Chapter 11: Epidemiology and Public Health PDF

Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN Introduction to Epidemiology 8.​ Mortality rate- number of deaths due to a disease per a s...

Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN Introduction to Epidemiology 8.​ Mortality rate- number of deaths due to a disease per a specific Pathology vs. Epidemiology: population (e.g.1 per 100,000 ang namamatay) Pathology ​ focuses on disease manifestations and diagnosis in individuals. Diseases Classifications 1.​ Sporadic diseases- occur Epidemiology occasionally (e.g., botulism, cholera, ​ studies disease distribution, causes, typhoid fever). and prevention in populations. 2.​ Endemic diseases- constant presence in a specific area (e.g. Key Questions in Epidemiology Palawan–malaria) ​ Who gets the disease? (e.g., tuberculosis, common cold). ​ What pathogens are involved? 3.​ Epidemic diseases- sudden ​ Where are the pathogens found? increase in disease cases in a ​ When do diseases occur? region (e.g. food poisoning ​ Why do some areas have higher outbreaks) disease rates? 4.​ Pandemic diseases- global outbreaks (e.g., COVID-19, Key Terms in Epidemiology influenza pandemics). 1.​ Communicable- transmissible from one person to another (e.g., Examples of Major Epidemics in the U.S. gonorrhea /STD). 1.​ Legionnaires' Disease (1976): 2.​ Contagious- easily spread from ​ Caused by Legionella person to person be it direct or pneumophila, spread through indirect contact (e.g., influenza). contaminated air-conditioning 3.​ Zoonotic diseases- from animals to water. humans (e.g., rabies, Lyme disease) 2.​ E. coli O157:H7 Outbreak Lyme disease is caused by ticks carrying (1992-1993): borrelia bacteria; most common in the upper ​ Linked to undercooked Midwest and the northeastern and mid-Atlantic states) hamburgers contaminated 4.​ Incidence- new cases of a disease with cattle feces. in a specific time period. 3.​ Hantavirus Pulmonary Syndrome 5.​ Morbidity Rate- new cases per a (1993): specified population (1 per 100,000 ​ Spread through aerosols people). from deer mice feces in the 6.​ Period prevalence- total cases U.S. Southwest. during a specific time period/ range 4.​ Cryptosporidiosis (1993): of time. ​ Waterborne outbreak in 7.​ Point prevalence- cases at a Milwaukee from specific moment. Cryptosporidium parvum.  Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN 5.​ West Nile Virus (2002-2003): ​ Disease surveillance by ​ Mosquito-borne virus causing organizations like the CDC/ Centers severe neurological illnesses. for Disease Control and Prevention Examples of Major Epidemics in the Pandemic Diseases Philippines: This passage provides a comprehensive ​ 1902 cholera/spread through overview of pandemic diseases, focusing on contaminated water and food three major infectious diseases: HIV/AIDS, ​ 2009 swine flu pandemic in the tuberculosis (TB), COVID-19, and malaria, Philippines by region. which are currently occurring in pandemic ​ 2017 Central Luzon H5N6 outbreak. proportions. Note: outbreaks of Highly Pathogenic Avian Influenza A (HPAI) H5N6 or bird It also outlines the factors influencing flu affected poultry in at least three disease occurrence, components of the towns in Central Luzon (particularly in chain of infection, and strategies for San Luis in Pampanga and Jaen and breaking the infection cycle. San Isidro in Nueva Ecija in August 2017). ​ 2019 measles outbreak in the 1.​ HIV/AIDS Philippines. ​ Origins: Likely transferred ​ 2019–2021 polio outbreak in the from primates to humans. Philippines. ​ Statistics (as of 2007): Note: There’s a vaccine mitigation now. ○​ 33.2 million people Dengvaxia scare- kaya nagkaroon ng vaccine are infected globally. hesitation and nagkaroon ng polio outbreak in ○​ 39.9 million people the Philippines around 2019-2021. as of 2024 ○​ 2.5 million new Environmental and Social Factors infections and 2.1 Influencing Epidemics: million deaths annually. ​ Poor Sanitation: Typhoid fever ○​ Sub-Saharan Africa (food poisoning e.g. Salmonella accounts for most typhi), cholera outbreaks. cases and deaths. ​ Crowded Living Conditions: 2.