Connecting Global Priorities Biodiversity and Human Health

valuable benefits to human communities (e.g.
energy, employment, access to food), they are
costly to build and maintain, have frequently
been accompanied by unintended consequences to
ecosystems¹³ and have had negative repercussions
on public health, in some cases considerably
increasing the availability of habitats for disease
organisms and their vectors (de Moor 1994)
and exacerbating waterborne disease outbreaks
(Dudgeon et al. 2006; Hotez and Kamath 2009;
Myers et al. 2014).
It has been estimated that some 2.3 billion people
suffer from diseases related to water, and diseases
transmitted by freshwater organisms kill an
estimated 5 million people per year. Unsustainably
managed ecosystems, such as wetlands, may
harbour waterborne and vector-borne pathogens
such as plasmodium and human schistosoma; the
latter is described in Box 3 (Horwitz et al. 2012;
Dale and Connelly 2012; Dale and Knight 2008;
Fenwick 2006).
The habitat degradation that often accompanies
human development activities, and corresponding
simplification of natural species assemblages, have
been found to foster the proliferation of disease
vectors. The maintenance of natural freshwater
communities and ecosystem integrity, where
possible, may correspondingly contribute to a
reduction in conditions for the transmission of
diseases, including those related to water (Dudgeon
et al. 2006). The development of dams and
irrigation projects, for example, can contribute to
expanding habitats for mosquitoes, aquatic snails
and flies, which can spread disease among resettled
agricultural populations. River damming changes
physical and chemical conditions, altering the
original biodiversity (Tundisi et al. 2002). Reduced
water current creates favourable conditions for
molluscs from the genus Biomphalaria, potential
vectors of schistosomiasis. This disease affects
over 200 million people worldwide, of which 88
million are under 15 years of age, with the heaviest
infections being reported in the 10–14 years’
age group in Africa and South America (UNEP,
UNICEF & WHO 2002).
Other species, such as aquatic plants, are also
affected by shifting environmental conditions,
which in turn may favour mosquito breeding,
including mosquitoes of the genus Anopheles,
potential vectors of a protozoan – genus
Plasmodium – causing malaria (Thiengo et al.
2005). Many studies have reported the increase
in malaria cases after the construction of large
dams. From the Chiapas hydroelectric power
plant in Mexico to Itaipu Binacional in Brazil/
Paraguay, thousands of malaria cases were linked
to dam construction (Couto 1996). In South
America, almost 60% of all reservoirs were built
since the 1980s. Prevalence of other diseases
may also increase with river damming. In the
area of influence of the Yacyreta dam (Paraná
River, Argentina/Paraguay), Culicoides paraensis
mosquitoes were found (Ronderos et al. 2003).
These are known vectors of Oropouche fever –
which registered epidemics in many urban centres
in the Pará State of Brazil (Barros 1990).
Biological and chemical threats (e.g. agricultural
run-off, pharmaceuticals) to water resources,
as well as the development of water-related
infrastructure and urbanization, have also had
their share of detrimental impacts on both
biodiversity and human health by diminishing
native biodiversity and sometimes increasing the
potential for waterborne illnesses.
The global community has widely acknowledged
the importance of access to clean water, sanitation
and hygiene as critical development interventions
¹³ Human activities can hamper the ecological balance of wetlands and thereby alter existing disease dynamics or introduce
novel disease problems (Horwitz et al. 2012). For example, flood risk may also increase as a result of degradation of coastal
wetlands, demonstrated with Hurricane Katrina’s impact on New Orleans, and extant deforestation exacerbated the health
impact of the 2010 earthquake in Haiti.
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