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Infectious Disease: Unit 2 > HIV > Flashcards

Flashcards in HIV Deck (15):
1

Origins of AIDS epidemic

  • 1900 - HIV enterd human populations from chimpanzees in east central Africa
  • 1981 - AIDS first described by CDC
  • 1984 - HIV-1 first isolated
  • 1987 - First antiretroviral approved by US FDA
  • 1996 - Beginning of HAART era
  • 2003 - Start of global rollout of antiretrovirals
  • 2009 - Over 7000 new infections/day

2

How HIV infection leads to AIDS

  • CD4+ T lymphocyte is main host cell for HIV-1
    • HIV uses CD4 receptor and co-receptor (CCR5 or CXCR4) to enter cell
  • CD4+ lymphocyte count correlates with disease progression
  • Plasma HIV RNA level (viral load) is measure of extent of ongoing replication in lymphoid tissue
    • Correlates with progression of disease without treatment
  • Infection leads to continual decline in immune function
  • AIDS defined as CD4+ level < 200 cells/mL

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3

Primary HIV infection

  • Primary HIV infection: 
    • Acute febrile illness, similar to mono, 2-3 weeks after infection, with or without aseptic meningitis
    • Occurs in 50% of patients, and they may or may not realize it
    • Frequently missed by providers, especially in situations like ED
    • Manifestations due to virus itself

4

Specific s/s of primary HIV infection

  • Fever
  • Fatigue
  • Maculopapular rash
  • Myalgia
  • Headache
  • Pharyngitis
  • Cervical nodes
  • Arthralgia
  • Oral ulcers
  • Odynophagia
  • Weight loss
  • Diarrhea
  • Oral candidiasis = thrush
  • Photophobia

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5

Chronic HIV infection

  • Result of immune suppression, often leads to opportunistic infections
  • Restoring CD4 count decreases frequency and intensity of infections, can even reverse them
  • Opportunistic infections take advantage of weakened immune system, typically only occur when CD4+ count is low (< 200 cells/mm3)

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6

Opportunistic infections in chronic HIV 

  • Pneumocystis pneumonia
  • Kaposi's sarcoma
  • Candida = thrush
  • CMV retinitis
  • CNS toxoplasmosis
  • Extrapulmonary TB
  • Cryptosporidium diarrhea

7

Pneumocystis pneumonia

  • One of earlier symptoms of infection
  • Particularly prevalent in 80s before advanced therapies
  • Characterized by diffuse pneumonia
    • As opposed to focal, lobar presentation of other bacteria
  • Interstitial infiltrates

8

Kaposi's sarcoma

  • HIV-induced cancer
  • More prevalent in the 80s

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9

Candida

  • AKA thrush
  • Sign of immunodeficiency
  • Flag for HIV in the clinic
    • But not exclusive to HIV

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10

CMV retinitis

  • Pre-terminal sign of severe infection
  • Common cause of HIV-related blindness

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11

CNS toxoplasmosis

  • Live within cysts in muscles, brains
  • Non-enhancing ring lesion on CT of brain

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12

Extra-pulmonary TB

  • Cysts found in muscles, etc.
  • Psoas abscess

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13

Use of antiretroviral drugs in HIV

  • Success story in medicine over last 20-30 years
  • Target specific steps of HIV life cycle
  • Classes of drugs include:
    • Entry inhibitors
    • Fusion inhibitors
    • Reverse transcriptase inhibitors: NTRIs or NNTRIs
    • Integrase inhibitors
    • Protease inhibitors

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15

Virologic and immunologic effects of antiretroviral treatment

  • Potent inhibition of viral replication
  • Early HIV: prevents immunologic deterioration
  • Advanced HIV: allows immunologic recovery

17

Clinical effects of antiretroviral treatment

  • Prevention of opportunistic infections
  • Improvement in existing opportunistic infections
  • Reduced hospitalization, long term care facility use, medications for opportunistic infections, and cost