Disease Surveillance to protect human health from adverse ... WEB/UPLOAD-4/Dr.Peter Kim...
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Disease Surveillance to protect human health from adverse effects of climate change
National Public Health Conference 2013, Dhaka
Peter Kim Streatfield, PhD Director, Centre for Population, Urbanization and
Climate Change ICDDR,B
“Climate change is the biggest global
health threat of the 21st century” The Lancet Commissions, 2009
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Questions • Which diseases are expected to be effected adversely
by climate change? And how?
• What is the current system of surveillance for these diseases?
• Are we only considering surveillance of mortality, and/or morbidity? What about vectors, risk factors?
• How good is the coverage of the current system?
• What needs to be done to improve the current system?
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Direct Health Impacts
• Infectious diseases (WHO, 2003)
– Malaria – Dengue fever – Kala Azar – Cholera
• Others? – Nipah, West Nile, other viruses?
• Extreme weather events – diarrhoea /cholera outbreaks
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Malaria • 11 million people at risk.
• Annually 57,000 positives through passive surveillance, and 330 deaths
• ICDDR,B shows 75% asymptomatic
• Actual cases may be 5,000 to 10,000” (DGHS, Health Bulletin 2008).
• Parasite prefers 24-26C temp (reproduction rate double vs 20C), mosquitoes like similar range
• Africa shows evidence of climate affecting malaria after heavy rain, but South America does not.
Dengue Fever
• Large variation in annual cases and deaths
• Outbreaks every 2-3 years, but deaths not correlated to cases
• Difficult to diagnose, largely unrecognized before 2000.
• Increase of 3-40C in average air temp may double reproduction rate of dengue virus
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Dengue Cases and Deaths, 2003-2011
Dengue Deaths
Dengue Cases
Kala Azar
• Now in 105 Upazila (from 8 in 1981-85).
• 3,000-9,000 cases and 15-30 deaths annually
• Prevalence expected to increase with warming
• “Surveillance weak, est. cases about 45,000” – so many cases are being missed
• “Definite data on morbidity and deaths…not available from the current reporting system. Age- and sex-segregated data are not available with the control program at present” (MOHFW Health Bulletin 2012:103)
Deaths due to Malaria, Dengue Fever, Kala-azar, Bangladesh 2000-2011
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478 490
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36 27 23 16 23 17 17 14 0 2
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Malaria Deaths
Kala-azar Deaths
Dengue Deaths
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Cholera • More attention paid to environ-
mental determinants of Cholera.
• V. cholera 01 increases with copepods (which feed on phytoplankton) in coastal waters. The timing of cholera matches (with lag) frequency of El Nino.
• It is predicted that rising sea surface temperatures will result in more frequent cholera outbreaks
• Many diarrhoea/cholera deaths unreported
Copepod Blue-green
algae
1282 1170
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393 360 345
(70)
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Diarrhoea Deaths, CDC, Bangladesh 2003-11
Blue green algae
= phytoplankton
Extreme weather patterns • Cyclones :
– Category 4 or 5 (most destructive) in 1975-89 = 1, 1990-2004 = 7
– Cyclone models uncertain about future frequency and intensity
• Tidal surges – Signs of more powerful surges in
future, but uncertain
• Disrupted chaotic post-cyclone conditions make measurement of health impacts difficult .
Cyclone Sidr, November 2007
NASA Earth Observatory
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Summary • Time scale of climate change slow, impacts may be
small, hard to detect
• Coverage of existing surveillance incomplete – is it sensitive enough to detect CC impacts?
• Do we need only deaths, or cases, risk factors, including vectors (mosquito counts, larval surveys)
• How to attribute changes (e.g., rising reported malaria cases) to CC rather than other changes?
• Do we need multiple sentinel surveillance sites, or nationwide epidemiological surveillance – how?
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Next Steps
• Most CDC data is currently coming from MOHFW facilities and NGOs.
• Need comprehensive community surveillance
• Health Assistants need to be collecting data on regular schedule, sending it to central level – at this time it largely stops at District level.
• Expansion of PDA based data collection could contribute to more complete and timely coverage.
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Maximum & Minimum Monthly Temperatures Celsius (Chandpur 1999-2008)
Monthly Max & Min Temperatures C
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1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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2 1 2 3 4 5 6 7 8 91
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1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Max T
Min T
Max: Y = 0.0014X + 29.9, R2 = 0.005 (1966-2008)
Min. Y = 0.006X + 19.6, R2 = 0.022 (1966-2008)
Source: Bangladesh Meteorology Department 13
Trends in numbers of ‘Hot Days’ (30C+) and ‘Very Hot Days’ (35C+) shows 10% and
400% increases, respectively
Very Hot Days 35.0+C
y = 0.5679x + 4.373
R2 = 0.3005
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Hot Days 30+C
y = 0.8399x + 217.29
R2 = 0.3931
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Salinity • When dry season river
flows decrease, salinity
moves inland up to 200
kms.
• When monsoon rains
come, salinity is pushed
back towards the Bay of
Bengal.
• Widespread land damage
has already occurred.
• Salt induced hypertension
(pre-eclampsia in
pregnant women).
Others too?
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Migration within Bangladesh is partly driven by ecological
change reducing agricultural production
Between 2001 & 2011, zero population growth in Barisal Division (green area), and little in Khulna, due to outmigration.
Many of these people living in slums in Dhaka
Action Research for Community Adaptation in Bangladesh (ARCAB)
• Partners: ActionAid,
WaterAid, Islamic Relief Worldwide, Plan, Care, Caritas, Practical action, Christian Aid, Oxfam.
• Coordinated by iied, uk and BCAS, Bangladesh
• Focuses on community adaptation to climate change in coastal districts, and erosion on big rivers
The Indian Ocean Dipole (IOD) normally involves cooling of SST
in the south eastern equatorial Indian Ocean and warming of SST
in the western equatorial Indian Ocean.
The normal convection over the eastern Indian Ocean warm pool
shifts to the west and brings heavy rainfall over east Africa and severe droughts/forest fires over the Indonesian region.
Monitor: JAMSTEC – Japanese Research Centre which named the Indian
Ocean Dipole in 1993. They report Dipole Mode Index regularly 18