Principles of infectious disease epidemiology 2024.pdf

Principles of infectious disease epidemiology Dr. Ibrahim Ismail Abu MBBS, MPH, MD, Fellow-EPI Assistant Professor of epidemiology in community medicine department King Abdul-Aziz University, Jeddah Dr. Ibrahim Ismail Abu 8/26/202...

Principles of infectious disease epidemiology Dr. Ibrahim Ismail Abu MBBS, MPH, MD, Fellow-EPI Assistant Professor of epidemiology in community medicine department King Abdul-Aziz University, Jeddah Dr. Ibrahim Ismail Abu 8/26/2024 Concepts, definitions and common terms used in IDE 2Images from Public Intended learning outcomes(ILOs) By the end of this session the student should be able: 1. To explain the importance of the communicable disease and why we study its epidemiology. 2. To be acquainted with common definitions and terms used in infectious disease epidemiology. 3. To recognize common periods (latent period, incubation period, infectious period and symptomatic period mean) used in IDE. 3  Epidemiology ▪ Definition? ▪ The epidemiology is used to refer both to: ◉ Methods of study of diseases ◉ Body of knowledge about the natural history of disease. ▪ What is the natural history of disease? ◉ It is adscription how that disease behaves and what factors affect its incidence and distribution. 4 5 Types of epidemiology 6 Why study the epidemiology of Infectious disease? 7 Study of infectious disease epidemiology 8  Infectious disease  Infectious disease (communicable) is defined as an illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or its products from an infected person, animal, or reservoir to susceptible host, either directly or indirectly. 9  Infectious disease vs. communicable disease Infectious diseases (tetanus) Communicable diseases (measles) Transmissible diseases: Through unnatural route from infected person(CJD) 10 Non-communicable infectious diseases. Examples include 11 Categories of Infectious Diseases 12 Categories of Infectious Diseases… 13 Epidemiology frame of infectious disease 14 The Epidemiology of Measles 15 Terminology in infectious disease epidemiology 16 Terminology in IDE 17 Terminology in IDE.. 18 Terminology in IDE… 19 Terminology in IDE… 20 Dr. Ibrahim Ismail Abu 8/26/2024 Endemic versus Epidemic 21 Terminology in IDE… 22 Dr. Ibrahim Ismail Abu 8/26/2024 Relationship between incubation period, laten period and infectious period 23 Examples MCQs 1.C 2.C 24 Principles of infectious disease epidemiology Dr. Ibrahim Ismail Abu MBBS, MPH, MD, Fellow-EPI Assistant Professor of epidemiology in community medicine department King Abdul-Aziz University, Jeddah Dr. Ibrahim Ismail Abu 8/26/2024 Cycle of infectious disease 26Images from Public  Intended Learning Outcomes (ILOs) By the end of the tutorial, you need to: 1. To recognize the dynamic and cycle of infectious disease. 2. To identify the importance and types of carriers 3. To recognized the epidemiologic triad. 4. To identify factors determined the occurrence and severity of infections disease. Dr. Ibrahim Ismail Abu 27 8/26/2024 Principles of infectious disease epidemiology  Dynamics of disease Transmission (Chain of Infection) I II III Source or Reservoir Modes of transmission Susceptible host Dr. Ibrahim Ismail Abu 28 8/26/2024 Principles of infectious disease epidemiology Dr. Ibrahim Ismail Abu 8/26/2024 29 Dr. Ibrahim Ismail Abu 8/26/2024 30  1-Infectious agent 1. Viruses: they are the causative agents of many infectious diseases such as measles, smallpox, etc. 2. Bacteria: including; Cocci, Bacilli, Rickettsia, etc. 3. Fungi: including moulds and yeast that cause many types of skin diseases. 4. Protozoa: one cell animal form such as; Entamoeba causing dysentery. 5. Parasites: such as Schistosoma, Taenia, Anclystoma and Ascaris. 31 Characteristics of biologic agents: 1. Infectivity 2. Pathogenicity 3. Virulence 4. Antigenicity (immunogenicity) 5. Dose relation 32  II- Reservoirs/source of infection Reservoir of infection:  Organism matter, in which an infectious agent lives, grows and multiplies in, such as a meter that can be transmitted to man (susceptible host).  Reservoir could be man, animal, plant, soil or inanimate objects.  Human reservoir of infection may be in form of cases or carriers. 33 Dr. Ibrahim Ismail Abu 8/26/2024 34 Carriers of infectious disease 35 Classification of carriers 36 37  Human reservoir Animal Non-living reservoir reservoir Human reservoir Type:  Incubatory cases  Primary case  Convalescent carriers  Index case  healthy  Secondary cases According to spectrum of disease: Duration: Portal of exit:  Clinical cases (mild/severe-typical/atypical)  Temporary  Urinary  Sub-clinical cases  Chronic  Intestinal  Latent infection cases  Respiratory  others 38 III- Exit of infection 39 VI- Mode of transmission 40 (VI- Mode of transmission)… 41 (VI- Mode of transmission)… 42 (VI- Mode of transmission)… 43 44  V- Portal of entry “outlet” 1. Respiratory tract 2. Gastro-intestinal tract by ingestion 3. Urogenital tract 4. Skin and mucous membrane 5. Insect bites, Syringes and blood transfusion 6. Utero transmission or transplacental 45  IV- Susceptible host” cont..” An organism, typically a human, animal, in which a parasite or pathogen lives and reproduces. The host factors affecting the occurrence of disease are: 1. Resistance 2. Genetic factors 3. Social and habitual factors 4. Physiological factors 5. Age and sex. 46 Dr. Ibrahim Ismail Abu 8/26/2024 47 Principles of infectious disease epidemiology Dr. Ibrahim Ismail Abu MBBS, MPH, MD, Fellow-EPI Assistant Professor of epidemiology in community medicine department King Abdul-Aziz University, Jeddah Dr. Ibrahim Ismail Abu 8/26/2024 Strategies to prevent and control infectious diseases 49Images from Public  Intended Learning Outcomes (ILOs) By the end of the tutorial, you need to: 1. To recognize the iceberg phenomena of disease in the community 2. To determine how to control and prevent of infectious diseases 3. To understand, apply and interpret the different levels of prevention. Dr. Ibrahim Ismail Abu 50 8/26/2024 Principles of infectious disease epidemiology  Iceberg phenomenon of disease The ice-berg phenomenon describe a situation in which; A large percentage of a problem is subclinical – under protected or otherwise hidden from view. 51  Prevention of infectious disease The word prevention itself says : PRE + EVENT + ACTION “ the action of stopping something from happening or arising” 52 Prevention of infectious diseases 53 Prevention of infectious diseases… 54 Phases of prevention disease 55 Phases of prevention disease 56 Phases of prevention disease 57 Preventable Causes of infectious Disease 58  Prevention Interventions applied at each link Isolation of cases Treatment Disinfection Control of carriers Surveillance Control of animals Quarantine Chemoprophylaxis Host Reservoir& Sero -prophylaxis Vaccination Source Mode of Prevention of overcrowding transmission Personal hygiene Vector control Environmental sanitation 59 8/26/2024  Quarantine: 64 8/26/2024  Levels of Prevention ▪ 67 Dr. Ibrahim Ismail Abu 8/26/2024 68 Dr. Ibrahim Ismail Abu 8/26/2024 Epidemiological triangle 69Images from Public Examples MCQs 1. Which of the following factors is most likely to disrupt the transmission cycle of a vector-borne disease? A. Increased rainfall B. Deforestation C. Climate change D. Improved sanitation 70 Thank you for attention 71