This document discusses vector-borne diseases, specifically dengue fever, in Suriname. It outlines three hypotheses: 1) that certain demographic and clinical factors are associated with severe dengue cases in Suriname, 2) that spatial and temporal trends can identify disease hotspots, and 3) that prediction models can identify effective prevention strategies. The methodology involves analyzing clinical data from hospitals to test the first hypothesis, integrating case data into a GIS to map trends and clusters for the second hypothesis, and conducting environmental surveys to inform low-cost interventions for the third hypothesis. The analysis will characterize dengue epidemiology in Suriname and identify priority areas and strategies for control efforts.

1. Vector Borne Disease and the Environment: A
Transdisciplinary Cumulative Risk Model Associated
with Dengue
Diana Hamer, MSc, PhD(c)

2. Different Trends in Disease…
WHO, 2011

3. The Range of Infectious Diseases

Bacteria


HOST
Influenza, chicken pox,
HIV, poliomyelitis, ebola
Parasites


The Disease Triangle
Viruses


Cholera, leprosy,
tetanus
Filariasis, giardiasis,
ameobasis
DISEASE
Fungi

Fungal meningitis,
mycosis
PATHOGEN
ENVIRONMENT

4. What are vector-borne diseases?




Definite host
Intermediate host
Reservoir host
HOST
Vector: an agent that
carries and transmits and
infectious pathogen into
another organism

Mosquitos and flies, other
arthropods, bats, copepods,
cats, fleas, ticks, rats, dogs
VECTOR
DISEASE
PATHOGEN
ENVIRONMENT

5. 
Factors affecting
the Emergence /
Resurgence of
Vector Borne
Diseases
Genetic and Biological



Physical Environmental



Urbanization
Climate change
Ecological


Human susceptibility to
disease
Pathogen adaptation
Encroachment
Social / Political /
Economical



Poverty
War
Lack of political will / money

6. Strategies to curve disease incidence
Vector Control Options
•
Biological Control
•
•
•
•
Lack of surveillance /
monitoring

Sterilization techniques

Environmental manipulation /
reduction
Chemical Control
•
•
Immature and mature stages
Predators / pathogens
Physical Control
•
•

Genetic Control
•
•
Challenges
Oils, insecticides
Personal Protection
Education
Population dynamics


At all stages of
intervention
Migration, poverty,
urbanization
Climate change

Increase in habitats,
vector expansion

7. Reemergence of Vector Borne Diseases

Global Problems with local challenges

Dengue Fever in Florida


Reemerged in 2009
(Monroe County)
Currently
Martin & St. Lucie County

8. Significance

Dengue Worldwide



First recognized in 1950
Currently 2.5 million at risk
50 - 100 million dengue fever / year
DengueMap-CDC-HealthMap Collaboration

9. Dengue: The Spectrum of Disease
• No clinical signs
•
•
•
•
Fever
Headache
Myalgia / athralgia
Leukopenia
• Rash
• Petechiae
• Thrombocytopenia
• Hematemesis
• Plasma leakage
• Hypovolemia

10. Dengue Virus (DENV)



Genus flavivirus
+, single stranded RNA
4 types (DENV1-4)



Homotypic immunity
Heterotypic immunity
Antibody-dependent enhancement
Cann, 2007
Mayo Foundation for Medical Research, 2012

11. The Vector

Aedes aegypti



Urban
Tropical / Subtropical
Vector Control
Ae. aegypti
WHO, 2012

12. Dengue in the Americas


hy
po
hy
pe
re
n
en
de
m
ic
de
m
ic

Incidence
Severity
Understudied
From San Martin, et al., 2010

13. Suriname



Population
Climate
Ae. aegypti endemic


Hyperendemic dengue
Bureau of Public Health
(BOG)

14. Dengue in Suriname

Frequency and severity (BOG)

15. A Neglected Tropical Disease
•
Shifting the focus to prevent the emergence and resurgence of
infectious diseases
•
Where do you start?
•
•
Lack of political will
•
•
•
Not a priority
Vertical command structure
Complicated diseases
•
•
•
Diseases of Poverty
No good vaccine
Uneducated populations
Globalization
•
•
•
Urbanization
Vector importation
New emerging diseases

