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“Climate change is the biggest global health threat of the 21st century”

The Lancet Commissions

Climate Change and Health in Bangladesh

Peter Kim StreatfieldDirector, Centre for Population, Urbanization and Climate Change

ICDDR,B

Framework for CC-Health Research - WHO

Direct Health Impacts• Infectious diseases

– Malaria

– Dengue fever

– Kala Azar

– Cholera

• Other mechanisms

– Heat stress

– Others

Malaria:

• 14.7 million people at risk.

• 37 deaths reported by MOHFW in 2010, but “actual cases may be 5,000-10,000”.

• Africa shows evidence of climate affecting malaria after heavy rain, but South America does not.

• Parasite prefers 24-26C temp (reproduction rate double vs20C), mosquitoes like similar range. So what impact will climate change have?

Dengue Fever• 500 cases (& 0 deaths) in

2007, down from 6,000 (58 deaths ) in 2002

• An increase of 3-4oC may double the reproduction rate of dengue virus

• Outbreaks every 2 year since 2000, (see graph)

• No vaccine, no specific treatment, need to control Aedes aegyptimosquito.

Kala Azar

• Now in 105 Upazilas (up from 8 in 1981-85).

• 15-30 deaths p.a. , tho’ only 1 reported in 2010.

• “Surveillance weak, est. cases about 45,000”

• Female sandfly carries the parasitic protozoa (Leishmania donovani).

• Favours habitats near embankments.

• Prevalence expected to increase with warming.

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Cholera

• Discovery of marine reservoir of the cholera pathogen in blue-green algae and copepods helps to explain the endemicity in the Ganges delta in Bangladesh.

• A Bangladesh study found that V. cholera 01 increases with copepods (which feed on phytoplankton) in coastal waters. The timing of cholera outbreaks matches (with lag) the frequency of El Nino.

Copepod

Blue-green algae

Heat Stress

• Globally, cities are experiencing “urban heat island effect”, with higher temperatures than surroundings.

• Consequences:

– Heat exhaustion (heat stroke)

– Reduced work capacity and outputs

– Dehydration

• New studies by Tord Kjellstrom and WHO

Infra-red image of Western Europe, August 2003, when a heatwave resulted in an additional

35,000+ deaths in France alone, mostly elderly people. Temperatures were 40oC+

(brown colour) for 7 continuous days

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Trends in numbers of ‘Very Hot Days’ (35oC+) shows 400% increase over 26 years in Matlab, Chandpur.

- Methodology difficult to study impact on human labour- This is threshold temperature for germination of rice and wheat.

Very Hot Days 35.0+C

y = 0.5679x + 4.373

R2 = 0.3005

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Salinity• Salinity moves inland up to 200

kms. in dry season. In monsoon, salinity is pushed back south. Overall moving N

• Links with hypertension and pre-eclampsia in pregnant women, and maybe other people

• Widespread land damage has occurred. Mass outmigration.

• We need to monitor water and crop soils in coastal districts

Water towers of Asia – the glacier-fed rivers from the Tibetan Plateau influence the lives of 40% of the world’s population (Indus, Ganges, Brahmaputra, Mekong, Irrawaddy, Yangtze). China have started to dam the Brahmaputra to provide power, and may divert water to northern dry areas of China

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Likely consequences of less water from the Himalayan rivers into Bangladesh

• In monsoon, Bangladesh receives 1,100 cu. kms. water, enough to cover entire country to 7+ metres depth. But we lose 98% of it as difficult to construct dams and capture water in a delta.

• Because of impending water shortages: “We’re talking about the return to large-scale famines in developing countries” Louis Verchot, World Agroforestry Centre, Kenya

Boys playing soccer in dry Ganges River,Rajshahi, Bangladesh ,June 2011

Sea Level Rise (SLR)• In predicting SLR, the IPCC

AR4 only took account of thermal expansion of the oceans (18-59 cms).

• Did not allow for melting ice caps, and glaciers (now expect 80-200 cms+).

• Melting of large ice shelves in Antarctica (e.g., WAIS) could produce several metres of SLR.

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• SLR in Indian ocean expected to be close to global average of 3 mm/yr (1993-2003).

New crack in Pine Island Glacier, Antarctica

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

(225,000 from Barisal and 125,000 from Khulna p.a.)

Many of these people living in slums in Dhaka

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'Mega' Countries with Population >100 million

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•Bangladesh is relatively less urbanized at 25%.

•This 34 m. urban population will triple this century

•1.5 to 2.0 m. per year migrating to cities

•Urban populations are 1/3rd slum. Overall urban pops growing at 3.5% pa (20 years doubling time), but slums at 7% (10 yrs)

•Pop densities: –rural = 800/sq.km.; –urban = 24,000/sq.km. (x30); –slums = 205,000/sq.km. (x300)

–Is there a ‘heat island effect’? WHO Hothaps study suggests ‘Yes’

In a 3 country study of adaptation, we are following ecological migrants who have lost their villages beside the Meghna River in Matlab. Some move to the CHT – there is a new village called Matlab. May contribute to bringing malaria down to lowlands again.Some move to the cities. Some to the Meghna-Dhonagodaembankment (a), at least temporarily.These farmers migrated to char in middle of Meghna River (b).

(a) (b)

Thank You

This study will (1/3):

• Identify association between salinity in drinking water and hypertension in coastal districts– Select sample of 2,000 HHs in a south

to north strip with salinity levels from high to low (16+ to 2 dS/m, 2009). All selected HHs must use tubewell for drinking water, must have been resident in area for at least 5 years. Test water samples.

– Select 1 child and 2 adults from each HH to measure BP.

– Take medical and treatment history if hypertension is known.

This study will (2/3):

• Establish system for monitoring changes in crop production in coastal areas with high salinity– Use secondary sources for trends in crop production

– Obtain data on soil salinity over time (CEGIS, others)

• Strengthen migration surveillance systems of NGOs in ARCAB Network who work in coastal districts to monitor rural to urban migration (urbanization). – Obtain mobile numbers to track outgoing families.

– Conduct telephone interviews to determine if outmigration was linked to local conditions (unproductive farmlands, etc.).

• Link decision to outmigrate to local conditions (income, farm production, employment, etc.)

This study will (3/3):

• Supplement ICDDR,B malaria surveillance in Bandarban to detect possible expansion of range of vectors and disease (with Dr. Wasif Ali Khan).

– Explore role of ‘Jhum’ cultivation and deforestation in increasing habitat of malaria vector (anopheles mosquito) and thereby expanding range of vector

• Supplement ongoing studies of Dengue Fever and Kala Azar to detect possible expansion of range and diseases (with Dr. Kazi Mizanur Rahman, Dr. Dinesh Mondal).