IM6.1-22 | HIV — Glossary

A cell-wall polysaccharide component of fungi (including Pneumocystis, Aspergillus, Candida) detected in serum; elevated in PCP (specificity ~90% in HIV respiratory presentations); a useful adjunct when BAL is not immediately available.

An evidence-based self-report method for assessing ART adherence: asking the patient to recall which doses were taken or missed in the last 3 days; combined with 30-day recall ('How many doses have you missed this month?'); more accurate than asking 'Are you taking your medicines?'

A mononucleosis-like illness occurring 2–4 weeks after HIV transmission, during peak viraemia; characterised by fever, pharyngitis, generalised lymphadenopathy, maculopapular rash (including palms), oral ulcers, and myalgia; standard HIV antibody tests may be negative during this period.

CDC-defined as HIV infection with either CD4 count <200 cells/µL OR presence of any CDC Category C AIDS-defining condition, regardless of CD4 count.

A measure of gas exchange efficiency calculated from ABG: A-a gradient = (FiO₂ × 713 − PaCO₂/0.8) − PaO₂; A-a gradient >35 mmHg on room air in PCP defines moderate-to-severe disease requiring adjunctive corticosteroids.

Consistency with which a patient takes antiretroviral therapy as prescribed; requires >95% adherence (missing <1 dose per week on once-daily regimen) to maintain viral suppression; suboptimal adherence leads to sub-therapeutic drug levels and selection of drug-resistant HIV variants.

The proportion of total T lymphocytes that are CD4+ cells; preferred over absolute CD4 count in children <5 years and adults with haematological conditions affecting total lymphocyte count; CD4% <14% corresponds approximately to CD4 count <200 cells/µL in adults.

A T-helper lymphocyte bearing the CD4 receptor; the primary target of HIV infection; orchestrates adaptive immunity. Normal count 500–1500 cells/µL; AIDS-defining level is <200 cells/µL.

Reactivation of latent Toxoplasma gondii in the brain at CD4 <100 cells/µL; presents with fever, focal neurological deficits, and multiple ring-enhancing lesions in the basal ganglia on CT/MRI; treat empirically with pyrimethamine + sulfadiazine + leucovorin.

Cytomegalovirus infection of the retina at CD4 <50 cells/µL; presents with visual field loss, floaters, and decreased acuity; fundoscopy shows characteristic 'pizza-pie' or 'scrambled eggs and ketchup' haemorrhages and exudates along vessels; an AIDS-defining condition.

The primary prophylaxis for PCP and Toxoplasma gondii encephalitis in PLHIV with CD4 <200 cells/µL (NACO threshold: <250 cells/µL); a single double-strength tablet daily; also protects against Salmonella, Nocardia, and Isospora.

The legal and ethical obligation to protect a patient's HIV status from disclosure to any third party without the patient's explicit written consent; under the HIV Act 2017, unauthorised disclosure is a criminal offence; applies to family members, employers, and other healthcare providers.

A polysaccharide antigen shed by Cryptococcus neoformans into blood and CSF; detected by lateral flow assay (LFA) or ELISA; sensitivity >95% in CSF for cryptococcal meningitis; serum CrAg used for screening at CD4 <100 under NACO guidelines.

Infection of the CNS by Cryptococcus neoformans at CD4 <100 cells/µL; presents as subacute meningitis with elevated ICP; India ink stain and CrAg in CSF are diagnostic; treat with Amphotericin B + flucytosine, then consolidate with fluconazole; therapeutic LP is critical for raised ICP.

An obligate intracellular protozoan causing profuse, watery, non-bloody secretory diarrhoea in HIV patients with CD4 <200 cells/µL; diagnosed by modified acid-fast stain or PCR of stool; treatment is limited (nitazoxanide has modest efficacy); ART and CD4 recovery are the most effective treatment.

Detection of Epstein-Barr virus DNA in cerebrospinal fluid by PCR; highly sensitive and specific for primary CNS lymphoma (PCNSL) in HIV patients; a positive result in the context of a single ring-enhancing CNS lesion that fails to respond to empirical toxoplasmosis treatment strongly supports PCNSL.

A clinical clue for PCP in which the degree of hypoxia (SpO₂ or PaO₂ on ABG) is markedly worse than expected from the chest examination findings (which may show minimal or absent crackles early in PCP); an exercise desaturation of >3% is diagnostically useful.

Systemic infection by M. avium-intracellulare at CD4 <50 cells/µL; presents with high-grade fever, night sweats, weight loss, anaemia, and markedly elevated alkaline phosphatase; hepatosplenomegaly and diarrhoea may be present; diagnosis by blood culture (lysis-centrifugation method).

