AIDS epidemiology Flashcards
What are the global statistics for HIV and AIDS.
People living with HIV 39M.
New HIV infections 1.3M.
Deaths due to AIDS 630K.
How many new HIV infections were diagnosed a day in 2022?
~3600 new ones.
1/2 in sub-Saharan Africa.
260 in children, 3200 in adults.
What is the 90/90/90 goal set by UNAIDS?
global target of
-90% of people living with HIV being diagnosed
-90% diagnosed on ART (antiretroviral therapy)
-90% viral suppression for those on ART by 2020
Fast-Track Cities
The Fast-Track Cities initiative
a global partnership
between a network of over 90 high HIV burden cities
where political leaders, affected communities, city health officials, clinical and service providers, and other stakeholders work together to accelerate their local HIV responses
UK data between 2021 and 2022
New diagnoses increased in men&women
In women: 55% increase in new diagnoses between 2021 to 1,348 in 2022 and among men, an 8% increase
Of persons newly diagnosed in 2022, 72% were aged between 25 and 49 years
23% rise among those aged 25 to 34
24% rise among those aged 35 to 49
21% rise among those aged 50 to 64
Did the UK achieve a 90-90-90 target?
Yes
HIV transmission routes
Sexual
Vertical
Blood
HIV prevention overview
- Voluntary medical male circumcision
- Treatment of STIs
- Female condoms
- Male condoms
- HIV counselling and testing
- Behavioural change
- Treatment as Prevention (TasP)
- PEP
- PrEP
- Microbicides for women and some gay men
Partner notification and HIV
Discuss soon after diagnosis
The length of ‘look back’ depends on individual circumstances
Document discussion of safer sex practices, PEPSE, PreP for their partner (if applicable), U=U
U=U
Undetectable = untransmittable
PreP
Several RCTs on PreP; providing evidence for the effectiveness of daily dosing and event-based dosing
Effectiveness has been demonstrated in MSM (men who have sex with men), heterosexual serodifferent couples, trans, and injecting drug users
PEP
Tablet after sex.
Post-exposure prophylaxis
PEP = 28 days Combination Antiretroviral Therapy –must be started within 72 hours after sex
Not to be confused with PreP
PEP is not as effective as PreP
Benefits of knowing HIV status
Access to appropriate treatment and care
Reduction in morbidity and mortality
Reduction of vertical transmission
Reduction of sexual transmission
Public health / partner notification
Cost-effective
Testing for HIV
Clinician initiated testing triggered by clinical indicators of immuno-suppression disease / seroconversion
Routine screening in high prevalence locations
Routine screening Antenatal screening
Screening in high risk groups
Patient initiated requests for testing
Why do doctors not test for HIV?
They don’t think of HIV
Underestimate the risk of HIV in their patients
Failure to recognise HIV as a modifiable prognostic indicator
Misconception they need pre-test counselling
Misunderstanding of the implications for insurance, etc
Fear of offending the patient
…but these concerns have been overcome in the antenatal setting
When to maintain a high index of suspicion?
- Generalised lymphadenopathy
- Acute generalised rash
- Glandular fever/ flu-like illnesses
- Think about seroconversion
- Oral candida
- Unexplained weight loss or night sweats
- Persistent diarrhoea
- Gradually increasing shortness of breath and dry cough
- Recurrent bacterial infections including pneumococcal pneumonia
Consider HIV if
Flu-like illness, rash
Blood dyscrasias eg low platelets
Multi-dermatomal shingles
Lymphadenopathy
Weight loss or diarrhoea, night sweats, PUO
Oral/oesophageal candidiasis or hairy leukoplakia
How does testing occur in A&E departments?
Routinely test (opt out testing).
Is pre-test HIV counselling required?
No
Screening test
Venous blood sample is preferred
4th generation HIV tests include p24 antigen and will detect the vast majority of infections at 4 weeks (if negative, repeat at 7 weeks if high index of suspicion)
High sensitivity and specificity
Point of Care tests
Finger prick blood
Immediate result
Lower sensitivity and specificity
False positive and negative results
Longer incubation period
What are some of the advantages of POCT?
