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Disease Dilemmas - Coggle Diagram
Disease Dilemmas
Global patterns for diseases and reasons for this
Disease classification
Contagious diseases
: Diseases that can be spread by direct/indirect contact between people such as
bacterial
infections like typhoid as well as
viral
like yellow fever and Ebola
If
infectious
diseases spread from host to host and
do not require quarantine
are sometimes referred to as
communicable
But some infectious diseases are non-contagious
: Malaria and leishmaniasis which are spread by
vectors
like mosquitoes, worms and their larvae
Zoonotic diseases
are infectious diseases transmitted from animals to humans : rabies and plague
Non-infectious are non-communicable
which are caused by lifestyle (diabetes, cancer) and/or genetic inheritance (heart disease, stroke)
Coronary heart disease, strokes and alzheimer's
(all non-communicable disease) are the top 3 causes of death in AC's in 2018
Most common:
malaria, sleeping sickness and dengue fever.
But may also be transmitted by domestic animals like dogs, bats, foxes and poultry
Spread of zoonotic diseases would
increase
if the movement of wild animals is unrestricted or ineffective by physical barriers, low vaccination rates for pets, poor hygiene and water contamination
Respiratory infections, diarrhoeal diseases and HIV/AIDS
(all infectious) are the top 3 causes of death in LIDC's in 2018
Endemic, epidemic and pandemic
Endemic
: diseases that exist permanently in a geographical area or population group such as sleeping sickness affecting 7 million people
Epidemic
: disease that attacks many people at the same time whilst spreading through a geographical area such as the outbreak of Ebola in West Africa (2014) going on to killing 25,000 people
Pandemic
: An epidemic that spreads worldwide - Spanish flu, The Black Death and Covid-19
Degenerative diseases and lifestyle
Non-communicative diseases include heart disease, stroke, cancer, diabetes and lung disease were responsible for around 70% of deaths and 82% of people who died prematurely were in LIDC/EDC's
Global distribution of
malaria, HIV/AIDS, tuberculosis, diabetes and cardiovascular disease
HIV/AIDS
2020, 38 million affected but the distribution is uneven with a concentration of the disease in sub-Saharan Africa
Tuberculosis
2018, over 10 million cases worldwide and 95% of deaths occur in LIDC'EDC's. Especially prevalent in parts of Africa, Nigeria and Mozambique as well as Asia, Afghanistan and Myanmar
Diabetes
Caused by an insulin deficiency, this disease affects almost 400 million people and affects both LIDC and AC countries with a particular prevalence in North and South America
Cardiovascular disease
Incidence rises steeply with age and is a main cause of mortality in AC's. However, the highest rates are found in Russia, sub-Saharan Africa and the Arabian Peninsula
Disease diffusion
Types of diffusion
Expansion diffusion
Relocation diffusion
Contagious diffusion
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Barriers to diffusion
Physical
Distance, mountain ranges, oceans, desert and climate
Other
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Hagerstrand's diffusion model
Probabilistic rather than deterministic and includes several important concepts such as 'A neighbourhood effect' where the probability of contact is determined by the number of people living in a 5x5 square grid
Temperature and precipitation
are important drivers in vector-borne diseases and epidemics such as dengue and yellow fever whose epidemiology's depend on warm, humid conditions and aquatic habitats like
stagnant water
allow vectors to flourish
Dengue fever affects around 400 million and kills 25,000. Climate controls dengue fever as it affects the lifecycle of the Aede mosquito. In the South Pacific, temperatures exceeding 32 degrees and humidity levels above 95% can trigger epidemics
Seasonal outbreaks:
diarrhoeal diseases
in South Asia peak during the pre-monsoon season and end, where fly populations are the highest
Climate change has increased precipitation, temperature and humidity and so extended their geographical range for the West Nile virus, dengue fever and malaria
Predicting and mitigating diseases
The World Health Organisation
The Covid-19 pandemic and mitigating
Announced as a pandemic in March 2020, the best prepared countries were South Korea and Taiwan whilst AC's like North America and the UK had underprepared and underfunded
By 2021, several vaccination programmes had been trialled and introduced - Israel and the UK amongst the first to develop a vaccine
Covid-19 pandemic may have served as a tipping point into the most significant global depression since the Great Depression in the 1920's
Due to the variants, some countries like India in 2021 failed to catch up with the virus but surprisingly, Cuba had major success despite having a low GDP per capita
Cuba's success is in part due to its very rapid response, setting up a commission to deal the virus as soon as it broke out. Cuba's personnel travelled to China to review the efficacy of its strategies
Contact tracing and door-to-door checks began immediately after 3 cases were identified and lockdown began in March.
