L2 - global health AIDS

Question 1

Define Incidence

Answer 1

The number of new cases of a disease measured within a defined population within a specific time period

Question 2

Define prevalence

Answer 2

The total number of cases of a disease in a defined population at a particular moment of time.

Question 3

Define mortality rate

Answer 3

The incidence of death within a defined population within a specific time period

Question 4

Reflect on the dramatic impact of emerging infectious diseases

Answer 4

With the emergence of HIV/AIDs, there were initially (1981) around 5 cases in young males from Pneumocystis pneumonia that couldn’t be explained, but which seemed to show an association due to demographic similarity. There were also some deaths. This then grew exponentially in the following months to 285 cases (March 1982) to 1.3 million people living with HIV in the US (2006).

Question 5

What are the 5H’s

Answer 5

Homosexuals, Haitians, Haemophiliacs…

Question 6

What were the risk factors of AID?

Answer 6

Injection drug use, male-to-male sexual contact, more sexual contacts, syphilis

Question 7

How were hypotheses (drugs/infection) of AIDs risk factors tested?

Answer 7

75% of living cases were interviewed, no association with popper (inhaled nitrate drugs)

Question 8

Define case-clustering

Answer 8

When all living cases are of a certain population sub-group and cases are all related to one another i.e. have many sexual partners in common

Question 9

What is a case-control study

Answer 9

A study that sets out a known outcome and compares individuals with that outcome to those without. The study determines what connects the members of each group i.e. odds ratios.

Question 10

How do you design a case-control study?

Answer 10

Retrospective.
Identify an outcome. Form a group of subjects with and without the outcome. Look back in time to identify exposures, compare the frequency of exposures in the case and control groups.

Question 11

Among gay men engaging in homosexual activity, what other population sub-groups were affected by HIV?

Answer 11

• Injecting drug users

- Transfusion/Factor VIII recipients

Question 12

What cases indicated that HIV was caused by an infection?

Answer 12

Monogamous sexual partners; babies transfused at birth; haemophiliacs

Question 13

How did the amount of HIV positive test results change?

Answer 13

1978 <1%

1980 20%

Question 14

Describe the distribution of HIV

Answer 14

90% in developing countries

Question 15

What is the equation for frequency of a disease in the population?

Answer 15

number of cases in the population/number of people in the population

Question 16

What was the number of people living with HIV in 2014?

Answer 16

36.9 million

Question 17

What names of countries are most affected by HIV?

Answer 17

S. Africa, C. Africa, Russia, S. America

Question 18

Describe prevalence of HIV from 1997-2006

Answer 18

Rapidly increasing up to around 1 100 000 (2006 level). Plateau in 1990s. Incidence roughly the same, although lower since 1991-2006.

Question 19

Describe the global changes in HIV prevalence from 2007-2014

Answer 19

Total change from 2.7 to 2 million. Sub-Saharan Africa 1.9 million to 1.4 million. South and South-East Asia slight difference.

Question 20

Describe 2016 HIV stats for UK

Answer 20

HIV diagnoses: 5000
AIDS + HIV diagnoses: 300
all-cause deaths in people with HIV: 500

Question 21

Describe global birth proportions of newly diagnosed HIV cases in the UK

Answer 21

UK: 45%
Rest of Europe: 17%
Africa: 20%
Asia: 7%
The Americas: 10%
Australasia: 2%

Question 22

When was mother-to-child transmission of HIV and syphilis stopped in Cuba?

Answer 22

2015

Question 23

How does incidence influence policy?

Answer 23

When the incidence nears 0, schools can be re-opened and outbreak can be declared over

Question 24

State the equation for mortality rate

Answer 24

Deaths from disease in a given time period/population at the start of the time period

Question 25

Since the beginning of the epidemic approx. how many people have been infected by HIV/AIDS?

Answer 25

60 million people

Question 26

How many people have died of HIV related causes?

Answer 26

25 million people

Question 27

How many infections are there per year?

Answer 27

2 million per year

Question 28

Compare deaths HIV in 2005 to 2014

Answer 28

2005: 2.8 million
2014: 1.2 million
SSA 2005: 2 million 2007: 790 000
S. Asia 2005: 560 000 2007: 240 000

Question 29

Explain the relationship between prevalence and mortality

Answer 29

For diseases where treatment confers survival benefit i.e. HIV (ART), the mortality falls. This results in increasing prevalence. As more people are alive and are able to transmit HIV, this also could result in higher incidence. If mortality = incidence the epidemic is stable.

Question 30

How many deaths have been averted since ART?

Answer 30

9 million

Question 31

How can prevalence of HIV increase but incidence decrease with treatment?

Answer 31

ART improves survival, the prevalence of HIV population increases. ART also reduces risk of onward viral transmission by limiting level of virus in the blood and secretions of people to 0. More people that take ART, less HIV transmission.

Question 32

Explain key IAS 2010 treatment 2 goals

Answer 32

Recognition and use of HIV treatment to prevent new infection, development of better combi ART and cheaper diagnostic tools, lowering of HIV-related costs, expansion of the availability of HIV testing and stronger links between HIV testing and care, encouragement and support in expanding and improving local HIV responses.

Question 33

State an effect of HAART and AZT

Answer 33

Lowered mother to child HIV transmission

Question 34

What is the main driver of transmission

Answer 34

Viral load

Question 35

Describe HPTN 052 study design

Answer 35

Randomised control trial looking at HPTN 052. This suppressed HIV in people with certain CD4+ count, leading to 96% reduction in risk of transmission to sexual partners.

Question 36

State HIV goals by 2020

Answer 36

90% of people with HIV will know their status (33.2 milli)
90% of all HIV diagnosed people will receive ART (29.5 milli)
90% of ART receivers will have durable suppression (26.9 milli)
73% of all people living with HIV will be virally suppressed

Current gap of around 10 milli from each target

Question 37

Compare mortality in high and low-income countries

Answer 37

57 million people die each year
High income: >66% live beyond age of 70
Main COD: man-made disease
Low income: <20% reach 70
Main COD: Lower respiratory tract, diarrhoeal disease, HIV/AIDs, IHD, Malaria, Stroke CVD, TB,  maternal

Question 38

What are the current and predicted costs if ART?

Answer 38

$42 billion 2010
$54 billion 2015
$26.6 billion 2020

Question 39

What is UNAIDS commitment

Answer 39

To end HIV epidemic as a public health threat by 2030