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IVC bio 15 Microbiology Ch 14 Epidemiology
Study Guide.
Key Terms:
Pathology is the scientific study of disease ( pathos = suffering; logos = science). Pathology is concerned with the
cause (etiology), how the disease develops (pathogenesis), structural and functional changes and effects on the body.
Etiology is the cause of disease.
pathogenesis is the manner in which a disease develops.
Infection is the invasion or colonization of the body by pathogenic microorganisms.
Disease is an abnormal state in which part or all of the body is incapable of performing its normal functions.
Disease occurs when an infection results in any change from a state of health. Other definition: An abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions; any change from a state of health.
Microbiomes is microbial/microorganisms communities that live in and on the human body.
Transient microbiota is microorganisms communities that live on the human body may be present for several
days, weeks, or months and then disappear.
normal microbiota The microorganisms that establish more or less permanent residence (colonize) but that do
not produce disease under normal conditions. Once established, the normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms. This phenomenon is called microbial antagonism , or competitive exclusion.
Symbiosis is a relationship between two organisms in which at least one organism is dependent on the other.
commensalism is a type of symbiosis in which one of the organisms benefits, and the other is unaffected.
Mutualism is a type of symbiosis that benefits both organisms.
Parasitism is a type of symbiosis in which one organism benefits by deriving nutrients at the expense of the
other.
opportunistic pathogens are microorganisms that do not ordinarily cause a disease but can become
pathogenic under certain circumstances (different environments)
probiotics are microbes inoculated into a host to occupy a niche and prevent growth of pathogens. Probiotics
(pro = for, bios = life) are live microbial cultures applied to or ingested that are intended to exert a beneficial effect.
Sign subjective changes, is a change due to a disease that a person can observe and measure.
Symptom objective changes, is a change in body function that is felt by a patient as a result of a disease.
syndrome A specific group of signs or symptoms that accompany a disease.
Communicable disease is a disease in which an infected person transmits an infectious agent, either directly
or indirectly, to another person who in turn becomes infected.
Contagious diseases are diseases that are very communicable and capable of spreading easily and rapidly
from one person to another.
noncommunicable is a disease that does not spread from one host to another. These diseases are caused by
microorganisms that normally inhabit the body and only occasionally produce disease or by microorganisms that reside outside the body and produce disease only when introduced into the body.
Incidence is the number of people in a population who develop a disease during a particular time period. It’s an
indicator of the spread of the disease.
Prevalence is the number of people in a population who develop a disease at a specified time, regardless of
when it first appeared. Prevalence takes into account both old and new cases.
sporadic disease ex: typhoid fever, is a particular disease occurs only occasionally,
Endemic disease ex: common cold, is a disease constantly present in a population.
Epidemic disease ex: influenza, is a disease in which many people in a given area acquire a certain disease in a
relatively short period.
Pandemic disease ex: influenza, AIDS, is an epidemic disease that occurs worldwide.
herd immunity most people in a population (herd) are immune to a particular disease.
acute disease is one that develops rapidly but lasts only a short time; ex: influenza.
Chronic disease develops more slowly. The body’s reactions may be less severe, but the disease is likely to
continue or recur for long periods. Ex: Infectious mononucleosis, tuberculosis, and hepatitis B.
subacute A disease that is intermediate between acute and chronic is described as a subacute disease ;
ex: subacute sclerosing panencephalitis, a rare brain disease characterized by diminished intellectual function and loss of nervous function.
Latent is one in which the causative agent remains inactive for a time but then becomes active to produce
symptoms of the disease; ex: shingles, caused by Varicellovirus, t he virus enters nerves and remains latent (dormant). Later, changes in the immune response can activate the virus, causing shingles.
local infection is one in which the invading microorganisms are limited to a relatively small area of the body. Ex:
boils and abscesses.
focal infection Very often, agents of a local infection enter a blood or lymphatic vessel and spread to other
specific parts of the body, where they are confined to specific areas of the body.
sepsis is a toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins,
from a focus of infection.
Bacteremia is the presence of bacteria in the blood.
Septicemia, or blood poisoning, is a systemic infection arising from the multiplication of pathogens in the blood.
Septicemia is a common example of sepsis.
Toxemia is the presence of toxins in the blood (as occurs in tetanus)
viremia refers to the presence of viruses in blood.
primary infection is an acute infection that causes the initial illness.
secondary infection is one caused by an opportunistic pathogen after the primary infection has weakened the
body’s defenses. Ex: skin and respiratory tract infections. Pneumocystis pneumonia as a consequence of AIDS is an example of a secondary infection; streptococcal bronchopneumonia following influenza is more serious than the primary infection.
subclinical disease, or inapparent infection, is one that doesn’t cause any noticeable illness. Ex: Poliovirus and
hepatitis A virus, can be carried by people who never develop the illness.
Carrier is organisms or people harbors pathogens and transmit them directly or indirectly to others.
With or without exhibiting any signs of illness. Ex: adult can carry Bordetella pertussis and can transmit an infection to a nonvaccinated infant.
zoonoses are diseases that occur primarily in wild and domestic animals and can be transmitted to humans. Ex:
rabies (found in bats, skunks, foxes, dogs, coyotes) and lyme disease (found in field mice).
