Disease Dilemmas Geography Paper 3 OCR

Page 348

what is an infectious disease?

• a disease spread by pathogens

• bacteria, viruses, parasites

• most, not all, transmitted from one person to another

• Ebola

what is a non-infectious disease?

• non-communicable

• nutritional deficiencies, lifestyle, genetic inheritance

• main cause of death in ACs

• diabetes, cancer

what are communicable diseases?

• an infectious disease that spreads from person-person

• spread through direct + indirect contact

• Covid-19

what are non-communicable diseases?

• a non-infectious disease that cannot spread through infection or by other people

• lifestyle choices, nutritional deficiencies, genetic inheritance

• Coronary Heart Disease

what is a contagious disease?

• a class of infectious disease

• easily spread by direct or indirect contact between people

• Ebola

what is a non-contagious disease?

• spread by disease vectors

• worms, mosquitoes

• malaria

what is a host?

• an animal that sustains a reservoir for pathogens

• bacteria, viruses

• bats + rabies, rats + plague

what is a vector?

• a carrier of disease

• mosquitoes are vectors of malaria

what are zoonotic diseases?

• infectious diseases transmitted from animals to humans

• 60% infectious diseases spread from animals

• rats + fleas + plague

what are endemic diseases?

• permanently exist in a defined geographical area or population group

• sleeping sickness contained in rural areas of sub-Saharan Africa

what is an epidemic?

• outbreak of a disease that attacks many people at same time

• spreads through a population in a restricted geographical area

• Ebola, West Africa 2014, 10500 deaths

what is a pandemic?

• epidemic which has spread worldwide

• 2020 Covid-19 pandemic, 180,000 deaths England

what is a degenerative disease?

• diseases that reflect an aging population

• due to medical improvements, unhealthy lifestyle choices, pollution

• stroke, dementia, cancer

• in 2019, responsible for 70% deaths worldwide

Global distributions of Malaria

• infectious, non-contagious tropical disease

• concentrated in Africa + South Asia

• in 2018, 220 million infected with malaria

• malarial parasite transmitted to humans by Anopheles mosquitoes

• thrive in warm, humid environments

• Australia eliminated malaria - public health measures

Global distribution of HIV/AIDS

• infectious, contagious disease

• HIV spread by human bodily fluids - blood + semen

• in 2020, 38mil infected worldwide

• uneven distribution, Nigeria + South Africa most cases

Global distribution of tuberculosis (TB)

• infectious + highly contagious

• associated with poverty + overcrowded living conditions

• in 2018, 10mil cases worldwide

• 95% TB deaths in LIDCs - Africa

Global distribution of diabetes

• non-communicable

• caused by deficiency of insulin, secreted by pancreas

• globally, 4.2mil deaths annually

• widespread, concentrated North America + Asia

• Type 1 - genetic

• Type 2 - poor lifestyle choices

Global distribution of cardiovascular disease (CVD)

• CVD is range of illnesses - stroke, coronary heart disease

• highest mortality rates in Russia + sub-Saharan Africa

• globally, 17mil deaths annually

• 80% CVD deaths in EDCs + LIDCs

• linked to poor lifestyle choices - degenerative diseases

what is diffusion (in relation to disease)?

the process where diseases spread outward from their origin and across geographical space

what are the 4 types of disease diffusion?

1. expansion

2. relocation

3. contagious

4. hierarchal

what is expansion diffusion?

• disease has a source + spreads out into new areas

• carries in the source area remain infected

• in 1918, Spanish flu, killed 40mil worldwide

what is relocation diffusion?

• disease leaves the area of origin + moves into new area

• cholera Haiti 2010, killed 7000, originated in Nepal brought to Haiti by international aid workers for earthquake

what is contagious diffusion?

• disease spread through direct contact with a carrier

• strongly influenced by distance

• 2014 Ebola epidemic West Africa

what is hierarchical diffusion?

• disease spreads through an ordered sequence of places

• usually from largest centres with highest connectivity to smaller more isolated rural centres

• diffusion channelled along road, rail + air transport. carriers contact with susceptible population

• in 2019/2020, Covid-19 virus became pandemic due to flights + rail journeys, killed over 700,000 globally

what are 5 physical barriers to diffusion?

• distance - probability of contagious disease spreading to area inversely proportional to source distance

• mountain ranges

• seas + oceans

• deserts

• climate

what are 6 socio-economic barriers to diffusion + example?

