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.

THANK YOU