Epidemiology and Public Health

epidemiological triad involves agent host and environment

agent
host
environment
time

PM Jumped In Ditch To Have Ruby

TRM

isolation is done for infected people

quarantine is done for apparently healthy people

isolation is done till period of communicability

quarantine is done till max incubation period

cordon sanitaire means buffer zone

primordial prevention prevents emergence of risk factors

primary prevention prevents contrction of disease

secondary prevention prevents complication from disease

tertiary prevention prevents death/disability from disease

current life expectancy in india is 67.5 years

0.5/1000

**
should be >5/1000

>5/1000

dependency ratio in india is 50.2%

age for effective literacy rate is >7 years

current effective literacy rate of india is 74%

impairment means loss of anatomical organ or physiological function

disability means loss of activity or action

handicap means social loss or job loss

DALY full form is disability adjusted life years

best indicator to assess burden of a disease in population is DALY

highest DALY is for depression

2nd highest DALY is for hearing loss

number of years of life lived free from disability

number of years lived in full health

which is free from ill health

QALY assesses value for money for health interventions

standard of living depends upon income

infant mortality rate
life expectancy at 1 year
literacy rate

longetivity of life
knowledge
standard of living

life expectancy at birth
mean school years
expected school years
income

PQLI

infant mortality rate
life expectancy at 1 year
literacy

MC route of nasocomial infection is unclean hands

nasocomial infection means hospital aquired infection

mc pathogen involved in hospital aquired infection is staph aureus

mc area for hospital aquired infection is long term urinary catheters

>2 standard deviation(SD) of cases and
>80% of expected frequency

rabies
japanese encephalitis
tetanus
bubonic plague

RJ TB announces end of humans

reservoir and source for tetanus are soil

index case is 1st case identified in a community

primary case is the 1st case in the community

latent case is never a carrier
subclinical case can be a carrier

Community Medicine is DPT

cholera
meningitis

diptheria
polio
typhoid

healthy carrier arises due to subclinical cases or avirulent strain

travel distance of droplet is 6 feet

airborne particle size is <10 microns

rubella virus is transmitted in 1st trimester

parvo virus is transmitted in 2nd trimester

tetanus
mycosis
soil transmitted helminthes(STH)

plague
covid

microfilaria

means no proliferation in numbers only devloopment

malaria

trans stadial transmission is infection is carried on between different stages of devlopmental stages in

infection is not carried on in different stages of devlopmental stages in trans ovarian transmission

TB
measles
disemminated varicella-not localized
influenza

generation time is the time between entry of organism to max. communicability of it

serial interval is the time between primary and secondary case

incubation period for hepatitis A is 15-50 days

food borne hepatitis are hepatitis A and E

1.apron
2.mask
3.eye cover(face shield\/glasses)
4.gloves[last ]

logical

1.gloves
2.eye cover
3.apron
4.mask

MCQ
(up to down in doffing
down to up in donning)

donning
1.apron
2.mask
3.eye cover(face shield\/glasses)
4.gloves

rate is expressed in terms of time

an example of proportion

kaplan mier analysis method is for survival statistics

1,2,6

1,5,7

all except 4 and 9

David Sackett

john snow

and froucastorian was founder
john M Last gave iceberg phenomenon

Edward Jenner

louis pasteur is the father of bacteriology

Louise pasteur

John M Last

last iceberg was lost with John

solidarity trial

kangari carcinoma is seen in jammu

kala azar is mostly seen in UP,Bihar,west bengal

age distribution of hodgkins lymphoma is bimodal

a cross sectional study starts with total population

cross sectional study determines prevalence of a disease

cross sectional study is aka snapshot study

case control study starts with diseased and non diseased population

case control study goes from effect to cause

case control study is associated with recall bias

individual is the unit of study in cohort study

cohort study goes from cause to effect

cohort study determines incidence of a disease

ad\/bc
aka cross production ratio
*
SUPRA
not total -but affected /non affected -NOT TOTAL

remember as logical divided by illogical

odd's ratio is calculated in case control study

risk ratio
attributable risk ratio
population atttibutable risk ratio

incidence in exposed=50%
incidence in non exposed=10%

risk ratio=5

nested case control is a type of cohort study

nested case control is the study of choice in rare/expensive investigation

cross sectional study is associated with selection and observation biases

cohort study is aka longitudinal prospective study

types of observational studies are descriptive and analytical

types of experimental trials are randomised and non randomised

historical controls are used in non randomised uncontrolled trials

uncontrolled trials are used for assesing of public health intervention

randomisation removes selection bias

randomisation is at the hearth of randomised control trials(RCT)