16. Transmission of Disease
Influencing factors
Competitors
Age
Human Host
Ethnicity
Gender
Immune status
Density
Breeding Sites
Dengue Virus
Serotype
Virulence
Vector
Climate
Environment
Sanitation
Urbanization

17. Hypotheses



Hypothesis 1:
There is a statistical association between demographic
and clinical factors and the progression of dengue into
the severe forms for the disease in Suriname
Hypothesis 2:
Spatio-temporal trends and relationships of factors
influencing dengue incidence and severity will identify
disease hotspots in Suriname
Hypothesis 3:
Prediction models and dengue disease cluster analysis can
identify effective prevention methods and risk reduction
strategies for dengue in Suriname

18. Study Population

19. Data Sources

Electronic databases
Source
Type of Information Aims
Saint Vincent Hospital Paramaribo (SVZ)
n ≈ 2092
-Demographic
-Clinical
Aim 1.1
Aim 1.2
Bureau of Public Health (BOG)
n ≈ 5298
-Demographic
-Clinical
Aim 2.1
Aim 2.2
Academic Hospital Paramaribo
Laboratory (AZPL)
-Demographic
-Clinical
Aim 1.1
Aim 1.2
Meteorological Service Suriname (MDS)
-Meteorological
Aim 2.1
General Bureau of Statistics (ABS)
-Census
Aim 2.1
Aim 2.2

20. Data Sources
Type of Information

Case data


Inclusion / Exclusion Criteria

Demographic
Clinical Context
Inclusion criteria



Additional Data


Meteorological
Census

Probable (hospital or clinic)
cases of dengue fever
Admitted into a hospital /
clinic - 2001 to 2012
Exclusion criteria


No available date of birth
No source or address

21. Case Classification
Definition
Criteria
Probable
Clinical
-Acute febrile illness
-Two or more of the following: headache, retro-orbital pain,
myalgia, arthralgia, rash, hemorrhagic manifestations,
leucopenia
Laboratory
-Compatible serology (reciprocal hemagglutination-inhibition
antibody titer > 1280, comparable IgG EAI titer or positive
IgM antibody test in serum specimen
Confirmed
-Clinically compatibility and
-DENV isolation in cell culture
-RT-PCR detection of nucleic acid in serum
Peeling et al. 2010

22. Methodology: Hypothesis 1





Aim 1.1: Characterize the incidence, prevalence and severity
of dengue – with an emphasis of pediatric dengue – in
Suriname from 2001 to 2012
Frequency distributions, incidence and mortality of DF & DHF
Aim 1.2: Examine the demographic and clinical factors that
influence the development of severe dengue
Univariate analysis to identify difference between groups
Multivariate analysis to test for associations
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

23. Hypothesis 2

Aim 2.1: Integrate clinical and demographic information
of all dengue cases reported in Suriname since 2001 into
a GIS platform



Generate a Geodatabase
Identify historic spatial and temporal trends
Aim 2.2: Identify spatial and temporal historic clusters of
DF and DHF from 2001 to 2012


Global clusters / local clusters
Poisson-model to assess spatial random distribution
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

24. Hypothesis 3

Aim 3.1: Characterize dengue-related entomological and
environmental data in previously identified high
transmission risk areas



Use the maps to identify areas of high dengue transmission
And conduct entomological and environmental surveys to
further assess the situation
Aim 3.2: Propose effective, low-cost dengue intervention
activities based on local information to reduce the risk of
dengue transmission in Suriname
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

25. Data Analysis

26. Hypothesis 1


Aim 1.1: Characterize the incidence, prevalence and severity
of dengue – with an emphasis of pediatric dengue – in
Suriname from 2001 to 2012
 Prevalence
Data cleaning / transforming


Incidence


In each district and resort
District and resort with
available census data
Stratified by gender, age,
ethnicity, type
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