An integrase strand transfer inhibitor (INSTI) that blocks HIV DNA integration into the host chromosome; the integrase component of NACO first-line TLD; high genetic barrier to resistance (multiple mutations required); once-daily dosing; caution in first trimester of pregnancy (small neural tube defect risk).

A decline in SpO₂ of ≥3% on minimal exertion (e.g., walking 10 metres); a sensitive early indicator of PCP-related gas exchange impairment even when resting SpO₂ is normal; assessed using pulse oximetry during a brief 6-minute walk or corridor walk.

The current standard HIV screening test that simultaneously detects p24 antigen and anti-HIV-1/2 IgG and IgM antibodies; reduces the window period to 18–45 days post-exposure; reactive results require confirmatory testing.

An RNA retrovirus of the Lentivirus genus that infects CD4+ T lymphocytes, macrophages, and dendritic cells via gp120-CD4 binding and CCR5/CXCR4 co-receptor engagement, causing progressive depletion of CD4 cells and combined immunodeficiency.

The principal Indian legislation governing HIV/AIDS; prohibits discrimination against PLHIV; legally protects HIV status as confidential information requiring written consent for disclosure; establishes the HIV/AIDS Ombudsman mechanism; mandates informed consent for HIV testing; provides guardianship protections for children with HIV.

The concentration of plasma HIV RNA measured in copies/mL by quantitative PCR; reflects active viral replication; should be undetectable (<50 copies/mL) by 6 months on ART; a detectable viral load after 6 months signals virological failure.

An official designated in each Indian state under the HIV Act 2017 to receive and investigate complaints of discrimination, confidentiality breach, or denial of rights by healthcare providers, employers, or other entities; patients may approach the Ombudsman without requiring legal representation.

Indian legislation that prohibits discrimination against PLHIV; legally protects patient confidentiality; mandates informed consent for HIV testing and disclosure; prohibits denial of healthcare, employment, or education on the basis of HIV status.

Paradoxical worsening of an existing OI (or unmasking of a subclinical OI) following initiation of ART; caused by restoration of pathogen-specific immune responses; most commonly seen with TB, cryptococcus, and CMV; managed by continuing ART ± corticosteroids for severe cases.

A simple staining technique using India ink (or nigrosin) to visualise the polysaccharide capsule of Cryptococcus neoformans as a clear halo against a dark background; positive in ~70% of cryptococcal meningitis CSF samples.

The mandatory process before HIV testing under the HIV Act 2017; the patient must be informed of the nature of the test, implications of a positive result, confidentiality protections, and voluntary nature of testing; HIV testing without informed consent is prohibited.

Antiretroviral drugs that block the integrase enzyme, preventing insertion of viral DNA into the host chromosome; high genetic barrier to resistance; examples: dolutegravir (TLD first-line), raltegravir, bictegravir.

Paradoxical clinical deterioration occurring 2–12 weeks after ART initiation, caused by restored immune responses mounting an exaggerated inflammatory reaction against OI antigens; most common with TB (TB-IRIS) and Cryptococcus; managed by continuing ART + NSAIDs or prednisolone for severe cases.

Administration of isoniazid to PLHIV with latent TB infection (after excluding active TB) to prevent progression to active disease; a key NACO recommendation given the high TB-HIV co-infection burden in India.

An AIDS-defining vascular tumour caused by HHV-8 (Human Herpesvirus 8); presents with violaceous/dark nodular lesions on skin, oral mucosa (hard palate), and viscera; ART alone can cause regression in limited disease.

A specialised blood culture system that lyses blood cells to release intracellular organisms, then concentrates the lysate before culture; the gold standard for detecting disseminated Mycobacterium avium complex (MAC) and fungaemia; routine automated blood culture systems have poor sensitivity for MAC.

The Indian government body responsible for coordinating HIV/AIDS prevention and treatment under the National AIDS Control Programme (NACP); provides free ART to all PLHIV under the 'Treat All' policy.

Antiretroviral drugs that bind to an allosteric site on reverse transcriptase, causing conformational change; examples include efavirenz (CNS side effects), nevirapine (hepatotoxicity, Stevens-Johnson), rilpivirine; low genetic barrier to resistance (single K103N mutation confers class resistance to EFV/NVP).

A class of antiretroviral drugs that act as chain terminators; incorporated into the viral DNA chain as nucleoside analogues lacking the 3'-OH group needed for chain elongation; examples include TDF, 3TC, AZT, and emtricitabine.

Harm reduction treatment for opioid-dependent injecting drug users using buprenorphine-naloxone; reduces injecting risk behaviour, HIV transmission, and mortality; provided under NACO targeted interventions for key populations.

An infection caused by pathogens that are ordinarily controlled by a competent immune system but cause disease when immunity is suppressed; in HIV, OIs have characteristic CD4 thresholds below which they emerge.

