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The impact of climate change on malaria in coastal Ghana

Authors:

Abstract

In coastal cities of Ghana, malaria prevalence is affected by climate-related factors such as flooding and a warmer climate. Environmental conditions are critical in malaria transmission, with mosquitoes adapting to breed in non-traditional locations, such as blocked surface drains. Community and institutional involvement in clearing the environment of potential mosquito breeding sites, coupled with health education and improved malaria control programs, are critical for reducing malaria incidence. Between 2020 and 2080, it is anticipated that the peak malaria transmission season (May-July) will shift by around 1-2 months due to a corresponding shift in the peak rainfall patterns. In the long term (2020-2080), however, it is projected that malaria disease prevalence will decrease with reduced rainfall and temperatures above 350C, conditions which make breeding difficult for mosquitoes that transmit malaria.
What is the issue?
Malaria is a major health challenge in the coastal
communities in Ghana. Across the country as a
whole, the disease affects about 50% of children
under ve years and accounts for over 32% of
hospital cases (NMCP, 2009). Moreover, most
people in coastal communities live in unplanned
settlements which have inappropriate waste
generation and disposal sites, and poor and
choked drainage systems. This creates numerous
places for mosquitoes to breed. Climate
change and variability have exacerbated these
environmental conditions, with heavy rainfall
and increasing temperatures further supporting
mosquito breeding and malaria prevalence.
In response, the IDRC-funded Climate change
adaptation research and capacity development in
Ghana project sought to strengthen public health
malaria policies through better understanding
how past, present and future climatic factors
affect malaria prevalence and to inform strategies
that can be used to prevent the disease.
What did we do?
The project investigated community perceptions
of climate change and malaria, and links
between them, in order to guide activities aimed
at reducing the inuence of climate change
on prevalence of the disease. Five focal group
discussions were conducted in the district of Ga-
mashie, 240 questionnaires were administered,
and 22 health personnel were interviewed in
selected coastal hospitals.
Scientic evidence of past, present and future
climate impacts on malaria prevalence in three
coastal cities of Ghana were investigated using
the VECTRI disease model developed by the
International Centre for Theoretical Physics
in Trieste, Italy (Tompkins and Ermert, 2013).
Key messages
In coastal cities of Ghana, malaria
prevalence is affected by climate-
related factors such as ooding and a
warmer climate.
Environmental conditions are critical in
malaria transmission, with mosquitoes
adapting to breed in non-traditional
locations, such as blocked surface
drains.
Community and institutional
involvement in clearing the
environment of potential mosquito
breeding sites, coupled with health
education and improved malaria control
programs, are critical for reducing
malaria incidence.
Between 2020 and 2080, it is
anticipated that the peak malaria
transmission season (May-July) will
shift by around 1-2 months due to a
corresponding shift in the peak rainfall
patterns.
In the long term (2020-2080), however,
it is projected that malaria disease
prevalence will decrease with reduced
rainfall and temperatures above 350C,
conditions which make breeding
difcult for mosquitoes that transmit
malaria.
December 2014
L.K. Amekudzi, S.N.A. Codjoe, N.A. Sah
and M. Appiah
The impact of climate
change on malaria in
coastal Ghana
1
© Moses Melphis Abaidoo
This model uses temperature and rainfall as its
primary inputs, and also factored population
density and growth rate. Using the model, the
human biting rate (the number of mosquito
bites per person per year) and the detectable
parasite ratio (the proportion of infected hosts
with detectable malaria) were computed and
compared.
What did we learn?
Female anopheles mosquitoes, the main
transmitters of malaria, are now adapting to
non-traditional breeding environments, such
as water-lled surface drains. Environmental
conditions have therefore become the critical
issue for malaria transmission in the study
area. Frequent ooding and indiscriminate
waste disposal create a conducive
environment for malaria transmission.
Malaria is climate-change driven. Cases are
mostly recorded when rainfall reaches its
peak during the months of May-July; this is
likely to shift in the future due to changes in
the rainfall pattern (Figure 1).
Projected malaria prevalence (2020-2080) is
however expected to decrease due to more
droughts and a rise in temperatures above
35°C (Figure 1), conditions which make
breeding difcult for mosquitoes that transmit
malaria.
Malaria mostly affects children under
ve years, whose overall immunity is less
developed, and women, who are frequently
outdoors in the evenings – when mosquitoes
are most active – carrying out responsibilities
such as petty trading, sh processing and
cooking.
Insecticide treated mosquito nets (ITNs)
have been distributed to the communities
as a control measure. However, about 70%
of the households do not use them, nding
the nets too uncomfortable to use or instead
preferring to keep them for visitors rather than
protecting themselves.
2
0
50
100
150
200
250
300
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Total rainfall (mm)
Rainfall seasonality - Accra
Baseline (1970-2013)
Projection (2020-2080)
25
26
27
28
29
30
31
32
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Mean temperature (degree C)
Temperature seasonality - Accra
Baseline (1970-2013)
Projection (2020-2080)
0
50
100
150
200
250
300
350
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Human biting rate (HBR)
Human biting rate - Accra
Baseline (1970-2013)
Projection (2020-2080)
10
15
20
25
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Detectable parasite ratio (PRd)
Detectable parasite ratio - Accra
Baseline (1970-2013)
Projection (2020-2080)
Figure 1: Seasonal climatology and projection for rainfall, temperature and malaria prevalence for
Ghana’s coastal zone
grounds. This community also collaborated with
Zoom Lion and the Accra Metropolitan Assembly
for waste collection and disposal, and over 800
households were provided with bins for organic
and inorganic waste separation. For a monthly
