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32 Cards in this Set
- Front
- Back
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What three modes of HIV spread count for nearly all cases of infection?
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-Sexual contact
-Contact with infected blood or blood containing bodily fluids -Vertical transmission from mother to child |
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What are cofactors for HIV transmission?
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-Genital ulcer disease
Potentially: -HIV strain -Innate resistance to infection by cells of the host |
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What is the key determinant of transmission risk in needle stick injuries?
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Concentration of infectious virions in the blood ("viral load")
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What is the key determinant of transmission risk in mother to child transmission?
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Concentration of infectious virions in the blood ("viral load")
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What is the key determinant of transmission risk in sexual transmission in sero-discordant couples?
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Concentration of infectious virions in the blood ("viral load")
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What virus is responsible for the worldwide AIDS pandemic?
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HIV-1
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Describe the global distribution of HIV-1 subtypes
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Subtype B is the dominant clade found in the US and Western Europe, but is rarely seen in Sub-Saharan Africa or Southeast Asia where clades A and C or E predominate.
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How many people are estimated to have been infected with AIDS?
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65 Million:
45 million alive 20 million dead |
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How many children have lost one or both parents to AIDS in the former Soviet Union, China, and India?
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14 million
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In what populations have the distinct HIV epidemics in the US been located?
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-Men who have sex with med
-Injection drug users |
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What is the 2 stage procedure for diagnosing HIV?
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1. A screening test by a highly sensitive enzyme immunoassay
2. A confirmatory test with a highly specific Western blot if the screening test is positive |
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How longs does it take for antibodies to appear after initial HIV infection?
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-6-12 weeks in most patients
-6 months in all patients |
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How do you initially detect HIV infection (right after infection)?
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During this period high levels of HIV viremia are present so tests that detect the virus directly are positive
This includes: -HIV culture -p24 antigen -nucleic acid detection tests such as PCR or the brain chain DNA assay |
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How was AIDS originally diagnosed?
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Diagnosis was based on indicator conditiosn such as Kaposi's Sarcoma and Pneumocystis pneumonia which were rare diseases in the general population only encountered in individuals such as transplant recipients known to have suppressed or deficient cellular immunity.
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Describe HIV disease
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-Chronic
-Progressive -Variable period of clinical latency -No microbial latency |
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When are levels of viremia highest?
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Right after infection
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What is the hallmark of the progressive immunodeficiency of HIV disease?
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CD4 T cell depletion
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What are AIDS restriction genes?
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A number of genetic variants that have been associated with faster or slower progression to AIDS.
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What are the clinical features of acute retroviral syndrome?
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-Fever
-Fatigue -Sore throat -Lymphadenopathy -Macular erythematous rash |
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Why is there great interest in identifying acutely infected patients?
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-They are extremely infectious so reducing their transmission-prone behavior is vital
-There are important pathogenesis and treatment studies directed at this stage of infection |
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What is occuring during the asymptomatic phase of HIV infection?
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-Ongoing viral replication
-Progressive CD4 cell depletion |
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Why is it important to identify asymptomatic HIV patients?
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1. Behavioral changes can be made to lower or eliminate the risk of further transmission
2. Prophylactic regimens to prevent life-threatening opportunistic infections can be utilized based on CD4 cell risk staging 3. If antiretroviral treatment is initiated before the late stages of HIV disease immune deterioration can be halted or reversed before complications develop |
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What are the early indicators of HIV infection?
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-Bacterial pneumonia (esp. due to S. pneumoniae)
-Herpes zoster -New onset or major flares of psoriasis and sebhorreic dematitis -Salmonella septicemia -Increasingly frquent or severe recurrences of ano-genital Herpes simplex Herpes zoster may proceed AIDS by years Kapsosis sarcoma can present with a much higher CD4 count than other opportunistic processes |
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What is the best established surrogate marker to predict time to AIDS?
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Absolute value of the CD4 count
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What is needed to get a very accurate prediction of the risk of developing AIDS 5 or more years in the future even in patients with nearly normal CD4 counts at baseline?
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HIV-1 viral load measurement
CD4 count |
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Describe Pneumocystis pneumonia
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-Pneumocystis is a fungus
-Appears to be widely distributed in nature -Most people become exposed during childhood |
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What are the risk factors for Pneumocystis pneumonia?
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-Opportunistic pathogen
-Seen in malnourished infants in postWWII Europe -Seen in co ngenitally immunodeficient or iatrogenically immunosuppressed transplant and cancer patients |
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What are the symptoms of Pneumocystis pneumonia?
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Oral thrush
Fever Weight loss Dry cough Slowly progressive dyspneua Chest x-ray may have diffuse interstitial infiltrate or various localized abnormalities Severe disease is defined by an A-a gradient >35 or pO2<70 |
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What is the pathogenesis of Pneumocystis pneumonia?
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Proliferation in the alveoli leading to an exudative response produces the typical
disease. Hematogenous dissemination occurs in some cases and extrapulmonary involvement at numerous sites has been encountered. |
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How do you diagnose Pneumocystis pneumonia?
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Histological identification of the cysts or trophozoites
Lung biopsy is definitive by alveolar contents obtains by bronchoscopic lavage also has excellent yield |
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What causes toxoplasmosis? What are the risk factors?
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Toxoplasma gondii, a protozoan parasite of members of the cat family
Risk factors include prior infection, CD4 counts <100 |
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Describe the pathogenesis of toxoplasmosis
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This appears in most cases to be reactivation of a dormant cyst. Most disease is
recognized in the brain although cysts are widely distributed throughout the skeletal as well as smooth muscles |