Candida albicans infection of the oral mucosa, the most common oral manifestation of HIV; three forms — pseudomembranous (white removable plaques), erythematous (red patches), and angular cheilitis; WHO Stage 2–3; treated with fluconazole 100–200 mg daily × 7–14 days.

White corrugated plaques on the lateral borders of the tongue caused by Epstein-Barr virus (EBV); cannot be scraped off (unlike candidiasis); a WHO Stage 2 lesion virtually pathognomonic of HIV infection.

IRIS occurring in a patient with a known, previously treated OI — the treated infection worsens paradoxically as immune function recovers; the classic form is paradoxical TB-IRIS with worsening lymphadenopathy, CXR, and fever after ART start in a TB-treated patient.

The process of informing the sexual or needle-sharing partners of a person with HIV of their possible exposure, enabling them to seek testing and PEP or PrEP; under the HIV Act 2017 in India, partner notification is voluntary and patient-led — the clinician supports and facilitates but cannot disclose without consent.

Lymphadenopathy in two or more extra-inguinal sites lasting >3 months without an identifiable cause other than HIV; a WHO Stage 1 feature; palpable, non-tender, rubbery nodes in axillary, cervical, and inguinal chains.

Communication convention that places the person before their condition — 'person living with HIV' (PLHIV) rather than 'HIV patient' or 'AIDS victim'; reflects the principle that HIV is a condition the person has, not their identity; evidence-based approach to reducing internalised and external stigma.

The addition of low-dose ritonavir or cobicistat to a primary protease inhibitor or certain INSTIs to inhibit CYP3A4 metabolism, increasing plasma drug concentration; allows less-frequent dosing and improves efficacy; can cause drug-drug interactions via CYP3A4 inhibition.

Adherence challenge characterised by a patient's psychological exhaustion from taking daily medications over months to years; particularly relevant for patients on multiple medications (ART + co-trimoxazole + IPT); addressed by acknowledging the burden, simplifying regimens (TLD as single tablet), and reinforcing the benefit of viral suppression.

The most common AIDS-defining OI in non-TB prevalent settings; occurs at CD4 <200 cells/µL; presents with insidious dyspnoea, dry cough, and bilateral ground-glass infiltrates on CXR; treat with high-dose TMP-SMX ± corticosteroids if severe.

A 28-day course of antiretroviral therapy (TDF + 3TC + DTG in NACO guidelines) started within 72 hours (ideally <2 hours) of a high-risk HIV exposure (occupational needlestick or sexual exposure) to prevent HIV seroconversion; requires follow-up HIV testing at 6 weeks and 3 months.

The Indian national programme to prevent vertical (mother-to-child) HIV transmission; includes ART during pregnancy and delivery, elective caesarean section in select cases, avoidance of breastfeeding, and infant prophylaxis with nevirapine.

The NACO programme to prevent vertical HIV transmission: ART throughout pregnancy (TLD), planned facility delivery, avoidance of breastfeeding when alternatives are safe, and infant nevirapine prophylaxis for 6 weeks; reduces MTCT from ~30% to <1%.

Daily antiretroviral therapy (TDF + FTC in India) taken by HIV-negative individuals at high ongoing risk of HIV acquisition; reduces risk of infection by >90% with adherent use; approved by NACO for high-risk groups (MSM, transgender women, sex workers, serodiscordant couples); requires 3-monthly HIV testing and renal monitoring.

An AIDS-defining B-cell lymphoma confined to the CNS, uniformly EBV-associated in HIV patients; presents as a single large ring-enhancing lesion on MRI (vs multiple smaller basal ganglia lesions in toxoplasmosis); CSF EBV PCR positive.

A demyelinating disease of the CNS caused by reactivation of JC polyomavirus in profound immunosuppression (CD4 <100); presents with progressive focal neurological deficits; MRI shows asymmetric non-enhancing white matter T2 hyperintensity, sparing U-fibres early; no specific antiviral treatment — ART and immune reconstitution are the mainstay.

Antiretroviral drugs that block HIV protease, preventing cleavage of polyprotein precursors into functional viral proteins; virions are produced but non-infectious; always pharmacologically boosted with ritonavir or cobicistat; examples: lopinavir/r (second-line NACO), atazanavir/r, darunavir/r; high resistance barrier.

NACO recommendation that health providers should actively offer HIV testing and counselling to patients attending healthcare settings with HIV-associated conditions, rather than waiting for patients to self-request testing.

The most common HIV-specific dermatosis in Africa and Asia; symmetrical itchy follicular papules on trunk and limbs at CD4 <200–350 cells/µL; represents exaggerated immune response to follicular antigens; resolves with ART.

