Climate Change and Human Health
Direct Health Impacts
Climate-Induced Extreme Weather Events
Climate-induced extreme weather events such as heavy
rainfall and various types of floods and droughts affect
health of populations by contributing to changes in
mosquito abundance as well as contamination of water
sources with faecal matter. Notwithstanding the fact that
catastrophic flood events can lead to deaths and injuries, and
respiratory and diarrhoeal diseases. Droughts also cause
food shortages and in turn, to widespread famine and
starvation of communities (Table 5).
Indirect Health Impacts
Table 6 presents the climate-sensitive vector-borne
diseases. It can be observed that malaria has the highest
likelihood of incidence with climate change. Malaria is
caused by a parasite that is transmitted by the bite of P.
falciparum mosquitoes. Other diseases that are
transmitted by mosquitoes are dengue fever, yellow
fever, and filariasis. Since mosquitoes are the vectors of
most of the climate-sensitive vector-borne diseases, it is
suggested that climate sensitivity of mosquitoes and the
transmission link of diseases brought about by this vector
can be studied.
Table 7 presents the list of communicable diseases that
have climate-epidemic relationship. Cholera and malaria
show the highest association of disease outbreak with
changes in climate. This was also reiterated in the study of
Xu, et al in 2014.24
Data on Climate-Related Diseases Incidences in the
Philippines
Figure 4 shows the link between dengue cases and
temperature change in the Philippines. Based on the graph,
it is observed that as temperature increases, the number of
cases of dengue also increases.
Figure 5 shows the link between malaria cases and
temperature change. Similarly, the number of cases of
malaria also increases with temperature increase.
Table 7. List of Communicable Diseases with Climate-Epidemic Relationship
Disease
Global Burden
(1000 DALYs)
Transmission
Distribution
Climate Epidemic Link
Influenza
94 603 (all respiratory
infections- only a
fraction due to
influenza)
61 966 (including
diarrhoeal diseases)
Air borne
Worldwide
Decreases in temperature (winter)
associated with epidemics. A range of
human-related factors is more significant.
Food and waterborne
Africa, Asia, Russian
Federation, South
America
Malaria
46 486
Bite of female
Anopheles
mosquitoes
Endemic in >100
tropics and subtropics
countries and some
temperature areas
Meningococcal
meningitis
Dengue
6 192 (all meningitis)
Air borne
Worldwide
616
Bite of female
Aedes mosquitoes
Africa, Europe, South
America, Southeast
Asia, Western Pacific
St. Louis
Encephalitis
NA
North and South
America
Rift Valley fever
Unquantified
Bite of female
Culex and Aedes
mosquitoes
Bite of female
culicine
mosquitoes
Ross River virus
Unquantified
Bite of female
culicine
mosquitoes
Australia and Pacific
islands
Murray Valley
fever
Unquantified
Bite of female
Culex mosquitoes
Australia
Increases in sea and air temperatures as
well as El Niño events associated with
epidemics. Sanitation and human
behaviour are also important.
Changes in temperatures and rainfall
associated with epidemics. Many other
locally relevant factors including vector
characteristics, immunity, population
movements, drug resistance,
environmental changes, etc.
Increases in temperature and decreases in
humidity associated with epidemics.
High temperature, humidity, and rainfall
associated with epidemics in some areas.
Non-climatic factors also have an
important impact.
High temperature and heavy rain
associated with epidemic. Reservoir
animal factors are also important.
Heavy rains associated with onset of
epidemic. Cold weather associated with
end of epidemic. Reservoir animal factors
are also important.
High temperature and heavy precipitation
associated with onset of epidemic. Host
immune factors and reservoir animals are
also important factors.
Heavy rains and below average
atmospheric pressure associated with
epidemics.
Cholera
Sub-Saharan Africa
Strength of
temporal climate
sensitivity
++
+++++
+++++
+++
+++
+++
+++
+++
+++
+ Climate link is very weak ++ Climate plays a moderate role +++ Climate plays a significant role ++++ Climate is an important factor +++++ Climate is the primary factor in
determining at least some epidemics, and the strength of the association between climate and disease outbreaks has been assessed on the basis of published quantitative (statistical)
rather than anecdotal evidence. Adapted from Kuhn et al, 2005 25
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