Understanding the Study of Epidemiology

Epidemiology
SUNNY YADAV
BPH, TU
12/16/2018 1SUNNY 12/16/2018YADAV BPH/BEd

Epidemiology
EPI DEMO LOGOS
Upon,on,befall People,population,man the Study of
The study of anything that happens to
people
“That which befalls man”
12/16/2018 2SUNNY YADAV BPH/BEd

Epidemiology: Definition
Dynamic study of the
Determinants
Occurrence
Distribution
Control
Pattern
Of health and disease in a population

Definition of Epidemiology
"The STUDY of the DISTRIBUTION and
DETERMINANTS of HEALTH-RELATED STATES
in SPECIFIED POPULATIONS, and the
APPLICATION of this study to control of health
problems."
*Last, J.M. 1988. A Dictionary of Epidemiology, 2nd ed.

Clinician Epidemiologist
Patient’s
diagnostician
Investigations
Diagnosis
Therapy
Cure
 Community’s
diagnostician
 Investigations
 Predict trend
 Control
 Prevention

Purposes of Epidemiology
1. To investigate nature / extent of health-
related phenomena in the community /
identify priorities
2. To study natural history and prognosis
of health-related problems
3. To identify causes and risk factors
4. To recommend / assist in application of /
evaluate best interventions (preventive
and therapeutic measures)
5. To provide foundation for public policy
6SUNNY YADAV BPH/BEd12/16/2018

Function / Uses of Epidemiology
• Study historically rise and fall of disease
• Conduction of a community diagnosis
• Health planning and evaluation
• Evaluation of individual’s risk and changes
• Syndrome identification
• Completion of natural history of disease
• Searching for causes and risk factors

Components of Epidemiology
• Disease frequency: Measurement of frequency of
disease, disability or death in the forms of rate and
ratio (Incidence rate, prevalence rate and death
rate)
• Disease distribution: Measurement of distribution
of disease in population by time, place and person
which helps in prevention and control of disease
• Disease determinant: Measurement of risk factors
or causes of disease

Kinds of Epidemiology
• Descriptive
• Analytic
• Experimental
Further studies to determine the
validity of a hypothesis concerning
the occurrence of disease.
Deliberate manipulation of the
cause is predictably followed
by an alteration in the effect
not due to chance
Study of the occurrence and
distribution of disease

Overview of epidemiologic design strategies
• Descriptive
Case Report
Case Series
Cross-sectional
• Analytical
Cross-sectional
Case-Control
Cohort
Correlation (ecological)
12/16/2018 SUNNY YADAV BPH/BEd 10
Interventional/Experimental
Randomized controlled trial
Field trial
Clinical trial
Community trial
 Observational: help to generate hypotheses
(descriptive) or to test hypotheses (analytic)

• First phase of epidemiological
investigation
• It formulates hypothesis
• Describes in term of person, place and
time
• This type of study is appropriate in acute
infectious diseases like cholera, typhoid,
dysentery, ARI, etc.
• The unit of study is population at risk
Descriptive Epidemiology
PERSON
PLACE
TIME

Procedure of descriptive epidemiology
• Defining the population
• Defining the disease under study
• Describing the disease in term of time , place and person
• Measurement of disease
• Comparison with known indices
• Formation of hypothesis

Person Distribution of disease
• Age: measles in childhood , cancer in middle age and
arthrosclerosis in old age
• Sex: lung cancer and coronary heart disease are more
common in male while obesity , diabetes and
hyperthyroidism are more common in female
• Marital status: STDs are more common in unmarried
• Occupation: silicosis is more common in workers of coal
• Socioeconomic status

Time Distribution of Disease
1. Short term fluctuation or outbreak
(Epidemic)
– Common source epidemic
• Point source or single exposure
• Continuous or repeated exposure
– Propagated epidemic
– Slow epidemic or modern epidemic
2. Midterm fluctuation or Periodic fluctuation
– Seasonal trend
– Cyclic trend
3. Long term fluctuation (Secular trend):
If normal expectancy is
zero, even one case is
considered “epidemic”
Epidemic
No. of cases > Mean +
2 SD

Common Source Eidemic
1. Group of people
2. Common exposure of
pathogen
3. Short incubation
period
E.g. food poisoning,
measles, chicken pox,
cholera, Bhopal gas
tragedy, etc

Propagated epidemic
1. Person
2. Individual contact
3. Spreading in
community
E.g. HIV, TB,
Arthropod vector,
animal reservoir,
etc.

