HIV & AIDS Flashcards
Human immunodeficiency virus (HIV) causative agent
Retrovirus is the causative agent
2 of 5 know. Human retroviruses
- HIV-1: 80% of cases worldwide
- HIV-2: mostly in west Africa
- Both deplete T4 cells & subsequent cellular immunity
- HSRV: foamy virus (not pathogenic in humans)
- HTLV1: T cell leukemia and lymphoma
- HTLV2: no known pathology, ? Hairy cell leukemia
HIV Epidemiology
Cases since 1976 but originally treated as Gay Related Immunodeficiency Disease (GRID)
1st AIDS cases reported in 1981
1993 new definition of AIDS: HIV &CD4 T-lymphocyte count of <200 per mm3- 1/5 normal level
Can HIV affect children?
13-48% perinatal transmission through gestation, delivery, and rarely breast milk
HIV Prevalence
Make>female in US; worldwide:50/50
> 2/3 cases are in African-Americans
417/100,000 in 2010-2015
CDC allocates all HIV & AIDS prevention planning project (ECHPP): 3 year demonstration project to maximize the impact of HIV prevention in the 12 metropolitan statistical areas with the highest AIDS prevalence in the US
HIV Transmission
Sexual contact
Parenteral exposure to blood, blood products, & blood containing body fluids
Mother to child
Body fluids: blood, semen, vaginal fluids
Not associated with casual contact
More than 1.1 million people in the US have HIV and almost 1 in 5 (18.1%) are unaware
About 38,000 new cases each year
Gay, bisexual, and other men who have sex with men are most seriously affected by HIV
~636,000 have died from AIDS in the US since the epidemic began
Who is at risk/ should be tested
Sexually active
Use injection drugs
Engaged in sex work
Had a partner who was at risk
Sexual encounters with men from high HIV incident countries
Transfusion between 1978-1985
Symptoms that could be HIV related
In a correctional institution
Routine prenatal screening
HIV Diagnostic tests
13 testing centers within 30 miles
“Window period”: most develop detectable antibodies within 3 months; average is 25 days; rare cases up to 6 months
HIV antibody testing (ELISA)
Western blot
Rapid assays
Viral load
CD4 count
Antibody detection facts
Most people form HIV antibodies within 3 weeks to 3 months after exposure but can lag up to 6 months
Lag period= window period
It is possible to detect anti-HIV antibodies 3 months after infection, even in asymptomatic individuals
ELISA
Enzyme-Linked ImmunoSorbent Assay
Highly specific & 99.6% sensitive for HIV-1 antibodies
False +: Recent influenza or hep B vaccine Multiparous women After multiple blood transfusions Those with multiple myeloma Alcoholic hepatitis Biliary cirrhosis
Western Blot and Rapid Assays
Western blot confirms + ELISA
More HIV-1 sensitive
Detects antibodies= not reliable in early stages of infection
Rapid Assays vary in time and $$$
Fast & cheap: immunochromatographic (lateral flow) strips. Results in <20 minutes, no refrigeration necessary, some can detect HIV 1 & 2
Viral load (HIV RNA levels)
Measure of HIV RNA levels: amount of virus
3 assays can measure it
Use to monitor effectiveness of antiretroviral therapy: administer 2 assays within 1-2 weeks to establish a baseline
Undetectable viral load does not mean that infection has been eliminated or that replication has been halted completely
CD4 Cell Counts
Measure extent of immune damage
Monitor the benefits of antiretroviral therapy
Predict possibility of disease progression with viral load
Baseline Q2-4 weeks on initial drug therapy; Q3-4 months when CD4 >350/ mm3
Interpretation of Viral Load & CD4
HIV RNA < 7000 copies/ml &
CD4 count >350/mm3
=
2% chance of progressing to AIDS within 3 years without treatment
HIV RNA >55,000 copies/ml &
CD4 count <200/mm3
=
85% chance of progressing to AIDS within 3 years
⬆️ viral load= ⬇️ CD4 count
HIV Staging
Initial exposure (asymptomatic)
Primary HIV Infection (acute infection): flu-like symptoms; HIV replicates; develop antibodies to HIV in 6-12 weeks
Clinical latency or asymptomatic HIV infection (HIV seropositivity; latency): infections but no evidence of illness except +HIV antibody test; CD4+ T-cell count >500 cells/mm3; HIV continues to replicate
Late symptomatic stage (symptomatic infection): CD4<200 cells/mm; viral load >100,000 copies/ml; opportunistic infections (AIDS defining illness)
Advanced HIV Disease (AIDS): opportunistic infections CD4 <50
What are opportunistic infections?
1: pulmonary infections (often the first manifestation of AIDS
Pathogens that take advantage of low immunity to progress disease
Most likely to develop when CD4 <200
Can people other than HIV+ get opportunistic infections? YES! Ofc- anyone with a compromised immune system can
HIV ➡️ AIDS
Opportunistic infections
Bacterial and mycobacteria: Mycobacterium avium (MAC)
Viral: cytomegalovirus, herpes simplex
Protozoans: cryptosporidium (watery diarrhea)
Fungal: candida, crytococcosis (pneumonia and meningitis), histoplasmosis (pneumonia), pneumocystis carinii (pneumonia)
HIV related cancers: Kaposi’s sarcoma
AIDS Signs & Symptoms
Severe fatigue (>several weeks)
Sudden weight loss (>10 lbs in <2 months)
Night sweats, fever
Diarrhea
Bruising/bleeding
Coughing, SOB
Skin rashes, spots
Persistent Generalized Lymphadenopathy
Oral thrush
Neuro problems
Frequent infections
HIV Complications
Encephalopathy/ dementia
Anemia
Others
