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IMPACT OF CLIMATE CHANGE ON ABUNDANCE, DISTRIBUTION, AND SURVIVAL OF AEDES SPECIES: SYSTEMATIC REVIEW

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Introduction: Aedes species is a common vector that causes various types of infection. One of the factors that can affect their distribution is the climate change. Identifying the components of climate change that can affect this distribution and how they affect it can aid in predicting and controlling the Aedes species distribution. Methods: Systematic search on articles related to the impact of climate change on Aedes species distribution was conducted using four databases namely Cochrane Library, PubMed, Ovid Medline and Science Direct. All the articles which were published within year 2014 till 2019, was then assesses by using the PRISMA checklist 2009 guided by the inclusion and exclusion criteria set. Results: Ultimately, 19 articles inclusive of six cross-sectional studies, six modelling and seven ecological studies were subjected to narrative and objective quality analysis using Newcastle- Ottawa Scale. Each component of climate change – rainfall, temperature, humidity and wind velocity were examined on its relational impact towards vector Aedes species distribution and survival. All studied climate components showed a unidirectional effect on the distribution and survival of Aedes species Temperature range 3.4oC-34.2oC, humidity <70%, post rainfall (<70mm) and low wind velocity related to increased vector Aedes species distribution, abundance and survival. Quality assessment yielded 17 high quality articles and two moderate quality. Conclusion: Climate change affects the Aedes species distribution and survival. By incorporating the knowledge on the effects of each component of climate change Aedes species vector control effort, a more objective and effective mitigation can be achieved.
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
Review Research
IMPACT
OF
CLIMATE
CHANGE
ON
ABUNDANCE,
DISTRIBUTION,
AND
SURVIVAL
OF
AEDES
SPECIES
:
SYSTEMATIC
REVIEW
Lavanyah Sivaratnam.1, Chin Mun Wong1, Diana Safraa Selimin1, Rozita Hod1, Sazaly Abu
Bakar2, Hasanain Faisal Ghazi3, Mohd Rohaizat Hassan1
1Department of Community Health, Faculty of Medicine, Universiti Kebangsaan Malaysia,
Cheras, 56 000, Kuala Lumpur, Malaysia.
2Department of Tropical Infectious Diseases Research &Education Center (TIDREC), Medical
Microbiology, Faculty of Medicine, University Malaya Medical Centre, Jalan Universiti,
Lembah Pantai, 50603 Kuala Lumpur, Federal Territory of Kuala Lumpur.
3 College of Nursing, Al-Bayan University, Baghdad, Iraq.
*Corresponding author: rohaizat@ppukm.ukm.edu.my
ABSTRACT
Introduction: Aedes species is a common vector that causes various types of infection. One of the
factors that can affect their distribution is the climate change. Identifying the components of climate
change that can affect this distribution and how they affect it can aid in predicting and controlling the
Aedes species distribution. Methods: Systematic search on articles related to the impact of climate
change on Aedes species distribution was conducted using four databases namely Cochrane Library,
PubMed, Ovid Medline and Science Direct. All the articles which were published within year 2014 till
2019, was then assesses by using the PRISMA checklist 2009 guided by the inclusion and exclusion
criteria set. Results: Ultimately, 19 articles inclusive of six cross-sectional studies, six modelling and
seven ecological studies were subjected to narrative and objective quality analysis using Newcastle-
Ottawa Scale. Each component of climate change rainfall, temperature, humidity and wind velocity
were examined on its relational impact towards vector Aedes species distribution and survival. All
studied climate components showed a unidirectional effect on the distribution and survival of Aedes
species Temperature range 3.4oC-34.2oC, humidity <70%, post rainfall (<70mm) and low wind velocity
related to increased vector Aedes species distribution, abundance and survival. Quality assessment
yielded 17 high quality articles and two moderate quality. Conclusion: Climate change affects the
Aedes species distribution and survival. By incorporating the knowledge on the effects of each
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
component of climate change Aedes species vector control effort, a more objective and effective
mitigation can be achieved.
Keywords: Aedes species, climate change, impact, rainfall, Dengue, Aedes aegypti, Aedes Albopictus,
vector abundance, vector survival, vector distribution
Introduction
Aedes species is the vector for seven important communicable diseases that are causing a pandemic
in humans and other reservoir hosts, including Dengue fever, Chikungunya, Zika virus, Yellow fever,
West Nile fever, Ross River fever and Murray Valley Encephalitis (Cavrini et al., 2009; Walter Reed
Biosystematics Unit, 2011). Aedes aegypti is a small to medium-sized mosquito of 4 to 7 millimetres
(Yimer, Beyene, & Shewafera, 2016). The adult Aedes aegypti has white scales on the dorsal surface
of that thorax resembled the shape of a violin or lyre while adult Aedes albopictus have one central
white stripe at the top of the thorax. The abdomen of Aedes species is generally dark brown to black,
some with white scales, the proboscis and the tip of the abdomen of the Aedes species come to a point,
which is characteristic of all Aedes species (Carpenter & LaCasse, 1995; CDC, 2006; Cutwa & O’Meara,
2007). Generally, the females are larger than males, which can be distinguished by small palps of white
or silver scales at tip. The female mosquitoes have sparse short hairs while mouthparts are modified
for blood feeding; while male mosquitoes have plumose antennae and their mouthparts are modified
for nectar feeding (Yimer et al., 2016).
The female Aedes aegypti feed almost exclusively on human blood only for the reason of ovi-
production, other than that, the mosquito survived long with food other than blood (Zettel & Kaufman
P., 2013). Feeding on humans generally occurs at one to two hours intervals, preferring to bite typically
from below or behind, usually the feet and ankles (Yimer et al., 2016). The female Aedes aegypti are
active biters, they are read to feed when the environment are favourable (Zettel & Kaufman P., 2013).
Aedes albopictus is an aggressive diurnal feeder feeding on a wider variety of hosts than the Aedes
aegypti , they often present near human habitat, breeds well in artificial containers around the human
habitat such as standing water bodies, coconut / durian shells, empty tins, opened water storage
containers, as well as in natural containers such as leaf axils of water-holding plants like the bromeliads,
or tree holes (Mu˜nnoz, Eritja, Alcaide, & al., 2011). The Aedes albopictus populations is capable to
resist desiccation in temperate regions by produce diapausing eggs to curb the freezing cold winter
season; and can feed on a wider diversity of vertebrate hosts by facilitating the establishment of
enzootic arbovirus transmission cycles as a bridge vector in the America continent from spill-over of
Dengue virus of sylvatic cycles in Asia (Motoki et al., 2019). With this, Aedes albopictus has a larger
geographical distribution than Aedes aegypti (La Ruche, Dejour-Salamanca, & Debruyne, 2010). After
taking a complete blood meal, female mosquitoes produce an average of 100 to 200 eggs per batch
placed at varying distances above the water line, usually clutching at two or more sites (Yimer et al.,
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
2016). The number of eggs produced is dependent upon the volume of blood meal feed. Females can
produce up to five batches of eggs during a lifetime (Yimer et al., 2016).