Fomites The general term for any nonliving object involved in the spread of an infection. Ex: contaminated
syringes, clothes from health care personnel…
Vectors are animals that carry pathogens from one host to another.
13.What did John Snow contribute to the field of microbiology?
14.Be able to explain the difference between public health and clinical health
15.Be able to explain and give examples of the three types of transmission (contact, vehicle
and vector) including mechanical and biological.
16.What are nosocomial infections? Be able to explain:
a. their importance in health care settings
b. how they are transmitted
c. how they can be prevented.
d. The top three sites of infection
e. Top three microbial causes
GAI: Nosocomial infections, also known as healthcare-associated infections (HAIs), are infections acquired in a healthcare setting like a hospital, clinic, or nursing home. They are a significant public health concern due to their potential for causing serious morbidity, mortality, increased healthcare costs, and prolonged hospital stays. a. Importance in healthcare settings: Morbidity and Mortality: Nosocomial infections can lead to complications like sepsis, organ failure, and even death, particularly in vulnerable patients. Increased Healthcare Costs: Treating these infections adds significantly to the cost of patient care due to prolonged hospital stays, additional medications, and specialized procedures. Antimicrobial Resistance: The overuse of antibiotics in healthcare settings contributes to the development of resistant bacteria, making nosocomial infections more difficult to treat. b. How they are transmitted: Nosocomial infections can be transmitted through various routes, including: Direct contact: Transmission can occur through contact with contaminated hands, equipment, surfaces, or bodily fluids of an infected patient. Airborne transmission: Droplets containing infectious microorganisms can be spread through coughing, sneezing, talking, or certain medical procedures like intubation. Contact with contaminated medical devices: Catheters, surgical wounds, and other invasive devices can serve as pathways for infection. Environmental contamination: Pathogens can survive on surfaces in healthcare settings, leading to indirect transmission. c. How they can be prevented: Hand hygiene: Frequent handwashing with soap and water or alcohol-based hand rubs is the most crucial measure to prevent transmission. Infection control practices: Adhering to proper protocols for cleaning and disinfecting surfaces, equipment, and medical devices. Isolation precautions: Isolating infected patients to minimize contact with others. Proper use of personal protective equipment (PPE): Wearing appropriate PPE, such as gloves, gowns, masks, and goggles, when necessary. Aseptic techniques: Practicing sterile techniques during procedures like catheter insertion and wound care. Antimicrobial stewardship: Using antibiotics responsibly, only when necessary and according to guidelines to prevent antibiotic resistance. Patient education: Educating patients about infection prevention practices.
d. Top three sites of infection: Surgical site infections (SSIs): These infections occur at the site of a surgical incision and can be caused by a variety of bacteria. Ventilator-associated pneumonia (VAP): This type of pneumonia develops in patients who are on mechanical ventilation and is often caused by bacteria that enter the lungs through the ventilator. Urinary tract infections (UTIs): These infections commonly occur in patients with catheters inserted into the bladder. e. Top three microbial causes: Staphylococcus aureus (Staph): This bacterium is a common cause of skin and soft tissue infections, as well as other types of nosocomial infections. Escherichia coli (E. coli): This bacterium is frequently associated with UTIs and other urinary tract infections. Pseudomonas aeruginosa: This opportunistic pathogen can cause a variety of infections, including respiratory tract infections, wound infections, and bloodstream infections.
17.Be able to explain what an emerging disease is and why they exist.
GAI: Emerging infectious diseases are diseases that either appear for the first time in a population or reappear after a period of decline, often due to factors like environmental changes, human behavior, or pathogen evolution. Ex: COVID-19, SARS, HIV, Ebola, and Zika. Why do Emerging Diseases Exist? Environmental Changes: Climate change, deforestation, and urbanization can alter ecosystems and bring humans into closer contact with animals that harbor pathogens. Human Activities: Changes in agriculture, food production, and human behavior (like travel and contact with animals) can facilitate the spread of diseases. Pathogen Evolution: Microorganisms, including bacteria and viruses, can evolve and develop new characteristics, such as antibiotic resistance, making them more virulent or adaptable to new hosts. Breakdown of Public Health Measures: Weakened public health infrastructure, reduced vaccination rates, or lack of access to healthcare can allow diseases to spread unchecked. Zoonotic Spills: Many emerging diseases originate from animals, with pathogens jumping from animals to humans, a process known as zoonotic spillover. Travel and Globalization: Increased international travel and trade can facilitate the rapid spread of diseases across borders. Human Population Density: High population density in urban areas can increase the risk of disease transmission.
18.What is the CDC? What do they do?
CDC website:
In 2003, the morbidity of hemolytic uremic syndrome was 176, and the mortality was 29, implying that one death occurs for nearly every six affected individuals ( 176÷29=6 176 ÷ 29 = 6 ). On the other hand, the morbidity of listeriosis was 696 and the mortality was 33, implying that there is one death for nearly every 21 affected individuals ( 696÷33=21 696 ÷ 33 = 21 ) As a result of the higher morbidity rate, hemolytic uremic syndrome is more likely to be fatal.
Review: 1-6, MC 1-4, 6-10, A 1