Compare Common Source Propagated source
1.Curve Bell curve Scatter bell
3.Transmission One source From person to
person
4.Duration Short Long
5. control Eradicate source Health education

Seasonal Variation
• Seasonal variation
can be seen for some
diseases or conditions
falling within a
calendar year
• E.g. measles-early
spring, URTI-winter,
GI infection-summer,
typhoid-rainy, etc

Cyclic Trends
• occurrence of disease in a cycle.
• E.g. measles (every 2-3 years), rubella (every 6-9
years), influenza pandemic (every 10-15 year), etc.

Secular trend (Long term fluctuation)
• Temporal variation
occur slowly over
long periods of time
generally several
years or decades
• E.g. Diabetes,
obesity,
hypertension are
increased in past few
decades, polio,
pertusis,12/16/2018 20SUNNY YADAV BPH/BEd

Place Distribution of disease
• International
• Variation within
countries
– Urban-rural
– Local
• Building Maps

Analytical Epidemiology
• Deals with risk factors of diseases
• Test hypothesis
• Unit of study is individual

Cross sectional study
• Prevalence study
• simplest form of
observational study
• SNAPSHOT of the
population study
• This type of study is
appropriate for chronic
diseases
Ecological study
• Co-relational study
• Only in this study, unit
of study is population

Cohort Study
• Prospective study /
forward study / follow up
study
• Study proceeds forward
from cause to effect
• Risk factor to Disease
• Measures incidence study
• Measured by relative risk
Case control study
• Retrospective study /
backward study
• Study proceeds backward
from effect to cause or
outcome to exposure
• Disease to Risk factor
• Measured by odd’s ratio
and Chi Square test (for
comparisons)

Experimental Epidemiology
• Confirms hypothesis
• Helpful for intervention
• 4 types
Randomized controlled trial
Field trial
Clinical trial
Community trials

Terminologies

Infection/Disease/Infestation
• Infection: entry, development and multiplication of
an infectious agent in the body of man
• Disease: derangement in the function of the whole
body of the host or any of its parts
• Infestation: lodgment, development and
reproduction of arthropods on the surface of body
• Nosocomial infection: hospital acquired infection
– E.g. infection of surgical wound, Hepatitis B, AIDS,
UTI, Hospital acquired pneumonia

• Iatrogenic infection: physician induced infection
– E.g. drug therapy, reaction to penicillin and
immunizing agent, aplastic anemia from
chloramphenicol, childhood leukemia due to prenatal
x-rays, etc
• Opportunistic infection: infection by any
organism that takes opportunity to provide other
infection to host.
– Very common in AIDS
– E.g. Tuberculosis in AIDS (common in Nepal),
pneumocystic cairini pneumonia in AIDS (common in
world), Cryptosporidium diarrhea in AIDS, Cytomegalo
viral infection in kidney transplant

Pollution/Contamination
• Pollution: presence of offensive but not
necessarily infectious matter in the
environment
• Contamination: presence of an infectious agent
in the body surface or other inanimate articles
or substances (water, milk, food)

Disease Distribution
• Endemic: constant presence of disease or infectious agent within
a given geographical area. E.g.:- malaria, kala-azar, etc
• Epidemic: unusual occurrence in a community or region of
disease or specific health related states or events clearly in excess
of expectation. E.g.:- cholera, measles, diarrhea, etc
• Sporadic: occurrence of irregular, haphazardly from time to time
and generally infrequently. E.g.:- tetanus, herpes zoster,
meningitis, etc
• Pandemic: affecting large proportion of population covering wide
geographical area. E.g.:- influenza pandemic in 1918 and 1957.

Screening and Surveillance
• Active search for unrecognized
disease or detects by rapidly
applied test , examination or
other procedures
• Find out sick people from
apparently healthy people
• 3 types
1. Mass screening
2. High risk screening
3. Multi-stage screening
• Continuous scrutiny factors
that determine the occurrence
and distribution of disease and
other condition of ill health
• Finds out the trends or
distribution of disease to
control disease
• 3 types
1. Active surveillance
2. Passive surveillance
3. Sentinel surveillance
Notifiable diseases of Nepal: Cholera, Plague, Yellow fever and AIDS