advantage of cross over study design is no ethical problems

drug with long t1/2
curative drug
acute/fatal disease

a type of RCT

intention to treat analysis
per protocol analysis

attrition means patients lost that dont follow up

intention to treat analysis method is preferred to interpret RCT

number needed to treat/harm is counted in randomised control trial

1/ARR
absolute risk reduction
*
MCQ

calulated in RCT

meta analysis is the best method to assess causality

forest plot helps to analyse the overall effect in meta analysis

funnel plot is used to detect bias publication

funnel plot is used to detect bias publication

quarternary prevention is done to prevent over diagnosis of patients

deductive research applies top to bottom aproach

inductive research applies bottom to top approach

specificity of association is the most difficult criteria to establish causal association

temporality of association is the most essential criteria to establish causal relationship

berksonian bias is seen in hospital based case control studies

berksonian bias is seen in hospital based case control studies

neyman bias is aka prevalance bias

neyman bias is aka prevalance bias

neyman bias is seen when there is long time between exposure and disease

change in attitude while under observation
**
SEEN IN COHORT STUDY

pygmalion bias

known confounder is treated with matching and randomisation

RSSR

randomisation
standardisation
stratification
regression
**
MCQ AIIMS 19

descriptive studies help in forming a hypothesis

analytical studies help in testing hypothesis

experimental and evidence based studies help in validation of hypothesis

evidence based medicine is most important for assesing causality

cohort study gives natural history of a disease

mass screening
high risk screening
multiphasic screening

prescriptive screening works on secondary level of prevention

presumptive screening works on primary level of prevention

latent period is time between start of pathogensis and 1st sign/symptom

screening time is the time between 1st possible point of diagnosis and critical point of diagnosis

lead time is the time between 1st possible point of diagnosis and usual point of diagnosis

bias means systemic errors

Fn/Fn+Tp

ecological fallacy bias is associated with ecological study design

false postitive error rate is related to type 1 error

false negative error rate is related to type 2 error

false positive error is more serious than false negative error

0.33

0.25

pre test probability means prevalence

post test probability means postitive predictive value (PPV)

positive predictive value is most affected by prevalence

R-charts give precision and validity of tests

LJ charts give validity and accuracy of a test

yield of a test corresponds to PPV

diagnostic capacity of a test is given by positive predictive value

remember---truth(both true values)/speak(everything all 4)

1-beta for ???

youden's index gives utility of a test

blood pressure is quantitative type of data

type I error[alpha] means when a true null hypothesis is rejected

Type 2 error[beta] means when false null hypothesis is accepted

geometric mean is calculated in cases of extreme values and exponential data

harmonic mean is calculated in cases of inverse data and fractional values

mean is the best measure of central tendency

mean measure is the most affected by extreme values

median measure is the least affected by extreme values

Mode=80

mode=3 median - 2 mean

mode is the most robust measure of central tendancy

mode is the last affected measure by extreme values

root mean squared deviation
take whole root

n-1 if <30

standard error mean is calculated for quantitative data

standard error means means of standard deviation

standard error proportions is calculated for qualitative data

normal distribution curve is aka gaussian distribution curve

zone of normalsy in normal distribution curve is between +2 and -2 SD(standard deviation)

cut off for z score is 2 SD(standard deviate)

z score=2

p value ranges from 0 to 1

null hypothesis is accepted if p value is >0.05

null hypothesis is accepted if p value is >0.05

parametric test of significance is done for quantitative and normal distriibution data

non-parametric test of significance is done for qualitative and non normal distribution data

test of significance for ordinal data is wilcoxan rank test

test of significance for ordinal data is wilcoxan rank test

test of significance for normalcy of data is kolmogorov smirnov test

test of significance for outliers is Dixon's Q test

cronbach's alpha score is a test of significance for internal consistency of questionnaire

cronbach's alpha score is a test of significance for internal consistency of questionnaire

Bland altman analysis is the test of significance for to compare a new test with a gold standard test

Bland altman analysis is the test of significance for to compare a new test with a gold standard test

KAPPA test is the test of significance for level of agreement bw 2 criteria

scatter plots are used to plot correlation

pearson correlation plot

spearman correalation plot

r being correlation value

regression in psm means prediction

linear type regression is used for quantitative variations

regression is logistic type in qualiitative variation

snowball sampling is done for diseases with social stigma

Most commonly used sampling method is simple random sampling

cluster sampling is done to evaluate the health services

cluster sampling is done in large homogenous population

cyclical trend for measles in pre vaccination era was 2-3 years

cyclical trend for rubella was 6-7 years

cyclical trend for influenza was 7-10 years

80%

found in cohort study

calculated in cohort study

formula

population
*
MCQ

ecological study is aka correlation study

hawthorne bias is seen in cohort study

1.pre post study
2.uncontrolled trial
3.natural experiment

India was declared small pox eradicated in april 1977

small pox was globally eradicated in may 1980

period of communicability(POC) of chicken pox is 2 days before rash and 4 days after rash