The adult Aedes aegypti life span can range from two to four weeks depending on environmental
conditions. Aedes aegypti comes in three polytypic forms: domestic, sylvan and per domestic. The
domestic form breeds in urban habitat, often around or inside houses. The sylvan form is a more in rural
form, breeds in tree holes and forests while the per domestic form thrives in environmentally modified
areas such as coconut groves and farms (Maricopa County Environmental Services, 2006). The
increasing vector-animal-human interaction has diverged the sylvatic cycle of transmission into the form
of domestic, anthropophilic and phagic transmission forms (Powell & Tabachnick, 2013). Various
natural habitat displacement and habitat creation by human activities, climate change and transmission
tetrad (vector, agent, host, environment interaction) have successfully enlarged the distribution of
Aedes species the region away from its originality (Shragai T, Tesla B, Murdock C, & LC., 2017).
Aedes aegypti and Aedes albopictus seem to have different susceptibilities to ZIKV, feeding rates, and
feeding preferences, as Aedes aegypti feeds more often and almost exclusively on human as
compared to Aedes albopictus which feeds on a broader range of hosts (Caminade C, McIntyre KM., &
AE., 2017). Therefore, given equal mosquito and human densities, regions with Aedes aegypti will
have a higher affinity for DENV, ZIKV, CHKV and YFV, but since Aedes albopictus extends beyond the
range of Aedes aegypti into more temperate regions, it is more often found as the Aedes species which
carry flavivirus transmission risk (Caminade C et al., 2017).
Extreme Weathers
More than 50% of the earth’s climate change was a result of anthropogenic activities and is happening
at a rate faster than the earth ecosystem can recover (Stocker et al., 2013). Intergovernmental Panel
on Climate Change forecasts an increase in world average temperature by year 2100 within the range
1.4 ºC 5.8ºC since year 1995; and the global temperature is rising at the rate of 0.5ºC annually since
year 1970 (McMichael, Woodruff, & Hales, 2006), more remarkably seen at higher latitudes areas. This
leads to extreme weather events in a more frequent, severe and higher variable mode (Hainesa,
Kovatsa, Campbell-Lendrumb, & Corvalanb, 2006; McMichael et al., 2006). The mortality rate related
to extreme weather is well established and represented by the U-shape / J-shape curve, where median
temperature (the thermo comfort zone) has the lowest death rate, and the mortality rate increases in
exponential relationship with the rise of temperature, also to lesser extent, the fall to low temperature
(Abdul Rahman, 2009; Hainesa et al., 2006; McMichael et al., 2006).
In a warming climate, extreme events like floods and droughts are likely to become more frequent. More
frequent floods and droughts will affect water quality and availability. Increases in drought in some areas
may increase the frequency of water shortages and lead to more restrictions on water usage. An overall
increase in precipitation or rain may create greater flood potential. Rising sea levels, meanwhile,
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
heighten flood dangers for coastal farms, and increase saltwater intrusion into coastal freshwater
sources making those water sources too salty for irrigation or drink (Backlund, Janetos, & Schimel,
2008). Precipitation also can washes-off pesticide from the agricultural site and spread the pesticide to
water sources such as underground water thus making it contaminated. Same as food supply, extreme
climate can result in greater water source spoilage and disrupt water distribution, water storage,
transport and dissemination.
Climate Change in Relation to Vector Distribution
Flood / rain fall related vector borne diseases like dengue fever, malaria, leptospirosis, Chikungunya
endemics are more prevalent in the country and worldwide; through the development of more breeding
sites, contamination of surface run-off and poor hygiene practice during the disaster. Urbanization
brings forth more complex human-vector interaction epidemiologically and ecologically, account for the
worsen endemicity (World Health Organization & United Nations Environment Programme, 2007). The
illegal logging activities may result in malaria virus transmission via rural-urban vector-human interaction
(World Health Organization & United Nations Environment Programme, 2007).
Mosquito Aedes species usually live between the latitudes of 35°N and 35°S below an elevation of
1000m at both natural and artificial terrestrial and aquatic habitats (NC. Dom, Abu, & Rodziah, 2013).
Climatic factors are strong environmental drivers for arbovirus disease transmission, this is particularly
true for factors such as environmental temperature, relative humidity and rainfall patterns (Rodo,
Pascual, & Doblas-Reyes, 2013). The risk of viral transmission from Aedes species is highly sensitive
to climate. Temperature impacts the ectoderm’s internal body temperature, hence directly affecting the
mosquito physiology (e.g., immunity) (Murdock, Blanford, & Luckhart, 2014), the mosquito
development, survival, reproduction, biting rates (Ciota, Matacchiero, & Kilpatrick, 2014), vector
competence and extrinsic incubation periods) (Ciota et al., 2014). In hot and dry climates, Aedes
albopictus eggs may be more susceptible to desiccation, thus becoming less competitive to Aedes
aegypti (Shragai T et al., 2017). This capacity of vector-borne disease transmission and affinity of
transmission are influenced by the mean number of blood meals in a typical mosquito’s remaining
lifespan after mosquitoes were infected (Shragai T et al., 2017).
Urbanization further changes the natural habitat of both mosquitoes and of human, as well as climate
suitable for the vector survival and transmission (Pincebourde, Murdock, & Vickers, 2016).
Temperature, humidity, and the number of breeding sites in the city appeared heterogenous, vary
depending on the economic status of the landowner or resident, mosquito control, zoning, and cultural
norms. Micro environmental niche in the urban that turn out to be the mosquitoes hotspots are usually
congested area with high population density, limited space, poor hygiene, sanitation and suboptimal
sewage management; and these niches are often inhabited by human population with higher
vulnerability to infection due to low socioeconomic and low sociodemographic status (Shragai T et al.,
2017).
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
Modelling and Prediction of Vector Survival
Environmental niche modelling is usually used to predict suitability for disease transmission for Aedes
Species. Modelling uses disease prevalence report against hypothesized environmental covariates to
derive future potential of vector distribution (Messina et al., 2016). For example, modelling results
indicate that temperature conditions related to the 2015 El Niño climate phenomenon were exceptionally
conducive for Aedes species mosquito-borne transmission of ZIKV over South America (Caminade C
et al., 2017). Regions with model prediction of high ZIKV transmission risk has high correlation with the
subsequent large outbreaks occurring in Brazil, Colombia and Venezuela in year 20152016. This
optimum thermal zones show largest simulated biting rates and lowest mosquito mortality rates and the
shortest extrinsic incubation period in year 2015 (Caminade C et al., 2017). The sub-Saharan Africa
regions demonstrated continuous suitability for ZIKV survival since the 1950s (Messina et al., 2016).
Nevertheless, the interpretation of relationships between mosquito abundance and land-use patterns is
not as straight forward. The variation occurs due to different categorizations of landscapes used, such
as the percent of vegetative coverage, human population density, outdated geographical map, map
resolution. The inaccuracy is complicated by inappropriate scales used to quantifying these patterns.
When large regions are used, the over broad geography may not appropriately representing the
microclimate and available habitats within the regions, obscuring pattern of transmission (Shragai T et
al., 2017).
With climate change being recognized fast as a determinant of health, this has become utmost
important to estimate the effect of weather on vector borne diseases (Roy, Gupta, Chopra, Meena, &
Aggarwal, 2018). Even though various control measures have been done, vector borne cases are still
persistent which is likely due to the changing climate that is not factored to our control measures. There
is no recent review done on the effect of climate change on Aedes species distribution globally. Being
able to anticipate vector abundance in relation to the changing climate, a better vector control can be
implemented. The review aims to understand how each component of climate change impacts the
distribution and survival of vector Aedes species.
