1. Epidemiology and Biostatistics Week 1 – Chapter 1 “Epidemiology” Oreta Samples, MPH, VT

2. Epidemiology…  Study of something that affects a population  Study of factors that determine the occurrence & distribution of disease in a population  One of the ways in which disease, injury and clinical practice are studied

3. Classical Vs. Clinical  Classical Population oriented studies of the community origins of health problems. Population oriented studies of the community origins of health problems.  Clinical Use of research designs and statistical tools to study patient in health care setting

4. Other Types of Epidemiology  Chronic Disease Epidemiology Sampling and statistical analysis Sampling and statistical analysis  Infectious Disease Epidemiology Laboratory support Laboratory support  Syndronic Epidemiology Patterns of symptoms and signs Patterns of symptoms and signs

5. Diseases  Natural History of Disease: Also known as the natural “progression” of a disease Also known as the natural “progression” of a disease  Intervention Against Disease: Therapeutic Example: Chemotherapy, radiation, surgical intervention Preventative Example: Anti-smoking public service message

6. Disease Profile  History of Disease: Diagnosis of Familial Adenomatous Polyposis (commonly known as “colon cancer”) Diagnosis of Familial Adenomatous Polyposis (commonly known as “colon cancer”)  Intervention: Therapeutic: Ileorectal anastomosis or ileostomy or colostomy (depending on severity) Preventive: Colonoscopy on a regular basis; dietary fiber increase

7. Stages of Disease  Pre-disease Stage: No disease present  Primary Prevention: Prevention of disease  Latent Stage: Asymptomatic; disease is in progress  Secondary Prevention: Treatment prevents progression  Symptomatic Stage: Manifestation of disease  Tertiary Prevention: Slowing of disease

8. So What Causes a Disease?  Biological Mechanisms?  Social Causes?  Environmental Causes? The answer is: Social factors and environmental factors can contribute to the biological mechanism which triggers a disease

9. Circumstances Contributing to Disease Manifestations  Host Factors: Ability to adapt to the stresses that are produced by an agent  Agent of Disease/illness (3): Biological Agents (allergens, organisms, toxins, and food) Biological Agents (allergens, organisms, toxins, and food) Chemical Agents (chemical toxins and dust) Chemical Agents (chemical toxins and dust) Physical Agents (Kinetically propelled energy such as bullets, cars, and blunt trauma) Physical Agents (Kinetically propelled energy such as bullets, cars, and blunt trauma)

10. Manifestations (continued)  Environmental: May effect the probability and circumstances of contact between host and agents. Examples include: Examples include: SanitationSanitation Road ConditionsRoad Conditions OvercrowdingOvercrowding Poor EconomicsPoor Economics

11. Challenge Time !!! # 1  A group of 20 male college students volunteer/consent to have their PSA levels checked three times yearly (every 4 months) for the four years they are in college as part of a study by University Hospital on prostate cancer. Is this study considered to be: A. Clinical Epidemiology B. Classical Epidemiology

12. # 2  If an epidemiologist is sent out to investigate suspected food poisoning at a church picnic after reports of 20 people becoming ill with symptoms of vomiting/diarrhea occurring three hours after the picnic ended, he is practicing: A. Infectious disease epidemiology B. Syndromic epidemiology C. Classical epidemiology D. Clinical epidemiology E. Both b and c F. Both a and d

13. # 3  The natural progression of a disease is also known as: A. Preventive intervention B. Pre-disease staging C. Natural History of Disease D. None of the Above

14. # 4  The susceptibility of an immuno- compromised individual to common colds and other illnesses is a: A. Environmental Factor B. Disease Factor C. Host Factor D. Conditional Factor

15. # 5  Within the stages of disease, which of the following stages may be defined by manifestation of disease symptoms? A. Secondary Prevention B. Symptomatic Stage C. Pre-disease Stage D. Latent Stage

16. VECTORS  Defined: Insects, arthropods and animals which aid in the spread of disease by themselves being a host capable of transmitting disease causing organisms to the host they are living on Insects, arthropods and animals which aid in the spread of disease by themselves being a host capable of transmitting disease causing organisms to the host they are living on  Examples: Mosquitoes = West Nile Virus Tick = Lyme Disease Rats = Bubonic Plague Mosquitoes = Canine Heartworm Snail = Haemonchus contortus (nematode)

17. How Vectors Work (Taken from http://www.grandriverveterinaryhospital.com/images/heartwormlifecycle.jpg)

18. Risk Factors for Diseases  B iological/Behavioral  E nvironmental  I mmunological  N utritional  G enetics  S ervices, Social, Spiritual

19. Any Questions ?