HIV/AIDS: Part 1, Epidemiology to Treatment Flashcards
1
Q
Describe the global summary of the AIDS epidemic:
A
- Incredibly quick spreading since the 1980’s (>1000 compared to 1 million today!)
- 35 million globally infected
- AIDS related death is 1.5 million
- Over 7000 new infections a day in 2011!
- About 97% in low and middle income countries; about 900 in children < 15 YO and 6000 adults >15 YO
- Interesting correlation between women’s status and HIV rates
- Can be found in every population on the globe, and we know it comes from Africa d/t working with and butchering animals who had a version of HIV
- Numbers are starting to stabilize d/t new drugs
2
Q
What is the UNAIDS New plan?
A
- 90-90-90 plan
- By 2020:
- 90% of people will know diagnosis
- 90% have access to treatment
- 90% are virologically suppressed
- Estimated that if plan put into place, HIV infection will be controlled by 2030 and AIDS epidemic will be over
3
Q
What are some factors influencing high Canadian figures?
A
- Public misperceptions about effects of drug therapy, so people more likely to engage in high-risk sexual behaviors
- Rate of new infections among young gay men has increased significantly
- Con’t use of injection drugs, especially cocaine
- Alberta and Manitoba heterosexual activity accounts for half of transmission!
- Saskatchewan, IDU = 70% of new infections
- BC, Ontario, Quebec and Atlantic provinces primarily driven by MSM
- Increased incidence rate in BC compared to national average
4
Q
What is the big problem in this epidemic?
A
- 34% of heterosexuals unaware of positive status!
- 20% of MSM
- 24% of IDU
5
Q
What is the sex degrees of separation?
A
- When you sleep with someone, you are sleeping with every partner they ever had, as well as their partner’s previous partners
- It is estimated that if you have slept with between 6 and 9 people you have potentially had 2.8 million “partners”
6
Q
Who is vulnerable to HIV in Canada?
A
- Men who have sex with men (18% of gay men affected in Vancouver, 14% unaware! Anal is the highest risk activity in relation to HIV transmission)
- Injection drug users
- Women
- Aboriginal women
- Youth
- People with concurrent mental health problems
7
Q
Describe injection drug users and HIV:
A
- Rate of infection has declined in this group who now account for approx - 13.7% of new infections – 12.1% in BC
- Safe needle exchange and injection sites responsible for this largely
- Prevalence rate among IDUs in the Downtown Eastside is about 14% for non-Aboriginals and 28% for Aboriginals
- Almost 100% of IDUs are infected with hepatitis C
8
Q
Describe women and HIV:
A
- Women are increasingly represented in the statistics
- Rate of infection among women has risen from 12% of the total to approx 23.3% - this represents an increase of 12.6% since 2008
- Women between the ages of 15 and 29 account for 35% of new infections in this age group and in BC women between 20 and 29 account for majority of new infections in women
- Women between the ages of 15 and 19 account for more positive tests than men
- 76.6% of infections are a result of unprotected sex
- Between 20 and 50% of women report that first sexual experience is coerced
- 24 HIV+ pregnant women had babies in 2012 – no infected infants
- Male to female transfer of virus is 2 to 2.5x as efficient as female to male with sexual contact (by physiology, women are the receptive partner)
9
Q
Describe why younger women are especially vulnerable:
A
- First sexual partners for many young women and girls are older men
- First sexual encounters may be non-consensual
- Complex social determinants
- Poverty, inequality, power imbalances, fear, violence
- Immature genital mucosa (until 19 to 20 y.o)
- Less reliable mucous production (less lubrication)
- Undiagnosed/untreated STIs and inflammatory disorders of the genital tract
10
Q
Describe Aboriginal’s and HIV:
A
- Aboriginal women are considered to be one of the highest risk groups for HIV infection, comprising 47.3% of total infections in the Aboriginal population – - Aboriginal women in BC account for 37.9% of new positives in women
- Aboriginals comprise 4.3% of the population but 8.9% of prevalent infections and 12.2% of new infections – 31.6% of new infections in Aboriginal youth (15-29)
