Urbanisation + climate change 2.6-2.10 Flashcards
Which factors will influence infectious diseases?
Climate change - water, vectors e.g. Dengue, malaria
Urbanisation, population growth
Air quality + pollution
Conflict
Finance, poverty + inequality
Drug resistance
Medical advances - access to vaccines, drugs and diagnostics
Consensus that climate change will alter the nature of IDs seen globally but little consensus on the overall impact
What is the impact of climate change on DALYs?
Increased DALYs mostly in Africa, SE Asia and Eastern Mediterranean regions
Name 3 infectious diseases with the evidence for a link with climate change (WHO)
Dengue
Malaria
Leishmaniasis
What effect will local warming have on vectors?
Increased pathogen replication + growth within mosquitoes e.g. WNV, dengue, malaria, tick-borne encephalitis
Insect/vector density increases
Where and why has there been a rise in dengue fever?
Substantial rise in dengue fever in the last 50 years
Most in SE Asia due to:
Increased urbanisation
Increased population growth/density
Association between rainfall, temperature + humidity and incidence
Effect primarily mediated through effect on aedes population but climate isn’t the only reason
What is the vector for dengue fever?
Aedes aegypti
What regions have an increased risk of transmission of dengue fever and why?
Subequatorial regions e.g. Central + S America; SSA; India or SE Asia
Usually in and around these regions due to temperature
Name arboviruses on the rise
Chikungunya
Zika
West Nile virus
What is an arbovirus?
Any virus that is transmitted by arthropod vectors (invertebrate with exoskeleton)
80% are asymptomatic with around 20% w/ moderate infection
What symptoms do you get with an arbovirus?
Fever Flu-like illness Rash Generalised lymphadenopathy Meningoencephalitis in patients > 50 y/o
What effect does climate change have on West Nile virus?
Warm winters and dry summers favours breeding of city dwelling mosquitoes
Mosquito predators decline with drought
Birds congregate around reduced water sites + birds and mosquitoes mix
WNV mainly transmitted by mosquitoes and primary host are birds i.e. bird-mosquito-bird transmission
Why is the UK environment increasingly able to support mosquitoes?
Stagnant water especially in water tanks
Which HIC is WNV particularly prevalent in?
USA
Severe disease can occur in horses but there are vaccinations available for this
What impact does climate change have on tick borne diseases?
Changes in exposure e.g .increased outdoor leisure activity, travel
Global increase in disease e.g. Lyme
Rise of tick borne encephalitis in central Europe
Congo-Crimean Haemorrhagic Fever
What is the current distribution of malaria prevalence and how will climate change affect this?
Currently, malaria can be found in subequatorial regions but by 2050 it is estimated that malaria cases will spread outside of these regions and breach into more northern latitudes
What are the predicted trends of climate change in the UK?
Increase by 2.5-3 degrees by the end of the century
Periods of cold weather less common
More extreme events e.g. floods, droughts
What effects will the predicted trends of climate change have in the UK?
Increase in food borne, water borne and vector borne diseases
Increase malarial transmission in the UK
What climate-related factors affect diarrhoeal disease?
Weather (short term) and climate (long term)
What methods can be used to assess the weather and what use will this data be for?
Time-series analysis; weather exposure + outcome at usually one location
Use: early warning systems
What methods can be used to assess the climate and what use will this data be for?
Cross-sectional analysis, use of mean values over longer time periods; multilocational
Use: infrastructure planning
What is the trend between food poisoning and climate change?
Increased food poisoning as mean temperatures increase
When does (a) Campylobacter and (b) Salmonella peak?
Campylobacter peaks in November
Salmonella peaks in March
What is the association between diarrhoea and El Nino?
Frequency of diarrhoea admissions associated with El Nino in Peru
El Nino is the warm phases of the warm and cold temperatures as measured by sea surface temperatures of tropical central and eastern Pacific Ocean and increased air pressure in West Pacific and decreased air pressure in East Pacific
What is the effect of climate change on severe weather events?