Methods
Literature Search
Systematic search related to relevant articles from four major search engines using Boolean search
strategy, search engines including Cochrane library, PubMed and Ovid Medline and Science Direct,
retrieving all articles published from year 2014 until 2019. PRISMA checklist 2009 is used to describe
the workflow of articles search for this study (Page MJ et al., 2021). The keywords used to search for
the articles are stated in Table 1.
Table 1: Initial keyword search using P.I.C.O. strategy
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GLOBAL JOURNAL OF PUBLIC HEALTH MEDICINE 2022, VOL 4, ISSUE 1
Keyword
Concepts
Alternative
Patient /
problem
Aedes sp
Aedes sp OR Dengue cases OR Dengue Haemorrh#gic Fever cases
OR Chikungunya cases OR Yellow fever case OR Zika case OR
Flavivirus case
Intervention
-
-
Comparison
Climate
change in SEA
Current Rain fall OR Current temperature OR current wind direction
Outcome
Vector
distribution
Vector survival
Vector distribution OR Aedes sp new case OR Pattern of Aedes sp.
Distribution OR Vector Aedes sp. Evolution OR Vector life cycle OR
Vector transmission OR Vector survival
Boolean Strategy Keyword search:
As the keyword combination did not yield sufficient search result after two rounds of Boolean Strategy
Keyword search, contraction using a set of new keywords was done.
Aedes sp OR Dengue cases OR Dengue Haemorrh#gic Fever cases
AND
Rain fall OR temperature OR wind direction
AND
distribution OR new case OR Pattern OR Evolution OR transmission OR survival
Inclusion criteria for the article search including: (1) full text, primary research articles on prevalence of
vector-borne diseases in relation to climate change (2) reported at least one outcome of the vector
distribution due to climate change (3) articles published from year 2014 2019. Exclusion criteria set
were: (1) reviewed articles of no original research work empirical data (2) entomology with no
association to climate change (3) Knowledge, Attitude, Practice studies (4) clinical treatment (5)
pharmaceutical study (6) vector distribution other than Aedes species
The articles obtained from the keyword search were first screened by titles to exclude totally irrelevant
articles, then abstracts of the articles to look for P.I.C.O. criteria. When full texts are retrieved, it was
assessed for relevance to include our inclusion and exclusion criteria. In total, there is a total of 440
articles retrieved based on Boolean search strategy, 36 accepted by title and further subjected for
abstract screening yielding 31 articles. After excluding one duplicate article and eight that did not fit the
inclusion criteria, a total of 22 articles were subjected for full text review. In the review, three more
articles were excluded due to irrelevant content. The final full article reviewed and proceeded for
analysis was 19. The progress of screening and selection is described through the Prisma flow chart in
Error! Reference source not found..
585
Figure 1: Prisma flow chart
Results & Discussion
Characteristic of study
A total of 19 articles which consist of six cross-sectional, six modelling and seven ecological studies
were finalized for full text analysis. The articles are mostly from Europe and Asia. Amongst which 17
articles studied on temperature in relation concerning vector survival, eight on rainfall, eight on humidity,
two on seasonality change and one on wind velocity. Table 2 provides a narrative review on the study
design, tools, variables used, outcome of vector and challenge / limitation / public health implications.
Total of 11 studies using ovitrap for mosquitoes sampling, the other eight uses secondary data from
meteorology data, environmental survey or geographical intelligence systems. Table 3 provide the
narrative analysis summary of various climate components effect on vector Aedes species distribution
and survival. Nine studies reported on rainfall, where 55.5% (n=5) studies shows inverse relationship
of rainfall with Aedes sp abundance, with each 1mm increase of rainfall contribute to 1% increase in
vector abundance, up to 70mm. Nine studies were done on humidity, 66.7% (n=6) studies reported
increased humidity will lead to increase in Aedes sp vector abundance, (Betanzos-Reyes, Rodríguez,
Romero-Martínez, Sesma-Medrano, & Rangel-Flores, 2018) specified that humidity range 30-70% is
586
suitable for vector survival, and consistently supported by (Da Cruz Ferreira et al., 2017) that humidity
beyond 70% leads to reduction of vector survival. Seventeen studies studied effect of temperature with
Aedes sp abundance and survival, 94.1% (n=16) supported that increase temperature proportionate to
the increase of vector abundance, but (Limper et al., 2016) provided contrast opinion. The lowest
temperature recorded for vector increment was 3.4oC (Taber, Hutchinson, & Smithwick, 2017), and
temperature maximum for increased vector was 34.3oC by (Das et al., 2014). Review supported the J-
shape relationship between temperature and vector abundance and survival, (Phung, Talukder,
Rahman, Shannon, & Cordia, 2016) reported with every 1˚C increment, there will be an additional 11%
risk to get Dengue infection (proxy to vector survival). Only three studies reviewed on wind velocity in
relation to Aedes sp survival, all studies show inverse relationship.
Table 2: Narrative Review of Characteristics of Studied Articles
N
O
Author/
Year
Country
Study
Design
Tool
Variables
Outcome
Challenge /
Limitation /
Public
Health
Implication
1
Barrera
et al.
2019
(Barrer
a,
Amador
,
Aceved
o,
Beltran,
&
Munoz,
2019)
Puerto
Rico (US
Territory)
Comparat
ive cross
sectional
(2014/201
6)
Mosquito
collection
Mosquito
density
Rainfall
Temperatur
e
Relative
humidity
Accumulated
rain
significantly
influenced
mosquitoes
density
(reduced
during rain
fall and
increase post
rain)
-
Comparing
the results
with a
previous
study may
not be
comparabl
e as the
number of
samples,
sampling
tools,
techniques
and
analysis
may differ.
2
Roy et
al. 2018
(Roy et
al.,
2018)
India
Cross
sectional
study
Secondary
data
Laboratory
confirmed
cases
Rainfall
Temperatur
e
Relative
humidity
1. Relative
humidity
was
associated
with burden
of positive
dengue
cases
2. Dengue
admission
was
preceded
by heavy
rain 46
weeks
earlier
-limited
number of
paediatric
cases
3
Xiang
et al.
2017
(Limper
China
Modelling
Dengue
notification
system
data
Clinical and
laboratory
confirmed
cases
Rainfall
1. Positive
temperature
-Dengue
association
s were
- Non-
climatic
data was
not
accounte
587
et al.,
2016)
Meteorologi
cal data
Temperatur
e
Relative
humidity
Sunshine
duration
Wind
velocity
found for
both Tmax
and Tmin at
the range of
21.6
32.9°C and
11.2
23.7°C
2. Relative
humidity
was
positively
associated
with
dengue;
however, a
negative
association
was
observed
during
extremely
humidity.
3. Extreme
rainfall and
high wind
velocity are
associated
with
reduced
cases.
d for in
this
model as
data was
not
available
4
Phung
et al.