Other Terminologies
• Disease control: reduction of disease incidence, prevalence,
morbidity or mortality to a locally acceptable level
– Reduction in transmission that no longer public health problem
• Outcome of disease control: reduction in
– Incidence of disease
– Duration of disease
– Effect of infection
– Financial burden to the community
• Disease elimination: reduction of disease to zero of incidence in
defined geographical area (complete interruption of transmission)
• Disease eradication: permanent reduction of disease to zero of
worldwide incidence (extermision of disease)
• Fatality: it is percentage of death among these attacked by a given
disease. It is the measure of the severity of disease12/16/2018 32SUNNY YADAV BPH/BEd

• Incubation period: the time interval between invasion
by an infectious agent and appearance of first sign or
symptoms of the disease
• Latent period: period from disease initiation to disease
detection
• Communicable period: the time during which an
infectious agent may be transferred directly or
indirectly from one host to another
• Serial interval: the gap between onset of primary case
and secondary case
• Generation time: the time interval between receipt of
infection by host and maximum infectivity of the host

• Lead time: time interval between diagnosis by early
detection and diagnosis by other means.
• ''Lead time" is the advantage gained by screening,
i.e., the period between diagnosis by early detection
and diagnosis by other means. In Figure, A is the
usual outcome of the disease, and B is the outcome
to be expected when the disease is detected at the
earliest possible moment

• Secondary attack rate: the number of exposed
persons developing the disease within the range of
incubation period following exposure to primary case
• It shows communicability of disease
• E.g. Chicken pox (90%), measles (80%), mumps
(86%), etc

Incubation period
• the time interval between invasion by an infectious
agent and appearance of first sign or symptoms of the
disease
• Depends on generation time, portal of entry, infective
dose, individuals (susceptibility)
• Use of incubation period
– Trace the source of infection and contact
– Determining the period of surveillance
– Apply immunization principle for prevention of disease
– Identification of point source or propagated epidemics
– Estimated prognosis of disease

Epidemiological measurement
1. Rate
– Measure the occurrence of some particular events in population
during a given time period, time always related to dinominator
– In rate , numerator is the part of denominator
– E.g. :- crude rate , standardize rate , specific rate , etc
2. Ratio
– Measure a relation in size between two random quantities
(x/x+y)
– In ratio, numerator is not the part of denominator (x/y)
– E.g. :- MMR, doctor-population ratio , sex ratio , bed-patient ratio
3. Proportion
– It is a ratio which indicates a relation in magnitude of a part of
whole
– In proportion , the numerator is always included in denominator
– E.g. Proportion, Case fatality rate

Measurement of morbidity
• By incidence, prevalence and case fatality rate
Incidence
• It is a rate
• Measures new cases of specific disease

Prevalence
• Prevalence is a proportion
• Prevalence = incidence x mean duration
• Prevalence increases with increase in duration of disease
• If population is stable then incidence and duration are
unchanged.

Case Fatality Rate
• Killing power of a disease
• Closely related to virulence of organism
• Proportion always represents in 100
• E.g. Rabies (100%), Yellow fever (80%), JE (30-50%),
chicken pox (<1%), Cholera (30-40%), tetanus (80-90%)
etc

Measurement of mortality

Disease causation

Concept of causation
1. Germ theory (Louis Pasteur in 1873)
– One relationship between causative agent and disease
1. Multi-factorial causation (Pattenkoffer)
– Multiple factors in disease causation (E.g. TB)
2. Epidemiological triad
– Shows relation between agent , host and environment
3. Web causation (Mac Mohan and Pugh)
– The predisposing factors of any type and their complex
interrelationship with each other (E.g. MI, cancer)

Iceberg phenomenon of disease
• Tip of iceberg (above
water line):
symptomatic/diagnostic
/clinical – applied
Diagnosis
• Submerged portion
(Below waterline):
asymptomatic/undiagn
osed/latent/carrier –
applied screening

• Disease is physiological and psychological
dysfunction (D – Doctor)
• Illness is subjective state of person who feels
aware of not being well (I – I am or Patient)
• Sickness is a state of social dysfunction (S –
Society)

Host
EnvironmentAgent
Epidemiologic Homeostasis

Agent
• Entity necessary to cause disease in a susceptible host
• Types
1. Biological agents: Bacteria, virus, fungi, protozoa, hookworm, etc
2. Physical agents: heat, cold, pressure, radiation, etc
3. Chemical: 2 types – exogenous (allergens, metals, dust, gas, poison,
etc) and endogenous (uric acid-gout, urea-uremia)
4. Mechanical agents: Wound fracture, sprain, etc
5. Nutritional agents: Obesity, night blindness, PEM, goiter, etc
6. Social factors: smoking, alcoholism, unhealthy life style, etc