Climate change likely to increase the frequency of extreme weather events
Especially, flooding - important effect on infectious diseases
What important effects will flooding have on infectious diseases?
Temporary reduction in vector populations
6-8 weeks later, vectors will return and may be a rise in malaria
El Nino rains associated with increase in dengue fever and malaria in Americas
Rise in WNV associated with heavy rains in Europe
Water-borne diseases can be more common - direct contact with polluted water
Epidemic potential e.g. leptospirosis or no. of outbreaks due to increase in rat populations
Population displacement e.g. Sudan (1980) diarrhoeal disease
Flood water can contaminate water supplies
Which areas of the world still have high proportions of the population with poor access to safe water?
Asia and Middle East have 1.1 billion people without an improved water source (=wells or public pipes; 20L a day, accessible with a few minutes walk)
What is the impact of AMR?
Direct human costs - morbidity and mortality
Economic costs - productivity, GDP growth etc
Indirect costs - “a return to the dark ages” of surgery
What are the different approaches to defining urbanisation?
Administrative definition i.e. in the capital
Size or density of population
Definition of economic activity
There is a global trend towards urbanisation
Where are the greatest changes of urbanisation taking place? Developing or developed?
Developing countries - transition in the next 20 years when the majority of individuals will live in urban environments
In developed, urban populations are the majority and are likely to grow slowly
Evolution of mega-cities
What is the estimated increase in worlds urban population?
From 3.3 billion to 6.3 billion in 2050 (UN, 2008)
Which countries will the growth of cities be in?
Mainly in China and India
Tokyo has the most number of people - 36.4 million people by 2025
What are the drivers to urbanisation?
Natural population growth
Significant rural to urban migration
Reasons for migration (economic, conflict etc)
What are the consequences of urbanisation?
Rise of morbidity and mortality due to NCDs (HICs)
Transmission of some IDs whilst reducing some (LICs)
What are the effects of ID in rural areas?
New diseases can emerge in urban settings
Emerging disease can spread rapidly in urban settings
Diseases previously seen in rural areas can adapt to urban ones
Certain behaviours more linked to dense populations e.g. IDU for HepC
Greater interaction between human + animal populations
Urban populations are often migratory + linked via travel patterns to many parts of the world
Which two types of disease will an increased population density increase the transmission of?
Airborne/respiratory infectious diseases e.g. Flu, measles, TB, SARS
Food/water borne IDs e.g. diarrhoeal disease, cholera
Why are informal settlements important to urban health?
Informal settlements are a far greater challenge to urban health in developing countries + can create conditions for spread of ID
Social inequality and health in the urban setting e.g. slums next to rich housing
What aspects of the urban physical environment will affect disease transmission and incidence?
Access to clean water and adequate sanitation is sometimes limited e.g. in Lagos 9% individuals have access to piped water
Condition for diarrhoeal disease - cholera
High levels of parasitic infection e.g. soil-transmitted helminths
Poor sanitation - increases rodent population - increases leptospirosis, plague
Large quantities of solid waste - pollution, mosquitoes (aedes for WNV)
What effect can urbanisation have on the vector population?
Air and water pollution can hinder vector proliferation
Many species of mosquitoes have adapted to urban environments and can breed in stagnant water (old tyres, tins, plastic containers) e.g. anopheles mosquitoes w malaria
Leishmaniasis - populations can expand into areas where disease is endemic or vectors can adapt to environments where transmission is more likely
What effect can deforestation have on infectious diseases?
Increase in displaced populations of vectors e.g. bats which increases ebola
What effects can international migration have on infectious diseases?
Migrants to urban areas can be vulnerable to infectious due to imported susceptibility rather than imported infection
In LICs, immunity might be acquired through childhood illness rather than vaccination
Give 2 examples of outbreaks which were exacerbated by international migration?
Swine flu
SARS 2003 - 26 countries affected and 774 deaths
What is the definition of a hazard?
Something with the potential to do harm