Download Public Health Responses - World Health Organization

Protecting our Health from
Climate Change:
a Training Course for Public
Health Professionals
Water Stress:
Chapter 11: Water and Foodborne Diseases
Overview: Water Stress and Water
and Foodborne Disease
 Water quantity and quality
 Burden of diarrheal disease
 How climate and weather affects diarrheal
diseases and food and waterborne
pathogens
– Season
– Temperature
– Precipitation (flooding and drought)
– Sea level rise
 Summary
Water Quantity and Quality
Issues
IPCC, 2007a
Water Quantity and Quality
Issues (cont.)
Burden of Waterborne Disease
 1.8 million deaths (4 million cases) in 2004
due to gastroenteritis (WHO)
– 88% due to unsafe water and poor sanitation
Prüss-Üstün et al., 2008
Burden of Waterborne Disease
(cont.)
Prüss-Üstün et al., 2008
Distribution of Fatal Drownings
World Health Organization, 2008c
Burden of Diarrheal Diseases
 Diarrheal diseases are vastly underestimated
– 211 million cases estimated in the US annually
(Mead et al., 1999)
Reported cases
Actual cases
> 38 x reported cases
Climate Change and Waterborne
Disease
 Climate change scenarios include
– Rising temperature
– Changes in hydrologic cycle
• Increased drought
• Increased storm intensity
– Change in frequency of “extreme events”
• Hurricanes
• Ocean-atmosphere oscillations
– ENSO
– NAO
– Others
– Sea level rise
 Can affect a wide range of enteric pathogens,
especially those with an environmental reservoir
Direction and Magnitude of
Climate Change Health Impacts
IPCC AR4, 2007
Climate Already Affects
Waterborne Disease
Hall et al., 2002
How Do Climate and Weather
Affect Enteric Pathogens?
Diarrheal Disease Pathways
Prüss-Üstün et al., 2008
How Climate Can Influence Water
and Foodborne Disease Trends
 Local temperature
– Replication in the environment or
associated with food products
– Persistence
 Local rainfall
– Loading into the environment
(contamination)
– Increased concentration of contaminants
(drought)
How Climate Can Influence Water and
Foodborne Disease Trends (cont.)
 Sea level rise
– Influx of marine pathogens
– Flooding (storm surge), contamination,
loss of infrastructure
 Range expansion among zoonotic
agents and their hosts
Seasonal Trends in Rotavirus
Infections
Cook et al., 1990
Local Temperature
Climate Driver: Temperate Effects
IPCC, 2007a
Impact of Climate Variation and
Change on Diarrheal Disease
Singh et al., 2001
Salmonellosis
Kovats et al., 2004
Salmonella Trends
Hall et al., 2002
Campylobacteriosis
Kovats et al., 2005
Vibrio spp.
 Vibrio are commonly estuarine and marine
bacteria and include at least 12 known
pathogens to humans
– V. vulnificus
– V. parahaemolyticus
– V. cholerae
 In general, this group replicates easily in
natural waters and biota, especially under
high temperatures
– Directly related to increasing water
temperatures
Cholera in South America
Vibrio parahaemolyticus Outbreak
Alaska – 2004
McLaughlin et al., 2005
Local Rainfall
Run-off
Flooding
Drought
Vulnerability of Freshwater
Resources
IPCC, 2007a
Climate Change Impacts on
Runoff
IPCC, 2007a
Very Wet Days: Importance to Total
Precipitation and Changes over Time
Bates et al., 2008
Flooding
 Risk factors
– Direct contact with contaminated water
• Skin
• Respiratory
• Ear and eye infections
– Ingestion of contaminated water (wells, etc.)
• Gastroenteritis
– Insufficient water treatment (i.e., problem at
the tap)
– Additional secondary spread
Extreme Precipitation and
Waterborne Disease Outbreaks
Curriero et al., 2001
Walkerton Rainfall
Auld et al., 2004
Example: Walkerton Outbreak
Worthington et al., 2002
Cryptosporidiosis and
Precipitation
C. hominis
Other Crypto spp.
Das et al., 2006
Rainfall, Run-off, and Pathogen
Contamination
 Building evidence for the association
between diarrheal disease and increased
precipitation, especially with heavy rainfall
events
 In addition, several studies note increased
pathogen loads related to floods, run-off,
and heavy precipitation including:
– Enteric viruses (e.g., enteroviruses, noroviruses,
adenoviruses)
– Protozoan parasites (e.g., Cryptosporidium,
Giardia, others)
– Enteric bacteria (e.g., Salmonella,
Campylobacter, E. coli, fecal indicator bacteria)
Drought Effects on Water Quality
CRCWQT, 2005
Sea Level Rise
Cities Vulnerable to Sea Level Rise
Heavily populated Delta regions that are vulnerable to sea level rise
World Health Organization, 1996, Figure 7.3
Cholera: South Asia
 Yearly epidemics correspond to natural
environmental cycles and contamination
–
–
–
–
Influx of estuarine water
Plankton blooms
Monsoons
Warm temperatures
 Cycles can be modeled for year to year
changes in outbreaks
Bay of Bengal: Sea Surface Height
Lobitz et al., 2000
Bay of Bengal: Sea Surface
Temperature
Lobitz et al., 2000
Bay of Bengal: Cholera and Sea
Surface Height
Lobitz et al., 2000
Waterborne Disease
 Climate projections for increased warming
and increased extreme events suggest
waterborne diseases may increase
 Mitigation and adaptation will be enhanced by
understanding the ecology of pathogens
– What underlying factors provide the link to
climate?
– How do changing landscapes affect disease
incidence under changing climate conditions?
Public Measures to Address Potential
Issues Associated with Climate Change
 The effects of climate change on water and
foodborne diseases can be mitigated
– Focus on public health response
– Focus on basic infrastructure
– Increased attention to treatment options
 We have tools to address problems and
prevent disease, understanding how climate
may increase risk can be used to prioritize
adaptation or rapid response measures