Emerging and re-emerging infectious diseases in the 21st century

Question 1

Global infectious diseases mortality burden

Answer 1

Roughly 1 in 4 deaths, globally attributed to infectious diseases
The vast majority are by respiratory infection (pollution etc)

Question 2

What is DALY?

Answer 2

Disability-adjusted life year

A year that is lost of healthy life

Question 3

Endemic =
Epidemic =
Pandemic =

Answer 3

already permanently present
when you have an infection that goes beyond geographical boundaries
influence is everywhere

Question 4

How did ebola begin?

Answer 4

Ebola began by the consumption of a dead bat in Liberia.
The family that consumed it then travelled to Guinea.
Within 3 months the outbreak had spread across three countries, Liberia, Guinea and Sierra.

Question 5

When people die in certain cultures, spread of disease is enhanced, why?

Answer 5

When people hug and kiss the bodies etc- cultural practises embedded by tradition.

Question 6

What are zoonotic diseases?

Answer 6

Often originate from viruses picked up by birds- often does not demonstrate any symptoms- transfer to other animals and then human beings (multiple living organisms).

Question 7

Understanding the epidemiological triad

Answer 7

Host = recipient of the disease
Environment e.g crowded
Agent = disease itself

Question 8

Infectious diseases of poverty?

Answer 8

The share of disease burden is prevalent amongst poorer countries/ income is much lower (clear pattern).
As income increases, burden decreases…

Question 9

Poverty and infectious diseases: vicious cycle

Answer 9

Life long disadvantage (work, family, community)
Can’t function, can’t work
Burden on people caring for you
Economic productivity
Social stigma
Marginalised, vulnerable population, those affected by conflict and war, natural disasters at high risk
Social stigma and discrimination (work, community, family)
Lost economic/employment opportunities
Catastrophic healthcare and economic burden
Heavy burden on families and carers

Question 10

Three eras of Global Public Health

Answer 10

Miasma (bad air) – the miasmatists
Germ Theory of Disease – the contagionists
Black box

Question 11

Three eras of Global Public Health

Miasma (bad air)

Answer 11

problem: foul emanations from the Water Air & Place
solution: improvement of water and sanitation

Question 12

Three eras of Global Public Health

Germ Theory of Disease – the contagionists

Answer 12

problem: disease agent (bacteria) —> Man —> Disease
solution: development of vaccines & antibiotics

Question 13

Three eras of Global Public Health

Black box

Answer 13

problem: multiple risk factors, difficult to understand disease structure
solution: no clear-cut explanation (association/causation)

Question 14

What is the Influenza pandemic?

Answer 14

Global outbreak of disease that occurs when a new influenza virus emerges in the human population

Question 15

Influenza pandemic history

Answer 15

Spanish flu (1918-19)– H1N1, avian origin, highly fatal, 40-100 million worldwide mostly young & healthy, re-emerged in 1977 (Russian flu, killed 0.7 million)
Asian flu (1957-58) – H2N2, origin China and later spread across continents, killed 2-4 million
Hong Kong flu (1968-69) – H3N2, origin Hong Kong and later spread across continents, killed 1-2 million
Pandemic (swine) flu (2009-) – H1N1, origin Mexico, 1.6 million cases killed 19,652

Question 16

How does the ZIKA virus spread?

Answer 16

Spread through infected Aedes mosquito bite (similar to dengue, yellow fever, chikungunya) – 84 countries affected: Americas, Africas and the Pacific

Question 17

Where was the ZIKA virus first identified?

Answer 17

First identified in Uganda (1947) in monkeys, re-emerged in 1952 in Uganda and Tanzania and again in Brazil in July 2015

Question 18

What does the ZIKA virus cause?

Answer 18

Causes congenital brain abnormalities, microcephaly and Gullian-Barré syndrome and closely associated with a range of neurological disorders

Question 19

How can the ZIKA virus be transmitted between humans?

Answer 19

Transmission possible via sex, blood transfusion
Fatality rare (1 in 5 affected)

Question 20

What is Avian (bird) flu?

Answer 20

Strain has limited ability to get transmitted from poultry to humans.
Not unlikely that those infected with Avian flu could suffer from common flu as well.
Increased viral load mixing with strain poses life threat to humans (re- assortment – viruses exchanging genes).
Could trigger potential pandemic strain, hence passes from one person to another.

Question 21

Phases of influenza pandemic

Answer 21

Phase 1: low risk of human infection even though the infection is present in animals.
Phase 2: circulating animal influenza virus subtype, substantial risk of human disease.
Phase 3: pandemic alert period where human infections with a NEW subtype, but no human-to- human spread, or at most rare instances of spread to a close contact.
Phase 4: limited human-to-human transmission spread highly localized, suggesting that the virus is not well adapted to humans.
Phase 5: larger clusters human-to-human spread still localized, suggesting that the virus is becoming increasingly better adapted to humans but may not yet be fully transmissible (substantial pandemic risk).
Phase 6: pandemic outbreak, increased and sustained transmission in general population