Spatial and Temporal Distribution of Dengue. A Case Study of Lahore
©2016
Textbook
61 Pages
Summary
This study was conducted to evaluate the dengue outbreaks pattern in spatial and temporal contexts and to identify the meteorological constraints behind the spread. The aim was to gain a complete picture of the scenario. The Lahore District was selected as the study area which was affected by mosquitoes to a great extent. Lahore is the second largest city of Pakistan with respect to its population due to its rapidly growing urbanization. The environmental factors affecting the spread of the disease have been identified and then mapped in a GIS based environment by using all the spatial and tabular data obtained from different sources. The factors affecting dengue spread were found to be Land Surface Temperature (LST), Land cover/Land use, Normalized Difference Vegetation Index (NDVI), Temperature, Rainfall, and Population Density.
Excerpt
Table Of Contents
3.2
3.3
3.4
3.5
3.6
Geographic Location of Study Area
Land Cover of Study Area
Hydrological Layer of Lahore City
Climatic Conditions
3.5.1 Temperature
3.5.2 Rainfall
Suitable Breeding Sites for Dengue
19
20
20
21
21
22
23
Chapter Four Materials and Methods
4.1
Data Collection
24
4.2
4.3
4.4
4.1.1 Epidemiological Data
4.1.2 Population Density
4.1.3 Identification of Environmental Parameters
4.1.3.1 Precipitation
4.1.4 Data from Landsat V
Methodology
4.2.1 Land cover/ Land use
4.2.2 Land Surface Temperature (LST)
4.2.3 Normalized Difference Vegetation Index (NDVI)
4.2.4 Spatial Units to analyze and map Dengue Incidence
data
4.2.5 Temporal Units
Data Analysis
Identification of risk areas
24
25
26
27
27
27
27
28
30
31
32
32
33
Chapter Five Results and Discussions
5.1
An Overview
34
5.2
Spatial Pattern of Dengue Occurrences
5.2.1 Land Surface Temperature and Dengue Incidences
5.2.2 Land Cover Map against Dengue Occurrences
5.2.3 Normalized Difference Vegetation Index
5.2.4 Population Density
34
34
35
37
38
iv
5.3
5.4
Identification of High Risk Areas Using overlay Analysis
for 2011
Temporal Analysis between 2011 and 2012
40
42
Chapter Six Conclusions and Recommendations
6.1 Conclusions
6.2 Limitations
6.3 Future Recommendations
References
44
45
45
47
v
List of Figures
Chapter One Introduction
Figure 1.1 Conceptual Framework of the Research
7
Chapter Three Study Area
Figure 3.1 Geographic Location of Study Area in the Country
18
Figure 3.2 Map of Lahore District with its UC boundaries
19
Figure 3.3 Map of Hydrological Layers of Lahore District
21
Chapter Four Materials and Methods
Figure 4.1 UC Wise population density of Lahore District - 2011
26
Figure 4.2 Land cover Classification done in ERDAS Imagine and
mapped in ArcGIS 9.3
28
Figure 4.3 Land Surface Temperature for September, 2011
29
Figure 4.4 Land Surface Temperature for September, 2012
30
Figure 4.5 Normalized Difference Vegetation Index (NDVI)
31
Figure 4.6 Map showing the most critical areas for dengue spread
33
Chapter Five Results and Discussions
Figure 5.1 LST of 2011 with No. of patients in all UCs of Lahore
35
Figure 5.2 Land Cover Categorization of Landsat V image for Sept, 2011
37
Figure 5.3 NDVI in Comparison with the number of patients for Sept,
2011
38
Figure 5.4 Population Density compared with the population density
39
vi
Figure 5.5 Accumulative map for spread pattern of dengue with all its
causal parameters
40
Figure 5.6 Accumulative map of dengue Spatial spread pattern with all
the parameters
41
Figure 5.7 Dengue Spread pattern for the year 2011
42
Figure 5.8 Dengue Spread pattern for the year 2012 43
vii
List of Tables
Chapter Three Study Area
Table 3.1:
Land Cover Classification with its percentage
20
Chapter Four Materials and Methods
Figure 4.1
Monthly no. of reported patients of Dengue
25
viii
List of Graphs
Chapter Three Study Area
Graph 3.1 Temperature curve for the year 2011
22
Graph 3.2 Comparison of rainfall in mm of the years 2011 & 2012
23
Chapter Four Materials and Methods
Graph 4.1 Graphical representation of patient count for 2011
24
ix
Introduction
Chapter
1
Chapter 1
Introduction
1.1 Background
Dengue Fever (DF) and Dengue Haemorrhagic Fever (DHF) are important public
health concerns in the tropic and sub-tropic areas all over the world, during past
50 years. Rapid urbanization, increasing population movement, Global Warming
and Drastic Climatic changes that contribute to the proliferation of man-made
habitats of the mosquito are the prominent factors for the increasing numbers of
Dengue incidences. The DF and DHF occur over 100 countries throughout the
Americas, Southern Europe, North Africa, Mediterranean, Asia and Pacific
regions.