- The infection rate in aboriginal peoples is 3.5x higher than the general population
- Rate of HIV in pregnant women in BC is 3.4/10,000; for Aboriginal women the rate is 33/10,000
- 58.1% of new positives are a result of IDU, as opposed to 13.7% for general population – 30.2% heterosexual and 11.6% MSM
11
Q
Describe youth and HIV:
A
- Comprise 19% of population but 26.8% of new positive tests
- More males are positive than females but female rate is rising rapidly
- 1/3 have sex with more than one partner – 1/3 of males and 18.2% of females report having had more than 10 partners
- 68% use condoms – males more likely to use than females – no difference in condom use whether they have one partner or multiple partners
- For males who engage in receptive anal intercourse, only 50% use condoms
- Most common route of exposure is MSM followed by heterosexual intercourse, especially for females
- 46.5% of positive tests in this population are in Aboriginal youth
12
Q
Describe HIV and mental illness:
A
- Rate of HIV infection amongst people with a mental illness and excluding a substance use disorder is 5.9 to 8.9%
- Rate of HIV infection amongst those with a concomitant substance use disorder is 16.3 to 22.9%
- Rate of infection in general population «_space;1%
- 80% of people with HIV have a mental health condition
- Risk increases when substance use present as well
13
Q
Describe older adults and HIV:
A
- Adults over the age of 50 account for 15.3% of new infections
- HCPs have a low index of suspicion for HIV infection in this population
- Viagra use is an independent predictor of HIV risk in this population
14
Q
What are the five routes of transmission?
A
1) Unprotected sexual activities
2) Blood & blood products
3) Sharing needles
4) Accidental exposure (e.g. occupational exposure)
5) Mother-to-baby (25% risk of transfer to child; drugs during pregnancy has essentially eliminated this risk though)
15
Q
What is the relative risks of sex?
A
- Receptive anal intercourse – estimated to be about 1.4% or an average of one transmission for every 71 exposures – this is the highest risk because the rectum does not naturally lubricate and it is lined with CD4 receptors
- Insertive anal intercourse – estimated to be about 0.06% or one transmission for every 1667 exposures
- Receptive vaginal intercourse – estimated to be about 0.08% or about one transmission for every 1250 exposures
- Insertive vaginal intercourse – estimated to be about 0.04% or one in every 2500 exposures
- Oral sex – no good quality studies but it is thought to be low but non-zero transmission possibility
16
Q
Describe rates of HIV transmission risk:
A
- By contaminated blood transfusion products 95 in 100
- Mother to child (without HAART) 1 in 4
- Needle sharing 1 in 50
- Occupational needle stick (from positive person 1 in 300
- Male to male receptive 1 in 200
- Male to male penetrating 1 in 1500
- Male to female vaginal 1 in 1000
- Receptive oral 1 in 10,000
17
Q
Describe stigma of HIV:
A
- Only 63% know that HIV is transmitted through sexual intercourse
- Only 31% know that sharing needles transmits HIV
- 23% believe you can spread HIV through kissing
- 87% believe that their personal risk is low
- 85% believe that health care providers are the best source of information about HIV
- 19% of Canadian would be uncomfortable working with someone with HIV
- 38% would be uncomfortable is a child with HIV attended the same school as their child
- 51% would be uncomfortable if a close friend or relative was dating someone with HIV
- 24% believe that people with HIV should not be hairstylists
- 32% believe they shouldn’t be dentists
18
Q
What are characteristics of the HIV virus?
A
- HIV is a retrovirus
- All viruses lack the necessary cellular components for reproduction which is why they hijack the nucleus of the cell they have invaded. What makes retroviruses unique is that they have the ability to convert their RNA to DNA with the aid of an enzyme - converting RNA to DNA is opposite to usual genetic sequence
- Retroviruses are very fragile, being easily inactivated by mild detergent, gentle heating, drying, or moderately high or low pH
- A fragile virus, cannot survive outside of host
19
Q
What makes HIV different from other viruses?
