HIV/Atypical Mycobacterium Lecture Flashcards
A unique type of virus (a retrovirus)
Invades the helper T cells (CD4 cells) in the body of the host (defense mechanism of a person)
*preventable, manageable but NOT curable
HIV
RNA virus
Retrovirus, subfamily lentivirus
Cytopathic
CD4 + lymphocyte is primary target but monocyte/macrohages also express CD4 and become infected
HIV
type 1= most common
type 2=West Africa, less aggressive
HIV
Disease limits the body’s ability to fight infection due to markedly reduced helper T cells.
Patients have a very weak immune system (defense mechanism)
Patients predisposed to multiple opportunistic infections leading to death.
AIDS
Positive HIV who have ever had a CD4 lymphocyte count below 200 cells/mcL or a CD4 lymphocyte percentage below 14%
AIDS
- Icosahedral (20 sided), enveloped virus of the lentivirus subfamily of retroviruses.
- Retroviruses transcribe RNA to DNA.
- Two viral strands of RNA found in core surrounded by protein outer coat.
HIV
- Outer envelope contains a lipid matrix within which specific viral glycoproteins are imbedded.
- These knob-like structures responsible for binding to target cell.
HIV
- direct cytopathic effects
- bystander (syncytia formation)
- failure to regenerate cells (bone marrow infect, thymus infexn)
- autoimmunity
Pathology of CD4 plus lymphocyte depletion
Sexual Vertical – mother to child, perinatal Parenteral – injection drug users Transfusion Nosocomial
HIV modes of transmission
Blood products
Semen
Vaginal fluids
HIV transmission thru bodily fluids
- Short, flu-like illness - occurs one to six weeks after infection
- Mild symptoms
- Infected person can infect other people
Which HIV stage?
Stage 1
- Lasts for an average of ten years
- This stage is free from symptoms
- There may be swollen glands
- The level of HIV in the blood drops to low levels
- HIV antibodies are detectable in the blood
Which HIV stage?
Stage 2
After a period of latency lasting up to 10 years viral replication is triggered and occurs at high rate.
CD4 cell may be destroyed in the process, body attempts to replace lost CD4 cells, but over the course of many years body is unable to keep the count at a safe level.
Destruction of large numbers of CD4 cause symptoms of HIV to appear with increased susceptibility to opportunistic infections, disease and malignancy.
Viral replication during latent stage (stage 2)
- HIV continues to reproduce, CD4 count gradually declines from its normal value of 500-1200.
- Once CD4 count drops below 500, HIV infected person at risk for opportunistic infections.
- The following diseases are predictive of the progression to AIDS:
- persistent herpes-zoster infection (shingles)
- oral candidiasis (thrush)
- oral hairy leukoplakia
- Kaposi’s sarcoma (KS)
Clinical latency period
SYMPTOMATIC
The immune system deteriorates
Opportunistic infections and cancers start to appear.
Which HIV stage?
Stage 3