It is the most common vector-borne viral disease of humans worldwide with an
estimate that 50 million infections occur annually, with 500,000 cases of DHF
which is an even more dangerous form of Dengue infection and at least 12,000
deaths. (Umor S et al, 2002). As far as the most affected areas are concerned,
prevalence of Dengue is highest in Tropical areas of Asia and America, with 50 to
100 million estimated cases of DF and 250,000 to 500,000 cases of DHF occurring
annually worldwide as explosive outbreaks in urban areas. (
Chinnock, 2009
)
This Tropical and Sub-Tropical disease is most prominent in urban and semi-urban
areas. DHF, a potentially lethal complication, was first recognized in 1950s in the
Philippines and Thailand, but today DHF affects most Asian countries
predominantly in the developing countries where environmental condition is quite
poor and health facilities are insufficient. DHF is now becoming a leading cause of
hospitalization and death, majority of them are children. (Bhandari K et al).
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Introduction
Chapter
1
Dengue has been the talk of the town during past almost five years in Pakistan.
The cause of its fame is its disastrous mortality rate, its rapid spread and the after
effects if the patient survives. It is a viral disease rather a tropical viral disease that
is caused by an infectious mosquito named Aedes Aegypti that directly attacks the
immune system of the infected person. Dengue has been a part of Pakistan since
1982 but during last two years it took form of a monster that horrifies everyone with
its wide spread across the country. Lack of efficient prevention planning
techniques, insufficient health facilities, poor sewerage systems, bad quality
sprays, and hazardous environment supported this monster making it even more
powerful. Moreover, the most alarming fact about Dengue is about its breeding
sites. It is a clean water mosquito that breeds well over clean stagnant water.
The DF/DHF is a Public Health problem in Pakistan where the number of such
reported cases has dramatically increased during the last ten years. Remote
Sensing and Geographic Information System (GIS) technologies have been used
in this study to link and update information on the environment, weather conditions,
reported number of Dengue cases and other prominent factors. These
technologies have been widely used in Public Health sector for managing and
monitoring the problem. Remote Sensing data is utilized to manage the problem
by incorporating population data and environmental factors such as changes in
land use/land cover, land surface temperatures, rainfall etc.
1.2 Need of Research
Dengue Infection (Anti-D3) was first documented in 1982 from Punjab (Central
Province of Pakistan) in 12 patients out of a blood sample of 174 blood samples
of different people collected in 1968 and 1978. The first reported outbreak of
Dengue Haemorrhagic fever in Pakistan was in 1994. According to a recent study,
WHO has classified Dengue Infection in Pakistan into Dengue Fever, Dengue
Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). Out of 225
cases (particularly taken for research purposes) 137 (61%) were found to have
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Introduction
Chapter
1
Dengue Fever, 81 (36%) were having Dengue Haemorrhagic Fever (DHF) and 7
(3%) were having Dengue Shock Syndrome (DSS). During year 2000 to 2004,
73% of Dengue Infected patients had Dengue Fever, 24% had DHF and 2.4% had
DSS whereas after 2005, the ratio of DHF was increased by 39% while 58% got
Dengue Fever and 3% got DSS.
Punjab got the highest outbreak of Dengue and more precisely, Lahore got the
maximum number of patients/deaths reported during last 2 to 3 years. The actual
figures are far greater than the ones we got from the clinical data which included
the number of people who got their treatment at home by self-medication. Lahore
is a very large district having nine towns which are further subdivided into 150
Union Councils each with slightly different environment in urban perspective.
Among them, some areas are having wealthier neighborhoods having more
greenery and hence a better and healthier environment but still was the hot spots
for dengue outbreak which causes confusion for health Authorities and simulated
a lot of researchers to find the reasons.
Dengue surveillance and control in large urban areas with high levels of dengue
transmission are the most important challenges. Clinical surveillance is impaired
by the high proportion of asymptomatic infections, and mosquito surveillance is
very time consuming and resource consuming task. Moreover, despite the
theoretical and numeric relationship between vector abundance and risk and
potential of transmission is still poorly known. And, due to unavailability of vaccines
or any particular medication, this quantitative assessment is quite necessary to
know.
