Edited by: PROF. DR. PRATIWI TRISUNUWATI, DRH, MSTIM EPID FAPETT 2017/II/III/PTS 3/20/2017 35 Sporadic level: occasional cases occurring at irregular intervals Endemic level: persistent

Edited by:

PROF. DR. PRATIWI TRISUNUWATI, DRH, MS

3/20/2017TIM EPID FAPETT 2017/II/III/PTS 1

Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations.

It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare.


Epidemiology is the study of disease in populations. ...

Epidemiological methods are used for disease surveillance to identify which hazards are the most important.

Epidemiological studies are also used to identify risk factors which may represent critical control points in the food production system.


Epidemiology is the study of the distribution and determinants of diseases in populations.

It is the key quantitative discipline that underpins public health, which is often defined as the organised efforts of society to prevent disease and to promote health.


Animal Diseases cause major economic loss through mortality, reduced productivity, lower fertility, condemned products and restricted access to potential markets

Newly emerging animal diseases are known to cross over to human population and vice versa

Approximately 60% of all known pathogens and 75% of emerging pathogens are zoonotic in nature (Taylor et al., 2001)


Of all the newly emerging diseases encountered on daily basis , almost all are having their reservoirs in animals

Impoverished settings mostly in tropical developing world act as hotspots for theses zoonoses.

World has seen epidemics of diseases like Avian Influenza, Swine Influenza, FMD, in the last two decades


Prevention and control disease agents (biosecurity) BASED ON LIVESTOCK MANAGEMENT

Health of animals, humans and environment◦ Concepts and methods of epidemiology

◦ Practical and information


“Hot Spots” of the World

South Asia

Bangladesh

India

Nepal

Southeast Asia

Cambodia

China

Indonesia

Laos

Malaysia

Philippines

Thailand

Vietnam

Congo region

Angola

Burundi

Cameroon

CAR

Congo

DR Congo

Eq. Guinea

Gabon

Rwanda

Tanzania

Uganda

Amazon

Bolivia

Brazil

Colombia

Ecuador

Mexico

Peru

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Epidemiological principles for disease control strategies:

- selection of strategies for disease control

- how do specific options affect riskBASED ON the analysis process ?



Principles and considerations when estimating disease level at country / region level

Measuring/estimating risk from survey / survaillance data

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Epidemiological principles and considerations for designing and conducting survey, monitoring and surveillance

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Methods for data collection, storage and management for these systems

Measuring disease frequency and its application in animal health decision-making


A model used to explain the etiology of infectious diseases.

Recognizes three major factors in the pathogenesis of disease: agent, host, and environment.


Epidemiology triad: explain why diseases occur in a population


Disease is the result of forces within a dynamic system consisting of:

agent of infection

host

environment

Epidemiologic Triad


Environment

Host Agent

Environment

Host

Agent

Environment

Host

Agent


Environment

Host Agent

Environment

Host Agent


Biological ◦ Viruses Bacteria Parasites or prions

Chemical◦ Toxins

◦ Man-made (Dioxins and melamine)

◦ Inorganic/organic: zearalenone

Physical◦ Foreign bodies

◦ Trauma

◦ Radiation



A case is a risk factor …

Infection in one person can be transmitted to others

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Agent and host in adequate number

◦ Recent increase in amount of the agent

◦ Recent increase in infectivity / virulence of the agent

◦ Recent introduction of the agent

◦ Enhanced mode of transmission

◦ Increase of host exposure

◦ Change in the susceptibility of the host response to the agent

◦ Introduction through new portals of entry


• Infectivity

• Pathogenicity

• Virulence

• Immunogenicity

• Antigenic stability

• Survival

• Weather

• Housing

• Geography

• Occupational setting

• Air quality

• Food

• Age

• Sex

• Genotype

• Behaviour

• Nutritional status

• Health status

AgentEnvironment

Host

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EPIDEMIOLOGY

• STUDIES ON AMOUNT OF DISEASE• DISEASE IN POPULATION / HERD • DISEASE DISTRIBUTION ON DIFFERS

POPULATION

• FACTORS THAT DETERMINE DISEASE/SOCCURRENCE

• CONTROL OF DISEASE IN POPULATION

ECONOMICAL IMPACT

POPULATION, LOCATION, TIMES

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1. KEY WORDS OF EPIDEMIOLOGY

