1.b. There is a relationship between physical factors and the prevalence of disease which can change over time.

Question 1

What climates are important drivers of vector-borne diseases and epidemics?

(Global patterns of climate and relief, and their effect on diseases)

Answer 1

Temperature and precipitation.

E.g. warm, humid conditions are within the tropics, e.g. Ethiopia.

Question 2

How does temperature influence disease?

(Global patterns of climate and relief, and their effect on diseases)

Answer 2

Temperature determines rates of vector development, behaviour and viral reception.

Question 3

How does precipitation influence disease?

(Global patterns of climate and relief, and their effect on diseases)

Answer 3

Precipitation can create pools of stagnant water, allowing insects and disease to flourish in their life cycle.

Question 4

How does relief/altitude causes abrupt changes in the climate and disease habits?

(Global patterns of climate and relief, and their effect on diseases)

Answer 4

Individuals that live in more mountainous settlements are less likely to come into contact with infectious diseases.

Most diseases, other than certain strains of influenza, tend to thrive in high temperature, high precipitation, and high humidity area.

For example, Malaria is prevalent in the lowland areas of Ethiopia, but minimal in the Central highland areas.

Question 5

How may contaminated water sources effect disease?

(Global patterns of climate and relief, and their effect on diseases)

Answer 5

Many diseases are waterborne, and many millions of people rely on water from wells and surface supplies contaminated by sewage.

Bacteria, such as the cholera bacterium, thrive in these conditions.

This can become extremely dangerous if unprotected and stagnant.

Question 6

Dengue fever thrives is prevalent where?

(Physical factors and disease vectors)
(Global patterns of climate and relief, and their effect on diseases)

Answer 6

Widespread in the tropics (warm, humid conditions).

Question 7

How many people are effected by dengue fever each year?

(Physical factors and disease vectors)
(Global patterns of climate and relief, and their effect on diseases)

Answer 7

400 million people (25,000 deaths).

Question 8

What can trigger dengue fever epidemic waves?

(Physical factors and disease vectors)
(Global patterns of climate and relief, and their effect on diseases)

Answer 8

Sustained high temperatures of higher than 32°C and humidity levels higher than 95%.

Short-term exceptional rainfall events can also trigger these epidemic waves - as some insects thrive in pools of rainwater.

Question 9

Outline seasonal variations within the Northern hemisphere.

(Seasonal variations in disease outbreaks)

Answer 9

Associated with epidemics of influenza.

This is a respiratory illness.

The transition of influenza is more efficient in the winter months.

Question 10

Outline seasonal variations within the Tropics and sub-tropics.

(Seasonal variations in disease outbreaks)

Answer 10

Associated with vector-borne diseases, from e.g. mosquitoes, flies, ticks and fleas.

Malaria is highly influenced by seasonal variations because outbreaks tend to follow significant precipitation events, such as the monsoon rains - March-April through to September-October.

It means that there’s lots of stagnant water on the surface, the ideal conditions for mosquitoes to lay their eggs, for their larvae to thrive, and complete their life cycle - thus bringing a seasonal spike in malarial transmission.

Other diseases do the same: such as diarrhoeal disease in South Asia.

Question 11

What transmits WNV?

(West Nile Virus)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 11

Mosquitoes.

Question 12

What does WNV mostly affect?

(West Nile Virus)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 12

Birds.

Question 13

Outline the global prevalence of WNV.

(West Nile Virus)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 13

Africa, Canada, South America (Venezuela), Europe, West Asia, Australia.

Question 14

How is climate change affecting WNV?

(West Nile Virus)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 14

WNV needs high temps for success in transmission.

Since 2012, there has been an increase of 5,500 cases in the USA annually - with high concentrations in Texas - (which may become an endemic if climate change worsens).

Question 15

How is Lyme disease transmitted?

(Lyme Disease)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 15

Ticks.

Question 16

How is climate change affecting Lyme disease?

(Lyme Disease)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 16

It is spreading northwards through the USA as temperature increase.

The first case in Canada is predicted soon.

Question 17

Sleeping sickness is endemic to how many sub-Saharan nations?

(Sleeping Sickness)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 17

36 sub-Saharan African nations.

Question 18

Sleeping sickness affects how many people?

(Sleeping Sickness)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 18

70 million people.

Question 19

What transmits sleeping sickness? What temperatures does it require?

(Sleeping Sickness)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 19

Transmitted by the vector tsetse fly, which requires temperatures of between 20.7°C - 26.1°C.

Question 20

How is climate change affecting sleeping sickness?

(Sleeping Sickness)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 20

The disease is set to spread north with climate change, but will have to be transmitted across the Sahara Desert - so this is unlikely to happen.

Instead, it will most likely spread to southern Africa, e.g. Zimbabwe.

The WHO, predicts 77 million more people will be affected each year by sleeping sickness by 2090.

Question 21

Outline malaria endemic in Europe.

(Malaria)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 21

Endemic in Europe even in climatic periods much colder than today (e.g. from the last ice age in the 18th and 19th centuries), when ‘ague’ was a common cause of death.

Question 22

Until the mid-20th century, what was the only effective remedy for malaria?

(Malaria)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 22

Cinchona powder, extracted from the bark of tree species native to the Andes, in South America.

The main active ingredient in this bark is quinine, which is still used now, but it was first used in tests with ague patients living in the salt marshes of Essex, in England.

Question 23

How is climate change affecting malaria?

(Malaria)
(Climate change enabling the emergence of infectious diseases, allowing transmission to new locations)

Answer 23

Even if future climates become more suitable for malaria transmission in southern Europe (due to temperature increase), a large epidemic is unlikely in ‘new’ regions given the availability of anti-malarial drugs and the relatively high standard of public health services.

However, it would be a mistake to be complacent as local transmission of P. vivax (the main type of malaria) occurred in Greece in 2009-10 in association with large cuts in government spending due to the economic crisis, migration, and the heatwave that struck the country at that time.

Question 24

What is ague?

Answer 24

A malarial fever marked by chills, fever, and sweating that recur at regular intervals.

Question 25

State 3 infectious diseases that are zoonotic.

(The spread of zoonotic infectious diseases to humans)

Answer 25

Malaria, sleeping sickness and dengue fever.

Question 26

What transmits zoonotic diseases? Give examples.

(The spread of zoonotic infectious diseases to humans)

Answer 26

Domestic animals, as well as wild animals.

E.g. dogs, bats, foxes, raccoons, and other mammals, transmit rabies.

E.g. poultry present a greater risk of transmitting Asian flu than wild birds.

However, in most instances, transmission occurs only with close contact between people and animals.

Question 27

The probability of zoonotic diseases being transmitted to humans is increased where…state 3.

(The spread of zoonotic infectious diseases to humans)

Answer 27

The movement of infected wild animals is unrestricted by physical barriers (e.g. mountain ranges).

Controls on the movement of diseased domestic animals within countries are ineffective; e.g. political barriers.

Urbanisation creates suitable habitats for animals such as foxes, raccoons and skunks.

Vaccination of pets and domestic livestock is sparse.

There is limited control within urban areas of feral dogs, cats, pigeons and other animals.

Hygiene and sanitation are poor. Drinking water is contaminated by animal faeces, blood and saliva.

Man-made habitats (e.g. surface pools, ponds) encourage insect vectors to breed.

There is prolonged contact between humans and animals, e.g. poultry farms and avian flu, cattle farming and anthrax