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

10 13

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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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577 535

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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

929

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537

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