An enzyme released by damaged cells; markedly elevated (>500 IU/L, often 700–1000 IU/L) in PCP due to alveolar damage; a useful surrogate marker when bronchoalveolar lavage is unavailable; also elevated in lymphoma and haemolysis.

A structured framework for breaking bad news: Setting (private space), Perception (assess patient's awareness), Invitation (ask permission to share result), Knowledge (disclose clearly and simply), Emotions (acknowledge emotional response before information), Summary (next steps); adapted for HIV diagnosis disclosure.

Social disapproval, discrimination, and devaluation directed toward PLHIV; the primary structural barrier to HIV testing, disclosure, adherence, and care engagement; occurs in healthcare settings (provider stigma) as well as in families and communities; identified by the Lancet HIV Commission as a central driver of the epidemic's persistence.

A clinical framework that integrates the presenting symptom with the estimated or known CD4 count to generate a CD4-contextualised differential diagnosis for HIV patients; the CD4 count functions as a prior probability modifier that re-ranks the generic differential.

Tuberculosis affecting the lymph nodes; the most common form of peripheral TB in India; presents with firm-matted non-tender cervical, supraclavicular, or axillary nodes; may fluctuate (collar stud abscess) and discharge; in HIV, may be the presentation of disseminated TB.

A communication technique to verify patient understanding by asking them to explain information back in their own words ('Can you tell me what the first tablet is for?'); evidence-based for improving health literacy and treatment adherence; different from simply asking 'Do you understand?'

A nucleotide analogue RTI (NtRTI) active against both HIV and hepatitis B virus; the tenofovir component of TLD first-line ART; key toxicities: renal impairment (proximal tubular dysfunction / Fanconi syndrome) and reduced bone mineral density; contraindicated if eGFR <50 mL/min.

The current NACO first-line antiretroviral therapy regimen for all PLHIV in India — a once-daily single tablet containing TDF 300 mg + 3TC 300 mg + DTG 50 mg; replaced TLE (TDF + 3TC + EFV) due to superior efficacy, higher resistance barrier (DTG vs EFV), and better tolerability.

NACO India policy (since 2017) of initiating antiretroviral therapy (ART) for all persons living with HIV (PLHIV) regardless of CD4 count or WHO clinical stage, eliminating previous CD4-count thresholds for ART initiation.

A trusted person designated by the patient — with their consent — who is aware of their HIV status and can support daily ART adherence (reminders, pill dispensing, emotional support); endorsed by NACO as a component of adherence support in the Indian ART programme.

Evidence-based principle that a person with HIV who maintains a sustained undetectable viral load (<200 copies/mL) on ART cannot sexually transmit HIV to a partner; endorsed by WHO, CDC, and NACO; transforms prevention messaging from restriction to empowerment.

The evidence-based principle that PLHIV with a sustained undetectable viral load (<200 copies/mL on stable ART) cannot transmit HIV sexually; endorsed by WHO and NACO; has significant implications for reducing stigma and supporting normal relationships.

IRIS presenting as a new OI that was subclinical (unrecognised) at the time of ART initiation — the recovering immune system unmasks and inflammatory responds to a previously silent infection; e.g., new cryptococcal meningitis presenting 4 weeks after ART start in a patient without prior recognised cryptococcal disease.

The stable level of HIV plasma viraemia (viral load) reached after the acute seroconversion response subsides, representing a balance between viral replication and host immune control; predicts the rate of CD4 decline and disease progression.

Persistent plasma HIV RNA >1000 copies/mL on at least two consecutive measurements ≥4 weeks apart after ≥6 months on ART; the most common cause is suboptimal adherence; may also result from drug resistance, drug interactions, or pharmacokinetic failure.

A four-stage clinical classification of HIV disease based on clinical features (not CD4 count); used in resource-limited settings; Stage 4 includes all AIDS-defining OIs such as PCP, cryptococcal meningitis, and cerebral toxoplasmosis.

A 0–4 scale measuring functional status in HIV: 0 = normal activity; 1 = symptomatic but fully ambulatory; 2 = ambulatory >50% of waking hours; 3 = bedridden <50%; 4 = bedridden >50% of waking hours. Correlates with WHO clinical stage.

The interval between HIV infection and the time when a specific test becomes reliably positive; shortest for HIV RNA PCR (10–12 days), intermediate for fourth-generation Ag/Ab assay (18–45 days), longest for antibody-only tests (45–90 days).

A cartridge-based nucleic acid amplification test (CBNAAT) for Mycobacterium tuberculosis and rifampicin resistance; the NTEP first-line diagnostic test for TB in HIV-positive patients; provides results in <2 hours; superior sensitivity vs sputum smear in HIV-associated TB.