophylaxis is stopped once the CD4 count stays above 200 for 3 or more months on therapy.
How soon after an exposure can HIV be detected, and when is a negative test conclusive?
Nothing detects HIV during the eclipse period, about 10 days after infection. After that, HIV RNA appears first — roughly a week after infection, depending on the assay — then the p24 antigen at 13 to 20 days, then IgM near 20 days and IgG near 30. The window phase runs up to 20 to 25 days. On a 4th-generation antigen/antibody test most people are positive within 3 weeks, but some do not seroconvert for up to 3 months, so a negative test more than 3 months after the last at-risk exposure is considered conclusive. After a known exposure, retest through the 4- to 6-week period with a final test at 12 weeks — and if the exposure was within 14 days, an HIV RNA test is the correct initial test, because a negative antibody result does not rule out acute HIV.

Sources

Reviewed by Hae Suk Lee, RN

Educational summary for nursing students. Scenarios are fictional teaching cases. Always verify against current guidelines and your institution's protocols before acting in practice. Not medical advice.

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