Section 5 slides

Section 5 slides - 10/24/11 Overview: HIV Transmission...

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10/24/11 1 Overview: HIV Transmission Organism: Infecting dose: with HIV, enough virus or virally-infected cells must be present Overview: HIV Transmission Organism: Pathogenicity/Virulence of the organism: ability to cause disease and its severity With HIV, wildtype more easily transmitted - slow disease progression Mutant harder to transmit - faster disease progression With HIV, different subtypes transmitted more easily via different routes e.g. (clade C vs B) Overview: HIV Transmission Organism: Invasiveness: ability to invade and move through tissue (HIV carried in/on immune system cells – Mø, APCs (DC-SIGN)) Transmission of Any Organism Requires Organism: HIV Survivability outside the host HIV does not survive well Susceptibility to antibiotics- HIV no cure Choice of Host- Humans long-lived; sex Host response- Human Immune System Initially controls HIV Period of infectivity during life cycle Environmental Factors Transmission Requires Host Susceptibility: Portals of entry Host resistance to infection (inherent or acquired) Genetic factors Condition of host Transmission of HIV Introduction of free viral particles and/or HIV-infected T-cells, or Mø, into body of uninfected person Particular isolate may determine likelihood of infection occurring, as well as disease progression
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10/24/11 2 Transmission of HIV Broken skin Mucous membrane Breaks or lesions of mucous membranes major opportunity for infection Transmission of HIV Latex, polyurethane, vinyl barrier devices block HIV and HIV-infected cells. use prevents spread of HIV if stored and used properly & consistently. Variables in HIV Infection Prevalence of HIV infection in population number of partners or infectivity of a single partner (sexual or needle sharing) type of behaviors engaged in proper use and failure rate of preventive measures (barriers, disinfectants) Variables in HIV Infection Perceptions of risk, peer norms, social ethics Compliance with decisions not to engage in risk behaviors Drug use can interfere with decision making and adherence to risk reduction behavior Ways in which disease causing organisms may be transmitted Not all are involved in HIV Transmission Common vehicles (fomites) Not HIV HIV utensils SHARED SEX TOYS food Ways in which disease causing organisms may be transmitted Not all are involved in HIV Transmission Direct Personal Contact HIV primarily transmitted via blood, semen, vaginal fluids and breast milk touching No kissing Deep with blood in mouth biting rare, unique cases sexual intercourse YES
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10/24/11 3 Ways in which disease causing organisms may be transmitted Indirect contact with infected person (Not HIV) airborne droplets (TB) or dust (Valley Fever) Mechanical Vectors transmission (Not HIV) Fly (sleeping sickness, campylobacter, oral- fecal diseases) Ways in which disease causing
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Section 5 slides - 10/24/11 Overview: HIV Transmission...

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