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TRANSCRIPT
DR MAZRURA SAHANI
5TH OCTOBER 2015
10th JOHOR SCIENTIFIC MEETING
Communicable Disease Transmission-
How Do We Deal with
Environmental Risk Factors?
Jabatn Kesihatan Negeri Johor
OUTLINE
Some concepts in Epidemiology for Disease Transmission, Risk
Assessment and Risk Management
Environmental Determinants of Communicable Disease
Increasing Environmental Risks to Communicable Disease
Emerging and Re-emerging Diseases
Drivers of Changes to Infectious Disease Risks
WHO, 2011. Public Health and Environment: Strategy Overview
Transmission of communicable diseases The epidemiologic triangle or triad is the traditional model of infectious
disease causation.
Environ-
ment
Agents HumanDirect contact
• Number of agents
• Characteristics of agents
• Pathogenicity
• Defense mechanisms
• Immunity
• Personal characteristics
Potential Exposure Pathways in the Environment
•Prevailing Wind Direction•Exposure
•Point•Exposure
•Point
•Ingestion
•Exposure
•Route
•Inhalation
•Exposure
•Route
•Transport
•Medium (Air)
•Release Mechanism
•(Volatilization)
•Exposure
•Point
•Release
•Mechanism
•(Spill)•Exposure
•Medium (Soil)
•Waste
•Pile
•(Source)
•Release
•Mechanism
•(Site Leaching)
•Transport Medium
•(Ground Water)
•Water Table
•Ground Water Flow
•Dermal
•Exposure
•Route
• RESEARCH RISK ASSESSMENT RISK
MANAGEMENT
•Laboratory and Field
Observation of
Adverse Effects from
Particular Agents
•HAZARD IDENTIFICATION
•Does the agent cause adverse effects
•Structure activity Analysis
•In vitro tests
•Animal bioassays
•Epidemiology
•New mechanistic
understanding of
toxicity
•Field Measurements
of exposures, exposed
populations
•DOSE-RESPONSE ASSESSMENT
•What is the relationship between dose
and response
•susceptibility
•EXPOSURE ASSESSMENT
•What types,levels and duration of
exposures are experienced or
anticipated
•RESEARCH
•RESEARCH
•NEEDS
•RISK
CHARACTE
RISATION
•What is the
nature and
estimated
incidence of
adverse
effects of a
given
population?
•How robust
is the
evidence?
•How certain
is the
evaluation?
•Development of
Regulatory
Options
•Evaluation of
Public Health
Economic,
Social, Political
Context for Risk
Management
Options
•Policy Decisions and Actions
RISK ASSESSMENT/MANAGEMENT FRAMEWORK
Public health and environment:
Increasing environmental risks
Increasing urbanization is driving greater exposure to/increasing the
intensity of air quality, water, and waste management risks
Rise of employment in informal sector exposing more and more
people to occupational hazards
Continued growth of chemicals industry (especially in lower and
middle income countries) and broader assessment of chemical risks is
raising chemicals management threats
Rising oil prices and efforts to improve energy efficiency have
potentially perverse effects – (e.g. higher exposure to radon gas in
energy efficient homes, increased particulates from switch to diesel
engines)
Climate change exacerbating a whole range of risks
Source:WHO 2011
Source : WHO. 2006. Preventing diseases through healthy environments. Geneva : WHO Press.
A wide range of environmental risk drivers are now known to lead to and/or
exacerbate the emergence and spread of infectious disease.
Source : WHO. 2006. Preventing diseases through healthy environments. Geneva : WHO Press.
Infectious diseases account for 29 of the 96 major causes of morbidity and mortality
representing a quarter of global burden of disease
Introduction Substantial studies on the health effects of ambient air pollution
were published internationally. These studies ranged from mortality, morbidity effects to molecular epidemiology.
Epidemiological studies have established the link
between ambient air pollutants and health effects (Makri & Stinakis, Int. J. Hyg. Environ.Health, 2008.
Human and animal toxicology has had a profound impact on our historical and current understanding of air pollution health effects (Stanek et al, Toxicol Sci 2011)
However limited environmental and occupational epidemiological studies were conducted locally.
Few studies undertaken locally will be presented.