cost of approximately US$5, the waste is then
collected and removed from the community by
local youth who were hired to deliver the door
to door waste collection services. In addition to
their wages, they can generate further income
from the sale of organic manure and plastics to
local recycling companies.
What are the policy
implications?
Climate change is expected to have an impact on
malaria prevalence. Increasing temperatures and
ooding in the short-term are likely to increase
the incidence of malaria, hence control efforts
have to be targeted to improve environmental
and sanitation conditions. In the long term
(2020-2080), however, climate models predict
drought due to changing precipitation patterns
and temperatures above 35°C, which will see a
decrease in the incidence of malaria.
Prevention activities must be year round
and should include refuse clearing, drainage
expansion and de-silting of choked drains.
Providing environmental and sanitation
education should also be considered and district
by-laws on environmental cleanliness should be
strengthened. Other malaria control measures
should include destruction of mosquito breeding
sites through improved drainage and introduction
of sh in ponds to feed on the mosquito larvae,
Stories of change
The project has rolled out a number of
intervention programs to promote malaria
prevention in coastal communities in Ghana.
These include a number of educational
campaigns on climate change and malaria
prevention delivered through youth theatre, radio
discussions, as well as community sensitization
meetings. Furthermore, climate change
community clubs of 150 members each have
been formed in James Town and Agblogbloshie
communities. This has led to improved social
support for environmental cleanliness, as
community members understand that preventing
the build-up of stagnant water will reduce
mosquito breeding, thereby reducing malaria
prevalence.
The Agblogbloshie club has collaborated with
Zoom Lion, a major private waste management
company, to clear drains in the communities
under the supervision of Accra Metropolitan
Assembly engineers.
In James Town, research ndings showed that
heavy rains and environmental conditions
favor malaria transmission, with mosquitoes
breeding in pools of water that collect in plastic
waste. As a result of the club’s sensitisation
activities, however, there is increased community
awareness and commitment to maintaining clean
surroundings in order to reduce these breeding
3
Campaigns delivered through youth theatre
have improved support for environmental
cleanliness
© Bismarck Ofori/RIPS
Waste collection and disposal is a source of
income for young people
© Moses Melphis Abaidoo
mass indoor and outdoor spraying of insecticides,
and continued offering of health education
programs on the use of the treated mosquito nets.
Finally, existing malaria control programs should
be extended to all coastal communities.
What next?
What can be done to stem the spread
of Anopheles mosquitoes in new, non-
traditional breeding habitats?
Further studies are needed to determine
the effect of increasing population on the
human biting rate and number of malaria
cases. It should also be investigated whether
the predicted human biting rates and
corresponding detectable parasite ratios (from
the VECTRI model) are consistent with on-
the-ground observations.
Better understanding of the spatial and
seasonal distribution of malaria in Ghana is
necessary. How will the geographic risk areas
for malaria increase or decrease with climate
change?
To what extent do the social intervention
and malaria control programmes need
strengthening?
Need more information?
Prof Samuel Nii Ardey Codjoe
Regional Institute for Population Studies,
University of Ghana
scodjoe@ug.edu.gh
Dr. Leonard K. Amekudzi
Meteorology and Climate Science Unit,
Kwame Nkrumah University of Science and
Technology
leonard.amekudzi@gmail.com
Website: http://rips-ccartcd.org/
@RIPSCCARTCD2013
4
Sensitization in primary schools has highlighted
the links between climate change,
environmental cleanliness and malaria
© Bismarck Ofori/RIPS
Ermert V., Fink A.H. and Paeth H. (2013) The potential
effects of climate change on malaria transmission
in Africa using bias-corrected regionalised climate
projections and a simple malaria seasonality model.
Climatic Change, 120, pp. 741-754.
Manzanas R., Amekudzi L.K., Preko K., Herrera S. and
Gutierrez J.M. (2014) Precipitation variability and trends
in Ghana: An intercomparison of observational and
reanalysis products. Climatic Change, 124, pp. 805-819.
National Malaria Control Program. (2009) National Malaria
Control Program Report. Ministry of Health, Ghana.
Tompkins A.M. and Ermert V. (2013) A regional-scale,
high resolution dynamical malaria model that accounts
for population density, climate and surface hydrology.
Malaria Journal, 12 (65), pp. 1-24. http://bit.ly/11AE0ka.
Tay S.C.K., Danuor S.K., Morse A., Caminade C., Badu
K. and Abruquah H.H. (2012) Entomological survey
of malaria vectors within the Kumasi Metropolitan
Area – a study of three communities: Emena, Atonsu
and Akropong. Journal of Environmental Science and
Engineering, 1 (2), pp. 144-154.
References
This brief reports on research supported by the International Development Research Centre’s Climate Change and Water program, with
funds from the Government of Canada’s fast start climate nance: www.idrc.ca/ccw.
Produced by WRENmedia in December 2014.
International Development Research Centre
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ntre de recherches pour le développement international
... The increased temperature trends and variability have adverse effects on both socio-economic factors and ecosystems in the coastal areas of Ghana. Several studies, such as those of Akpalu et al. (2015), Amekudzi et al. (2014), Atindana et al. (2020), Klutse et al. (2014), Owusu-Sekyere et al. (2011), andWilliams et al. (2019), have been undertaken. According to Owusu-Sekyere et al. (2011), there was a decrease in crop yields in the Cape Coast metropolitan area from 1993 to 2008. ...
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Background The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. Methods A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Results Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. Conclusions A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.
National Malaria Control Program Report. Ministry of Health
National Malaria Control Program. (2009) National Malaria Control Program Report. Ministry of Health, Ghana.