HIV Flashcards
Estimated # of HIV infections each year
56000
Most likely source of human infection was from _______
nonhuman primates
HIV
retrovirus. RNA virus. Cannot replicate unless it is in a living cell. It infects human cells that have CD4+ receptors on their surfaces, including lymphocytes, monocytes/macrophages, astrocytes, and oligodendrocytes. Immune dysfunction is caused predominantly by destruction of CD4+ T cells (T helper cells).
Major concern of the immune suppression in HIV
Development of opportunistic diseases
Specific conditions allowing transmission of HIV
Contact with infected blood, semen, vaginal secretions, and breast milk
When can an HIV infected individual transmit HIV to others?
Within a few days of becoming infection. The ability to transmit it is lifelong.
Blood transfusions as a source of HIV infection
They are not a significant source. Each unit of donated blood is tested. Only recipients who had a blood transfusion before 1985 are at significant risk for infection via the blood supply.
It is possible for a contaminated unit of blood to test negative for HIV if the donor has not yet formed antibodies to the virus at the time of donation.
Clinical manifestations of acute HIV infection
HIV-specific antibodies are produced and a mononucleosis-like syndrome of fever, lymphadenopathy, pharyngitis, headache, malaise, nausea, and/or a diffuse rash may occur.
When do symptoms generally occur with acute HIV infection?
2 to 4 weeks after initial infection and last for 1 to 2 weeks. During this time a high viral load is noted and CD4+ T cell counts fall temporarily but quickly return to baseline. Often mistaken for a bad case of the flu.
When does HIV antibody test become positive?
Median delay of 2 months after infection before antibodies can be detected.
Clinical manifestations of early chronic HIV infection
The median interval between untreated HIV infection and a diagnosis of AIDS is about 11 years. During this time, CD4+ lymphocyte count remains about 500 cells/uL, and the viral load in the blood is low. This is referred to as the asymptomatic phase, but fatigue, headache, low-grade fever, night sweats, persistent generalized lymphadenopathy (PGL), and other symptoms often occur.
Clinical manifestations of intermediate chronic HIV infection
When the CD4+ T cell count drops below 200 to 500 cells/uL, and the viral load increases, HIV advanced to a more active stage. Symptoms include persistent fever, frequent drenching night sweats, chronic diarrhea, headaches, and fatigue. Other problems include localized infections, lymphadenopathy, and nervous system manifestations.
Clinical manifestations of late chronic HIV infection
AIDS diagnosis cannot be made until one of the following criteria is established: CD4+ cell count <200/uL, opportunistic infection developed, opportunistic cancer (Kaposi sarcoma, etc), wasting syndrome (loss of 10% or more of ideal body mass), or development of AIDS dementia complex
Tests to diagnose HIV
Highly sensitive enzyme immunoassay detects serum antibodies that bind to HIV antigens,
Western blot (WB) or immunofluorescence assay (IFA) more specifically confirms HIV if a repeat EIA indicates the blood is HIV antibody positive,
Rapid HIV-antibody testing provides highly accurate screening results within 20 minutes. Positive results are then confirmed by WB or IFA.
Progression of HIV infection
CD4+ T cell count and viral load monitor the progression of the infection
White blood cell (WBC) count, red blood cell (RBC) count, and platelets decrease with progression of HIV