Human Immunodeficiency Virus (HIV) – Pathogenesis, Clinical Manifestations, Diagnosis, and Treatment

HIV-1 infects lymphocytes with the CD4 marker. CD4 lymphocytes are involved in cell-mediated immunity and their depletion also impairs B-cell activation. This process results in the syndrome known as AIDS (acquired immunodeficiency syndrome) which then makes the patient susceptible to infections (opportunistic infections) that normal individuals are able to fight off.

HIV can be transmitted by sexual contact, IV drug use, breast-feeding, and needle-stick injuries.

Acute HIV infection results in fever, fatigue, rash, headache, lymphadenopathy, pharyngitis, myalgia, GI upset, night sweats, aseptic meningitis, oral&gential ulcers. within days to weeks after exposure.

In the Prolonged Asymptomatic Period, the body makes antibody to the virus in 3-4 weeks and enters a period with no symptoms (up to 12 yrs) but the HIV-1 RNA and antibody levels can be measured during this time. In the AIDS stage of the HIV infection, immune deficiency, high levels of the virus, opportunisitic infections result.

When examining a patient with HIV, you want to look for weight changes, skin lesions (signs of opportunistic infections), fever. Consider a weight loss of more than 10%. Pneumocystis carinii pneumonia is the most common cause of fever. Patients may have normal lung function even with active infection.

You also want to look for the Opportunistic infections such as sinusitis, oral thrus, CMV retinitis, toxoplasmosis, cryptococcal meningitis, Kaposi sarcoma, psoriasis, seborrheic dermatitis, molluscum contagiosum, and herpes zoster.

The following tests are used in diagnosing HIV:

1) ELISA (enzyme-linked immunosorbent assay) & Western blot test.

-A positive ELISA should be followed up with a Western blot test which will react with 2/3 different antigens. It is inaccurate in first 3-4 weeks after HIV exposure.

2) PVL (plasma viral load): this test can detect as early as 11 days. It can determine the stage of disease by looking at CD4 count and PVL.

-For Asymptomatic patients & and CD4 count above 350/mm3, you don’t treat the patient!

-For Asymptomatic patients but CD4 count is less than 350/mm3 or PVL is elevated (30k copies/mm3 by B-DNA or 50k copies/mm3 by PCR), you give patient retroviral therapy.

-3 types of drugs can be used: NRTIs (nucleoside reverse transcriptase inhibitors), PIs (protease inhibitors), nNRTIs (nonnucleoside reverse transcriptase inhibitors).

-Regimen of 3 total drugs: 2 NRTIs (zidovudine+didanosine OR zidovudine+lamivudine) + 1 PI (indinavir) or 1 nNRTI (efavirenz)

-For pregnant mothers, C-section and Zidovudine therapy can reduce incident in child. Babies will have positive test (Immunoglobulins cross placenta) and should be given ziduvidine for at least 4-6 weeks with repeat tests every month until 2 negative tests.

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