2016
(Phung
et al.,
2016)
Vietnam
Modelling
Secondary
data
Dengue
cases
Rainfall
Temperatur
e
Relative
humidity
1. A 1 ̊C
increase
in
temperatu
re
increased
the
Dengue
risk 11%
(95%CI,
9-13) at 1-
4 weeks
and 7%
(95%CI,
6-8) at 5-
8weeks.
2. A 1% rise
in
humidity
increased
Dengue
risk 0.9%
(95%CI,
0.2-1.4) at
lag 1-4
and 0.8%
(95%CI,
0.2-1.4) at
- Uses
mean
value
of
climate
factors
rather
than
minimu
m,
maxim
um or
diurnal
.
588
lag 5-8
weeks
3. A 1 mm
increase
in rainfall
increased
Dengue
risk 0.1 %
(95%CI,
0.05-0.16)
at lag 1-4
and
0.11%
(95%CI,
0.07-0.16)
at lag 5-8
weeks
5
Limper
et al.
2016
(Dhimal
,
Gautam
, Joshi,
O’hara,
&
Ahrens,
2015.)
Netherland
s
Modelling
Distributed
lag non-
linear
model
Secondary
data
Dengue
cases,
Rainfall,
Temperatur
e, Relative
humidity,
Sunshine
duration
lower
temperatures
lead to higher
rates of
infection
-data for
Dengue
cases is
obtained
by month
unlike
climate
changes
by week.
6
William
s et al.
2015
(William
s et al.,
2015)
Malaysia
Modelling
mechanistic
entomology
and
disease
model
secondary
data
Dengue
cases
Daily
temperatur
e
Increase in
temperature
resulted in an
overall
decrease in
Dengue
activity
Model
unable to
predict
future
number of
Dengue
cases
7
IM
Nurin-
Zulkifli
et al.
2015
(IM
Nurin-
Zulkifli.
et al.,
2015)
Malaysia
Cross
sectional
study
Mosquito
collection
HLC
human
landing
catch
Mean
number of
Ae.
albopictus
mosquitoes
and
meteorologi
cal
parameters
-mosquito
population
correlated
significantly
with humidity
&
temperature
-no significant
correlation
of mosquito
species with
Temperature
and humidity
-
8
Taber
E.D et.
al. 2016
(Ciota
et al.,
2014)
Pennsylva
nia, USA
Modelling
geographic
information
systems
(GIS) over
10 years
risk of
Dengue
virus
transmissio
n using a
model that
captures
the
probability
of
-Ae.
albopictus
population
density
-monthly
pattern of
population
increase
correlate with
BG
Sentinel
traps was
not used
during
earlier part
of the
study,
given lower
yield of Ae.
589
transmissio
n
temperature
3.4-32.7oC
-winter
temperatures
limit Aedes
sp. egg
survival
Albopictus
catch
evaluation
of
temperate
Ae.
albopictus
population
s helps in
developme
nt of better
biological
models of
DENV
transmissio
n.
9
Dutto
M. &
Mosca
A.
2017
(Dutto
&
Mosca,
2017)
Northwest
ern Italy
Cross
sectional
study
Environmen
tal risk
assessment
- interview,
larvae
sampling
Indoor
mosquito
breeding
sites -for Ae
albopictus
only
Low external
temperature
(winter, 2-
6oC)
restricted
vector
survival,
encourage
indoor vector
survival
Insufficient
survey
sites to
define real
entity of
winter
presence
of Aedes
species in
the area
and the
associated
risk of
vector-
transmitted
diseases
10
Rodrigu
es et.
al. 2015
(Grech
et al.,
2019)
Brazil
Cross
sectional
study
Mosquito
collection -
Portable
electrical
catcher
Female
Aedes
aegypti &
Ae.
Albopictus
over
number of
residents
for
intradomicili
ary and
peridomicili
ary
premises
strong
association
between no.
of
female adult
mosquitoes
and the
number of
residents in
both
intradomiciliar
y and
peridomiciliar
y premises
77% (p =
0.000) female
adult Aedes
sp
intradomiciliar
y premises
and and 48%
female adult
Aedes sp
peridomiciliar
y premises
due to mean
high
probability
of human-
vector
contact
can
increase
possible
transmissio
n and
spread of
the DEN
virus.
Part of the
Aedes sp
mosquito
behaviour
is the
adaptability
to vast
differentiat
ed
environme
nts
590
rainfall
(p=0.001)
Min
temperature
in both types
of premises
contributes to
40% of no. of
female
mosquitoes
Entomologi
cal
indicators
of adult
females
should be
use for
vector
control
11
Marta
R.H.S
et. al.
2018
(Marta,
2018)
Brazil
Cross
sectional
study
Mosquito
collection
using
ovitrap
- rainfall
and
temperatur
e
- oviposition
rates
seasonal
variation
(min, max
temperatures
significantly
associated
with
oviposition
rate of both
Aedes sp.
Cumulative
rainfall
(weekly) not
associated
with vector
abundance
Ae.
aegypti,
closely
associated
with
inhabited
region
(more
human);
Ae.
albopictus
was more
closely
associated
with area
with
a greater
vegetation
coverage
12
Sadie
J.R. et.
al. 2019
(Sadie
J. R.,
Colin J.
C., Erin,
& Leah,
2019)
USA
Modelling -
general
circulation
models
secondary
data
Temperatur
e
mosquito
range shifts
track optimal
temperature
ranges for
transmission
(21.334.0˚C
for Ae.
aegypti;
19.929.4˚C
for Ae.
albopictus
-poleward
shift pattern
observed
- significant
reductions in
climate
suitability at
southeast
Asia and west
Africa are
expected for
Ae.
albopictus
climate
change will
lead to
increased
net and
new
exposures
to Aedes-
borne
viruses
both Aedes
species
vary in
transmissio
n rate
under
climate
change,
Ae.
Aegypti
endures
wider
range of
climate
change,
but
intermediat
e climate
changes
591
make Ae.
albopictus
a more
suitable
survival
and
successful
competitor
13
Dhimal
et al.
2014
(Dhimal
,
Gautam
, Kreß,
&
Müller,
2014)
Nepal
Ecologica
l study
Entomologi
cal survey:
Adult
mosquito
collection
by using
BG-
Sentinel
and CDC
light traps
Number of
mosquitoes
per trap
and
meteorologi
cal
parameters
Temperature,
rainfall and
relative
humidity had
significant
effects on the
mean number
of A. aegypti
per BG-
Sentinel trap:-
Each
degree
rise in
temp
increased
female A.
aegypti
abundanc
e (ß =
1.63; 95%
CI =
1.34
1.98;
p,0.001)
Every
increased
in rainfall
(mm)
reduced
abundanc
e (ß =
0.94;
95%CI
=0.92
0.97;
p,0.001)
Every
increased
humidity
(%) also
reduced
abundanc
e (ß=
0.59;
95%CI=0.
440.77;
p,0.001).
No significant
effect of
rainfall and
temperature
Ae. aegypti
and Ae.
albopictus
established
stable
population
s up to the
Middle
Mountains
of Nepal,
but not in
the High
Mountain
localities.
