Effects of Climate Changeon Health

Dr. Troy D. Gepte

Coverage of Presentation

• Overview of the Effects of Climate Change on Health:– Temperature-related and Weather-related effects– Natural Disasters due to extreme climate/weather

events– Other likely health impacts

• Emerging and Re-emerging

Infections and their Impact on Public Health

Health effects

Temperature-relatedillness and death

Extreme weather-related health effects

Air pollution-relatedhealth effects

Water and food-bornediseases

Vector borne and rodent borne diseases

Health Effects

Temperature-relatedillness and death

Extreme weather-related (floods, storms, etc.) health effects

Air pollution-relatedhealth effects

Human exposures

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•

•Sea-level rise

Climate ChangeClimate Change

Why are these important?

• These disruptive events have their greatest impact in poor countries.

• The two categories of climatic extremes are:– Simple extremes of very low or very high

temperatures – Complex events: droughts, floods, or

hurricanes

Deadly effects

• Extremes of temperature can kill– The very old, the very young and the frail

are most susceptible

• There will be more intense heatwaves– as well as warmer summers and milder

winters– effects of weather will vary between

populations

Source: WHO

Natural Disasters• Increasing trend in the number of victims due to

natural disasters is:– partly due to better reporting– partly due to increasing population vulnerability, and – may include a contribution from ongoing global climate

change

• Developing countries are poorly equipped to deal with weather extremes– especially in high-risk areas (coastal zones &cities)– Number of people killed, injured or made homeless by

natural disasters is increasing rapidly

Source: WHO

Additional likely health impacts that are hard to assess:

• changes in air pollution and aeroallergen levels• altered transmission of other infectious diseases• effects on food production via climatic influences on

plant pests and diseases• drought and famine• population displacement due to natural disasters,

crop failure, water shortages• destruction of health infrastructure in natural

disasters• conflict over natural resources• direct impacts of heat and cold (morbidity)

Patterns of Infectious Diseases are expected to change

• Climatic factors are related to vector-borne diseases, many enteric illnesses and certain water-related diseases.

• With climate change, we will have a tougher fight against infectious diseases.

• This is most evident in areas where climate variations are marked and especially in vulnerable populations.

Health effects

Temperature-relatedillness and death

Extreme weather-related health effects

Air pollution-relatedhealth effects

Water and food-bornediseases

Vector borne and rodent borne diseases

Health Effects

Temperature-relatedillness and death

Extreme weather-related (floods, storms, etc.) health effects

Air pollution-relatedhealth effects

Human exposures

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•

•Sea-level rise

Contaminationpathways

Transmissiondynamics

----rodent

Microbial changes:

Contamination paths

Transmission dynamics

Water and food-bornediseases

Vector borne and borne diseases

Climate ChangeClimate Change

• EID refers to newly identified, previously unknown infections w/c cause public health problems locally or internationally

e.g. SARS, H5N1 influenza, Nipah, Ebola, Hepatitis C, hantavirus, etc.

• The emergence of these diseases may be due to the combined impacts of rapid demographic, environmental, social, technological, lifestyle changes as well as climate change.

Emerging Infectious Diseases (EID)

Emerging Infectious Diseases (EID)

• Previously known diseases but are becoming to be a public health problem for the past two decades •These may vary from one country to another and in different regions of the country

Bacteria Leptospirosis Legionella pneumophila Parasites Paragonimiasis Neurocysticercosis

Viruses Japanese encephalitis Chikungunya Dengue Hepatitis C HIV Monkeypox

Contributors to emerging infections

1. Changing demographics

2. Pressure on the environment

3. International travel and commerce

4. Food supply and food technology

5. Microbial adaptation and change

6. Health systems breakdown

Re-emerging Infectious Diseases

•Known diseases which reappear after being eradicated (e.g. malaria, polio)• Infections which are increasing in incidence after they have been previously controlled (e.g. Meningococcemia, Plague, Cholera old serotype, Yellow Fever, Diphtheria)

VECTOR-BORNE DISEASE

Malaria and Dengue

• Mosquito vectors that spread malaria and dengue need access to stagnant water in order to breed, and the adults need humid conditions for viability.

• Warmer temperatures enhance vector breeding and reduce the pathogen’s maturation period within the vector organism.

• However, very hot and dry conditions can reduce mosquito survival

Malaria

• Changes in vector-borne diseases are predicted (areas bordering current endemic zones).

• Smaller changes in current endemic areas (seasonal Malaria).

• Most temperate regions would remain unsuitable for transmission

1990

2085

Estimated population at risk of dengue fever under “standard” climate change scenario: 1990, 2085

Source. Hales S et al. Lancet (online) 6 August 2002. http://image.thelancet.com/extras/01art11175web.pdf

.

Food and Water-borne Diseases

• Higher temperatures & heavier rainfall events may increase occurrence of water-borne diseases

• Sanitation services may be severely compromised contributing to potential contamination of local water supplies

• There may also be increases in infectious illnesses in people using recreational waters (e.g. pools & beaches)

• Food-related concerns:– outbreaks of toxic algae in saltwater that contaminate shellfish

(e.g. “red tide”)– increased incidence of food poisoning related to warmer

temperatures that increase the survival of microbes and the spread of toxins

Health effects

Temperature-relatedillness and death

Extreme weather-related health effects

Air pollution-relatedhealth effects

Water and food-bornediseases

Vector borne and rodent borne diseases

Health Effects

Temperature-relatedillness and death

Extreme weather-related (floods, storms, etc.) health effects

Air pollution-relatedhealth effects

Human exposures

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•

•Sea-level rise

Contaminationpathways

Transmissiondynamics

----rodent

Microbial changes:

Contamination paths

Transmission dynamics

Water and food-bornediseases

Vector borne and borne diseases

Climate ChangeClimate Change

Changes in agro-ecosystems, hydrology

Socioeconomic and demographic disruption

Effects of food and water shortages

Mental, nutritional,infectious-disease and other effects

How do we monitor?

Source: WHO

How can we respond?

Source: WHO

What should be done now

• Community-wide understanding and response, guided by policies informed by good scientific advice

• Policy-focused assessment of the potential health impacts of climate change

• Advocacy for:– multidisciplinary assessments– obtaining responses to questions asked by

stakeholders– evaluation of risk management adaptation options– addressing research gaps to facilitate decision-making

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