A
- In general, a virus either kills the host in a short period of time (relatively rare), is completely eliminated from the body (most common outcome) or enters a state of latency (e.g. herpes simplex)
- Transition from acute to chronic infection with persistent replication makes HIV virtually unique among viruses
- Sets up a state of chronic, persistent infection the body constantly has to fight off
20
Q
Describe the pathophysiology of HIV:
A
- All viruses require a host cell in order to reproduce
- HIV prefers a host cell known as the T helper cell
- T helper cells are an integral part of our immune system
- Over time (8 to 15 years), chronic infection by HIV causes a depletion in functional T helper cells, leading to a compromised immune system
- HIV also stimulates immune activation and this immune hyperactivity also damages the T helper cells
- 80 % of CD4 cells are lost in the early stage of acute infection
- HIV infection leads to increased gut permeability > microbial translocation and immune activation > chronic diarrhea and malabsorption
- Biomarkers which are associated with inflammation increase, particularly d-dimer and IL-6
21
Q
Describe AIDS as it relates to HIV:
A
- When the immune system becomes compromised, it is no longer capable of warding off infections
- People with HIV become susceptible to a multitude of disabling and life threatening opportunistic infections
- As the immune system becomes progressively more impaired, illnesses become more difficult to recover from
- Ultimate outcome is death, usually within two years of the initial onset of AIDS related illnesses
22
Q
Describe the life cycle of the virus:
A
1) Attaches to the target cell
2) Penetrates the host cell membrane
3) Viral RNA is transcribed into host cell DNA (reverse transcription)
4) Viral genetic material is integrated into the host cell chromosome
5) Production of new viral components and assembly of new virions
6) Virions exit from host cell and maturation occurs
23
Q
What are the physical responses to HIV/AIDS?
A
- 8 to 10 years of symptom free living after initial infection with the virus
- As CD4 count drops and the viral load increases the potential for opportunistic infections increases (trend more important than actual number **)
- CD4 tells you how far the train is from the cliff; viral load tells you how fast the train is travelling
- HIV/AIDS is a chronic episodic disease with an uncertain trajectory
- Median survival after CD4 < 200 is 3.7 years
- Median survival after onset of AIDS defining illness is 1.3 years
24
Q
What is important about CD4?
A
- CD4 counts vary widely - affected by viral illnesses, vaccines, etc.
- Trend is more important than 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 to 60%
- CD4 fraction is the percentage of total lymphocytes with the CD4 marker
25
What are the stages of infection?
- Primary acute – symptoms of seroconversion illness 2-4 weeks after infection – usually flu like
- Chronic asymptomatic – generalized lymphadenopathy, thrombocytopenia
- Chronic symptomatic – weight loss, fatigue, diarrhea, candidiasis, herpes simplex and zoster
- AIDS – AIDS defining illnesses
26
What is non-nominal testing?
- Clients wishing to be tested for HIV antibodies can do so using their real name (nominal) or by using a pseudonym or initials.
- Follow up by public health can occur whether the test is nominal or non-nominal
27
What does reportable mean? Why has HIV been made reportable?
- HIV was added to the list of reportable conditions as of May 1, 2003
- Positive test results must be reported to the local medical health officer for follow-up by the local public health nurse or personal healthcare provider
- The testing healthcare provider is responsible for ensuring that partner notification is initiated
- 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
28
What is the importance of partner notification?
- An active, supported partner notification system can identify up to seven times more contacts than a system where this level of assistance is not provided
- Partners who are notified have been shown to have HIV+ rates of between 15 to 30% on testing
- Women who know they are HIV+ are much less likely to pass it on to their unborn children
29
What is pre-test counseling?
- 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
30
What is the ELISA test?
- 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 4th generation EIA test is conducted to confirm reactivity
31
What is the Western blot test?
- Western Blot is an antibody test that is done to confirm reactivity – it has a sensitivity and specificity of 99.9%
- 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
32
What is pooled NAAT?
