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Unformatted text preview: Principles of Disease and Introduction to Ethical Principles in Research
Lecture 3 PH 150A: Introduction to Epidemiology Spring 2010 Lisa F. Barcellos, Ph.D. Associate Professor
January 25, 2010 PH150A 1 Objectives Principles of disease Review surveillance Natural history of disease Disease of the Day Introduce principles of ethics in epidemiology January 25, 2010 PH150A 2 Epidemiologic Principles of Disease Disease, illness, and ill health are not randomly distributed in a population, but follow predictable patterns. Disease occurs as a function of host, agent and environmental interaction, i.e. the epidemiologic “triad”. Individuals have characteristics that predispose them to (or protect them from) different diseases, host characteristics. Characteristics may be genetic or result from exposures to environmental agents. Diseases may have multiple causes.
PH150A 3 January 25, 2010 Public Health Approach
Intervention: What Works? Risk Factors: Surveillance: What is the cause? What is the problem?
January 25, 2010 PH150A Implementation: How do you do it? Response
4 Public Health Surveillance
Systematic and ongoing Collection Analysis Interpretation Dissemination Link to public health practice Assess public health status Define public health priorities Evaluate programs Stimulate research Policy development January 25, 2010 PH150A 5 Types of Surveillance Passive Routine data used or physician or lab reports cases of disease; inexpensive, not comprehensive Project staff seek out cases of disease; expensive, more comprehensive Intensive collection of case data from only part of the population, example: active surveillance at specific hospitals to track specified disease. Monitoring key health events through specific sites, providers, vectors, animals, etc. Active Sentinel January 25, 2010 PH150A 6 Data Sources and Methods for Surveillance Notifiable diseases Laboratory specimens Vital records Sentinel surveillance Registries Surveys Administrative data systems Other data sources January 25, 2010 PH150A 7 National Notifiable Disease Surveillance (NNDS) Reporting mandated by state law/regulation Health care providers, laboratories report to local Health Department (HD, city or county) County HD submits reports to State HD Reports transmitted to Centers for Disease Control and Prevention (CDC)* primarily through National Electronic Telecommunications System for Surveillance (NETSS) Most of this work mandated at state level *www.cdc.gov
January 25, 2010 PH150A 8 Examples of Surveillance Systems in the US Reportable Infectious Diseases Vital Statistics (birth or death certificates) Disease Registries, e.g., cancer registries Health Surveys Ambulatory Systems Linked vital statistics with health insurance data Sentinel Systems (example: NIOSH Sentinel Event Notification System for Occupational Risks (SENSOR), e.g., case of mesothelioma
9 January 25, 2010 PH150A SENSOR Sentinel Event Notification System for Occupational Risks
The mission of the Sentinel Event Notification System for Occupational Risk (SENSOR) program is to build and maintain occupational illness and injury surveillance capacity within state health departments (www.cdc.gov)
January 25, 2010 PH150A 10 Lead Poisoning
Michigan, 1990 www.cdc.gov
January 25, 2010 PH150A 11 AIDS Chlamydia Some Examples of Notifiable Diseases E. coli O157:H7 Gonorrhea Hepatitis C/non-A, non-B Legionellosis* Lyme disease Malaria Syphilis Tuberculosis Rabies, Animal Rabies, H. influenzae, invasive H. influenzae Hepatitis A Hepatitis B Measles Meningococcal disease Mumps Pertussis Rubella SARS (Severe Acute Respiratory SARS (Severe
Syndrome- coronavirus) Syndrome- coronavirus Smallpox (no cases globally for years) * Legionnaire’s Disease Legionnaire http://www.cdc.gov/mmwr/distrnds.html http://www.bt.cdc.gov/agent/smallpox/response-plan
PH150A 12 January 25, 2010 January 25, 2010 PH150A 13 Levels of Prevention Primary: educate individuals and communities to avoid exposure Secondary: screen to find early disease and treat before it becomes established; use surveillance systems to identify high risk groups Tertiary: treat established disease to avoid progression of disease and complications of disease
PH150A 14 January 25, 2010 Modes of Disease Transmission Direct Person-to-person contact Indirect Common vehicle Single exposure Multiple exposures Continuous exposures Vector
PH150A 15 January 25, 2010 Natural History of Disease
sis no es iag g t an se of D Ch On me c mi re gi u o to al T p ol os h p m su x at E Sy U P Susceptibility Sub-clinical Clinical Recovery, Disability or Death
