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EPIDEMIOLOGY

EPIDEMIOLOGY. What is Epidemiology?. Distribution of Disease WHEN Time WHERE Place WHO Person. EPIDEMIOLOGY. Distribution of Disease. Time Changing or stable Cyclic Seasonal secular. EPIDEMIOLOGY. Distribution of Disease. Place Geographic

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EPIDEMIOLOGY

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  1. EPIDEMIOLOGY What is Epidemiology? Distributionof Disease WHEN Time WHERE Place WHO Person

  2. EPIDEMIOLOGY Distribution of Disease • Time • Changing or stable • Cyclic • Seasonal • secular

  3. EPIDEMIOLOGY Distribution of Disease Place Geographic -Restricted/Wide spread -Coastal/inland Weather(temp. , humidity , rainfall) Altitude/latitude/longitude Urban/rural

  4. EPIDEMIOLOGY Distribution of Disease • Person • Age • Sex • Race • Education • Occupation • behavior

  5. EPIDEMIOLOGY Distribution of Disease morbidity rates Incidence rate • The numerator is newcases • The denominator may change over time as people develop disease • However, in practice • in large studies, the denominator is often the mid- year population • in small studies, the denominator includes persons at risk of the disease

  6. EPIDEMIOLOGY Distribution of Disease morbidity rates Attack rate عليه مسائل Number of episodes during specified period x 10n Attack rate = Population at risk/ period • Acute recurrent diseases , • e.g. URTI, food poisoning. • A person may catch the disease more than once.

  7. EPIDEMIOLOGY Distribution of Disease morbidity rates Attack rate Example: In a village of 600 persons, 120 visits to the PHCC were due to food poisoning. What is the attack rate of food poisoning in the village ?

  8. EPIDEMIOLOGY Distribution of Disease morbidity rates Attack rate Example: In a village of 600 persons, 120 visits to the PHCC were due to flu. 0 What is the attack rate of flu in the village ?

  9. EPIDEMIOLOGY Distribution of Disease morbidity rates Incidence rate Factors affecting incidence: 1- New risk factor Contraceptive pills & thromboembolism. 2- Changing virulence H1N1virus & influenza pandemic 3- Changing pattern of intervention Chemoprophylaxis & meningitis

  10. EPIDEMIOLOGY Distribution of Disease morbidity rates Incidence rate Factors affecting incidence: 4-Population pattern Aging & degenerative diseases & cancer 5- Reporting incidence Increase in reporting & Early stage of surveillance & incidence

  11. EPIDEMIOLOGY Distribution of Disease morbidity rates Incidence rate Factors affecting incidence: 6-Screening 7-New diagnostics Screening New diagnostic early detection of cases detection of cases incidence incidence

  12. EPIDEMIOLOGY Distribution of Disease morbidity rates Incidence rate Factors affecting incidence: 8- Changing classification Blood pressure 140/80 mmhgVs 160/90 mmhg incidence Fasting blood sugar 126 mg/100ml Vs 140 mg/100ml incidence

  13. EPIDEMIOLOGY Distribution of Disease morbidity rates Prevalence rate مسائل وتفهمي ايش يعني • Point prevalence • Period prevalence • It involves old and new cases • It measures the disease status in the population. • It measures the disease burden. ( All Cases)

  14. EPIDEMIOLOGY Distribution of Disease morbidity rates Prevalence rate Point prevalence: Total cases (old + new) at fixed point of time in a place X = 1On total population in that place

  15. EPIDEMIOLOGY Distribution of Disease morbidity rates Prevalence rate Period prevalence: Total cases (old + new) during a period of time in a place X = 1On total population in that place

  16. EPIDEMIOLOGY Distribution of Disease morbidity rates prevalence rate example MOH conducted a survey for RVF among workers in slaughterhouses in Makkah . 224 seropositive workers were identified among 6000 workers. Calculate the prevalence of RVF.

  17. EPIDEMIOLOGY Distribution of Disease morbidity rates prevalence rate Factors affecting prevalence : 1- Incidence rate & 2- Disease duration average duration of disease Prevalence rate Incidence rate X = Incidence Prevalence Prevalence Longer duration

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