(
Chinnock, 2009
)
1.3 Scope of Research
Dengue fever over the last 5 years has become one of the most serious diseases
in Pakistan. Dengue is an arboviral disease transmitted by a mosquito called
Aegypti having four serotypes, i.e. DEN-1, DEN-2, DEN-3, and DEN-4. It is a pre-
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Introduction
Chapter
1
domesticated mosquito that prefers to breed in clean water sites such as artificial
containers, swimming pools, ponds etc. Lahore has been the major target of this
perilous virus where the count of reported cases was maximum throughout
Pakistan. Considering the fact that there is no vaccine available for this severe viral
disease, it is very important to map dengue outbreak dynamics with all the
environmental parameters for the prediction of high risk areas and conditions
under which this virus persists in order to take precautionary measures.
Secondly, mapping the current situation of patient count along with their location
may also help to properly plan the medical facilities. It has seen that, in areas with
a wealthy population, the access for medical facilities is not a big deal and hence
it directly influences the fatality rate, no matter the number of infected people is
lesser or greater. Pakistan being a developing country, lack in financial resources
and there for it is the need of the hour to launch an effective planning program
which should be efficient enough so that wastage of finance, resources and efforts
could be avoided. Mapping of accurate patient count along with their access to
medication would definitely help in achieving this goal.
Geographic Information System (GIS) and Remote Sensing can efficiently be used
for disease mapping to highlight the high risk areas for pre-planning against spread
of that particular epidemic to avoid a large number of fatalities. GIS has made it
easy to analyze the clusters of reported cases with their geographic location and
the environmental parameters of the location where the major outbreak took place
and the prediction of other high risk areas with temporal dynamics of different
epidemics, which further incorporated with different types of data may help to
launch a planned medical.
Advances in Remote Sensing technology and GIS have enabled us to get crucial
information and their modeling on Dengue transmission. Remote Sensing provides
up to date information for Land use and Land change, Vegetation, Surface
Temperatures, and Water Bodies etc. Whereas GIS enables us to model all the
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Introduction
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1
available information for a better understanding and illustration of all phenomenon
taking part in the spread of the disease as well as prediction and planning for the
prevention in future outbreak areas.
1.4 Problem Statement
A lot of our Administrative Authorities are working day and night to overcome this
disastrous outbreak of Dengue in as planned manner as possible. The need to
figure out the actual reasons why Dengue appeared on this part of land is as
important as the need of provision of effective health facilities. The reason why
some places are best breeding sites of Dengue, which kind of environment
enhances its breeding, its cycle (i.e. the peak months of Dengue outbreak) and the
pattern on spread is very important to know. Are the expected parameters really
affecting the breeding of Dengue or is it just a myth? All these problems are yet to
be known and are quite significant so that, with the passing years, the loss of
precious lives could be avoided.
1.5 Objectives and Work Flow
About 2500 million people are reported to live in the regions with the estimated risk
greater than 50% for Dengue transmission, one of the world's most widespread
vector-borne diseases. An Empirical Model Analysis also shows that, if climate
stays mild, about 3.5 billion people, 35% of the population will be at risk of Dengue
transmission in 2085, and about 5 to 6 billion people (50 to 60% of the projected
global population) is the change worsens. (Hales et al., 2002). Unavailability of
vaccines has made the situation even more dreadful. The mortality rate in
developing countries is more alarming as compared to developed countries due to
poor health facilities and certain environmental factors. The only cure for this vector
borne disease is no cure and hence prevention has become null and void.
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Introduction
Chapter
1
A quick launch of control activities has already been done but prediction of high
potential risk areas is still a major issue due to the great diversity in the
epidemiological pattern of the DHF which makes DF difficult to predict.
Two main patterns may describe the fluctuations of in occurrence of DHF. The
cyclic pattern refers to the seasonal variations of transmission. The viral disaster
reaches a peak during the hot and rainy season (conditions being suitable for
breeding of Dengue Mosquito). The end of the rainy season results in a return to
a lower level of transmission. This phenomenon is repeated every year and
characterizes the regional mode of transmission. This Cyclic Pattern of Dengue or
more precisely called the Dengue Wave has been identified in this study using the
clinical data. (Barbazan. P et al. 2000)
Secondly, another range of temporal changes has been identified, taking two years
i.e. 2011 and 2012 as sample for our study. The clinical as well as meteorological
data has been compared between these two years to figure out the causes behind
the change between these two consecutive years. In 2012, a drastic decrease in
number of patients has been analyzed which was quite surprising. The later
sections include the changing patterns and the caused behind them. The temporal
analysis was aimed to map the changing trends and to make the results of control
and prevention so that it may become a sample for other affected areas
6
Details
- Pages
- Type of Edition
- Erstausgabe
- Year
- 2016
- ISBN (PDF)
- 9783960675532
- ISBN (Softcover)
- 9783960670537
- File size
- 4.1 MB
- Language
- English
- Institution / College
- University of the Punjab
- Publication date
- 2016 (June)
- Grade
- A+
- Keywords
- Lahore Pakistan Spatial pattern Epidemiology Spatio-temporal Mapping Dengue fever Dengue virus GIS based environment
