General Medicine
HIV and AIDS
HIV and AIDS for MBBS: seroconversion, CD4-linked opportunistic infections, antiretroviral therapy and post-exposure prophylaxis, mapped to NMC codes IM6.1 to IM6.23.
MedNext Academy | 3 min read
HIV and AIDS
HIV and AIDS for MBBS: seroconversion, CD4-linked opportunistic infections, antiretroviral therapy and post-exposure prophylaxis, mapped to NMC codes IM6.1 to IM6.23.
This chapter covers HIV from acute seroconversion through immunosuppression to AIDS, linking the CD4 count to specific opportunistic infections. It sets out modern antiretroviral therapy for all, post-exposure prophylaxis, opportunistic-infection prophylaxis, and the ethical duties of confidentiality and non-judgemental care.
High-yield: HIV and AIDS
- Acute HIV seroconversion presents as a mononucleosis-like illness with fever, rash, sore throat and lymphadenopathy.
- The CD4 count predicts the risk of specific opportunistic infections and guides prophylaxis.
- AIDS is defined by an AIDS-defining illness or a CD4 count below 200 cells per cubic millimetre.
- Pneumocystis jirovecii pneumonia typically occurs when the CD4 count falls below 200 and is treated with co-trimoxazole.
- Cerebral toxoplasmosis presents with ring-enhancing brain lesions when the CD4 count is below 100.
- Cryptococcal meningitis and cytomegalovirus retinitis appear at very low CD4 counts, usually below 50.
- Antiretroviral therapy is now recommended for all people with HIV regardless of the CD4 count.
- A standard first-line regimen combines two nucleoside reverse transcriptase inhibitors with an integrase inhibitor.
- Post-exposure prophylaxis should start as soon as possible, ideally within hours and no later than 72 hours after exposure.
- Co-trimoxazole prophylaxis is given when the CD4 count falls below 200 to prevent Pneumocystis pneumonia.
- Immune reconstitution inflammatory syndrome can worsen an infection soon after starting antiretroviral therapy.
- Tuberculosis is the commonest opportunistic infection and leading cause of death in people with HIV in India.
- Fourth-generation combined antigen and antibody tests shorten the diagnostic window compared with older assays.
- Confidentiality and informed consent are central ethical and legal duties in HIV care.
- Good adherence to antiretroviral therapy suppresses the viral load and makes transmission negligible.
CD4 count and opportunistic infection risk
- **Below 200:** Pneumocystis jirovecii pneumonia; start co-trimoxazole prophylaxis.
- **Below 100:** Cerebral toxoplasmosis with ring-enhancing lesions.
- **Below 50:** Cryptococcal meningitis and cytomegalovirus retinitis.
- **Therapy:** Antiretroviral therapy for all; first line is two NRTIs plus an integrase inhibitor.
NMC competencies in this chapter
- **IM6.1:** Acute HIV seroconversion illness
- **IM6.2:** Classification of HIV and AIDS
- **IM6.3:** CD4 count and opportunistic infection risk
- **IM6.4:** Common HIV-related opportunistic infections
- **IM6.9:** Diagnostic tests for HIV and disease severity
- **IM6.16:** Principles and classes of antiretroviral therapy
- **IM6.17:** Post-exposure prophylaxis
- **IM6.22:** Ethical and legal issues: confidentiality and disclosure
Frequently Asked Questions
What CD4 count defines AIDS?
AIDS is defined by a CD4 count below 200 cells per cubic millimetre or the presence of an AIDS-defining opportunistic illness, regardless of the count.
When should post-exposure prophylaxis be started?
It should be started as soon as possible after exposure, ideally within a few hours and no later than 72 hours, and continued for 28 days.
Which opportunistic infection is commonest in India?
Tuberculosis is the commonest opportunistic infection and the leading cause of death among people with HIV in India.
How does this chapter help for NEET-PG?
The CD4 thresholds for opportunistic infections, first-line antiretroviral regimens and post-exposure prophylaxis timing are frequently tested and map directly to exam questions.
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