• political boarders - check international movement of carriers of infectious disease

• imposing curfew + limiting contact between people

• quarantining

• wearing face masks in public places

• cancelling public events

• vaccination programmes, if available

• all shown in England during Covid-19

what is neighbourhood effect of the Hagerstrand diffusion model?

neighbourhood effect - probability of contact between a carrier + non-carrier is determined by number of people living in each 5×5km grid square + their distance apart. More likely to be infected with closer proximity

what is the logistic curve of the Hagerstrand diffusion model?

number of people infected by epidemic approximates an S-shaped or logistic curve over time - slow beginning, number infected rapidly increases, then even out as most have become infected

what is the progress of diffusion of the Hagerstrand diffusion model?

the progress + diffusion of a disease may be interrupted by physical barriers

what are global patterns of temperature + how it affects patterns of disease?

• drives of vector-born diseases

• malaria, yellow fever and sleeping sickness depend on warm, humid conditions - are endemic to topics

• climate influenced diseases show seasonal patterns

• determines vector development

what are global patterns of precipitation + how it affects patterns of disease?

• seasonal in topics

• create aquatic habitats - ponds + stagnant pools

• allow insects + disease vectors to flourish + complete life cycles

what are global patterns of relief + how it affects patterns of disease?

• altitude causes sudden changes in climate + disease habitat

• in Ethiopia, malaria concentrated in humid lowlands + largely absent in cooler highlands

what are global patterns of water sources + how it affects patterns of disease?

• water-borne diseases

• millions rely on water from wells + surface supplies contaminated by sewage - bacteria (cholera) thrive

• unprotected + stagnant drinking water supplies are habitats for disease vectors - copepod vectors, Guinea worm, West Africa

what are physical factors that influence disease vectors - Dengue fever

• infects 400mil globally

• climate controls epidemiology - life cycle of mosquitoes that transmit to humans

• mosquitoes thrive in warm + humid

• temps more than 32 + humidity levels about 95% cause dengue epidemic in South Pacific - summer/exceptional rainfall

what are seasonal variations in disease outbreaks?

• winter in northern hemisphere, influenza - lower temps + atmospheric humidity

• topics + sub-tropics, vector-borne diseases peak at rainy reason

• diarrhoeal disease in South Asia peaks pre-monsoon + end of monsoon rainfall (March-September)

• drought can cause less vector-borne diseases

how does climate change provide conditions for emerging infectious diseases?

• increases rainfall, temp, humidity - stimulated vector-borne diseases + increased their geographical range

• West Nile Virus (WNV) - transmitted by mosquitoes, birds main host, spread globally. In 2012, 5500 cases reported in USA, high temps Texas worst affected

• Tick seasons longer due to warmer conditions - more Lyme disease, spreading northwards in USA

• Tsetse fly increase - cause sleeping sickness, sub-Saharan countries currently but predicted to spread to South Africa. WHO predict will affect 77mil by 2090

• even with climate change ACs still less at risk due to public health services - anti-malarial drugs

how do zoonotic diseases spread to humans?

• viruses

• bacteria

• fungi

• parasites

• domestic animals - dogs spread rabies

• poultry - wild bird flu

when does the probability of zoonotic diseases being transmitted to human increase?

1. movement of infected wild animals unrestricted by physical barrier or infected domestic animals by political barriers

2. ineffective control of movement of diseased domestic animals

3. urbanisation creates habitats for racoons + foxes

4. vaccination of pets + livestock is sparse

5. limited control in urban areas of feral cats, pigeons …

6. poor hygiene + sanitation, drinking water contaminated by animal faeces + blood, man-made habitats (lakes) encourage vectors to breed

7. prolonged contact between humans + animals - poultry farms

what is epidemiological transition?

• Relationship between development and changes in age, mortality, fertility and cause of death

What is the first phase of the epidemiological transition?

1. Age of pestilence and famine

   • Pre industrial societies morbidity is high

   • Life expectancy is low

   • Poor sanitation, lots of contamination

   • Slow population growth

What is the second phase of the epidemiological transition?

2. The age of receding pandemics

   • Industrial societies that have medical advancement, hygiene

   • Life expectancy rises

   • Many LIDC and EDC are in this stage today

What is the third phase of the epidemiological transition?

3. Post industrial society mortality slackens

   • Further medical improvement, hygiene and standard of living

   • Mortality to infectious disease is rare

   • Degenerative disease is the main cause

   • Cancer more common

   • Many EDC are in this stage

   • However ACs fall in a further 4th stage

Why does non-communicable disease increase in Advanced Countries?

• Cancer and CVD dominate

• Overnutrition and poor life style choices such as lack of physical activity and diet all lead to these things

• Communicable diseases death mostly eliminated due to better standard of living and medical advancement

Why does communicable disease increase in Lower Income Developing Countries?

