Chapter 1
HIV and AIDS
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Pathogenesis |
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Chapter 2 |
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Tuberculosis & HIV Infection |
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Counseling
and Testing |
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Chapter 5
Health
Care and HIV/AIDS |
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Strategies
for Preventing Disease |
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Overview
of Florida Law and HIV/AIDS |
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Florida Laws (power point)
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Pathogenesis and Natural History
Acquired Immunodeficiency Syndrome (AIDS) was first recognized in the United States in 1981 and is caused by the retrovirus human immunodeficiency virus (HIV). The structure of the virus consists of ribonucleic acid (RNA) and reverse transcriptase within the core capsid protein surrounded by an outer lipid membrane or viral envelope.
After infection with the virus, the person may remain asymptomatic or develop acute retroviral syndrome within days to weeks. This primary infection is characterized by a flu-like illness with fever, headache, fatigue, muscle aches, sore throat, rash, or generalized lymphadenopathy which may last from days to weeks.
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HIV Virology |
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· Type: human retrovirus (RNA) · Two recognized types: HIV-1 and 2. · Origin: evidence points to zoonosis · Size: 100 nm · Composition: glycoproteins, lipid layer, protein shell and core, RNA, enzymes. · Transport/Attachment: HIV is lymphotropic. Macrophages carry to CD4s. Collision. · Entry: Receptor-mediated endocytosis. · Reproduction: Reverse Transcription/DNA Synthesis, Transport, Integration, Proviral Transcription, Proviral Synthesis, Assembly, Budding/Release, Maturation
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In HIV-infected persons, the immune system recognizes the virus proteins as foreign material and produces antibodies through complex mechanisms involving the white blood cells and the virus. Usually within an average of 25 days to a maximum of three months from infection, the number of antibodies against the virus rises to detectable levels. At this time seroconversion can be detected through HIV antibody tests.
After the primary infection, most patients remain asymptomatic for months to years. Although this is called a period of clinical latency, there is continued replication of the virus and destruction of immune cells.
The CD4 positive T-helper cell is the primary target for HIV infection because the virus is attracted to the CD4+ surface marker. The loss of these cells leads to a progressive impairment of the immune response and development of opportunistic diseases or cancers. Persons infected with HIV who are diagnosed with life-threatening opportunistic diseases and cancers, have CD4+ absolute cell counts <200 cells/mm3, or <14% of total lymphocytes meet criteria for CDC-defined AIDS.
*Candida esophagitis, tracheitis, or bronchitis; extrapulmonary coccidioidomycosis, cryptococcosis, or histoplasmosis; diarrhea > 1month due to cryptosporidiosis or isosporosis; CMV other than liver, spleen, or LN; mucocutaneous HSV >1 month or HSV of esophagus, bronchus, lungs; disseminated Mycobacterium avium complex; tuberculosis; pneumocystis; recurrent bacterial pneumonia; recurrent salmonellosis; toxoplasmosis +Invasive cervical cancer, dementia, wasting, Kaposi’s sarcoma, lymphoma (Burkitt’s, immunoblastic, primary CNS), progressive multifocal leukoencephalopathy |
Types of HIV
HIV-1 is the predominant type of HIV in the United States. HIV-2 causes a similar immunodeficiency syndrome but is seen primarily in patients in West Africa. All U.S. blood donations are tested for antibodies to both viruses. According to some reports, HIV-2 has a longer incubation period than HIV-1. However, prevention aimed at HIV-1 can also help prevent and control the spread of HIV-2.
Modes of Transmission
HIV is transmitted most commonly through contact with infected blood such as with injection drug use or with semen or vaginal secretions during sexual intercourse (vaginal, oral or anal). In addition, infected women can pass HIV to their baby during pregnancy, delivery, and breast-feeding.
Common misperceptions about
HIV have included the virus living in the environment or in the air,
transmission through kissing, biting, contact with saliva, tears or sweat, and
insects (such as a mosquito). Unless there has been a potential for contact with
blood, semen, vaginal, other body fluids visibly contaminated with blood, or
body fluids to which Universal Precautions apply, there have not been any cases
reported where HIV was transmitted in any of these ways. HIV can only survive
outside of the human body for a very short period of time.
Main |
Chapter 1
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Chapter 2 |
Chapter 3 |
Chapter 4
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Chapter 5 |
Chapter 6 |
Chapter 7
Test Questions |
Final Test/Evaluation
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