27. Hypothesis 1

Aim 1.2: Examine the demographic and clinical factors
that influence the development of severe dengue
ADE
Prior
Infection
Increased risk
for DHF
Age
Human Host
Dengue Virus
Virulence
Ethnicity
Gender
Serotype
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

28. Hypothesis 1 (Aim 1.2)

Univariate analysis

Predetermined sample



Presence of absence of severe disease (DHF)
P1 : did not develop DHF; P2 : did develop DHF
Chi-square test for homogeneity

Ho: Pi = Pj

H a: Pi ≠ Pj

Significance: p < 0.05
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

29. Hypothesis 1 (Aim 1.2)

Multivariate analysis


Test for association of indicators on the development of DHF
Logistic regression model



Test for indicators and interaction variables (α = 0.5)



Binary outcome: [Y = 0]: no DHF; [Y = 1]: DHF
Stepwise forward selection of categorical indicator variables
Maximum Likelihood method / likelihood ratio
Odds ratio (95% confidence interval)
Chi Square goodness of fit (α = 0.5)

Significance: p < 0.05
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

30. Hypothesis 2

Aim 2.1: Integrate clinical and demographic information
of all dengue cases reported in Suriname since 2001 into
a GIS platform

Geodatabase includes


Suriname basemap (administrative level)
Layers



Cases of DF and DHF
Hospitals and clinics in Suriname
Attribute table (for data exploration)



Demographic and clinical information of cases
Weekly meteorological data- relative humidity, precipitation, average
temp
Additional district / resort characteristics- SES, access to piped water, etc.
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

31. Hypothesis 2

Aim 2.2: Identify spatial and temporal historic clusters of
DF and DHF from 2001 to 2012

Identify IF clusters exist
Global clustering – obtain Moran’s I (-1 to +1)
Yes
No
Identify specific clustering
(SatScan)
Poisson regression analysis
(log(pop)) is an offset for the population
Local Moran’s I
Overdispersion
Ho: No spatial association between the ith region
and its neighbors
Ha: There is spatial association between the ith
region and its neighbors
Ho: The data follow a Poisson distribution
Ha: The data do not follow a Poisson distribution
Create cluster map
Map Predicted values
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

32. Hypothesis 3

Aim 3.1: Characterize dengue-related entomological and
environmental data in previously identified high
transmission risk areas

Epidemiological Maps



Sample size
Unit classification
Replicates

Wet v dry season

Environmental Surveys

Unit Classification




Residential v non-residential
Rural v urban
Local characteristics
Container classification




Non traditional v traditional
Non disposable v disposable
Size & location
Water source
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

33. Hypothesis 3 (Aim 3.1)

Surveys


Immature Ae. aegypti
Larval and Pupae indices
Container
Index
# of containers w/ larvae or pupa
# of containers examined
x 100
House Index
# of houses w/ larvae or pupae
# of houses inspected
x100
Breteau Index
Pupae / person
survey
# of containers w/ larvae or pupae
100 houses inspected
# of pupae in a community
# of people in a community
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

34. Hypothesis 3

Aim 3.2: Propose effective, low-cost dengue intervention
activities based on local evidence-based information to
reduce the risk of dengue transmission in Suriname



Historical cases of dengue help identify spatial and temporal
patterns of transmission
The importance of environmental and entomological data
collection in elucidating populations at higher risk of
transmission
Epidemiological, entomological and environmental surveillance
is necessary to move from an ad hoc basis to a more
prevention oriented approach
Significance • Background • Transmission of Disease • Hypotheses • Study Population • Methodology • Data Analysis

35. Increased risk
for DHF
Prior
Infection
Age
Competitors
Human Host
Adult
Larva
Pupae
Race
Gender
Temperature
Density
Rainfall
Vector
Dengue Virus
Serotype
Breeding Sites
Virulence
Climate
Humidity
Environment
Sanitation
Urbanization
Pop. Density

36. Acknowledgements



Dr. Lichtveld
Dr. A. Jessurun at the Saint Vincent Hospital
Dr. Hiwat and Dr. Jubithana at the Bureau of Public
Health

37. Questions & Comments