16 January 25, 2010 PH150A Important Terms Herd immunity - the resistance of a group to an attack by an infectious disease to which a large proportion of the group members are immune Incubation period - interval from time of infection to the time of onset of clinical illness Induction period - interval from time of disease initiation to diagnosis January 25, 2010 PH150A 17 Epidemiology Triad
Host Vector Environment Environment Agent Disease arises from an interaction of the host Disease host with an agent in a particular environment with agent environment
January 25, 2010 PH150A 18 Epidemiology Triad for
Host Host influences exposure susceptibility and response and Time Environment Influences opportunity Influences for exposure for
January 25, 2010 PH150A Agent cause cause 19 Epidemiology Triad for Tuberculosis
HIV infection, poor nutrition, older age, male Host Host influences exposure susceptibility and response and Crowding, Crowding, poor ventilation poor Environment Influences opportunity Influences for exposure for
January 25, 2010 Time Mycobacterium Mycobacterium tuberculosis tuberculosis Agent cause cause PH150A 20 A Multi-factorial Epidemiologic Triad: Breast Cancer
Examples: Genetics: BRCA1 Age Host: Female White Reproductive history Menopausal Status Exercise patterns Obesity Hormone Use Agent: Examples: Estrogen levels Ionizing radiation Alcohol intake ?DDT, PCB ?Dietary fat ?Electromagnetic fields ?Tobacco Smoke January 25, 2010 Examples: Environment: Social Environment: High income, education Chemical Contaminated Environment? ?PH150A Geography 21 A Way to Think about a Disease What is the disease: method of diagnosis, symptoms, What is prognosis? How much of the disease occurs in a population? occurs Who in population is susceptible? When does the disease occur in the population? What causes the disease and how virulent is it? Where does the disease occur? How disease treated and prevented? treated January 25, 2010 PH150A 22 Disease of the day…………?????
“At the end of the Middle Ages the French Army attacked Naples and this disease quickly spread from Italy to France and then all over Europe. As a result, over the centuries it was called the ‘French disease’ . The French, of course, called it the Italian disease (the Dutch called it Spanish, the Russians Polish, the Turks called it Christian, and the Japanese called it the Portuguese disease). The frightening spread of this disease soon spelled the end of medieval sexual lassitude. The formerly popular public bath houses were closed, and people became increasingly prudish.”
http://www2.hu-berlin.de/sexology/ECE4/html/historical_notes.html Charles VIII of France January 25, 2010 PH150A 23 Transmission/Cause Sexually transmitted or congenital transmission (from mother to child) Caused by Treponema pallidum spirochaete bacterium
PH150A 24 January 25, 2010 Syphilis
Reportable Disease Diagnosis: symptoms and laboratory tests Cured with penicillin Syphilis increases HIV transmission Spread by direct contact with person who has syphilitic lesions. See http://www.cdc.gov/std/stats/app-casedef.htm for case definitions
January 25, 2010 PH150A 25 Syphilis Major disease problem prior to introduction of antibiotic therapy 1998: 38,000 cases in U.S. and 800 congenital cases Southern US: 2-5x national rate Effectively treated with penicillin/cured with penicillin January 25, 2010 PH150A 26 Primary Syphilis
3 weeks after infection, chancre appears highly contagious sores disappear after 1 -5 weeks; but disease does not. January 25, 2010 PH150A 27 Secondary Syphilis
Weeks or months after chancres heal rash may cover the entire body May experience flulike symptoms Remains contagious January 25, 2010 PH150A 28 Tertiary Syphilis
Latent stage: Bacteria may silently attack internal organs and tissues for years. The infected person is no longer contagious. Tertiary Syphilis: Heart disease, nerve damage, necrosis or mental defect, death.
January 25, 2010 PH150A 29 Congenital Syphilis World Health Organization (WHO): 500,000 newborns + 500,000 stillbirths or miscarriages per year worldwide Mental retardation, deafness, blindness, structural abnormalities
January 25, 2010 PH150A 30 Primary and Secondary syphilis Rates (per 100,000 population) by Gender: United States, 1981–2004 and the Healthy People 2010 Target
Rate (per 100,000 population) 25 20 15 10 5 0 1981 83 85 87 89 91 93 95 97 99 2001 03 Male Female 2010 Target Note: The Healthy People 2010 target for P&S syphilis is 0.2 case per 100,000 population.