​ Tuberculosis (TB) Influenza epidemics. ​ Cause: Mycobacterium ​ Travel and Migration: Introduces tuberculosis, with drug new diseases to isolated resistant strains like MDR-TB communities. and XDR-TB. Preventive Measures in Epidemiology: Note: Mahirap gamutin- ​ Immunization programs. MDR-TB (Multidrug-resistant ​ Public health policies for sanitation tuberculosis) and XDR-TB and clean water. extensively drug-resistant tuberculosis Co-infection ng HIV patients ang pneumonia.  Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN ​ Global Impact: ​ Inoculum Size: Sufficient ○​ 9.2 million new cases quantity of pathogens and 2 million deaths required to cause infection. yearly. ○​ 2 billion people 2.​ Factors Related to the Host: infected worldwide. ​ Health Status: Underlying ○​ TB is particularly diseases, surgeries, or deadly among invasive procedures increase HIV-infected susceptibility. individuals. ​ Nutritional Status: Proper nutrition boosts immunity. 3.​ Malaria ​ Immunity & Lifestyle: Age, ​ Cause: Parasite Plasmodium behavior, hygiene, falciparum, transmitted by immunizations, and mosquitoes. occupation affect ​ Global Impact: vulnerability. ○​ 247 million cases annually, with about 1 3.​ Environmental Factors: million deaths. ​ Physical Conditions: ○​ Most cases occur in Climate, geography, and Africa, affecting seasonal changes can affect children severely. disease spread. ​ Sanitation & Water Supply: 4.​ COVID-19 Clean water, waste disposal, ​ Cause: SARS-CoV-2 and hygiene infrastructure ​ Global Impact: are essential. ○​ approximately 6.9 ​ Healthcare Access: million, according to Availability of medical care the World Health reduces infection risks. Organization (WHO). The Chain of Infection Interactions Among Pathogens, Hosts, 1.​ Pathogen: Microorganism causing and Environments the disease (e.g., a virus). 2.​ Reservoir: Source where the 1.​ Factors Related to the Pathogen: pathogen lives (e.g., infected ​ Virulence: Determines the individuals, animals). severity of infection. 3.​ Portal of Exit: Path by which the ​ Portal of Entry: The pathogen leaves the reservoir (e.g., pathway through which sneezing, wounds). pathogens enter the host 4.​ Mode of Transmission: How the (e.g., wounds, respiratory pathogen travels (e.g., contact, tract). droplets, vectors).  Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN 5.​ Portal of Entry: Entry point into the ​ Animals (Zoonoses): Pets, new host (e.g., inhalation, cuts). livestock, and wildlife 6.​ Susceptible Host: A person with transmitting diseases like reduced immunity. rabies or Lyme disease. ​ Arthropods: Insects and arachnids act as vectors (e.g., ticks for Lyme disease). 2.​ Non-Living Reservoirs: ​ Air: Pathogens spread via droplets and dust particles. ​ Soil and Water: Contains spores and microbes causing diseases like tetanus or cholera. ​ Fomites: Contaminated objects like doorknobs, bedding, and medical instruments. Breaking the Chain of Infection: Modes of Transmission: ​ Eliminate Reservoirs: Sanitize 1.​ Direct Contact: Skin-to-skin or environments, manage waste, and mucous membrane contact (e.g., quarantine carriers. STDs). ​ Block Exit Pathways: Use 2.​ Droplet Transmission: Respiratory protective barriers like masks and droplets from coughing or sneezing. gloves. 3.​ Airborne Transmission: Inhalation ​ Stop Transmission: Follow hand of fine infectious particles. hygiene, disinfect surfaces, and 4.​ Vehicular Transmission: isolate infected individuals. Contaminated food, water, or ​ Protect Entry Points: Use personal surfaces. protective equipment (PPE) and 5.​ Vector-Borne Transmission: ensure wound care. Through insects and arthropods ​ Boost Host Immunity: (e.g., malaria from mosquitoes) Immunizations, good nutrition, and stress management. Public Health Agencies' Role ​ Public health agencies prevent and Reservoirs of Infection control epidemics by: 1.