Host
• An organism which harbors the disease agent
• Types of host are
1. Definite or primary host: the host in which the adult stage or
sexual mode of reproduction takes place. E.g. mosquitoes in
malaria, man in filarial
2. Intermediate or secondary host: the host in which larval stage or
asexual mode of reproduction takes place. E.g. man in malaria,
hydatid disease, toxoplasmosis
3. Obligate host: only one host e.g. man for typhoid, tuberculosis,
cholera etc
4. Transport host: organism remains alive but does not undergo
development, host factor (age) – strongly related to disease

Environment
• Conditions / influences that influence
interaction between agents & host
• Types of environment
1. Physical environment: air, water, soil,
climate, noise, heat, light, radiation, etc.
2. Biological environment: bacteria, virus, etc.
3. Psychosocial environment: culture, tradition,
health service, etc.

Dynamic of disease
transmission

Chain of Infection

Mechanism of Transmission

1 - The Infectious Agent
• Any microorganism that is capable of producing an
infection. E.g. Bacteria, virus, protozoa, etc

2 - The Reservoir
• The habitat in or on which an infectious agent
normally lives, grows and multiplies

• Source of infection is defined as “the person , animal ,
object or substance from which an infectious agent
passes or is disseminated to host”
• Reservoir of infection is defined as “any person , animal
, plant or substance in which an infectious disease lives
and multiplies , on which it depends for survival”
• The reservoir may or may not be the source from which
an agent is transferred to a host. For example, the
reservoir of Clostridium botulinum is soil, but the source
of most botulism infections is improperly canned food
containing C. botulinum spores

• Reservoir may be of 3 types
1. Human reservoir
2. Animal reservoir
3. Reservoir in non-living things
Types of reservoir
• Human reservoir serves in the form of case or
careers

Case
• Case: a person in a population identifies as having a
particular disease, health disorder or condition under
investigation.
• On the basic of state , case are of following types
– Clinical case
– Subclinical case
– Latent case
• According to epidemiology host may be classified into
– Primary case: first case of communicable disease
– Index case: first case come to investigator
– Secondary case: case developing from primary case

Features Clinical
case
Subclinical case Latent case
Agent √ √ √
Signs and
Symptoms
√ X X
Transfer √ √ X
Examples Cholera,
Typhoid,
measles, etc
Poliomyelitis,
Mump,
influenza,
Hepatitis A and
B, etc
Herpes
simplex,
ancylostomias
is, etc

Carrier
• Carriers: an infected person or animal that Shows
– Presence of infectious agent
– Absence of signs and symptoms
– Transmission of disease
– Disease agent seen in discharge

Types of carriers
1. According to types – 3 types
• Incubatory carrier: E.g. measles, polio, mumps, hepatitis B,
pertusis, influenza, diphtheria
• Convalescent carrier: E.g. typhoid, bacillary dysentery,
cholera, diphtheria, pertusis
• Healthy carrierE.g. polio, typhoid, cholera, diphtheria,
meningococcal infection
2. According to duration – 2 types
• Temporary carrier: shed the infection for short time. It may
be incubatory, convalescent and healthy carriers.
• Chronic carrier: excretes the infectious agent for long
period of time. E.g. typhoid, malaria, dysentery, hepatitis,
gonorrhea.

3. According to portal of exits
• Urinary
• Intestinal
• Respiratory
• Urinary carrier more dangerous than intestinal
carrier

Animal and Non-living Reservoir
• Animal reservoir: animals and birds may be
reservoir.
• Animal reservoir found in two forms – case or
carriers.
E.g. rabies (case), influenza (carrier), plague,
anthrax, bovine tuberculosis, brucellosis, etc
• Reservoir in non-living thing: water- typhoid,
soil-tetanus, cane food- food poisoning.

3 - The Portal of Exit
Path by which an agent leaves the reservoir or host
E.g. hepatitis A- stool, SARS-droplet, AIDS- vaginal
discharge or semen, etc.