SAR(secondary attack rate) in chicken pox is 90% in non immunised children

active vaccine of varicella contains OKA strain

2nd dose of varicella active vaccine is given at 2 years

immunity from active varcella vaccine starts from 5-7 days and lasts 10 years

PICA
pregnancy
immunocompromissed
anaphylaxis

varicella zoster immunoglobulins(VZIg) are given within 72 hours of exposure

koplic's spots inside mouth are diagnostic of measles

mc feature of measles is diarrhea

mc complication of measles is otitis media

MC cause of death in measles is severe pneumonia

IP for vaccine induced measles like illness is 7 days

period of communicability for measles is 4-5 days before and 4-5 after rash

period of isolation for measles is from catarrhal stage to 7 days after rash

measles Ig are given within 3-4 days of exposure

measles vaccine is given after 2-3 months of gap after giving Ig

measles vaccine has Edmonsten Zagreb strain

live vaccien of measles should be used within 4 hours time

sorbitol
gelatin
neomycin

so C/I in neomycin allergy

1st dose of measles vaccine is given at 9 months of age

2nd dose of measles vaccine is given at 16-24 months of age

immunity from measles vaccine starts at 10 days

immunity from measles vaccine lasts till lifetime

mc adverse effect of measles vaccine is mild measles like illness

rare adverse effect of measles vaccine is subacute sclerosing pan encephalitis(SSPE)

1 dose of vaccine to all children between 9 months to 14 years age

keep up-2nd dose
follow up

2nd dose of vaccine

measles vaccine in HIV patients should be given at 6 months of age

>95% coverage
>95% reduction in mortality

POC(period of comm.) for mumps is 5 days before onset of signs till swelling subsides

maximum infectivity of mumps is at onset of parotitis

secondary attack rate of mumps is 86% in non immune persons

jerryl lynn
L zagreb
RIT 4385 strain

JaLZiRA

1.1 year
2.4-6 years of age

remember large gap

rubella is aka 3 day measles

period of communicability for rubella is 7 days before rash and 7 days after rash

rubella vaccine(MMR) uses wistar RA27/3 strain

CCID(cell culture infective dose 50%) for measles and rubella in MMR vaccine should be >1000

CCID(cell culture infective dose 50%) for mumps strain in MMR vaccine should be >5000

in outbreak of rubella,vaccine is 1st given to all non pregnant women of reproductive age

IP of influenza is 18-72 hours

POC of influenza is 1-2 days before symptoms to 1-2 days after onset of symptoms

H1N1(MC circulating)
H3N2
Type B virus

SAR of influenza is 50-60% in non immune

killed vaccine for influenza is egg based

live attenuated vaccine of influenza is in nasal spray form

contraindication of killed vaccine for influenza is egg allergy

mc age of presentation of diptheria is 1-5 years

nasal carriers are more dangerous than throat carriers in diptheria`

nasal carriers are more dangerous than throat carriers in diptheria`

mode of transmission in diptheria is done via nasopharyngeal secretions

untreated diptheria may spread for 14-28 days after onset

treated diptheria becomes non infectious within 48 hours

Case fatality ratio in untreated diptheria is 10%

range of diptheria antitoxin dose is 20,000-1,00,000 IU

DOC for diptheria case is penicillin G or erythromycin

DOC for diptheria carriers is erythromycin

erythromycin is given for atleast 10 days in diptheria carriers

0.5 ml I.M.
left anterolateral thigh

3 primary+2 booster doses-
6,10,14 weeks
+16-24 months and 5 years

side effect of DPT vaccine is neurological problems

neurological problems in DPT vaccine are mostly due to pertusis component

MC age of presentation of pertusis is <5 years

pertusis is aka 100 days cough

POC of pertusis is from 1 week after exposure till 3 weeks of paroxysmal stage

maximum communicability of pertusis is in early paroxysmal phase

case fatality ratio in pertusis is 5-6%

SAR in pertusis is 90% in unimmunised

DOC for pertusis is erythromycin

cholera is the father of public health

IP for cholera is 1-2 days

POC in cholera is 8 days to months

15-20% of cholera cases devlop severe dehydration

epidemic tail phenomenon is seen in cholera

coal tar is the disinfectant of choice in cholera

doxycycline is used for chemoprophyaxis in cholera

dukoral
sanechol
euvicol

dukoral vaccine is for O1 serotype of cholera

dukoral vaccine of cholera is effective is for 2 years