Ae. aegypti
and Ae.
albopictus
trapped
even when
minimum
temperatur
es had
dropped to
8oC
suggesting
a
considerab
le adaptive
capacity of
local Ae.
aegypti
and Ae.
albopictus
population
s to low
temperatur
es à for
better
planning
and
scaling-up
of
mosquito-
borne
disease
control
programm
es in the
mountaino
us areas of
Nepal that
had
592
on the
number of
Aedes eggs
per ovitrap
(p.0.05).
Humidity had
significantly
negative
effects on the
mean number
of Aedes
eggs per
ovitrap (b =
0.83; 95%CI
= 0.710.97;
p,0.001).
previously
been
considered
risk free
Increase
temp
shorten the
extrinsic
incubation
period of
pathogens,
lead to
increases
in biting
frequency
and
extensions
of the
average
life span of
mosquitoe
s
è Increas
ing
temp
can
make
temper
ate
regions
of
Nepal
vulnera
ble to
DF
epidem
ic
14
Da
Rocha
Taranto
et al.
2015
(M. F.
Da
Rocha
Taranto
et al.,
2015)
Brazil
Ecologica
l study
Mosquito
egg
collection
by using
ovitrap
Average
monthly
temperatur
e and
precipitatio
n was
compared
with the
number of
eggs
collected in
each month
The presence
of the vector
was
significantly
influenced by
temperature
variation
(P < 0.05)
Rainfall
provided
physical and
climatic
conditions
favourable to
the
development
of eggs and
to the
increased
survival of the
mosquito.
However,
The higher
temperatur
es
provided
better
conditions
for
mosquito
breeding,
thus
greater
probability
of
transmittin
g DENV
593
extreme
rainfall
conditions are
not
associated
with vector
presence
over time, as
the pattern
may result
from the
elimination
of larvae from
overflowing
containers.
15
Betanz
os-
Reyes
et al.
2018
(IM
Nurin-
Zulkifli.
et al.,
2015)
Mexico
Ecologica
l study
Mosquito
egg
collection
by using
ovitraps
Correlation
between
climate
variables
eg. weekly
report of
temperatur
e (average,
minimum
and
maximum),
rainfall (mm
accumulate
d) and
relative
humidity
(RH,
percentage)
and
ovitraps
data
Daily mean
temperature,
relative
humidity and
rainfall
parameters
were
associated
with mosquito
egg
abundance:
Significant
correlation
was seen
between the
weekly Aedes
egg counts
with:
The mean
weekly egg
counts
(WEC):
- increased
with 12oC to
18oC, but
decreased as
temperature
increased
beyond this
point.
- similar at
RH between
30 and 70%
and
increased as
humidity
increased
beyond 70%
- increased
as rainfall
increased up
to 70mm, but
unchanged
with further
Time lags
between
egg counts
and
dengue
incidence
could be
useful for
prevention
and control
interventio
ns. This
time lag
represents
an
opportunity
to use
ovitrap
monitoring
as a
predictive
tool for
Dengue
fever
incidence
incre-
ments.
594
increases in
rainfall
16
Da
Cruz
Ferreira
et al.
2017
(Da
Cruz
Ferreira
et al.,
2017)
Brazil
Ecologica
l study
MI-Dengue
system
(intelligent
dengue
monitoring,
or
MosquiTRA
Ps)
Daily
rainfall,
temperatur
e
parameters
(minimum,
average
and
maximum),
and
average
relative
humidity
-Dengue
incidence
Adult
mosquito
abundance
was strongly
seasonal,
with low
infestation
indices during
the winters
and high
infestation
during the
summers.
Weekly
minimum
temperatures
above 18 °C
were strongly
associated
with
increased
mosquito
abundance,
whereas
humidity
above 75%
had a
negative
effect on
abundance.
Continuous
monitoring
of dengue
vector
population
allows for
more
reliable
predictions
of
infestation
indices.
The adult
mosquito
infestation
index was
a good
predictor of
dengue
occurrence
. Weekly
adult
Dengue
vector
monitoring
is a helpful
dengue
control
strategy
especially
in
subtropical
areas
17
Bezerra
et al.
2016
(Bezerr
a et al.,
2016)
Brazil
Ecologica
l study
Adult
female
Aedes
albopictus
(and other
Aedes sp.)
were
caught
using BG-
Sentinel
Full
Version®tra
ps
-rainfall,
temperatur
e
(minimum,
maximum
and
average)
and relative
humidity
-The field-
caught Ae.
albopictus
collected
females
- The field-
caught
DENV-
infected Ae.
albopictus
1. Minimum
temp of 12.1-
23.2DegC
(r=0.34, p<
0.0001 and
maximum
temp of 18.6-
34.2oC
(r=0.25, p=
0.004) were
correlated
with the field-
caught Ae.
albopictus
(n=511) in
four different
periods and
districts.
Neither the
rainfall nor
relative
humidity was
associated
Inverse
association
between
the number
of human
Dengue
cases and
field-
caught
DENV-
infected
Ae.
albopictus
à in
Brazil,
possible
that Ae.
albopictus
would be a
less
efficient
DENV
vector
595
with the field-
caught Ae.
albopictus
collected
females
2. None of
the climate
variables
were
correlated
with the field-
caught
DENV-
infected Ae.
albopictus (n
= 79) in four
different
periods and
districts
18
Dhimal
et al.
2015
(Dhimal
et al.,
2015.)
Nepal
Ecologica
l study
Entomologi
cal survey:
Collecting
Aedes spp.
Larvae
-daily
rainfall,
temperatur
e and
relative
humidity
Significant
effects of
climatic
variables on
the mean
abundance of
each
mosquito
species:
1. Aedes
aegypti:
- Each
degree rise in
mean
temperature
increased Ae.
aegypti
abundance (β
= 1.23; 95%
CI = 1.18
1.29; P<
0.001)
- Increased
rainfall
reduced
abundance (β
= 0.99;
95%CI =
0.990.99;
P<0.001)
- Increased
relative
humidity
reduced the
vector
abundance (β
= 0.91; 95%
CI = 0.85
0.98;
P<0.05).
Abundance
of DENV
vectors
with mean
temperatur
e ranging
from 10
25°C:
shorten the
extrinsic
incubation
period of
pathogens,
lead to
increases
in biting
frequency
and
extensions
of the
average
life span of
mosquitoe
s
596
2. Aedes
albopictus:
- An increase
of mean
temperature
had a positive
effect (β =
1.12; 95% CI
= 1.06
1.20;
P<0.05),
- Total rainfall
had a
significant
negative
effect (β =
0.99; 95% CI
= 0.990.99,
P<0.001)
- Relative
humidity had
a significant
positive effect
(β = 1.21;
95% CI =
1.081.35,
P<0.001)
19
Das et
al. 2014
(Das et
al.,
2014)
India
Ecologica
l study
Ovitrap
surveillance
Larvae
density per
trap
Data on
max.
temperatur
e (Tmax),
min.
temperatur
e (Tmin),
morning
relative
humidity
(0830 h),
evening
relative
humidity
(1730 h,
total rainfall
1. Positive
and
significant
correlations
to vector
density:
- Maximum
temperature
(r = 0.45; P =
0.01)
- Mean
temperature
(r = 0.408; P
= 0.021)
- Minimum
temperature
(r = 0.381; P
= 0.032).
The
relationshi
ps
established
between
the
weather
parameters
and the
abundance
of dengue
vectors in
the study
areas
could
provide
valuable
inputs for
the
developme
nt of a
decision
support
system for
dengue
esp. in
Northeaste
rn India.
