GOAL. Disclosure. Objectives 11/12/2014. Epi 101: Basic Epidemiological Definitions and Principles for Non-Epidemiologists

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1 Epi 101: Basic Epidemiological Definitions and Principles for Non-Epidemiologists Anil T. Mangla., MS., PhD., PHD., FRIPH Assistant Director, San Antonio Metro Health Associate Adjunct Professor University of Texas-School of Public Health Mercer University- School of Medicine Disclosure I have no relevant conflicts to disclose. November 6 th 2014 GOAL Decrease the fear-factor of infectious diseases affecting our community at any given time Objectives 1. Explain basic epidemiology terms and definitions, and their applicability. 2. Discuss measures taken during vaccinepreventable disease exposure or outbreak situations, and the public health professionals' role in assisting in this process. 3. Questions What is epidemiology? What is epidemiology? The study of skin diseases? 1

2 What is epidemiology? The study of skin diseases? The study of the distribution and determinants of health-related states in specified populations, and the application of this study to control health problems." Epidemiology - Journalists are taught: The 5 W s are the essential components of a news story because if any of the five are missing, the story is incomplete. Epidemiologic Synonyms for the 5 W s: 1) What 1) Diagnosis or health event 2) Who 2) Person 3) Where 3) Place 4) When 4) Time 5) Why / How 5) Causes, Risk factors, and Modes of transmission Epidemiology Tenets of Epidemiology i. Find the Disease ii. Isolate iii. Identify Contacts iv. Stop Exposures v. Control Measures Latency and infectiousness Susceptible Host Subclinical Disease TIME Clinical Disease Death Recovery Public Health Surveillance can be Active, passive or sentinel Active: Public health agency staff call or go to clinics Latent Incubation Infectious Non-infectious Passive: responsibility on health care provider Sentinel: representative sample of clinics selected for active surveillance Infection Clinical onset -11 2

3 Passive Reporting: How? For further information contact an Epidemiologist at (210) or (210) For further information about TB or STDs, including HIV/AIDS contact an Epidemiologist at (210) Traditional Passive Notifiable Disease Surveillance Lab confirmed case Lab tests for organism Specimen collected Person seeks care Disease Report to Public Health By laboratories, infection preventionists, healthcare providers Surveillance Can Detect Outbreaks Outbreak = Epidemic Several definitions: More cases of disease than expected 2 or more cases of similar illness (linked in place and time) with the same source Even one case of a rare disease can be considered an outbreak, like botulism Worldwide epidemic = pandemic Person becomes ill Exposures in population Examples of Epidemiology Data Sources Death certificates Birth certificates Hospital discharge data Questionnaires (BRFSS) Disease registries Laboratory tests(hga1c) Key Principles: Measures of Disease Frequency: a count of affected individuals. Percents of totals: provide for comparison between groups and within groups. Rates per population: used to compare the occurrence of disease in different groups 15 cases / 1, cases / 4, 000 3

4 Primary & Secondary Syphilis Cases Number of Cases/Deaths Rates (Cases per 100,000 Population) Primary & Secondary Syphilis Cases, Bexar County, Primary & Secondary '05 '06 '07 '08 '09 '10 '11 '12 '13 Year There was a 6% decrease in the number of P&S syphilis cases from 2012 to ( 1 year) There was a 169% increase in the number of P&S syphilis cases from 2004 to ( 9 years) Source: local and central STD*MIS data Primary and Secondary Syphilis Rates, Bexar County Texas US '05 '06 '07 '08 '09 '10 '11 '12 '13 Year 2013: Bexar County s rate of P&S syphilis was 3.0 times higher than the Texas and the preliminary US rate. Source: local and central STD*MIS data = US 2013 data preliminary Syphilis Cases, Bexar County, 2013 Cases (all stages) N = 1, to to 14 5 to 9 3 to 4 1 to 2 Incidence and Prevalence Incidence: the number of new cases that develop in a group of individuals during a specific time period. Prevalence: the total number of new and existing cases of a disease or health condition in a population at some designated time. Source: local STD*MIS data Estimated Incidence of AIDS, Deaths, and Prevalence by Quarter-Year of Diagnosis/Death, US, * 25,000 20,000 15,000 10,000 5,000 AIDS Deaths Prevalence 1993 definition implementation 350, , , , , ,000 50,000 Causation What is cause? Are there causes? A sense of cause-and-effect is inherent in all living creatures A factor that produces an effect A factor that Makes a difference Although intuitively appealing, such definitions do not clarify much Quarter-Year 0 *Adjusted for reporting delays 4

5 Coverage rate % Ranking How Epidemiology Is Used To Identify Target Populations. Local vaccination coverage rates. How that data can be used to identify subpopulations at higher risk for disease. Comparing rates Using data to identify HOT zones GA and SA Ranking and 4:3:1:3:3:1 Coverage for 24 Month According to National Immunization Survey (NIS) Source: CDC NIS Year 28 Hot Spots for Ebola Peak Month of Flu Activity in US 5

6 Percent of All Influenza B Viruses Days Absent Graduation Rate 0 Days 79.63% 1 to 5 Days 79.19% 6 to 10 Days 72.71% 11 to 14 Days 61.42% 15 or More Days % The Predominantly Circulating Influenza B Lineage Was Different Than That Contained in Influenza Vaccines in 6 out of 11 influenza Seasons 1 Influenza Viral Surveillance % of All Circulating Influenza B Viruses Tested 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Influenza B (matched lineage) Influenza Seasons Influenza B (Opposite lineage)

7 Vaccine Coverage Polio Poliomyelitis is a viral disease that can affect nerves and can lead to partial or full paralysis. It is a crippling and potentially deadly infectious disease. 42 7

