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Global Health BSc 2018/19 - CDMM1 > HIV - 23, 25-7 > Flashcards

HIV - 23, 25-7 Flashcards

1
Q

What are the 3 types of transmission methods for STIs?

A

Direct sexual contact
Mother-to-child
Blood-to-blood

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2
Q

What are the risk factors for STIs?

A 
Unprotected sexual activity
Age
Gender
Ethnicity
Sexual orientation
Setting/sexual network
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3
Q

What are the complications of STIs? (x5)

A 
Pre-term/low birth weight
Congenital defects - syphilis
Reproductive health
Malignancies
Interaction with HIV acquisition/transmission
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4
Q

What are the general STI prevention methods? (x6)

A 
Condom use
Prompt diagnosis + treatment
Sexual abstinence
Contact tracing + partner treatment
Screen medical blood products
No needle sharing
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5
Q

What is the epidemiology of STIs?

A

In LDCs, STIs + complications rank in top 5 disease categories for which adults seek health care
4% of deaths worldwide (6.6% in LICs) due to unsafe sex

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6
Q

What is a DALY?

A

Disability Adjusted Life Year
1 lost year of ‘healthy’ life
By summing all the DALYs across a population, you can measure the burden of disease

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7
Q

How is a DALY calculated?

A

DALY = YLL + YLD
Years Life Lost = no of deaths x life expectancy at age death occurred
Years Lost due to Disability

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8
Q

What is the incidence of gonorrhoea in England?

A

41 193 cases diagnosed in England (PHE, 2015)

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9
Q

What is the trend in gonorrhoea diagnoses in England + Wales over last 100 years?

A

Massive increase in 1918 + 1946 as troops return from World Wars
Decline in 1947-54 due to Abx + social stability
Increase in 1960s as sexual liberation; OCP; homosexuality decriminalised
Decrease from 1980s due to behaviour modification in response to PH campaigns for AIDs
Increase 74% 2005-10 due to diagnoses incidence

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10
Q

What is the relationship between infection and transmission in STDs?

A

Dynamic interplay among pathogen, subpopulation behaviour + prevention efforts
Infection + transmission are dynamic - risk depends on availability of Tx + behaviour
Phase appropriate prevention strategies + research issues important

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11
Q

What is R0?

A

Basic Reproductive number = average number of secondary cases generated by a single primary case in a fully susceptible population

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12
Q

What must R0 be in an epidemic/growth phase?

A

> 1

Each infected person must infect more than 1 person

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13
Q

How is R0 calculated?

A

Mean length of time infectious x rate at which sexual contact occurs x likelihood of transmission in a sexual partnership

TIME X RATE X LIKELIHOOD

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14
Q

What does the standard epidemiological model for STI in the population involve?

A

Core group/subpopulation who have a lot of partners that sustain transmission + persistence in wider population
Bridging population
General population

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15
Q

What are some examples of subpopulations who have higher rates of partner changes?

A

Young people
Urban
Sex workers

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16
Q

What is the definition of primary, secondary and tertiary prevention in STIs?

A 
Primary = reduce risk of disease in UNAFFECTED people
Secondary = reduce SEVERITY of disease in people with EARLY SIGNS
Tertiary = Reduce IMPACT of disease in people with clinical condition
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17
Q

What is the definition of screening?

A

Process of identifying apparently healthy people who may be at an increased risk of disease

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18
Q

What are the components of control strategies for STIs?

A 
Surveillance
Early Dx
Screening
Effective Tx
Contact tracing
Population groups
Monitoring + evaluation
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19
Q

What are the challenges to effective control interventions for STIs?

A 
Undiagnosed/asymptomatic cases
Resources for prevention/treatment
Abx resistance
Vaccination
Partner notification
Sexual behaviour change
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20
Q

What is the epidemiology of HIV?

A

HIV prevalence 36.9 million people living with HIV worldwide (WHO, 2018)
18 million on ART
35 million have died from HIV
Drastic decline of mortality since 2005
Incidence is decreasing but prevalence is increasing as better testing + Tx so more people living longer with HIV
Increased transmission in Africa as ARTs were rolled back

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21
Q

What are the problems with HIV medication?