• DEFINITE LOCATION

• DEFINITE TIME

• DEFINITE POPULATION

2. LARGE SCALE OF

OUTBREAKS. • DURING PERIODE

• PRECIPITATING CRISES

3. CRISES

• LOSS OF PRODUCTION

• LOW OF QUALITY PRODUCT

• LOW OF REPRODUCTION RATE

• IN EFFICIENCY OF FEED INTAKE

• SUB CLINICAL DISEASE

• HIGH MORBIDITY RATE

• HIGH MORTALITY RATE

• COMPLEX INFECTIOUS DISEASE

• RETARDED GROWTH RATE



PREVALENCY RATE

MORBIDITY RATE

MORTALITY RATE

POPULATION AT RISK

INCIDENCY RATE

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Calculate and interpret the following epidemiologic measures:

– Ratio

– Proportion

– Incidence proportion (attack rate)

– Incidence rate

– Prevalence

– Mortality rate

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Discipline: the general approach is to creating order and structure from incomplete knowledge

Study: combines learning about epidemiology theory with on the job field application

Frequency: means that we count characteristics in a population of people or animals

Distribution: describes the patterns of disease in a population, in a particular place during a period of time


Health: refers to measures of optimum productivity due to lack of disease (meat, eggs or milk)

Disease: refers generally to an imbalance in the health status of individuals or populations that result in decreased productivity, illness or death

Population: refers to the group of individual animals or people that are considered or affected


Prevent: means not providing the opportunity for a disease to occur

Control: method to reduce the extent of disease in a population or area

Risk factors: risk is the probability that a factor the population is exposed to be associated with the occurrence of disease


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Define the problem.

Appraise existing data.◦ Case identification◦ Clinical observations◦ Tabulation and spot maps◦ Identification of responsible agent

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The number of deaths caused by a disease among those who have the disease.

Examples of diseases with a high CFR are ND and AI

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Number of deaths due to disease “X “ x 100

Number of cases of disease “X “

Sample calculation:

Assume that an outbreak of AI occurs in an Asian country. Health authorities record 98 case of the disease, all of whom are untreated. Among these, 60 deaths are reported.

CFR = (60/98) x 100 = 61.2%

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EndemicTransmission occur, but the number of cases remains

constant

EpidemicThe number of cases increases

PandemicWhen epidemics occur at several continents – global

epidemic

Time

R = 1

R > 1

R < 1

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Sporadic level: occasional cases occurring at irregular intervals

Endemic level: persistent occurrence with a low to moderate level

Hyperendemic level: persistently high level of occurrence

Epidemic or outbreak: occurrence clearly in excess of the expected level for a given time period

Pandemic: epidemic spread over several countries or continents, affecting a large number of people

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Endemic EpidemicNum

ber

of

Cases o

f a D

isease

Time

Endemic vs Epidemic

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DISTRIBUTION PATTERN

ENDEMIC

EPIDEMIC

SPORADIC

DISEASES EXAMPLES

DISTOMATOSIS COCCIDIOSIS MASTITIS

AVIAN INFLUENZA NEW CASTLE DISEASE

ANTHRAX


STATUES DISEASES

ECONOMIC DISEASES

STRATEGIC DISEASES

FASCIOLIASIS MASTITIS GUMBORO

BRUCELLOSIS AVIAN INFLUENZA FMD



Documents

Edited by: PROF. DR. PRATIWI TRISUNUWATI, DRH, MSTIM EPID FAPETT 2017/II/III/PTS 3/20/2017 35 Sporadic level: occasional cases occurring at irregular intervals Endemic level: persistent