Portals of Exit
• Respiratory Tract (Coughing or Sneezing)
• Gastrointestinal Tract (Saliva or Feces)
• Urogenital Tract (Secretions from the Vagina or
Penis)

4 - Mode of Transmission (Spread)
the mechanism of
spread of infection
through the
environment or through
another person

Modes of Transmission
1. Direct Transmission
a) Direct contact
b) Droplet infection
c) Contact with soil
d) Inoculation into skin
e) Vertical (transplacental)
2. Indirect Transmission
(@5F – flies, food, finger, fluid and
fomites)
a) Vehicle borne
b) Vector borne
c) Air borne
d) Unclean hands and fingers
e) Fomite borne

E.g. Droplet Transmission
Direct Spread by Droplets
• Close contact with infected person (<3 ft)
• Infected person coughs, sneezes, talks, sings
• Droplets land directly on mucous membranes (eyes,
nose, mouth) of susceptible person

Indirect Spread by Droplets
Droplets with the infectious
agent land on a table,
doorknob etc.
Someone touches
contaminated object

5 - The Portal of Entry
• Route through
which the pathogen
enters its new
susceptible host

Portals of Entries
Sexual
contact
Breaks in Protective Skin Barrier
Ingestion
Inhale germs

6 - The Susceptible Host
-A person who can get sick when they are
exposed to a disease causing pathogen

Stages of Susceptible Host
• Portal of entry
• Site of selection
• Portal of exit
• Search for new host

Investigation of an
epidemic

Objectives of epidemiological investigation
• To define magnitude of problem (time, place,
person)
• To determine responsible condition and
factors
• To identify causes, sources and mode of
transmission
• To make recommendations to prevent
reoccurrence

Prevention and Control

• The science and art of preventing disease, prolonging life,
promoting physical and mental health
• It is not necessary to know everything about natural history of
disease to initiate preventive measures, removal of single known
essential cause is sufficient to prevent a disease
Successful prevention depends upon:
• A knowledge of causation
• Dynamics of transmission,
• Identification of risk factors and risk groups,
• Availability of prophylactic or early detection & treatment
• An organization for applying these measures to appropriate
persons or groups
• Continuous evaluation of & development of procedures applied

Levels of Prevention
Stage of disease Level of prevention Type of response
Pre-disease Primary
Prevention
Health promotion
Specific protection
Latent
Disease
Secondary
Prevention
Early Diagnosis
Prompt Treatment
Symptomatic
Disease
Tertiary
Prevention
Disability limitation
Rehabilitation

Primordial prevention
• Prevention of emergence or development of risk
factors in countries or population groups in which
they may have not yet appeared
• Intervention that is taken when the risk factors are
not even present
• Best prevention for non-communicable diseases start
from early childhood by Health Education
• Main intervention- individual and mass education

Primary prevention
• Action taken prior to onset of disease which removes
the possibility that the disease will ever occur
• Intervention that is taken when the risk factors are
present but disease has not developed
• Intervention in pre-pathogenesis phase
• applied for chronic disease such as hypertension,
cancer, diabetes, asthma, COPD, etc
• Primary prevention may be accomplished by measures
of “Health promotion” and “specific protection”

Primary prevention
Specific protection
Health
promotion
Health education
Environmental
modifications
Nutritional
interventions
Life style and
behavioral changes
Immunization and seroprophylaxis
Chemoprophylaxis
Use of specific nutrients or
supplementations
Protection against occupational
hazards
Safety of drugs and foods
Control of environmental hazards,
e.g. air pollution
Achieved by

Secondary prevention
• Strategies applied in early disease
e.g. preclinical & clinical
• Interrupts the disease process before it becomes
symptomatic
• directed to finding the sick component of the
community
• mostly applied for acute diseases such as tuberculosis,
leprosy, syphilis, cholera, typhoid, etc It halts the
progress of a disease at its incipient stage and
prevents complications

Nature of measures
Early diagnosis and Prompt treatment.
to limit spread of infectious diseases
Example
• screening and individual case finding
• recognition and treatment of hypertension and transient
ischemic attack for preventing a stroke

Tertiary prevention
• Applied when disease is advanced
• Direct to the sick component of the community
• Nature of measures
Rehabilitation

• Prevention of
complications of a disease
before irreversible
changes set in
Example
• Early mobilization or
splinting for stroke patients to
prevent contractures
Disease
Impairment
Disability
Handicap
Accident
Loss of foot
Cannot walk
Unemploym
ent

Rehabilitation
• Alleviation of disability resulting from disease
• Attempts to restore functioning
• Components
– Medical – restoration of function
– Vocational-restoration of capacity to earn
– Social-restoration of family and social relationship
– Psychological- restoration of personal dignity and confidence
• Example
A stroke patient-rehabilitated physically, mentally and socially to
take part in daily social life and be a productive member of the
society