• They rely on natural water for drinking so its often contaminated causing cholera and diarrhoea

• Inadequate healthcare services

• Malnutrition

• Lack Vitamin D leads to rickets, Lack Vitamin C leads to scurvy

• Slum housing and overcrowding has poor sanitation

Who are the WHO?

• World Health Organisation

• 1948 they headquartered in Geneva

• They direct and coordinate on health with the UN

• Work closely with NGOs such as UNICEF, Red Cross

What is WHOs brief?

• Gather health data

• Identify priority areas

• Research different health problems

• Support UN member states in making decisions

• Provide support during health crisis

Why is the quality of WHOs data sometimes unreliable?

Because 2/3 of deaths are not registered

What happened during the 2009-2010 influenza pandemic?

• April 2009 swine flu identified in Mexico

• Spread to North America

• WHO declared international public health emergency

• By June pandemic in 74 countries

• In June cases doubled every 15 days

• In autumn numbers began to decrease

• May 2010 there was steep decline

• They quoted 18,000 deaths but likely to be way over 300,000

What are physical barriers to mitigation strategies?

• remote communities can be at an advantage in terms of infection but also very hard to access for medical assistance

• e.g. Amazon rainforest has many indigenous tribes who previously lived peacefully but then exploiters cam in and were carriers of disease that the indigenous had not been vaccinated against

What is HIV/AIDS?

• First identified in USA 1981

• Weakens human immune system

• Leads to AIDS if untreated

• 70% of people with it in Sub-Saharan Africa

• Funding by governments and WHO HIV infections were 35% lower in 2013 than 2001

• Poorest places in Africa worst affected

How do we mitigate against HIV/AIDS?

• Education and public understanding of the fact it is spread through semen and blood

• Promote safe sex and needle usage

• Free condoms, dirty needle bins

• Protect human rights of the groups worst affected such as gay men, women and girls, refugees

• More tolerant attitudes of people so help is less shameful

How are people diagnosed with HIV?

• screening for HIV antibodies in blood/saliva

• Widely used in ACs

How is HIV managed?

• Antiretroviral drugs suppress HIV and halt its progression into AIDS

• Low cost drugs are available

• But not low enough for poorest countries

How does nature provide medicine?

• Many medicines originate from natural plants

• Hippocrates recorded more than 300 plants and herbs

• First naturally deprived medicine was morphine in 19th centaury

Give 2 examples of drugs made from natural sources?

1. Caffeine

   • From tea, coffee and cocoa plants

   • Grows in tropical conditions

   • Stimulates the central nervous system

2. Nicotine

   • Comes from tobacco plant

   • Grows in 20-30 degree

   • Helps with Alzheimer’s and depression

How are wild medical plants surviving?

• At the moment its unsustainable

• Over harvesting is wide spread

• Reduces plant populations and genetic diversity

• Results in extinction

• Slow and niche growing conditions are most vulnerable

Why do habitats need to be protected?

• Deforestation is 325km² a day

• At least one potential drug is lost every 2 years

• Pharmaceutical companies majorly profit and often steal of indigenous tribes

• As a result part of the HIV drug prostialin’s revenue goes back to the Samoa tribe as compensation to protect the rainforest

When was smallpox eradicated?

1980

What diseases is WHO currently trying to eradicate?

• Polio which got a vaccine in 1952

• Previously paralysed 600,000 a year

• Global polio eradication initiative in 1988

• By 2011 it was only an endemic in 3 countries Afghanistan, Pakistan and Nigeria

What top down strategy is being used to eliminate malaria?

• In Mauritius malaria was an epidemic in 1867 and killed 1/8 of the population

• Major government campaign in 1948

• Spray buildings and breeding sites of mosquitos with DDT

• 1973 WHO announced elimination of malaria in Mauritius

• 2 years later cyclone causes another outbreak and further spraying an drugs implemented

• Only been 1 case since 1997

How is guinea worm being eradicated?

• Ghana West Africa

• Partner with the Red Cross Women’s Clubs

• Teach women volunteers about prevention

• They then visit the villages and educate

• Previously tried this with men but women are the ones collecting water so they need to be told about it

What are the responsibilities of the women volunteers?

• Monitor identify and report new cases

• Ensure infected don’t contaminate the water

• Distribute replace and check the filters that remove water fleas

• Identify where there are water sources

What is the life cycle of a guinea worm?

1. Drink water containing water fleas infected with guinea worm larvae

2. Fleas are digested and release larvae into abdomen where they mate

3. Female worms growing up to 1m move through body

4. A year later a worm emerges from a blister its created causing immense pain making a person rush to water

5. They then infest water and worm releases larvae

6. Water fleas then consume the larvae