A 
Expensive
Lifelong medication
S/Es; toxicity
Adherence
Doesn't eradicate virus
High levels of mutation
Rapid development of resistance to monotherapy led to combination of drugs (HAART)
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22
Q

Who are the key populations in HIV epidemic settings?

A

Homosexuals
Healthcare workers
Sex workers
Transgender people

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23
Q

What are the barriers to HIV treatment?

A 
Access
Resources
Belief
Drug availability
Health care facilities
Stigma
24
Q

What are the different types of biomedical interventions used for HIV? (X5)

A 
GP41 inhibitors 
GP120 + CCR5 antagonists
Reverse transcriptase inhibitors
Integrase inhibitors
Protease inhibitors
25
Q

Describe the MOA of a GP41 inhibitor

A

Virion envelope covered in GP41 to bind with T helper cells

Prevent HIV from fusing with cell

26
Q

Describe the MOA of a GP120 + CCR5 antagonist

A

Virion envelope covered in GP120 to bind to T helper cells

Prevent HIV from attaching to cell

27
Q

Name + describe the MOA of a reverse transcriptase inhibitor

A

Prevents replication as retrovirus has RNA + virus uses reverse transcriptase to turn RNA into DNA which is then inserted into host DNA

28
Q

Name + describe the MOA of an integrase inhibitor

A

Raltegravir

Prevent insertion into host genome

29
Q

Describe MOA of a protease inhibitor

A

Prevent processing of HIV proteins which host cell machinery produces

30
Q

What is the definition of efficacy?

A

The ability to produce a desired/intended result

31
Q

What is the definition of effectiveness?

A

The degree to which something is successful in producing a desired result

32
Q

What are the issues with the biomedical interventions for HIV?

A 
Drug resistance
High compliance required
Need for 'simpler' regimens
Management of long term toxicity 
Treatment NOT cure
33
Q

What are the next steps of HIV treatment for the future?

A 
Very early treatment e.g. HIV+ neonates
Therapeutic vaccines
Immune modulation
Gene therapy
Early ART (NEJM 2011 + 2016) - treatment as method of prevention + reduces risk of transmission by 96%
34
Q

List the prevention strategies for HIV

A 
Condoms (M+F)
PEP (Post exposure)
Prevention of vertical transmission
Tx as prevention
Male circumcision - Gray et al, 2012 found > 57% reduction
Voluntary counselling + testing
Clean injecting equipment
PrEP (prophylactic)
35
Q

Name 2 ART trials

A 
PROUD trial (Lancet, 2016)
IPERGAY trial (NEJM, 2015)
36
Q

What are the issues of the current HIV biomedical interventions?

A

Hard to have trained staff
Lack of funding = lack of services
Gender based violence
Human rights - homosexuality is still illegal in some countries so by accessing care it is risky

37
Q

What are the barriers to developing an effective biomedical prevention intervention?

A

Classic vaccines mimic natural immunity but no one has survived HIV
Most vaccines protect against disease NOT infection
Long latent period
Safety concern using live, attenuated pathogen
HIV has multiple mechanisms of immune evasion
High levels of mutation
Absence of neutralising antibodies
Destruction of immune response

38
Q

How will progress of finding a HIV vaccine be accelerated?

A

Better understanding of antigenicity vs immunogenicity
Better understanding of how broadly neutralising antibodies evolve in HIV infections
Methods to stabilize the native Env trimer, to immunize as well as elucidate the crystal structure

39
Q

What did the Thai trial (RV144),2006 show?

A

Protection from infection is possible
Protective efficacy around 31%
Highest protection in first 6-12 months

40
Q

What are the prospects for HIV cure?

A

Requires elimination of all free HIV particles + all infected cells
Latently-infected cells persists for years + HIV starts replicating again immediately when therapy is stopped
Would take 70 years to eliminate all virus + infected cells w/ current therapy
New goal is to identify new strategies to eliminate latent infection

41
Q

What are the strategies to eliminate the HIV reservoir?

