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general epidemiology
- transmission =
- blood products/ contaminated fomites
- transplacental and neonatal
- milk of infected nursing mothers
- saliva
- vaginal secretions
- semen
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general prevention
- standard STD prevention
- screening of body fluids donated to others
- universal precautions - new needles, gloves etc.
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Hepatitis B Virus
enveloped DNA virus - gets envelope from host, looks like host's cells
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Hepatitis B Virus and Cirrhosis
virus causes serious inflammation of the liver and can lead to liver cancer or liver failure
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Hepatitis B Virus epidemiology
- global problem - asia accounts for most of the burden
- many people infected
- leads to liver cancer
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Hepatitis B Virus pathogenesis
- fusion
- partial DNA genome repaired into cccDNA
- stays in nucleus as template for viral proteins
- reverse transcriptase converts into DNA template for packaging
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outcomes of Hepatitis B Virus infection
develop long-living immunity
- die of acute infection from liver failure
- become chronically infected - most die/ill from this, often asymptomatic
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Hepatitis B Virus immune response
- antibodies are important in mounting response for acute infection - anti-HBe
- chronic infection does not mount response - age at infection matters
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Hepatitis B Virus diagnosis
- Hepatitis B surface antibody test + have immunity
- Hepatitis B surface antigen test + have hepatitis
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Hepatitis B Virus treatment
- no cure
- monitor liver regularly
- if needed, treat with antivirals
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Hepatitis B Virus prevention
- vaccination
- HBIG and vaccination soon after birth to prevent maternal to child transmission
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Human Immunodeficiency Virus
- retrovirus - RNA as genetic material
- uses reverse trancriptase
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HIV infection
targets CD4 receptor and coreceptor on CD4 T cells and monocytes
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HIV classification
HIV-1 = includes M(major) - responsible for most infections
HIV-2 = in West Africa
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HIV course of infection
- exposure:
- infects CD4 cells
- replicates rapidly (acute phase)
- 2-4 weeks:
- flu like symptoms
- immune system fights back - symptoms subside (latent phase)
- 10-12 years:
- development of Acquired Immunodeficiency Syndrome (AIDS)
- death due to opportunistic infections
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CD4 cell death possible causes
- budding
- apoptosis
- CD8 T cell killing
- anergy
- damage to precursor cells
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HIV-2
- found mostly in western africa
- longer latent period
- less aggressive AIDS
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clinical definition of AIDS
- CD4 cell count less than 200/uL
- less than 14% of total
- AIDS-defining illness
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AIDS-defining illnesses
- would normally only get if immune system compromised
- pulmonary tuberculosis - most common infectious cause of death
- Kaposi's Sarcoma
- CMV retinitis
- Fungal infections
- cerebral toxoplasmosis
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routes of HIV infection
- sexual intercourse
- IV drug use
- trans-placental
- breastfeeding
- transfusion
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HIV immune response
- proper protective response not known
- probables - neutralizing antibodies, CTLs
- genetics - delta 32 mutation
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HIV Diagnosis
- centrifuge blood, look at T cell count
- look for pathogen - protein, nucleic acid detection
- look for an immune response - ELISA, western blot
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HIV treatment
- entry: CCR5 inhibitors, Fusion inhibitors
- reverse transcriptase inhibitors
- integrase inhibitors
- viral protease inhibitors
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HIV prevention
- no vaccine
- re-exposure prophylaxis
- circumcision?
- maternal to child transmission - given antiretrovirals to breastfeeding women
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