Risk Factor Disease Complication
Primordial X X X
Primary √ X X
Secondary √ √ X
Tertiary √ √ √

Some examples

• A patient with fever and cough > 3 weeks
comes to DOTS Clinic for Sputum for AFB

A child coming to immunization clinic
for OPV Vaccine

A 20 year old male takes
chemoprophylaxis during an epidemic
of memingococcal meningitis

A patient with fever and chills comes
to Malaria clinic and was given Radical
therapy

A class of 5 year old children
discouraged from adopting harmful
lifestyles and smoking

A village community was given health
education to prevent spread of malaria

Control of Disease
Control
Cases Contacts Carriers Community
Diagnosis
Notification
Isolation
Disinfection
Treatment
Followup
Release
Observation Detection Epidemiological
Investigation
@4C
Quarantine

Immunity

Exposure to infection Resistance to infection
•Climate
•Vectors
•Population
•Housing
•Water / sewage
•Public health
•Mutation
•Age
•Previous exposure
•Vaccination
•Nutrition
•Disease
•immunodeficiency

Racial
Active
Species
Acquired Immunity
Passive
Natural
Individual
Artificial
Innate Immunity
Immunity
Active Passive
Recovery
from
previous
exposure to
disease
Antibodies of
babies from
mother
through
placenta
Immunization
/ vaccination
Anti-toxin, Anti-sera,
Immunoglobulin12/16/2018 98SUNNY YADAV BPH/BEd

• The resistance exhibited by the host towards injury
caused by micro-organism or their products
Innate immunity Acquired immunity
Defense First line of defense Second line of defense
Specificity Non-specific Specific
Immunological memory Absent Present
Control of infection Able to control infection Not able to control
infection
Prior contact not affected by prior
contact with micro-
organism
affected by prior contact
with micro-organism
Presence of immunity Present since birth Immunity persists life long
Cellular components Macrophages, granulocytes,
mast cells, NK cells
T cells, B cells
Time scale of response Quick (maximal in minutes
to hours)
Slow (maximal in days to
weeks)
Phylogeny Ancient (all multicellular
organisms)
Recent (vertebrates only)12/16/2018 99SUNNY YADAV BPH/BEd

Innate immunity Acquired immunity
Functions Prevents infection to host
by microbes and can
eliminate the microbes
•Effectors mechanisms of
innate immunity are often
used to eliminate microbes
even in adaptive immunity
•Stimulates and influence
the nature of adaptive
responses
Humoral Immunity:
provided by antibodies
floating free in body fluids
Cell mediated immunity:
lymphocytes directly
attack specific invaders by
lysis or indirect attack
• Interferon: protein inhibits replication of virus

Antibody Isotypes and their properties
IgA IgD IgE IgG IgM
Molecular forms Monomer
or dimer
monomer monomer monomer pentamer
% total Ig in
serum
10-20 <1 <1 70-85 10
Where found in
body
Found in
bodily
secretions
Found on
B-cell
surface
Attach to
basophils
and mast
cells
Blood &
extracellula
r fluid
Blood &
extracellular fluid
Functions Protect
external
openings
Unknown
; maybe
antigen
detection
Allergic
response
and defend
infection by
large
parasite
Long term
Ab that
protect the
body
Appear ealier in
the infection and
offer valuable
defense during
critical stage of
the infection
Trasferrable to
offsprings?
Via
Mother
milk
No No Via
placenta
No

Vaccines
• Immuno-biological substance designed to produce
specific protection against a given disease
• Vaccine – Louis Pasteur
• Vaccination – Edward Jenner
• First developed vaccine is small pox (1798) by Edward
Jenner
• All vaccines are contra-indicated in pregnancy except
Yellow fever vaccine

Types of vaccine
1. Live attenuated : measles , mump , BCG , polio (sabin)
, rubella
2. Killed vaccine : hepatitis B, polio (salk), pertussis,
influenza, typhoid, rabies
3. Toxoid : diptheria, tetanus
4. Combined: DPT, MMR, etc.
5. Cellular fractions: PCV, Hib, etc.

