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

Question 1

Briefly explain how physical factors have an influence in diseases

Answer 1

physical factors such as temperature, precipitation and water sources are important drivers- vector borne diseases such as malaria (absent from cool, dry climates) but also illnesses such as influenza (related to low levels of climate) and respiratory illnesses (related to poor air quality)

Question 2

How does climate (temperature and precipitation) impact diseases

Answer 2

• many diseases rely upom warm, humid climates and so are endemic to tropics and sub tropics
• this means these diseases see seasonal variations with changes in temperature and precipitation across the year
• precipitation creates aquatic habitats that allow disease vectors to flourish

Question 3

How does altitude and changes in relief impact diseases

Answer 3

• these can cause abrupt changes in climate, influencing the diffusion of diseas
• e.g. Malaria is endmic to the lowlands of Ethiopia, but minimal cases are reported in the cooler central highlands

Question 4

How does the developing world impact diseases

Answer 4

• many people in the developing world rely on local stagnant and contaminated water sources for drinking
• these aquatic habitats are breeding grounds for many bacterial diseases and vectors
• Guinea worm endemic in West Africa

Question 5

How do physical factors influence vectors of disease (example-Dengue fever)

Answer 5

• dengue fever widespread in tropics and anually infects 400 million
• climate controls dengue fever epidemiology and the life cycle of Aede mosquitoes that transmit the dengue virus to humans
• mosquitoes thrive in warm, humid conditions, which favours the outbreak of dengue
• in the South Pacific, sustianed temperatures of more than 32 degrees trigger waves of dengue epiemics
• short term weather changes and exceptional rainfall events can lead to outbreaks

Question 6

How do seasonal variations influence disease outbreaks

Answer 6

• many diseases have seasonal variations in both temperate regions, the tropics and the sub tropics
• in temperate regions, influenza causes rise in winter because it diffuses more effectively at lower temperatures
• for tropics/sub tropics, vectors rely upon rainy season

Question 7

How are zoonotic diseases spread to humans

Answer 7

• via animals (from animals to humans)
• malaria is an example- infection may be transmitted by domestic as well as wild animals
• in most instances, transmission only occurs wtih close contact between people and animals

Question 8

The probability of zoonotic diseases being transmitted to humans increases where…

Answer 8

• controls on the movement of diseased domestic animals within countries are ineffective
• urbanisation creates suitable habitats for animals such as raccoons
• vaccination of pets and domestic livestock is sparse
• limited control within urban areas

Question 9

Explain how climate change provides conditions for emerging infectious disease to spread to new places

Answer 9

• warmer and wetter conditions mean vector bourne diseases such as dengue fever will spread in terms of geographical area
• climate change responsible for spread of Lyme disease and sleeping sickness as they spread northwards
• as temperatures rise, the WHO predicts sleeping sickness will spread to southern Africa and affect 77 million people by 2090
• diseases may disappear from some areas that become too hot e.g. East Africa

Question 10

Example of zoonotic transmission- Ebola in West Africa- key facts

Answer 10

• March 2014- case of Ebola confirmed in Guinea
• cases reported in the forested rural region of South eastern Guinea
• 8th May 2016- 28,646 cases
• December 2013- single zoonotic transmission event to a 2 year old boy- infected by bats

Question 11

Example of zoonotic transmission- Ebola in West Africa- diffusion

Answer 11

• scientists found the virus was rapidly mutating, changing and adapting to medical treatment
• high risk of contagion for those helping
• virus spread to Guinea’s bordering countries
• those diagnosed with the disease would flee isolation wards- spreading the disease

Question 12

Example of zoonotic transmission- Ebola in West Africa- symptoms

Answer 12

• fever
• aches
• red eyes
• skin rash

Question 13

Example of zoonotic transmission- Ebola in West Africa- response

Answer 13

• CDC activated its Emergency operations center in July 2014
• travelers leaving West Africa were screened
• burials in Sierra Leone
• recovery food for quarantined housesholds

Question 14

Example of zoonotic transmission- Ebola in West Africa- impact

Answer 14

• March 2016- WHO lifted the PHEIC status on Ebola in West Africa
• affected countries include Italy, Mali, Nigeria
• 11,310 deaths in Guinea, Liberia and Sierra Leone