1. Dr. IZZELDIN EL-JACK, M.D Consultant Public Health DHA
A Guide To The oral Exam
Dr. IZZELDIN EL-JACK, M.D Consultant Public Health
DHA

2. Oral Exam Setting General advices Face to face Comfortable position
Be a good listener
Understand the question
Think before you speak
Organize what you say, short pause permissible
Good start is essential (1st impression is the last)
Say what you know, do not bluff or guess
Rationalize and defend your answer
Show good manners & do not argue with the examiner

3. ICD International Classification for Disease
Viral hepatitis A => ICD – ;ICD –10B15
Malaria => ICD – 9 084; ICD-10 B50-B54

4. Epidemiology
The study of distribution, determinants and disease frequency in human population
Descriptive Epidemiology
Analytical Epidemiology
Distribution: time, place, person
Determinants of health: hereditary, environmental, lifestyle, socio-economic, family and serviced welfare services
Frequency: prevalence , incidence

5. Screening
Is the presumptive identification of unrecognized disease or disability by rapid application of tests, examination, or other procedures
Screening criteria
Disease
Test

6. Reliability - Errors: - Repeatability
The ability of the test to provide consistent results
- Errors:
Observer error
( intra-observer error): observer him self
( inter-observer error) : different observers
Instrumental error
Biological error: pt himself: not fasting, smoking before doing BP check

7. Validity Sensitivity Specificity
The ability of the test to correctly identify those individuals who actually have the disease and those who do not
Sensitivity
The ability of the test to identify correctly those who have the disease
Specificity
The ability of the test to identify correctly those who do not have the disease

8. Validity Positive Predictive Value Negative Predictive Value
The likelihood that a person with a positive test has the disease
Negative Predictive Value
The likelihood that a person with a negative test has not got the disease
Likely hood ratio
+ = sensitivity / 1- specificity
_ = 1- sensitivity / specificity

9. Surveillance
The ongoing and systematic collection, analysis, and interpretation of health data in the process of describing and monitoring a health event. The information is used for planning, implementing and evaluating public health interventions and programs.

10. Sources of disease surveillance data
Individual case reports
Laboratory reports
Accident & Emergency (A&E) records
Hospital discharges summaries
Case investigations revealing additional cases
Death certificates
Surveys

11. Purposes of Surveillance
Monitor disease trends so that planning can be adjusted to meet new situations.
Identify,investigate and help control outbreaks or epidemics.
Identify specific population groups at high risk of illness or death from priority health events.
Evaluate the impact of preventive and curative control activities on the incidence and prevalence of priority diseases in the community.
Confirm current priorities among disease control activities.

12. Health
It is the over-all Physical, Mental and Social well-being of a person.
WHO definition
Is state of complete physical, mental, and social well being and not merely the absence of disease.
in order to lead socially and economically productive live.

13. Dimensions of health Physical Mental Social Others
From the definition (scope of health):
Physical
Mental
Social
Others

14. Determinants of health
الاشياء المؤثرة على الصحة
Heredity: genetic : what we born with
Environmental: newborn: malaria bite
Life style: smoking, diet
Socio economic conditions
Health and family welfare services

15. Indicators of health Tools to measure health Mortality
Morbidity and disability
Nutritional
Environmental: municipality
Psycho-social
Health services
Utilization :of services
Health policies: budget provided by government , and their interest in heath

16. Why indicators are important
Compare between countries
Plan for services
Plan for control and prevention
Indentify measures of health problem
To allocate resources
Evaluation of the problem

17. Health care
Multitude of services rendered to individuals, families or communities by the agents of the health services for the purpose of promoting, maintaining, monitoring or restoring health.
Largely a government function.
Medical care is a subset of health care

18. Health care
Group of services provided to individual, family, community by the agent of health services (PHC, community doctors, municipality..) for the purpose of:
promoting, maintaining, monitoring or restoring(those who have disease)health.

19. Definitions
Disease (Morbidity): pathology
It is a departure from state of well-being to unhealthy state…when one organ go unwell
The inability of the human body to meet internal or external stresses with adequate reaction
Illness:
Subjective..sense of feeling unwell
Sickness:
Social dysfunction: he can’t come today because he is sick, he took sick off

20. Disability Risk Factors
Any temporary or long term reduction of an individual activity as a result of acute or chronic condition ;CVA consider temporarily as pt might recover after rehabilitation
Risk Factors
Factors favoring development of disease often are present early in life outdating the appearance of disease by many years
e.g.: person obese (risk factor) now, after 10 years will develop DM

21. Concept Of Disease Sickness refers to state of social dysfunction.
Disease = without ease (uneasiness-discomfort):
when something is wrong with the bodily function.
Illness :
Individual’s perceptions and behavior in response to the disease.
(a subjective state of the person who feels aware of not being well)
Sickness refers to state of social dysfunction.