However,
disease
outbreaks
also
597
depend on
factors
such as
the source
of
infection,
susceptible
human
population
apart from
vector
density
and
climate
All the climate factors were associated with at least one outcome of vector distribution or vector survival.
Error! Reference source not found.3 analysed on the summative effect of each climate components
to the vector survival / distribution. Objective analysis of quality of the studies was assessed using
Newcastle-Ottawa Scale, with score range from 6 to 9 as described in Table 4. Total of 16 articles were
rated as of good quality, two others with moderate quality of evidence from the objective quality
assessment.
Table 3: Summarised Effects of Climate Components on Vector Distribution / Survival
NO.
STUDY
RAIN
HUMIDITY
TEMPERATURE
WIND
VELOCITY
1.
Barrera et al.
2019 (Barrera et
al., 2019)
-
abundance of
Aedes sp.
during rain
-
abundance of
Aedes sp.
after rain
-
-
-
2.
Roy et al. 2018
(Rodrigues et al.,
2015)
-
- ↑ humidity ↑
Dengue
cases
-
-
3.
Xiang et al. 2017
(Oliveira
Custódio et al.,
2019)
- ↓ Dengue
cases during
extreme
rainfall
- ↑ humidity ↑
dengue
cases
- extreme
humidity ↓
Dengue
cases
↑ Dengue cases
during:
- Tmax: 21.6˚C-32.9˚C
- Tmin: 11.2˚C -23.7˚C
- extreme wind
velocity will ↓
Dengue cases
4.
Phung et al. 2016
(Taber et al.,
2017)
- ↑ 1mm rain
↑ 0.1%
Dengue
cases
- 1% ↑
humidity will
↑ 0.9% risk to
get Dengue
- 1˚C ↑ in temp. will ↑
11% risk to get
Dengue
-
5.
Limper et al.
2016 (Rodo et
al., 2013)
-
-
- ↓ temp. will ↑
Dengue cases
-
6.
Williams et al.
2015 (Williams et
al., 2015)
-
-
- ↑ temp. will ↑
Dengue cases
-
598
7.
IM Nurin-Zulkifli
et al. 2015 (IM
Nurin-Zulkifli. et
al., 2015)
-
- ↑ humidity ↑
Dengue
cases
- ↑ temp. ↑ Dengue
cases
-
8.
Taber E.D et. al.
2016 (Liu-
Helmersson,
Stenlund, &
Wilder-Smith,
2014)
-
-
- Optimal temp.
between 3.4˚C-
32.7˚C will ↑ Aedes
sp.
- Winter temp. limit
egg survival
-
9.
Dutto M. &
Mosca A.
2017 (Dutto &
Mosca, 2017)
-
-
- ↓ temp. during
winter (2˚C-6˚C) will ↓
Aedes sp. survival
outdoor, and ↑ Aedes
sp. indoor
-
10.
Rodrigues et. al.
2015 (Xiang et al.,
2017)
- ↑ rainfall will
Aedes sp.
density
-
- ↓ temp. will ↓ Aedes
sp.
-
11.
Marta R.H.S. et.
al. 2018 (Marta,
2018)
-
-
- 1˚C ↑ in min. temp.
will ↑ 8% abundance
of Aedes sp.
- 1˚C ↑ in max. temp.
will ↑ 7% abundance
of Aedes sp.
- For Ae.
albopictus, the
abundance ↑
in summer,
winter &
autumn
- For Ae.
aegypti, the
abundance ↑
in spring
12.
Sadie J.R. et. al.
2019 (Sadie J. R.
et al., 2019)
-
-
- Ae. aegypti during
temp. between
21.3˚C-34˚C
- Ae. albopictus
during temp. between
19.9˚C-29.4˚C
-
13.
Dhimal et al. 2014
(Powell &
Tabachnick, 2013)
- ↑ rainfall will
↓ abundance
of Aedes sp.
↑ humidity:
- ↓ abundance
of Aedes sp.
- Aedes sp.
eggs
- ↑ temp. will ↑ Aedes
sp.
-
14.
Da Rocha Taranto
et al. 2015 (M. F.
Da Rocha Taranto
et al., 2015)
- ↑ rainfall ↑
Aedes sp.
eggs
- extreme
rainfall will ↓
abundance of
Aedes sp.
eggs
-
- ↑ temp. will ↑ Aedes
sp. eggs
-
15.
Betanzos-Reyes
et al. 2018 (Walter
Reed
Biosystematics
Unit, 2011)
- ↑ rainfall up
to 70mm will ↑
Aedes sp.
eggs
- rainfall >
70mm will
have no
change in
Aedes sp.
eggs
- ↑ humidity
30-70% will ↑
abundance of
Aedes sp.
eggs
- Humidity >
70% will ↓
abundance of
Aedes sp.
eggs
- Aedes sp. eggs
during temp. between
12˚C-18˚C
- Aedes sp. eggs
during temp. >18˚C
--
599
16.
Da Cruz Ferreira
et al. 2017 (Da
Cruz Ferreira et
al., 2017)
-
- ↑ humidity
>75% will ↓
abundance of
Aedes sp.
- ↑min. temp. >18˚C
will ↑ abundance of
Aedes sp.
Abundance of
Aedes sp.:
- ↓ in winter
- ↑ in summer
17.
Bezerra et al.
2016 (Bezerra et
al., 2016)
-
-
Ae. albopictus
during:
- min. temp. between
12.1˚C-23.2˚C
- max. temp. between
18.6˚C-34.2˚C
-
18.
Dhimal et al. 2015
(Dhimal et al.,
2015.)
- ↑ rainfall will
↓ abundance
of Aedes sp.
- ↑ humidity
will ↓
abundance of
Aedes sp.
- ↑ temp. will ↑
abundance of Aedes
sp.
-
19.
Das et al. 2014
(Das et al., 2014)
-
-
- ↑ max temp.
between 21.6˚C-
34.3˚C will ↑
abundance of Ae.
albopictus larvae
density
-
Table 4: Newcastle Ottawa Quality Assessment Scale
N
o
Study
Selection
Comparability
Outcome
Quality
score
Rep
rese
ntati
ven
ess
of
the
sam
ple
Sam
ple
size
Non-
respo
ndents
Ascerta
inment
of the
exposu
re (risk
factor)
The
study
control
s for
the
most
importa
nt
factor
The
study
control
for
any
additio
nal
factor
Asses
sment
of the
outco
me
Statisti
cal
test
1.
Barrera et al.
2019 (Barrera
et al., 2019)
*
*
*
**
*
6
2.
Roy et al. 2018
(Dhimal et al.,
2014)
*
*
*
**
*
6
3.
Xiang et al.
2017 (Xiang et
al., 2017)
*
*
**
*
**
*
8
4.
Phung et al.
2016 (Zainon,
Mohd Rahim,
Roslan, & Abd
Samat, 2016)
*
*
*
*
**
*
7
5.
Limper et al.
2016 (Limper
et al., 2016)
*
*
**
*
**
*
8
6.
Williams et al.
2015 (Williams
et al., 2015)
*
*
**
*
**
*
8
7.