​ Living Reservoirs: ○​ Reporting communicable ​ Humans: May be diseases. symptomatic or carriers (e.g., ○​ Educating the public about incubatory, convalescent/ disease transmission and recovering after an illness or sanitation. operation, passive).  Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN ○​ Conducting immunization ​ Possible water or food programs. contamination. ○​ Isolating and treating infected individuals. 3.​ Smallpox (Variola major): ​ Eradicated globally, but Key Organizations samples exist in labs. ​ Causes severe rash, fever, 1.​ World Health Organization (WHO): and sometimes death. ​ Established in 1948 to combat global health issues. 4.​ Plague (Yersinia pestis): ​ Achievements: Eradication ​ Forms: Bubonic, pneumonic of smallpox, ongoing efforts (most contagious), and to eliminate polio and other septicemic. diseases. ​ Transmitted by fleas or 2.​ Centers for Disease Control and aerosols. Prevention (CDC): ​ U.S. federal agency focused on epidemiology and public health. Water and Sewage Management ​ Manages infectious diseases Water Contamination Sources: and bioterrorism threats. ​ Chemical pollution: Industrial ​ Publishes Morbidity and waste, pesticides, acid rain. Mortality Weekly Report ​ Biological pollution: Human waste, (MMWR). pathogens like cholera and typhoid. 3.​ Research Institute for Tropical Medicine Water Treatment Process: 1.​ Filtration: Removes debris. Bioterrorism and Biological Warfare 2.​ Sedimentation: Settles heavier Agents particles. 3.​ Coagulation: Binds small particles Bioterrorists may use pathogens to cause using alum. disease, fear, and chaos. Four notable 4.​ Disinfection: Chlorination, UV light, pathogens include: or ozone treatment kills pathogens. 1.​ Anthrax (Bacillus anthracis): ​ Forms: Cutaneous, Sewage Treatment: inhalation (most severe), and 1.​ Primary Treatment: Removes large gastrointestinal. solids and debris. ​ Bioweapon potential: 2.​ Secondary Treatment: Uses Spores easily aerosolized. aeration and microbes to break down organic matter. 2.​ Botulism (Clostridium botulinum): ​ Neurotoxin causing paralysis ​ These measures are vital in and respiratory failure. maintaining public health and  Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN preventing epidemics through safe d. Rocky Mountain spotted fever water and sanitation systems. ___________________________________ 6.​ Which one of the following organisms is not one of the four Self-Assessment Exercises most likely potential BW or 1.​ Which of the following terms best bioterrorism agents? describes chlamydia genital a. B. anthracis infection(preventable and curable b. Ebola virus sexually transmitted infection) in the c. V. major United States? d. Y. pestis a. arthropod-borne disease b. epidemic disease 7.​ All of the following are major steps in c. pandemic disease the treatment of a community's d. sporadic disease drinking water except: a. boiling 2.​ Which of the following are b. filtration considered reservoirs of infection? c. flocculation a. carriers d. sedimentation b. contaminated food and drinking water 8.​ The largest waterborne epidemic c. rabid animals ever to occur in the United States d. all of the above occurred in: a. Chicago 3.​ The most common nationally b. Los Angeles notifiable infectious disease in the c. Milwaukee United States is: d. New York City a. chlamydia genital infections b. gonorrhea 9.​ Typhoid fever Is caused by a c. the common cold species of: d. TB a. Cempytobacter b. Eschettchla 4.​ Which of the following arthropods Is c. Salmonella the vector of Lyme disease? d. Shigella a. flea b. mite 10.​Which of the following associations c. mosquito is incorrect? d. tick a. ehrlichiosi~tick b. malaria-mosquito 5.​ The most common zoonotic disease c. plague~flea in the United States is: d. spotted fever rickettsiosis~mite a. Lyme disease b. plague c. rabies Chapter 11: EPIDEMIOLOGY AND PUBLIC HEALTH FIRST SEMESTER I ACADEMIC YEAR 2024-2025 I PROF. JOHN LEONARD CHAN