22. Concept of Epidemic Epidemic Vs outbreak
The occurrence of a number of cases of a disease (or condition) in excess of a number expected in a given time and place.
In some instances a single case will constitute such an unusual occurrence
e.g UAE is free of malaria: 0 cases, so one case consider epidemic
The cases are present in the country in certain percentage, but when it exceed this percentage expected, so here we call it epidemic
And to know if the number is exceed normal: we go back to surveillance we did about this disease

23. 1.Common source epidemic
Epidemic curve
1.Common source epidemic
Point source: e.g people invited to dinner, all ate same food, all get food poison, all report to hospital at the same time.
Continuous source: one same source
like the story of water source in London.
OR shawarma cook has salmonella , every day he will transmit the disease to some one, continuously from same source.
2.Propagated epidemic: not same source
people got dystenry, they treated, but one of them partially recovered, we to al ain, transmit the disease to other group, this group treated, but one transmitted to other group and so on.
Slow epidemic
Investigation of outbreak

24. Investigation of outbreak
Verification of diagnosis: confirm Dx
Confirm the existence of an out break: No. exceed expected
Defining the population at risk: case definition
Rapid search for all cases and their characteristics
Evaluation of ecological factors: cause of the problem
Formulation of hypothesis: dystentry from water source in khawaneej
Testing hypothesis: Data analysis: odds ratio, epidemic curve
Control and prevention: action
Final report: recommendation

25. Steps by Ameera Confirm the Dx Make sure it is an out break
Make case definition and search for the cases
Put the hypothesis: the cause is ….
Test the hypothesis: collect the data and analyze, odds ration, epidemic curve
Develop and implement control and prevention
Report.

26. Endemic e.g. TB in India - Hyper-endemic  - Holo-endemic 
Continuous presence of a disease or infectious agent within a given geographical area
e.g. TB in India
- Hyper-endemic 
Expresses a persistence intense Transmission
- Holo-endemic 
A high level of infection beginning early in life which affect most population.

27. Control Vs Eradication
It is reduction of the disease transmission to an acceptable minimum, or to a level not be considered a major public health problem
Eradication:
Complete elimination of a disease, or complete cessation of transmission and infectious agent

28. Communicable disease every communicable d. is infectious
A disease capable of being transmitted from an infected person or species to a susceptible host, either directly or indirectly.
Carrier carry disease without symptoms : HIV
A person or animal that harbors a specific infectious agent in the absence of clinical disease and serve as a potential source of infection.
Contact
A person or animal that has associated with an infected person or animal that might provide an opportunity to acquire the infection.
Infectious disease: disease caused by infectious agent

29. Disinfection
Killing of infectious agents outside the body by direct exposure to chemical or physical agents.
High level disinfections refers to the inactivation of all microorganisms except some bacterial spores.
e.g. what we do at home: cleaning
Concurrent disinfection
Immediate disinfections and disposal of discharges and infective matter all through the course of a disease.

30. Concept of communicability
Infectivity:
Ability of the infective agent to enter, survive, and multiply in the host
He has the disease but not showing S&S
Pathogenicity: cause destruction of organs
The property of an organism that determines the extent to which overt disease is produced in an infected population i.e the power of an organism to cause disease
Virulence:
The degree of pathogenicity, it is the disease-evoking power of the organism in a given host

31. Measures of Morbidity
1. Incidence: new cases, need immediate action, it measure risk
2. Prevalence : existing cases: new & old: used to plan for future, measure magnitude of disease

32. 3. Attack rate: for primary cases
Index case: first person report health services (went to hospital)
Primary cases: people who first exposed directly to the source of infection
4. Secondary attack rate
Secondary cases :who got the disease but didn’t expose to the source of infection, bur from the primary cases
Why we calculate the 2ndy Attack rate:
To know the infectivity(communicabilty) of the disease .i.e. if it is infectious or not.

33. Measures of Mortality
Crude death rates : all death in dubai, it is not accurate , can’t be used for comparison, to make it better we have standardized it
Specific death rates
Standardized rates
Case fatality rates: اكثر فتكا
Proportionate mortality ratio :اكثر تسببا في الوفاة e.g.We have 10 diseases causes death, breast cancer PMR is the highest
Fetal and maternal mortality rate

34. Disaster
An event that overwhelmed the affected community and that really requires outside assistance.
Emergency: same but require inside assistance only

35. Define treatment and control groups.
What’s the Design?
Define treatment and control groups.
Administer exposure to treatment group, but not controls.
Follow through time and compare rate of disease in treatment group with rate of disease in control group.
Epidemiologist is involved during the entire time from exposure and disease.
 First descriptor (Randomized Trial)
 Second descriptor (Randomized Trial)
 Third descriptor (Randomized Trial)
 Fourth descriptor (Randomized Trial)
 “Randomized Trial”
Next Slide
Randomized Trial

36. Select a healthy study sample.
What’s the Design?
Select a healthy study sample.
Observe who is exposed and who is not exposed.
Follow through time and compare rate of disease in exposed group to rate of disease in unexposed group.
Epidemiologist is involved during the entire time from exposure and disease.
 First descriptor (Cohort Study or Randomized Trial to prevent disease)
 Second descriptor (Cohort Study)
 Third descriptor (Cohort Study)
 Fourth descriptor (Cohort Study)
 “Cohort Study”
Next Slide
Cohort Study

37. Ask both groups about their exposures in the past.
What’s the Design?
Select a group of people with disease and a similar group of people without the disease.
Ask both groups about their exposures in the past.
Compare proportion of exposure in diseased group to proportion of exposure in non-diseased group.
Epidemiologist is involved after disease has occurred and relies on subjects’ memories to gather information about exposure.
 First descriptor (Case-Control Study)
 Second descriptor (Case-Control Study)
 Third descriptor (Case-Control Study)
 Fourth descriptor (Case-Control Study)
 “Case-Control Study”
Next Slide
Case-Control Study

38. Cross-Sectional Study
What’s the Design?
Select a study sample.
Ask each person about both exposure and disease at that point in time.
Disease rate in exposed group is compared to disease rate in unexposed group.
 First descriptor (Cross-Sectional Study)
 Second descriptor (Cross-Sectional Study)
 Third descriptor (Cross-Sectional Study)
 “Cross-Sectional Study”
Next Slide
Epidemiologist gathers data only at that one point in time.
Cross-Sectional Study

39. Thank You and Good Luck