IM Nurin-
Zulkifli et al.
2015 (IM
Nurin-Zulkifli.
et al., 2015)
*
*
*
*
**
*
7
600
8.
Taber E.D et.
al. 2016 (Taber
et al., 2017)
*
*
**
*
**
*
8
9.
Dutto M. &
Mosca A.
2017 (Dutto &
Mosca, 2017)
*
**
*
**
*
7
1
0.
Rodrigues et.
al. 2015
(Rodrigues et
al., 2015)
*
*
*
**
*
**
*
9
1
1.
Marta R.H.S.
et. al. 2018
(Marta, 2018)
*
*
*
*
**
*
7
1
2.
Sadie J.R. et.
al. 2019 (Sadie
J. R. et al.,
2019)
*
**
*
*
*
6
1
3.
Dhimal et al.
2014 (Dhimal
et al., 2014)
*
*
*
*
**
*
7
1
4.
Da Rocha
Taranto et al.
2015 (M. F. Da
Rocha Taranto
et al., 2015)
*
*
**
*
**
*
8
1
5.
Betanzos-
Reyes et al.
2018 (Á. F.
Betanzos-
Reyes et al.,
2018)
*
*
**
*
**
*
8
1
6.
Da Cruz
Ferreira et al.
2017 (Da Cruz
Ferreira et al.,
2017)
*
*
**
*
**
*
8
1
7.
Bezerra et al.
2016 (Bezerra
et al., 2016)
*
*
**
*
**
*
8
1
8.
Dhimal et al.
2015
(Maricopa
County
Environmental
Services,
2006)
*
*
**
*
**
*
8
1
9.
Das et al. 2014
(Das et al.,
2014)
*
*
**
*
**
*
8
601
Climate Components and Recommendation of Vector Control
Rainfall
Findings showed that extreme rainfall will cause reduction in vector abundance (Martinelle Ferreira da
Rocha Taranto et al., 2015; Dhimal et al., 2015.; Dhimal et al., 2014; Rodrigues et al., 2015; Xiang et
al., 2017), but the abundance increases post rainfall. This could be due to its catastrophic effects on a
local population of vectors by constant washing of soil by flooding, reducing the vector habitat, leads to
an inverse relation to vector intensity (Epstein, 2004). Rainfall up to 70mm is found to be the optimal
for mosquito breeding, thus supportive factor towards Aedes species abundance in the environment
(Ángel Francisco Betanzos-Reyes et al., 2018). A study done in Kuala Lumpur concluded that there
was strong association between dengue cases and monthly rainfall, where incidence always preceded
by rainy season (Aziz et al., 2014). In Tirunelveli, India where city has poor rainfall stored water in
various containers for daily use, in which these containers became the main breeding habitats for Aedes
mosquito, the situation is similar to root cause of urban dengue in Petaling Jaya District, Malaysia
(Zainon et al., 2016). This result provided privilege of vector control which is in contrast with the
conventional belief that rainy season causes increased in vector abundance, as 10mm rainfall and
humidity of 30-70% only contributes to 1% of increased vector abundance (Phung et al., 2016).
Therefore, increasing awareness for search and destroy of stagnant water bodies post rainfall is an
effective measure to prevent vector breeding, as rainfall does not contribute to the increase of vector
abundance, but the human activities do.
Temperature
Temperature change will lead towards change in incidence and prevalence of disease pattern by
adjustment of vector’s biting rates, human contacts, and also the vector abundance (Figueroa, 2015).
Amazingly, vector Aedes species adapt well to temperature changes by changing their geographic
distributions, and there is evidence that some have produced genetic adaptation to increasing
temperatures (Patz et al., 2003). Any increase in the temperature will cause increase in growth rate of
vectors, and decrease the extrinsic incubation period which may prolonged the pathogen’s transmission
period (Figueroa, 2015). The feeding frequency (estimated by biting rates), longevity of the mosquitoes
and the time to virus replication (extrinsic incubation period) are highly sensitive to environmental
temperature conditions (Caminade, McIntyre, & Jones, 2017). Both the Aedes species and viral life
cycle exhibit non-linear relationships of transmission with temperature. A parabolic relationship with
temperature is exhibited, where maximum biting performance occurs at optimum thermal zones, while
lower or higher temperature than the optimum thermal zones exhibits lower vector performance in zero
order, similar to previous findings (Liu-Helmersson et al., 2014). Our review showed that optimum
temperature range of Tmin 3.4˚Cto Tmax 34.3˚C (minimum and maximum temperatures) is suitable for
vector Aedes sp survival. At different temperature regimens the length of the Aedes aegypti life cycle
showed variety of development rate. Faster development of life cycle recorded at temperature of 34◦C
than at 32◦C, while most larvae found to be dead at temperature of 36◦C (Mohammed & Chadee, 2011).
A study done also found almost the same findings, in which immature Aedes sp stage dead when
temperature more than 34.5◦C (Chadee & Martinez, 2016). Malaysia weather is predicted to have 0.6-
602
1.2ºC rise of surface temperature in the next 50 years (1969-2009) and projected to increase another
1.5-2.0ºC by year 2050 (Begum, March 1, 2017; Ministry Of Natural Resources And Environment
Malaysia, 2015).
This is clear evidence that climate conditions alterations such as global warming in sub-tropical
countries has resulted in a regional temperature closer to the thermal optima, explaining the increased
vector-borne disease transmission. At the same time, global warming of geopolitical regions of current
flavivirus endemicity which is conducive to mosquito-borne diseases transmission may experience
lower rate of disease transmission as the warming temperatures might move the environment away
from the thermal optimum that becomes less favourable to the Aedes sp survival (Shragai T et al.,
2017). Understanding temperature-vector survival relationship, health advises to modify time to daily
outdoor activity, such rubber harvesting, palm oil harvesting and working in construction to noon hours
where temperature peaks beyond the thermal comfort zone 3.4-34.2oC may reduce human-vector
contact. Heat modality above 34oC can be used to destroy the vector habitat.
Humidity
The acceptable range for Aedes species survival would be around 30-70mm. The annual cumulative
precipitation with is higher would strongly increase transmission for not only DENV but also ZIKV
(Messina et al., 2016). In Malaysia, there was an average increase of 17% in one-hour duration and
29% in three hours duration of precipitation intensity in 2000-2017 when compared to 1971-1980) and
is projected to experience increment in frequency of extremes weather within wet cycles (-5 to +9 ºC
change in Peninsular Malaysia, -6 to +11 ºC in Sabah and Sarawak) by year 2050 (Begum, March 1,
2017; Ministry Of Natural Resources And Environment Malaysia, 2015). In the subtropics country of
Brazil, an increase in humidity of more than 75% showed a reduction of Aedes species Density, similar
to our review (Da Cruz Ferreira et al., 2017). The development cycle of larvae and pupae is also affected
with the changing of humidity, where it varied from 5 to 42 days, with an average of 9.4 days at 24.3 °C
and 62% relative humidity but an increase relative humidity reduced the duration of development cycles
(Oliveira Custódio et al., 2019). Absolute humidity would also restrict the distribution from the drier areas
and increase in coastal areas, this will lead to an increase in vector importation due to human and trade
movement.