Anyone in lockdown had 50% of their salary guaranteed by the state and Cuba closed its borders
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Trump froze all funding of the WHO, claiming it had 'failed in its basic duty' yet later appealed to the WHO for an extra $1bn in funding
Established in 1948, the WHO collects data from 194 member states to provide insights into the affects of communicable and non-communicable diseases however globally, 2/3 deaths are no registered
Currently collaborating with the agency Stop TB to have TB eradicated by 2050
Increases awareness of outbreaks such as the Zika virus in 2016
Following the 2015, Nepal earthquake disaster, aid workers were sent to protect those who had been most adversely affected by the earthquake
Relationship between disease and levels of economic development
Epidemiological transition model
3 main phases
The age of pestilence and famine
The age of receding pandemics
Post-industrial societies
Some experts suggest a 4th stage called the age of delayed degenerative diseases where medicine can delay the onset of degenerative CVD
Further improvement in medical tech, degenerative disease is the main cause of mortality - many emerging economies like Brazil and Chin are in this phase
Industrial societies with tech: epidemics causing large-scale mortality are rare and life expectancy rises to above 50 years, shift between main cause of death being from infectious disease to more degenerative disease like CVD
Life expectancy is low and variable averaging around 30 years, population growth is slow/intermittent and low standards of living
Non communicable diseases in ACs
Communicable diseases in LIDCs
Animal-borne, water-borne and food-borne
Undernutrition, mal-nutrition = diarrhoea, kwashiokor and marasmus as well as scurvy and pellagra due to vitamin deficiencies
Slums and overcrowding = TB
CVD and cancer dominated the mortality of the UK until the Covid-19 pandemic
Overnutrition and excessive consumption are the main causes of non-communicable disease
Crude cancer rates 316/100,000 for men and 253/100,000 women
Can diseases ever fully be eradicated
Medicines from nature: habitats and growing conditions
Conservation issues and protection of habitats and natural ecosystems
Strategies for disease eradication
Demand is very high as 80% of populations in EDC/LIDC's rely on natural medicines
The harvesting of plants to be used globally is unsustainable and around 4000 plants are threatened with 14 listed as endangered
The tropical rainforest is extensively diverse and yet only 1% of it has been screened for potential medical use and so with deforestation totalling 325km2/day, many species may become extinct before scientists are able to identify them as medically useful
According to the Centre for Biological Diversity, at least 1 potential major drug is lost every 2 years due to tropical deforestation
Pharmaceutical giants may create a trade-off with indigenous communities as if they help to conserve a portion if they communities are promised a portion of the company's profits - such agreements exist in Costa Rica and Samoa
In the 1980s scientists found prostialin in the Samoan TRF and so a portion of the revenue goes to Samoa and organisations founded in the US and Sweden also provide funds for economic development in Samoa
GLAXOSMITHKLINE
Controversies for making excess profits, overcharging government and individuals for drugs, spending more on 'lobbying' governments, concentrating on developing drugs that require repeated prescription like opioids and pain killers, don't fund research in neglected areas of drug development, neglecting to research the development of antibiotics
In 2019, made £7 million in profits with 84 manufacturing sites in 36 countries
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GSK employs 15,000 in R&D and focusses on treatments for HIV/AIDS malaria and TB, similarly to the WHO
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Caffeine: tea, coffee, cocoa and other plants
Quinine: dried bark of the evergreen tree, malaria
Nicotine: tobacco plant
Morphine: dried latex from seed pods
Digitalis: foxglove
All of these drugs need warm, moist environments to flourish
The Rosy Periwinkle
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