- 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 NAAT had a negative 3rd generation elisa
33
Describe post-test counseling for non-reactive results:
INTERPRET:
- Means either no infection or too early to test
- Risks within the past 3-6 months dictate need for retesting, as necessary, 3 months after the last possible exposure
REINFORCE:
- Reduction of risks (avoid high risk activities, avoid sharing needles or other drug use equipment, use safer sex practises)
34
Describe post-test counseling for positive results:
- Clarify difference between HIV and AIDS
- Verify client’s understanding of test result
- Emphasize importance of regular followup with primary care provider
- Review what client should expect in terms of followup care (vaccines, lab tests, etc.)
- Discuss partner notification process
- Review transmission prevention strategies
- Emphasize importance of finding support (friends, family, ASO, etc.)
35
Describe expanded testing in BC, and why this is a good idea:
- In BC, testing will be offered to all low risk adults once every five years – high risk adults once a year
- Testing is also offered for all hospital admits at SPH, VGH, MSJ and UBC – this will also be expanded
- Earlier identification to prevent late diagnosis
- Less than 25% of patients with a STI dx have an HIV test within three months!!
36
What is HAART?
Highly, Active, Anti, Retroviral, Therapy
37
What are the goals of anti-viral therapy?
- Maximal and durable suppression of viral load
- Restore/preserve immune function
- Improve quality of life
- Reduce HIV related morbidity/mortality
- Treatment has led to a 94% drop in AIDS related deaths in Canada
38
What is the impact of suppressed viral load?
- Reduced transmission of virus – has led to treatment as prevention program in BC
- New positive rate in BC declining across all populations including IDU
- Higher rate of averted HIV cases than anywhere else in Canada
- If load suppressed, much less likely to transmit
39
When should anti-retroviral therapy recommended? (ART)
- ART is recommended and should be offered regardless of CD4 cell count
- The strength of the recommendation increases as the CD4 count decreases
- ART should be offered to all persons in the acute phase of primary HIV infection
- Pregnant women, persons with chronic Hep B or Hep C infection, persons over the age of 60 and persons with HIV associated nepropathy should all be started on ART
- ART should be started ASAP in persons with opportunistic infections
- ART is recommended in all HIV infected persons with TB
40
What is the impact of CD4 counts on life expectancy?
- It has become clear that a normal life span can only be expected if CD4 cells recover to > 500
- A partial reconstitution (between 350 and 500) is associated with non-HIV health problems (CV, renal, hepatic, cancers)
- Average CD4 then HAART is started in Canada is 184 – CD4s below 200 are associated with a lower probability of achieving optimal counts
41
Describe the role of viral load:
- High VL: above 50,000-100,000 copies/mL
- Monitor CD4 closely
CD4 >350 and VL >50,000: 3-year risk of AIDS 40%
- Consider ARV therapy even if CD4 >350, especially if CD4 declining rapidly (>100 cells/year)
- Viral load is closely monitored for people on ART - goal is undetectable
42
What are different classes of ART's?
- NucleoSide reverse transcriptase inhibitors (NTRI)
- NucleoTide reverse transcriptase inhibitor (NTRI)
- Single tablet combinations of NRTI's
- Non-nucleoside reverse transcriptase inhibitors (NNRTI)
- Single tablet combinations of NNRTI
- Protease inhibitors (PI's)
- Integrase inhibitors
- Entry inhibitors
43
What is a typical drug regimen?
- Start on 3 drugs from different classes - usual first line treatment is two NRTIs and a boosted PI or two NRTIs and an NNRTI or two NRTIs and an integrase inhibitor
- Pill count - can be 20/day or more
- Power of drug combination
- Avoid resistance (MUST take doses appropriately because missing doses can quickly cause resistance!)
44
What is pre-exposure prophylaxis?
- Targeted at high risk populations – MSM who engage in unprotected anal intercourse, IDUs who share and inject multiple times a day, sex trade workers
- Consists of tenofovir or truvada once a day as a preventive measure for HIV negative individuals
45
What can't we cure HIV?
- Because virus persists in resting CD4 T cells and other body tissues
- As soon as HAART is stopped this latent virus begins to replicate
- A cure could be possible if you could eliminate the reservoir
- There are trials looking at latency reversing agents that could achieve this
