Microbiology Test 4 Study

Microbiology Test 4 Study - M icrobiology Test 4 Study...

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Microbiology Test 4 Study Guide Chapter 29: HIV Disease and Complications of Immunodeficiency HIV Disease Symptoms Incubation period: 6 days to 6 weeks Usually fever, headache, sore throat, muscle aches, enlarged lymph nodes, and generalized rash Acute Retroviral Syndrome (ARS) Typically subsides in 6 weeks Followed by asymptomatic period May end with persistent enlargement of the lymph nodes Lymphadenopathy syndrome (LAS) Immunodeficiency symptoms include fever, weight loss, fatigue, and diarrhea AIDS-related complex (ARC) Cachexia Chronic extended weight loss Caused by infection of intestinal epithelial cells Also caused by inflammatory cytokine necrosis factor alpha Causative Agent In the U.S. and most other parts of world: HIV type 1 (HIV-1) HIV-2 is antigenically distinct Prominent parts of the West Africa and India; has appeared in the U.S. Transmission less efficient and disease progresses slower than HIV-1 gp120: surface glycoprotein is the adhesor, target is CD4 molecule Steals MHC molecules (HLA antigen) Pathogenesis HIV attacks variety of all types Most critical are Helper T-cells Attach to CD4 surface receptors Virus enters cells Viral reverse transcriptase makes DNA copies of viral RNA genome DNA copy integrates and hides in host chromosome In activated cells, virus leaves cell genome and kills cell Release additional viruses to infect other cells Macrophages have CD4 receptors Virally infected macrophages are not generally killed but
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function is impaired Eventually immune system becomes too impaired to respond In 80% of cases, immune system slowly succumbs to virus Peripheral CD4 count steadily falls Atypical progression of disease occurs in roughly 10% of infected individuals Rapid progression to AIDS within a few months Another 5-10% do not experience a fall in CD4 cells Maintain high levels of antibodies and CD8 cells May be AIDS free for 20 years Epidemiology Indiscriminate sexual intercourse a major factor Promiscuous sexual men hit the hardest Survey: Before AIDS 30-40% of homosexual men had > 500
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lifetime partners By 1984, 2/3 of those were infected Transmission through blood and blood products By 1984, > 50% of hemophiliacs and 10-20% of their sexual partners were infected Mother to infant 1 in 10 pregnant HIV-positive women will miscarry; 15-40% of live-born infants will develop AIDS Breast-feeding carries significant risk of mother-infant transmission Prevention No approved vaccine Most people infected are unaware Virus on surfaces can be inactivated with commercially available disinfectants or heat 56 ° C for > 30 min Viruses in dried blood or pus may be more difficult to inactivate Knowledge of transmission greatest tool for control Condoms not 100% effective but decreases transmission Avoidance of practices that favor HIV transmission Treatment directed Treatment Treatment directed at “cocktails” of drugs Combination of reverse transcriptase inhibitors and protease inhibitors HAART : highly active antiretroviral therapy
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Microbiology Test 4 Study - M icrobiology Test 4 Study...

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