•25/10/2015•Page 12
•WHO, 2002: Urban air pollution contributed to 800,000 deaths per year, 2/3 in Asia
of respiratory mortality at lagged 5 (OR=1.66; 95% CI=1.03-1.99). This study clearly indicates that exposure to haze
events showed immediate and delayed effects on mortality.
•25/10/2015•Pa
ge
14
Environmental determinants of infectious disease
(EnvID) framework.
Source: Eisenberg et al 2007
Source: Patz, et al 2005
EMERGING INFECTIOUS DISEASES
Emerging infectious diseases are “New diseases; new problem (New threats)”
Emerging infectious diseases are those whose incidence has increased over the past 30 years. Some are diseases that have never been seen before.
Some were previously documented but without a known etiology.
•More than 30 new
diseases have been
identified in the past
30 years, including:
Re-emerging Infectious Diseases
Re-emerging infectious diseases are “old diseases, new
problem. (New threats)”.
A re-emerging infectious disease is a one which was
previously controlled but once again has risen to be a
significant health problem.
This term also refers to that disease which was formerly
confined to one geographic area, has now spread to
other areas.
Global examples of emerging and re-emerging
infectious diseases
•Source: Morens et al. 2004. The challenge of emerging and re-emerging infectious diseases. Emerg Infect Dis. 430: 242-249
Drivers of Changes to Infectious
Disease Risks
The Factors Responsible for Disease Emergence
Improper planning of the township
Population explosion
Poor living conditions
Over crowding
Industrialization
Urbanization
Migration of population
Lack of health care services
Intense international travel
Globalization
Cont… Indiscriminate use of antibiotics and development of
resistance
Increase in contact with animals
Insecticide resistance
Alterations in micro-organisms
Environmental degradation with changing weather pattern.
Illiteracy and ignorance
Natural disasters
Predisposing Factors for the
Epidemic
Before the on set of
epidemic
Flood/ landslide/ Haze/ Earth
quake
• During the epidemic
Migration of the people
Eruption of slums
Collection of garbage
Scarcity of antibiotics
Daszak et al,
Science 2000
EMERGING INFECTIOUS DISEASE OF WILDLIFE-THREATS
TO BIODIVERSITY AND HUMAN HEALTH
Emerging Diseases in Malaysia and Global
Diseases due to new agents (Eg.Nipah,AIDS)
Diseases due to new variants of known pathogens (Eg.AvianFlu)
Diseases caused by an infectious agent but resulting in non-communicable diseases. (Eg.Hep. B and Hep C results in livercancer)
RE-EMERGING INFECTIOUS DISEASE Many of these diseases were thought to be controlled through
antibiotics.
In some cases the re-emerging disease is resistant to
antibiotics.
•Reported prevalence
of XDR-TB among
MDR-TB cases,
•2002-2007
•World Health
Organization
Safe water
Sewage treatment and disposal
Food safety programme
Animal control programme
Vaccination programme
Public health organization
Public health measures to prevent infectious diseases
Control of Emerging and
Re-emerging Diseases
Controlling the reservoir
Interrupting the transmission
Protecting the susceptible host
Strengthening of the disease surveillance system
Encouraging research initiations for treatment regimens and diagnostics
Encouraging research for new methods of control measures
Establishment of drug resistance
Role of Health Professionals in Prevention Increase knowledge and skill
Encourage partnerships with consumers and other disciplines to identify needs, set priorities, develop strategies and evaluate progress
Support health care legislation
Involve in research
Encourage using trans-disciplinary efforts.
Influence local and national economic and political options
Continue to advance public health control measures
Educate the public
Way Forward McMichael 2000: Transdisciplinary is more than mixing and interbreeding of
disciplines: Trans-disciplinary transports us: We then ask different questions, we see further and we perceive complex
world, and its problem with new insights.
All hands on deck!: Trans-disciplinary approach in EID (Parkes et al 2005 Transdisciplinary approaches to EID.pdf )
One Health: The Human-Animal-Environment Interfaces in Emerging Infectious Diseases (Mackenzie et al 2013): One Health is an emerging concept that aims to bring together human, animal, and
environmental health.
One-Health University Network: MyOHUN: since 2012 http://www.myohun.com/p/blog-page.html
To promote the philosophy and spirit of One Health in working together to respond to new and emerging diseases.
Aims to forge collaborations between academicians, professionals, scientists and communities across sectors with responsibility for health of humans, domestic animals and wildlife.
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