Outreach into community settings/ non-specialist clinics
Increased patient choice
Increased access to testing and case detection
Earlier diagnosis in non-healthcare seeking individuals
Managing results
Negative test
Repeat if within “window period”
Positive result or result not clear
Phone Sexual Health for advice and we’ll arrange an appointment within 48 hours
Explain test “reactive” and needs further investigation
Key populations to HIV prevention
Sex workers and their clients, gay men and other MSM, people who inject drugs,
transgender people) - account for >70% new infections globally
We should also consider which populations?
Refugees (30.5m), asylum seekers (4.6m) and displaced people (53.2m)
Over 96% of new infections occur where?
LMICs
What are the socio-economic impacts of HIV in Africa?
Significant impact on life expectancy
Loss of economically-productive adults (including health-care workers)
Increased spending on healthcare (particularly as ART drug use becomes more widespread)
Distortion of health-care spending
Change in social structure: orphans cared for by elderly grandparents
Stigma of HIV infection persists
Who are most at risk of acquiring HIV?
50% of all new infections occurring world-wide are in 15-24 year olds
Who is more likely to get HIV?
Women 2x
The risk of HIV transmission differs by biological sex
Male to female HIV transmission is 2-3x as efficient as female to male transmission
Young women and teenagers are particularly vulnerable to HIV infection
Risk is also increased during pregnancy and for 6 months post partum
What mechanisms make women more susceptible?
STIs causing inflammation/ulceration in the female genital tract
Bacterial vaginosis can cause alterations in vaginal pH
Hormonal effects on mucosal immunity
Sexual violence
1 in 4 women infection occurs due to
Intimate partner violence
Paediatric HIV-1 infection in Africa occur via 3 routes…
In utero: transplacental, mostly during the third trimester
Intra partum: exposure to maternal blood and genital secretions during delivery
Breast milk: ingestion of large amounts of contaminated milk (45%)
Transmission can largely be prevented by ART given to pregnant women and to the infant (MTCT)
If maternal pVL is undetectable, risk of transmission is <2%
What is the first line treatment to prevent mother to child transmission?
Mother: First line antiretroviral therapy
Breastfeeding infants: daily Nevirapine or AZT from birth until 4 to 6 weeks after cessation of breastfeeding
Early infant diagnosis
Most countries provide mass testing of infant dried blood spots before 6 weeks of age (using PCR).
Untreated HIV = particularly aggressive in African infants
Mortality of 35% - 54%
Abundance of HIV target cells
Infants have high lymphocyte counts
‘Immaturity’ of infant immune system
May not make adequate immune response to HIV
Genetic similarity of infant with donor of virus (i.e.mother)
Likely to acquire HIV strains that have already “escaped” from maternal immune responses
High incidence of co-infections
Transmission of maternal infections
Impact of maternal infection on placenta, e.g. malaria, CMV, EBV, TB
More likely in low income countries
What are the barriers to adolescent testing?
difficulties in obtaining consent for HIV testing of older children in clinics
Absent/ poorly defined/changing guardianship,
Diagnosis leads to automatic disclosure of parental HIV status
What co-morbidities are seen in older children?
Heart muscle abnormalities
Chronic lung disease
Bronchiolitis obliterans
Growth failure
Osteoporosis is more likely
Prevention of HIV-1 transmission
Consistent condom use (80 – 90% effective)
Male circumcision (60% reduction in infection – no benefit to female partners)
Treating STIs (genital ulcers and HSV infection increase transmission risk)
Microbicide gel for women (30 – 40% reduction in transmission risk)
Needle and syringe exchange for IVDUs
Post-exposure prophylaxis (PeP)
Treatment as prevention (TasP) (96% reduction)
Pre-exposure prophylaxis (PreP)
How does male circumcision prevent HIV?
By removing foreskin, circumcision reduces the ability of HIV to penetrate due to keratinization of the inner aspect of the remaining foreskin.
The inner part of the foreskin contains many Langherhans cells (tissue DCs expressing CD4) which are prime targets for HIV.
Ulcers, characteristic of some STI’s that can facilitate HIV transmission, often occur on the foreskin - by removing the foreskin, the likelihood of acquiring these infections is reduced.
The foreskin may suffer abrasions or inflammation during sex that could facilitate the passage of HIV.
UNAIDS target for 2025
95-95-95
Examples of vaccine trials
AIDSVAX 2003
T-cell vaccines
The Thai Vaccine trial (Rv144)
Animal trials (CMV-vectored SIV)
