Chp 16 Epidemic Flashcards
What is epidemiology?
The study of where and when diseases occur and how they are transmitted within populations.
What is etiology?
The study of the causes of diseases.
What are the three types of reservoirs for infectious diseases?
- Animal reservoir, 2. Human carriers, 3. Nonliving reservoir (soil, water, food).
What are zoonoses?
Diseases that naturally spread from animal hosts to humans.
What is a passive carrier?
A person who is not infected but can mechanically transmit pathogens to others (e.g., a healthcare worker who fails to wash hands).
What is an active carrier?
An infected individual who transmits the disease to others, possibly without showing symptoms.
What is an asymptomatic carrier?
An infected individual who does not show signs or symptoms of disease but can still transmit it (e.g., herpes simplex virus, HIV).
What are the three groups of disease transmission?
- Contact transmission, 2. Vehicle transmission, 3. Vector transmission.
What is direct contact transmission?
Transmission that involves body contact between hosts, such as touching, kissing, or sexual contact.
What is vertical direct transmission?
Pathogens transmitted from mother to child during pregnancy, birth, or breastfeeding.
What is indirect contact transmission?
Pathogens spread via fomites (inanimate objects like doorknobs, needles, or drinking glasses).
What is droplet transmission?
Spread of pathogens in droplets of mucus through coughing, sneezing, or exhaling (limited to less than 1 meter).
What is vehicle transmission?
Spread of pathogens through air, water, food, or bodily fluids handled outside the body.
What is airborne transmission?
When pathogens travel more than 1 meter via aerosols (e.g., through sneezing, coughing, or air-conditioning systems).
What is waterborne transmission?
Spread of gastrointestinal diseases via fecal-oral route or contaminated water, often due to poor sanitation.
What is the fecal-oral route of transmission?
Pathogens from feces contaminate food or water, which is then ingested by another person.
What is a biological vector?
An arthropod (e.g., mosquito, tick) that transmits pathogens and serves as a host for some stage of the pathogen’s life cycle.
What is a mechanical vector?
An animal (e.g., housefly) that passively carries pathogens on its body but is not a host for the pathogen.
What is morbidity?
The state of being diseased, which can be expressed as the total number of cases or as a rate (e.g., per 100,000 people).
What is mortality?
The number of deaths in a population, often expressed as a rate (e.g., deaths per 100,000 people).
What is incidence?
The number of new cases of a disease in a given area during a specific period.
What is prevalence?
The total number of cases of a disease in a given area during a specific period, including new and pre-existing cases.
What is a sporadic disease?
A disease that occurs in scattered or isolated cases (e.g., a few cases of plague in the western US).
What is an endemic disease?
A disease that is widespread within a certain area or population most of the time (e.g., malaria in Brazil).
What is an epidemic?
A disease that is widespread within a certain area or population at a particular time (e.g., influenza in the US during some winters).
What is a pandemic?
A disease that spreads over a whole country, continent, or the world (e.g., COVID-19).
What is quarantining?
The isolation of individuals suspected or known to have been exposed to a contagious pathogen to prevent disease transmission.
What is an exogenous infection?
A healthcare-associated infection where the pathogen comes from the healthcare environment.
What is an endogenous infection?
A healthcare-associated infection where the pathogen arises from the patient’s own normal microbiota.
What is an iatrogenic infection?
A healthcare-associated infection resulting from modern medical procedures.
What is an opportunistic infection?
An infection that occurs when the use of antimicrobial drugs inhibits some resident microbiota, allowing other microbes to thrive.
What is the most effective way to reduce healthcare-associated infections?
Handwashing.
What is an emerging infectious disease?
An infection that has recently appeared within a population or whose incidence or geographic range is rapidly increasing.
What are re-emerging infectious diseases? Give ex.
Diseases whose incidence had significantly declined in the past but have reappeared (e.g., tuberculosis).
What are some risk factors for emerging infectious diseases?
Microbial adaptation, climate change, human demographics, poverty, war, and bioterrorism.
What is the primary route of transmission for Chikungunya fever?
Mosquito-borne.
What are the general steps in how a disease is transmitted?
- Reservoir: where pathogen resides. 2. Portal of exit: pathogen leaves the reservoir through a portal of exit. 3. Mode of transmission: pathogen is transmitted via direct contact, indirect contact, airborne, or vector-borne routes. 4. Portal of entry: The pathogen enters a new host through a portal of entry. 5. Susceptible host: The new host must be susceptible to the pathogen for infection to occur.
What are the three types of contact transmission?
- Direct contact transmission (physical contact between an infected person 2. Indirect contact transmission (transmission via fomites). 3. Droplet transmission (spread of pathogens occurs in droplets of mucus).
How does airborne transmission differ from droplet transmission?
Airborne transmission involves small particles (aerosols) that remain suspended in the air for long periods and can travel long distances (e.g., tuberculosis, measles). Droplet transmission involves larger respiratory droplets that travel short distances ( less than 1 meter) and quickly settle on surfaces (e.g., influenza, common cold).
Besides air, what are the other three types of vehicle transmission?
- Waterborne transmission (e.g., cholera). 2. Foodborne transmission (e.g., Salmonella). 3. Bodily fluids handled outside the body: Improper use of PPE can lead to exposure from infected fluids such as blood, urine, saliva, etc.
What are the two types of vector transmission?
- Biological vectors: Transmit pathogens and serve as hosts for some stage of the pathogen’s life cycle (e.g., mosquitoes, ticks). 2. Mechanical vectors: Animals that passively transmit pathogens present on their body to new hosts (e.g., houseflies).
What are the types of carriers of infection?
- Active carriers: Infected individuals that transmit the disease to others. 2. Passive carriers: Contaminated with the pathogen and can mechanically transmit it to another host. 3. Asymptomatic carriers: Active carriers who do not show signs or symptoms of disease despite being infected.
How are carriers different from vectors?
Carriers are humans or animals that carry and transmit pathogens. Vectors are typically arthropods (e.g., mosquitoes, ticks) that transmit pathogens.
Can carriers, vectors, or both cause zoonoses?
Both carriers (animal reservoirs) and vectors (biological vectors) can cause zoonoses.
What are two ways incidence, prevalence, and mortality can be expressed?
- As a total number of cases or deaths. 2. As a rate (e.g., per 100,000 people).
What are nosocomial infections?
Infections acquired while receiving treatment in a healthcare facility.
What are the four most common types of nosocomial infections?
- Surgical infections. 2. Pneumonia. 3. Urinary tract infections (UTIs). 4. Bloodstream infections.
How can nosocomial infections be controlled?
Hand hygiene, environmental hygiene, screening and cohorting patients, surveillance, antibiotic stewardship, following guidelines, and safety culture.
How is an emerging infectious disease different from someone getting sick with the common cold?
Emerging infectious disease: An infection that has recently appeared within a population or whose incidence or geographic range is rapidly increasing (e.g., Ebola). Common cold: A well-known, endemic disease caused by common viruses and not considered emerging.
What are two reasons why an infectious disease might emerge?
- Microbial adaptation: Genetic drift and genetic shift in Influenza A. 2. Changing human susceptibility: Mass immunocompromisation with HIV/AIDS.
