Human Immunodeficiency Virus

(HIV)

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Description

-  Incurable blood borne sexually transmitted virus

 

Features

-  First described in 1983

-  HIV-1 & HIV-2 identified w multiple subtypes

-   HIV-2

-   Lower risk of transmission & slower development of AIDS

-   Rare in developed world

-   Usually lower viral load but increased load correlates to AIDS development

-  Approx 33million people infected worldwide

-  Vast majority in subsaharn Africa (5%+/- of population)

-  May progess to AIDS

-  Coinfection w HCV, HBV &/or HHV8 common

-  HIV readily inactivated by simple detergents

-  To date is incurable

-  Premature death in vast majority of infected pts

-  Gender incidence

-  Male > female in developed world

-  Male = female in developing world

 

Risk Factors

-  Unprotected sexual intercourse

-  Females more likely to acquire from infected male than male from infected female

-  Male homosexual contact

-   Receptive anal intercourse x8 risk

-  Prior or current STI

-  Gonorrhoea, Chlamydia infections x3 risk

-  Syphilus x7 risk

-  Active outbreak of genital HSV1 or HSV2 x25 risk

-  Shared IV drug paraphernalia

-  Mother to child transission

-  Breast feeding

-  Delivery

-  Receipt of blood products

-  Contact w infected blood or needle stick injury

 

Phases of Infection

-  Acute seroconversion

-  Weeks to months

-  50% pts S/S+/-: fever, malaise, lymphadenopathy, rash

-  Infection establishes itself in cells

-  Proviral reservoir

-  High viral load

-  Low CD4

-  Anti-HIV Ab + CD8 response

-  CD4 count +/- normalizes

-  Asymptomatic HIV infection

-  Years+ (decades+/-)

-  Little to no S/S

-  Ongoing immune response

-  +/- persistant generalised lymphadenopathy

-  +/- weight loss

-  Progressive CD4 decline

-  AIDS

-  Development of opportunistic infections secondary to impaired immune system

 

Classification of Infection

-  Category A

-  Asymptomatic infecetion

-  Category B

-  S/S from HIV infection

-  Category C

-  AIDS defininig opportunistic infections

 

Associated S/S

-  AIDS

-  Pneumocystis pneumonia (PCP)

-  Karposi sarcoma x30,000 incidence

 

Ix

-  HIV serology: ELISA + Western Blot

-  CD4 Helper T cells: low

-  Normal 500-2000 cells/uL

-  < 200: increased risk opportunistic infections +/- AIDS

-  Viral load

-  Surrogate marker for replication rate (majority in nodes)

-  W adequate therapy load may be undetectable

-  Consider Ix for opportunistic infections as indicated esp new Dx

-  Mantoux or Quantaferon Gold for TB

-  CMV serology

-  VDRL for syphilis

-  Gonorrhoea & Chlamydial swabs

-  Hepatitis serology: HBV, HCV

-  +/-

-  LFT, U&E

-  Dipstick: HIV nephropathy

-  Fasting lipids

-  Opthalmic R/V: CMV retinitis

 

Mx

-  Notifiable disease in Australia

-  Highly Active Antiretroviral Therapy (HAART)

-  Reduced mortality rates

-  NOT recommended if CD4 >500 cells/uL wo clinical evidence

-  Indicated for all pts if CD4 <350 cells/uL, pregnant of HBV infected

-  Aim is to largely prevent opportunistic infections

-  +/- prophylaxis for opportunistic infections

-  Infectious Disease specialist

 

 

 

References

 

eMedicine: emedicine.medscape.com/article/211316-overview