HIV/AIDS Flashcards
How many people are living with HIV today?
36.7 million (34.0-39.8)
Which population has the highest rates of new HIV diagnosis?
Men who have sex with men (58% in 2014)
What is the most common mode of transmission for HIV?
Sexual transmission (unprotected anal)
What are the known routes of transmission?
Sex, blood, blood products and other body components, mother to child
What are some modes of transmission that there is no evidence for transmitting HIV?
Tears
Saliva
Normal social contact
Insect vectors
What are the four stages of HIV infection?
Acute infection
Early chronic
Intermediate chronic
Late chronic/AIDS
What occurs during the acute infection stage of HIV infection? (and how long does it last)
HIV antibodies develop (seroconversion)
1-3 weeks after initial infection
Usually flu-like symptoms
What occurs during the early chronic stage of HIV infection? (And what is the CD4 count)
AKA asymptomatic disease
Fatigue, headache, low grade fever, night sweats, generalized lyphadenopathy
CD$>500
What occurs during the intermediate chronic stage of HIV infection? (And what is the CD4 count)
Symptomatic, weight loss, fatigue, diarrhea, candidiasis, herpes simplex and zoster, oral hairy leukoplakia
CD4 200-500
What occurs during the late chronic/AIDS stage of HIV infection?
At least one AIDS defining illness as defined by WHO
What are some important markers for detecting immune system function in HIV?
CD4 counts vary widely - affected by viral illnesses, vaccines, etc.
Trend is more important than the actual number.
CD4 fraction provides a better picture of the state of the immune system because it is a more stable number - should be above 15% - normal range varies by lab - generally around 27-60%
CD4 fraction is the percentage of total lymphocytes with the CD4 marker
What are some methods for HIV testing (what is the protocol)
Nominal or non-nominal
Reportable
HIV antibody diagnostic test (infection status) - ELISA and western blot
What is ELISA?
ELISA is the screening test that is initially done to test for HIV antibodies - it has high sensitivity and relatively low specificity
The first test applied is a third generation EIA test - if there is any reactivity, a fourth generation EIA test is conducted to confirm reactivity
What is the Western Blot?
Western Blot is an antibody test that is done to confirm reactivity - it has a sensitivity and specificity of 99.9%
What is a NAAT test?
If there is a weak signal on EIA or the Western Blot is non-reactive or indeterminate, an individual nucleic acid amplification test (NAAT) is done - if viral RNA is detected the individual is considered to have an acute infection
What is point of care testing?
In British Columbia, point of care testing is used in the outreach setting. It has a similar sensitivity to traditional third generation HIV testing. Confirmatory testing is required for indeterminate, invalid, and preliminary positive results. Point of care testing is insufficient to rule out acute HIV infection and is not recommended for those with a recent exposure.
What is the window period for the 3rd generation EIA test?
20-22 days
What is the window period for western blot test?
27-34 days but can take up to 6 to 8 weeks
What is the window period for individual RNA NAAT test?
6 to 8 days
What is the window period for P24 antigen test?
15 to 17 days
What is the window period for the individual DNA NAAT test?
8 to 10 days
What is the window period for the point of care HIV test?
Same or up to one week longer than 3rd generation EIA (which is 20-22 days)
What is the window period for the 4th generation EIA test?
16-18 days
What is the window period for pooled RNA NAAT test?
10-12 days
What is pooled NAT?
Targeted to clinics with a large MSM population
Has a diagnostic gain of 6.4% over 4th generation ELISA
25 of 54 MSM who got pooled NAAAT had a negative 3rd generation ELISA
Why has HIV been made reportable?
To improve and facilitate partner notification
To provide public health the opportunity to be directly involved with index cases and thus to add to case management resources
To enhance epidemiological surveillance
What is the purpose of pretest counselling?
Emphasize confidentiality and ensure understanding of non-nominal testing
Review transmission risks and prevention strategies
Describe partner notification process
Explore psychological preparedness, coping and support mechanisms
Emphasize need to return for result