8 Symptoms Transmission About 1 out of 4 people with poliovirus infection will have flu-like symptoms that may include Sore throat Fever Tiredness Nausea Headache Stomach pain A smaller proportion of people with poliovirus infection will develop other more serious symptoms that affect the brain and spinal cord: Paresthesia (feeling of pins and needles in the legs) Meningitis (infection of the covering of the spinal cord and/or brain) occurs in about 1 out of 25 people with poliovirus infection Paralysis (can t move parts of the body) or weakness in the arms, legs, or both, occurs in about 1 out of 200 people with poliovirus infection Poliovirus only infects humans It is very contagious and spreads through person-to-person contact. The virus lives in an infected person s throat and intestines. It enters the body through the mouth and spreads through contact with the feces of an infected person and, though less common, through droplets from a sneeze or cough. You can get infected with poliovirus if you have feces on your hands and you touch your mouth. An infected person may spread the virus to others immediately before and about 1 to 2 weeks after symptoms appear. The virus can live in an infected person s feces for many weeks. It can contaminate food and water in unsanitary conditions. People who don t have symptoms can still pass the virus to others and make them sick. Prevention Polio vaccine protects children by preparing their bodies to fight the polio virus. Almost all children (99 children out of 100) who get all the recommended doses of vaccine will be protected from polio. POLIO CASE STUDY There are two types of vaccine that can prevent polio: inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV). Only IPV has been used in the United States since 2000; OPV is still used throughout much of the world. Case-Study Live attenuated vaccines still used (OPV) Risk associated ( Immune Deficiencies) Vaccine-Derived Poliovirus (VPDV) can emerge to cause Polio Outbreaks Change to Inactivated Polio Virus(IPV) Other countries still use (OPV) What happens if Child travels to other countries Receives OPV and is Severe Combined Immunodeficiency (SCIDS) Case - Study A boy 7 months old show up at a hospital Had a 6 week history of fever and draining skin lesions Kid diagnosed with lymphadenitis and sent home 8

9 Results Kid comes back to ER Increased irritability and decreased movement of the left leg Physical exam Negative for meningeal signs No respiratory distress. Magnetic resonance imaging suggested abnormal signals in the cervical spinal cord suggesting a demyelinating process Further evaluation 1. Received two additional OPV vaccinations during immunization days in India 2. New diagnosis was identified Vaccineassociated paralytic poliomyelitis (VAPP) 3. Stool culture analyzed (ivdpv1) Conclusions Ebola Virus International travel carries a small risk for importation of attenuated vaccine organisms into the US. Vaccine-associated diseases can be diagnosed early and the spread can be prevented by immunizations of exposed persons in the community and amoungs contacts Prototype Viral Hemorrhagic Fever Pathogen Filovirus: enveloped, non-segmented, negativestranded RNA virus Severe disease with high case fatality Absence of specific treatment or vaccine >20 previous Ebola and Marburg virus outbreaks 2014 West Africa Ebola outbreak caused by Zaire ebolavirus species (five known Ebola virus species) 52 Ebola Virus Zoonotic virus bats the most likely reservoir, although species unknown Spillover event from infected wild animals (e.g., fruit bats, monkey, duiker) to humans, followed by human-human transmission 53 9

10 Population is 21 million EVD Cases (United States) As of October 24, 2014, EVD has been diagnosed in the United States in four people, one (the index patient) who traveled to Dallas, Texas from Liberia, two healthcare workers who cared for the index patient, and one medical aid worker who traveled to New York City from Guinea Index patient Symptoms developed on September 24, 2014 approximately four days after arrival, sought medical care at Texas Health Presbyterian Hospital of Dallas on September 26, was admitted to hospital on September 28, testing confirmed EVD on September 30, patient died October 8. TX Healthcare Worker, Case 2 Cared for index patient, was self-monitoring and presented to hospital reporting low-grade fever, diagnosed with EVD on October 10, recovered and released from NIH Clinical Center October 24. TX Healthcare Worker, Case 3 Cared for index patient, was self-monitoring and reported low-grade fever, diagnosed with EVD on October 15, currently receiving treatment at Emory University Hospital in Atlanta. Information on U.S. EVD cases available at Ebola spreads Slower but More Fatal than other diseases Human-to-Human Transmission Ebola Viral Load Progression Infected persons are not contagious until onset of symptoms EVD viral load Infectiousness of body fluids (e.g., viral load) increases as patient becomes more ill Remains from deceased infected persons are highly infectious EXPOSURE INCUBATION Symptoms typically begin 2 21 days after exposure. DEATH Human-to-human transmission of Ebola virus via inhalation (aerosols) has not been demonstrated DAYS 1 3 DAYS 4 7 In the first few Around days 4-7, days of illness, patients may also patients have flulike symptoms and diarrhea, nausea, have vomiting, profound low blood weakness. pressure, headaches and anemia DAYS 7 10 Toward the end of the illness, there is confusion and bleeding, both internal and visible. After 10 days Illness progresses toward coma, shock and death

11 Latency and infectiousness Ebola Viral Load Progression TIME EVD viral load Susceptible Host Subclinical Disease Clinical Disease Death Recovery EXPOSURE DEATH Latent Infectious Non-infectious INCUBATION Symptoms typically begin 2 21 days after exposure. Infection Incubation Clinical onset DAYS 1 3 DAYS 4 7 In the first few Around days 4-7, days of illness, patients may also patients have flulike symptoms and diarrhea, nausea, have vomiting, profound low blood weakness. pressure, headaches and anemia DAYS 7 10 Toward the end of the illness, there is confusion and bleeding, both internal and visible. After 10 days Illness progresses toward coma, shock and death. -61 Gatekeepers in San Antonio Metro Health ER EMS Donnie Diaz Mary Thomas John Berlanga Cara Hausler Acknowledgements Thank you Any Questions??? 11