A

‘Flush out’ virus by activating latently infected cells and killing them (kick + kill)
Immunologic Tx targeted at reservoir
Gene therapy (CCR5 modification/elimination)
CCR5 delta32 stem-cell transplants

42
Q

What is the continuum of care in HIV?

A

Testing
Enrol + retain in care - loss to follow up
Early retention in care - stop taking drug in early stages of ART
Lifelong retention in care - non-adherence to ART

43
Q

What are the issues with the HIV continuum of care?

A

Identification - if not diagnosed, no ART to suppress viraemia
Evidence shows that having the diagnosis makes you less likely to engage in high risk sexual behaviour, even if not seeking treatment

Retention - viral resistance develops + inadequate suppression of viraemia if inadequate retention

44
Q

When is a HIV patient most infectious?

A

Primary infectious period = first 3 months
Highest viral load
Generic flu-like symptoms, abdo pain, rash
VERY FEW PEOPLE PRESENT at this stage when most ideal to treat
AIDS-defining illness at the end also has high viral load but this is too late as they are probably too old to be very sexually active

45
Q

What is the relevance of behavioural + structural interventions for success of biomedical prevention interventions?

A

Hand in hand

In UK, MSM are most affected group but globally, sex workers are

46
Q

Name 3 behavioural interventions for HIV

A

Encourage regular testing for HIV - Universal testing, regular sub-population testing at intervals
Encourage health seeking behaviour - sexual health education, health training
Increase adherence to biomedical prevention interventions (non-ART) - youth condom promoters, peer support, counselling, motivational interviewing

47
Q

Name 3 structural HIV interventions

A

Decriminalisation of sex work, IVDU, homosexuality, needle exchange
Reduced inequality - business start-up grants, CCT, Single-sex/joint group meetings
Increased access to health services - universal health coverage plan

48
Q

What was found in S Africa with regards to age-specific gender disparity?

A

HIV prevalence increases with age from teens and more rapidly for women > men
Young women have sex with older men as they have more power and money
School attendance significantly reduced risk of HIV acquisition

49
Q

What are the 5 key barriers to ART increase in resource-limited settings

A

Access to medicines - affordability
Funding
Simplification - public health approach needed due to lack of doctors + labs in LICs –> task shifting + decentralisation; also drug regime is too complicated, pushing for once daily pill
Models of delivery - access in primary care clinics in rural areas where hospitals are far away

50
Q

What is AIDs exceptionalism?

A

HIV is unique in that there are billions of dollars of funding AND specific programmes that exist specifically for reducing the burden of HIV

51
Q

What is the only UN programme for one disease?

A

UNAIDS (1996) has 90 90 90 by 2030
90% tested
90% treated w/ ART
90% suppressed virologically

52
Q

Is the testing target of UNAIDs 90 90 90 being achieved?

A

No country is reaching 90% target
Globally < 60% know their status
Large variability - men’s testing is getting neglected especially in countries where being gay is illegal

53
Q

What are the enablers for testing for HIV?

A

Lay testing
Community testing - especially partner testing
Self-testing - will people actually seek care if positive?

54
Q

Is the treatment target of UNAIDs 90 90 90 being achieved?

A

People present late to care
High rates of lost to care pre-ART
IeDEA-WHO Collaboration, 2015 found > 15% lost within 12 months in 55 countries
Long delays in starting ART

55
Q

What are the enablers of treatment for HIV?

A

Earlier testing + improved linkage
Accelerated ART initiation (WHO, 2017 recommended to start ART same day as diagnosis)
Advanced disease package - enhanced prophylaxis in advanced disease
Treat all

56
Q

What are the problems with the suppression part of UNAIDS 90 90 90?

A

High rates of loss to follow up - treatment fatigue
Sub-optimal adherence - forgetting, travel + migration, change to routine, distance to clinic, stock-outs
Differentiated service delivery - timing, location + mode of delivery depend on context

Global Health BSc 2018/19 - CDMM1 (12 decks)

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