Since humidity beyond 70% does not favour survival of vector, in which Malaysia is having 70-72% of
humidity and humidity is always associated with monsoon season; search and destroy activity should
be intensify during dry season in April-September yearly, such as elimination of plastic containers, tyres,
durian shells and coconut husks outdoor by the residence as well as local sewage management
company and the local authority, dengue cases can be controlled. This is correlate with the data of
increased dengue cases in Selangor and Johor compared to other states for the past 5 years in
Malaysia, where both states have undergone rapid urbanization in recent years, which has introduced
problem of worsen irrigation, sewage management due to increased population density and further
displacement to high-risk environment, with pre-existing vulnerability due to low socioeconomic status.
603
By picking up this strong point, Communication for Behavioural Impact strategy used by the health
authority (COMBI) shows important role in vector control for Aedes species both globally and in
Malaysia.
Wind Velocity
In Malaysia, the optimum speed for survival and breeding of the mosquitoes are 0.05 ± 0.01 m/s. Higher
wind speed will contribute to immature mosquitoes (N. Dom & Abu, 2013), whereas a slower wind speed
will facilitate the production of larvAedes In Argentina, the average speed of more than 3km/h will lead
to a reduced density in that area (Grech et al., 2019). Since the wind velocity affects the flight range of
Aedes species mosquitoes, utilizing meteorological data in conjunction to Wolbachia release shall
synergizes the success of biological control. Wolbachia infection to Aedes species aim to induce
wingless female mosquito Aedes offspring, in which a high windspeed background can produce
synergistic effect with it for the reduction of vector abundance. Having the optimal speed would help in
the successful dispersion of the Wolbachia.(Liu, Sun, Wang, & Guo)
Strengths
The strength to this review is that no recent review on climate change in association with vector
distribution or survival was done to the best of our knowledge. Secondly, specific analysis is done on
different climate components in relation to vector distribution and survival. Recommendations of vector
control are tailored to Malaysia setting utilizing review of climate change components. The quality of
articles is being accessed narratively and objectively; combining articles on ecology, entomology,
modelling and vector prevalence worldwide and the recommendations of vector control are tailored to
local situations.
Limitations
Limitations encountered included only limited representative articles from Southeast Asian countries,
particularly Malaysia, mmodeling studies gave general estimation without considering variation in
microenvironment niche and also that most entomological / genetic studies that relates to climate
change do not directly associate to prevalence of disease during study period. Lastly would be the
possible dilutional effect of outcome from non-pathogenic carrying Aedes species has been controlled
by article selection / inclusion.
Conclusion
In conclusion, we can conclude that climate components like rain fall, temperature, humidity, wind
velocity and season affects the distribution of Aedes species Among all the components, the one that
has the most effect on the mosquito density are the rainfall and temperature. Climate change expanded
604
the transmission zone of dengue by latitude and altitude. Therefore, the climate factors should be
considered in the planning and implementation process of mosquito control and prevention. By the
implementation, improved outbreak prediction and detection through coordinated epidemiological,
meteorological and entomological surveillance can be achieved. Also, by understanding their
distributions, new technologies can be developed to reduce vector density and vector borne diseases.
List of Abbreviations
Aedes aegypti : Aedes aegypti
PRISMA: Preferred Reporting Items for Systematic Review and Meta-analysis
ZIKV: Zika Virus
DENV: Dengue virus
CHKV: Chikungunya Virus
YFV: Yellow fever virus
P.I.C.O.: population, intervention, comparison, outcome
COMBI: communication for behavioral impact
Conflicts of Interest
The author declares no conflicts of interest.
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Dengue, yellow fever, chikungunya and Zika are important arboviruses present in various countries of the world, the etiological agents of which are transmitted to human-beings by the bite of infected females of Aedes aegypti and Aedes albopictus. Biological aspects of these vectors, such as their distribution and abundance, are influenced by climatic variables such as rainfall and temperature. We assess the spatial and seasonal distribution of Ae. aegypti and Ae. albopictus, during spring 2014 and spring 2015 and autumn 2015 and autumn 2016, in an urban Municipal Park, São Paulo (SP, Brazil), using 36 ovitraps. The Park was divided into three areas: internal, intermediate and peripheral, and 12 geo-referenced ovitraps were randomly installed in each area. We evaluated the association between the environmental variables maximum and minimum temperatures and rainfall with oviposition rates in the park using negative binomial regression models. Further, to estimate the distribution of the species in the three areas during the seasons, we employed the geostatic interpolation method with the use of krigagem. Our results show the presence of the two species in the area in both the seasons but with a greater predominance of Ae. albopictus. Both species were significantly more abundant in spring than autumn. However, our results suggested that this seasonal variation was mediated by the maximum and minimum temperatures, which were significantly associated with the oviposition rate of both species, in all regression models. Cumulative rainfall of the week of collection was not associated with the abundance of the vectors in the multiple models. Moreover, regardless of climatic variables, the oviposition of Ae. aegypti was positively associated with the peripheral area of the park compared with the internal area (oviposition rate ratio [ORR]: 4.92; 95% CI: 2.46 – 9.83). On the other hand, the oviposition of Ae. albopictus was negatively associated with the peripheral area as compared with the internal one (ORR: 0.59; 95% CI: 0.38-0.91). The spatial distribution revealed a pattern of spatial segregation, confirming the ecological preferences of each species. Green areas in urban centers can serve as important habitats for various mosquito species, including especially Ae. albopictus. Thus it is that our study highlights the importance of maintaining surveillance for the targeting of control strategies in green areas as well, since most control strategies are focused on Ae. aegypti and urban residential centers.
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Objective: We conducted a study to find a relationship between main weather parameters with admission of positive dengue cases in a tertiary hospital. Methods: Retrospective analysis was undertaken to identify epidemiological trend of dengue in 2016 from paediatric wards of a tertiary hospital in New Delhi. Data were collected on patient particulars and daily weather from January to December 2016. Results: A total of 266 confirmed cases of dengue were considered. Relative humidity (RH) was associated with burden of positive dengue cases. On week-wise analysis, each surge of dengue admission was preceded by heavy rain 4-6 weeks earlier. Monthly averaged daily temperature range and RH were noted to have strong correlations with dengue burden, keeping an interval of 2 months in between. Conclusions: Weather parameters seem to influence magnitude of dengue epidemic, particularly in dengue season. There is need to have an in-depth study about developing a prediction model for dengue epidemic.
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In recent decades, the Asian tiger mosquito expanded its geographic range throughout the northeastern United States, including Pennsylvania. The establishment of Aedes albopictus in novel areas raises significant public health concerns, since this species is a highly competent vector of several arboviruses, including chikungunya, West Nile, and dengue. In this study, we used geographic information systems (GIS) to examine a decade of colonization by Ae. albopictus throughout Pennsylvania between 2001 and 2010. We examined the spatial and temporal distribution of Ae. albopictus using spatial statistical analysis and examined the risk of dengue virus transmission using a model that captures the probability of transmission. Our findings show that since 2001, the Ae. albopictus population in Pennsylvania has increased, becoming established and expanding in range throughout much of the state. Since 2010, imported cases of dengue fever have been recorded in Pennsylvania. Imported cases of dengue, in combination with summer temperatures conducive for virus transmission, raise the risk of local disease transmission.