January 25, 2010 PH150A 31 Primary and Secondary Syphilis Rates (per 100,000 population) by State: United States and Outlying Areas, 2006 The total rate of P&S syphilis was 3.3 per 100,000 population. The Healthy People 2010 target is 0.2 case per 100,000 population
January 25, 2010 PH150A 32 Congenital Syphilis: Infections by Race and Ethnicity
Reported incidence per 100,000 live births
125 100 75 50 25 0 1997 2002 2010 Target Total American Asian/ Indian Pacific Islander
PH150A Black White Hispanic Note: Data represent the mother’s race and ethnicity. American Indian includes Alaska Native. Black and white exclude persons of Hispanic origin. Persons of Hispanic origin may be any race. Persons were asked to select only one race category; selection of more than one race was not an option. Source: STD Surveillance System, NCHSTP,CDC. January 25, 2010 33 Syphilis Cases, 2004 Most cases today (64%) are transmitted by Men who Have Sex with Men (MSM) Heterosexual transmission is responsible for ~ 34% of cases.
PH150A 34 January 25, 2010 Epidemiological Triangle: Syphilis
Males Multiple Sexual partners Men who have sex with men Crack and meth use HIV+ Fetus of Syphilis+ mother Environment
Poverty Social/Behavioral norms Chronic joblessness Male incarceration
January 25, 2010 PH150A Agent
T. pallidum T. pallidum 35 Natural History of Syphilis
Symptoms: None Chancre Rash and other None Symptoms Paralysis Blindness Dementia Heart Disease Death No Tertiary Infectious: None Stage of Incubation Disease: Years: Highest Primary High Secondary Low Latent 0 3 8 14 10-20+ years Infection with Treponema pallidum
January 25, 2010 PH150A 36 Levels of Prevention Primary: Educate people to use condoms and avoid risky sex Secondary: Screen to find people with early disease and treat infected people; use surveillance systems to identify high risk groups Tertiary: Treat people with established syphilis to avoid complications
January 25, 2010 PH150A http://www.cdc.gov/stopsyphilis/plan.htm 37 Conduct of Ethical Research January 25, 2010 PH150A 38 Tuskegee Study of Untreated Syphilis in Negro Male
US Public Health Service working with Tuskegee Institute Macon County, Alabama,1932-72 Cohort study of “bad blood” Original Goal: 6 month study to justify treatment programs for Blacks 600 men: 399 with syphilis, 201 without syphilis
January 25, 2010 No informed consent
PH150A 39 Tuskegee Study
Study lasted 40 years. Men freely agreed to be examined and tested. Treatment promised but not given. Penicillin treatment available in 1947 but not offered. US panel, 1972: Study declared“ethically unjustified” 1974: National Research Act 1995: National Bioethics Advisory Commission established
PH150A 40 Documentary: “Ms. Evers’ Boys”
January 25, 2010 "We were treated inhuman at all times. Nobody knows what we went through except those of us who are living participants right today." Herman Shaw “I was there when President Clinton said the words, ‘I am sorry.’ (1997) Tears streamed down the faces of many black people in the audience. I heard people sobbing. The pain inflicted by the syphilis study was not limited to the citizens in and around Tuskegee. For many African Americans, the fact that the Tuskegee study occurred at all proves their lives are not valued in America.” Dr. Vanessa Gamble, Director of
Tuskegee University National Center for PH150A Bioethics in Research and Health Care
41 January 25, 2010 Objective of Epidemiology is to Improve Human Health Ethical issues go beyond those that apply to other scientific disciplines
Findings have direct and often immediate societal relevance Studies are generally funded from public resources Human subjects are involved and most often derive NO personal benefit from study results. derive NO January 25, 2010 PH150A 42 Ethical Principles in Epidemiology
Respect for people’s rights Beneficence: Participant benefits proportionate to risks Justice: Benefits and burdens fairly distributed among population Nonmaleficence: Avoid causing harm Study results intended to improve population health January 25, 2010 PH150A 43 Ethical Issues Scientific validity versus human rights Confidentiality – Access to data Confidentiality Need to intervene based on study results Conflict of interests Related to funding Related to investigator Interpretation of findings to the public January 25, 2010 PH150A 44 Ensuring Ethical Quality of the Work and Informed Consent Institution Review Board (IRB) review Informed consent Monitor compliance Investigator training nature of project study procedures potential study risks /benefits assurances that participation is voluntary confidentiality right to ask questions about study
45 January 25, 2010 PH150A January 25, 2010 PH150A 46 January 25, 2010 PH150A 47 Ethics in Epidemiology: Summary Minimize risks to participants and ensure they are proportionate to benefits Equitable selection of participants Protect vulnerable people Protect confidentiality Obtain fully informed consent
PH150A 48 January 25, 2010 Summary Understanding disease natural history increases chances of prevention. Prevention can occur at several stages. Disease results from interaction between host, agent and environment. Disease can have one cause or many different causes. Ethical research principles are critical
PH150A 49 January 25, 2010 ...
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This note was uploaded on 02/21/2010 for the course PH 150A taught by Professor Adams during the Spring '08 term at University of California, Berkeley.
- Spring '08