Live vaccine @ BOY LOVE THE CRIME
B – BCG
O – OPV (Sabin)
Y – Yellow fever
LOVE – Live vaccine
Th – Typhoid
E – Japanese Encephalitis
C – Chicken pox (Varicella)
R – Rubella
I – Influenza
M – Measles Mumps
E – Epidemic typhus
Coverage percentage =
Vaccine Coverage

Routine Vaccination Schedule of Nepal
Name Protect against Use and dose Age Time
BCG TB meningitis ID/0.05ml At birth 1
DPT-HepB-
Hib
Diptheria, pertussis,
Tetanus,
Hepatitis B, Influenza
IM/0.5ml 6,10 and 14 weeks 3
Polio
(OPV)
poliomyelitis Oral/2 drop 6,10 and 14 weeks 3
IPV Poliomyelitis IM/0.5 ml 14 week 1
PCV Pneumonia IM/0.5 ml
6 week, 10 week, 9
month
3
MR Measles, rubella SC/0.5ml 9 and 15 month 2
Td Tetanus, Diptheria IM/0.5ml
Pregnant women (First as
early as possible of
pregnancy period and
next after 1 month
2
JE JE SC/0.5ml 12 – 23 month 1
Typhoid Typhoid SC/0.5ml >10 years 212/16/2018 SUNNY YADAV BPH/BEd 105

Demography

• Demography: scientific study of human population
• Demographic process: fertility, mortality, marriage, migration and
social mobility
• Population pyramid (age-sex or age structure): graphical
presentation that shows the distribution of various age groups in
a population which normally forms the shape of pyramid
• There are three types of population pyramid –
1. Expansive pyramid
•Fertility is high, mortality is high
•Life expectancy is shorter
•Population of children is higher
•Population growth rate is +ve
(i.e. increasing)
•E.g. India, Nigeria, Nepal, etc
2. Constructive Pyramid
•Low birth and low death
•Life expectancy is longer
•Older population is high
•Population growth rate is -ve
(i.e. decreasing)
•E.g. US, China, etc

3. Stationary Pyramid
• In this, low birth and low death but death exceeds birth
• High proportion of aged population
• Population growth rate is zero (i.e. remains constant)
• It is the population structure of typically developed
countries such as Spain, etc

Demographic cycle
Stage 1 - High stationery
• Both death and birth
rate high and cancel
each other, population
remain stationary at
high Level

Stage 2 - Early Expanding
• Birth rates remain high, but
death rates fall rapidly
causing a high population
growth
Stage 3 - Late Expanding
• Birth rates now fall rapidly
while death rates continue to
fall
• The total population begins
to peak and the population
increase slows to a constant

Stage 4 - Low Stationery
• Both birth rates and death
rates remain low,
fluctuating with 'baby
booms
• Population becomes
stationary
Stage 5 – Declining
• Population begins to
decline because birth rate
is lower than death rate

Relation between growth rate and
population
• Population doubling time =
• Sex ratio =
• Dependency ratio =

Important Indicators
Human Development
Index (HDI): 0 to 1
• Knowledge
• Income (real GDP per
capita in dollar)
• Life expectancy at birth
(Longevity)
Physical Quality of Life
Index (PQLI): 0 to 100
• Life expectancy at 1
year age
• Infant mortality rate
• Literacy rate
•Life expectancy is positive mortality indicator
•Disability free life expectancy = Sullivan’s index
•DALY (Disability Adjusted Life Year): best measure of burden of
disease in a population and effectiveness of interventions12/16/2018 113SUNNY YADAV BPH/BEd

Standard of Living
• Income and occupation,
• Standards of housing,
• Sanitation and nutrition,
• Level of provision of health,
• Educational, recreational
and other services
Standard of living depends on
“per capita GNP”
Quality of Life
• Determining health
• happiness (including
comfort in the physical
environment and a
satisfying occupation),
• Education,
• Social and intellectual
attainments,
• Freedom of action,
• Justice,
• Freedom of expression

Disaster Management

• Disaster is defined as “Any occurrence that cause
damage, economic disruptions, loss of human life,
deterioration in health and health service on a scale
sufficient to warrant an extraordinary response from
outside the affected community or area.” –WHO
• Hazard: Any phenomenon that has the potential to
cause disruption or damage to people and their
environment
• Disaster area: A place where a disaster has happened
and which needs special help
• Main features of disaster: Unpredictability,
Unfamiliarity, Speed, Urgency, Uncertainty, Threat

TYPES OF DISASTER
1. Natural Disaster:
a) Acute or sudden onset: Earthquake, flood, landslide,
volcanic eruption, etc,
b) Chronic: Desertification, Famine, etc
2. Man-made disaster: Bhopal gas tragedy (methyl isocyanide),
chemical explosion, bomb blast, road accidents, bomb blast,
etc.
3. Complex emergencies: global warming, war and conflict
4. Pandemic/epidemic Emergencies: influenza pandemic, ebolla
pandemic, etc.

Effects or consequences of disaster
Short term
• Disability, injuries, death
• Shortage of food
• Shortage of drugs and other
equipments
• Increase in communicable
disease
• Environmental disruption
• Socio-economic losses,
Psychological problems
• Destruction of
infrastructure
Long term
• Ecological disruption
• Destruction of
governmental, public
infrastructure and
industries
• Destruction of health care
infrastructure
• Disruption of essential
drugs for many years

Disaster management cycle
• Disaster mitigation: minimize effects of disaster:
E.g. public education, building codes,
immunization, protection of vulnerable groups
• Emergency preparedness: Activities that are taken
to strengthen the capacity of a country to manage
all types of emergencies. E.g. development of
multi-agency co-ordination, preparedness plan,
water and sanitation, warning system, etc.
•
• Disaster response: efforts to minimize the hazards
created by disaster. E.g. rapid health assessment,
collection of health status information,
surveillance, rescue, relief, search, triage, etc.
• Rehabilitation: restoration of affected area to its
previous state. E.g. temporary housing, re-
employment, debris removal, etc.

Triage
• Method of ranking injured people according to
the severity of their injuries
• There are four priorities –
– Red (immediate, first and highest priority, for
severe cases)
– Yellow (second priority, necessary, moderate
cases)
– Green (third priority, wait, mild injuries)
– Black (last or lowest priority, death)

Rapid Response Team (RRT)
• It is also called as medical emergency team or medical response team.
• In 2000 AD, EDCD (DoHS)/MoH established a mechanism of RRT for
managing epidemics. This mechanism consists of RRT at 3 levels –
central -1, Regional-5 and district-75
• RRT consists of Medical doctors, HA, Nurses, AHW, ANM, Public health
professionals, Clinical respiratory, therapist and technician
• Objectives of RRT
– To establish early warning and respiratory mechanism for potential
epidemics
– To prepare for potential epidemics
– To manage disease outbreak
– Institutionalization of disaster management

Central Natural Disaster Relief
Committee (CNDRC)
• CNDRC takes overall responsibilities of coordination
and policy decision regarding any disaster
• Defines the national disaster relief system with relief
committee at the national, regional and district level to
coordinate the implementation
• MoHA chairs the committee with members from line
ministries, police, army, scout, Red Cross, etc
• Natural disaster relief act (milestone for disaster
management in Nepal) was developed in 1982 AD12/16/2018 122SUNNY YADAV BPH/BEd

Important Remember
• Nepal is 30th rank of risk of water related disease in World
• Nepal is in 11th rank in risk of earthquake
• Minimum standard in disaster response is based on sphere guideline
• Most commonly reported disease in post disaster phase is
gastroenteritis
• Common micronutrient deficiencies in disaster are Vitamin A
Deficiency, scurvy, anemia, TB, malaria, measles, diarrhea, niacin
deficiency, parasitic disease, etc
• Most practical and effective strategy of disease prevention and
control in post-disaster phase is supplying safe drinking water and
proper disposal of excreta
• Foremost step for disease prevention and control of post disaster
phase is chlorination
• The current disaster management system in Nepal is leading by
MoHA.
• The current disaster (earthquake) occurred in Nepal in 2072-01-12 (at
12:50 PM of 7.9 Rector scale) and 2072-2-01 (of 7.8 Rector scale)

International code – green signal:
ambulatory patient isolation period of time
• Chicken pox: 6 days after onset of
rash (until crust)
• Measles: starting of catarrhal
stage through 3rd day of rash
• Mumps: until swelling subside
• Influenza: 3 days after onset
• Pertusis: 4 weeks or until
paroxysm cease
• Cholera and diphtheria: 3 days
after antibiotic or culture
negative
• Sigellosis and salmonellosis: until
3 consecutive negative stool
culture
• Hepatits A: 3 weeks
• Polio: 2 weeks adult and 6 weeks
pediatrics
• Herpes: 6 days after onset of rash
• TB: until 3 weeks of
chemotherapy
• Meningitis, pharyngitis: until the
first 6 hours of effective
antibiotics

Understanding the Study of Epidemiology

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