Chapter 14 Flashcards
What is etiology in the context of disease?
Etiology refers to the cause of a disease.
How is disease defined when there is a change from a state of health?
Disease is defined as any change from a state of health, where part or all of the body is incapable of performing its normal functions.
What is infection?
Infection is the invasion or colonization of the body by a pathogenic microbe.
What is the primary cause of death worldwide?
Infectious disease is the primary cause of death worldwide.
What are some factors affecting the distribution and composition of the human microbiota?
Factors affecting the distribution and composition of human microbiota include:
- Nutrients,
- Physical
- Chemical factors (temperature, pH, O2, CO2),
- Host defenses (immune system)
- Mechanical factors.
What is the role of normal microbiota in protecting the host?
Normal microbiota protect the host by:
* Competing for nutrients
* Producing substances harmful to invading microbes
* Affecting pH and available oxygen
There are three types of symbosis depending on the relationship between the microbe and the host. What are the three types?
- Commensalism: One organism benefits, and the other is unaffected.
- Mutualism: Both organisms benefit.
- Parasitism: One organism benefits at the expense of the other.
What are opportunistic pathogens, and when do they cause disease?
Opportunistic pathogens do not cause disease in their normal habitat in a healthy person but may do so in a different environment.
What are Koch’s postulates, and how are they used to prove the cause of an infectious disease?
Koch’s postulates are a set of criteria used to prove the cause of an infectious disease. They include:
- The same pathogen must be present in every case of the disease.
- The pathogen must be isolated from the diseased host and grown in pure culture.
- The pathogen from the pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal.
- The pathogen must be isolated from the inoculated animal and shown to be the original organism.
What are some exceptions to Koch’s postulates?
- Some diseases are caused by a variety of microbes (Pneumonia, Meningitis)
- Some pathogens can cause several disease conditions
- Some pathogens cause disease only in humans (HIV)
- Some microbes have never been cultured
What scientific theory is Koch’s work related to?
Think about Chapter 1
Germ Theory of Disease.
What is the difference between symptoms and signs in the context of disease?
Symptoms are changes in body function that are felt by a patient as a result of a disease, such as pain or malaise.
Signs are changes in the body that can be measured or observed as a result of disease.
What is communicable disease and give an example. What is a non-communicable disease?
- A communicable disease is a disease that can be spread from one host to another. They are very dangerous when it becomes a contagious disease, because they easily spread from one host to another. For example, chickenpox is a contagious communicable disease.
- Non-communicable diseases are diseases that do not spread from one host to another, such as tetanus.
What is the difference between incidence and prevalence in epidemiology?
- Incidence refers to the frequency of new cases of a disease. Incidence measures how often new cases occur
- Prevalence refers to the frequency of existing cases of the disease. Prevalence measures how widespread the disease is in the population.
Differentiate between sporadic, endemic, epidemic, and pandemic diseases.
Sporadic disease occurs only occasionally.
Endemic disease is constantly present in a population.
Epidemic disease is acquired by many people in a given area in a short time.
Pandemic disease is a worldwide epidemic that spreads across continents or even globally.
Describe the different types of diseases based on their duration: acute, chronic, subacute, and latent.
Acute disease: Symptoms develop rapidly, but the disease lasts only a short time.
Chronic disease: Symptoms develop slowly.
Subacute disease: Intermediate between acute and chronic.
Latent disease: The causative agent is inactive for a time but then activates and produces symptoms.
What is herd immunity, and how does it affect the spread of diseases?
Herd immunity refers to the immunity in most of a population, which limits the spread of outbreaks. It occurs when a sufficient portion of the population becomes immune to a disease through vaccination or previous infections, reducing the number of susceptible individuals.
Explain the difference between local infection, systemic infection, and focal infection.
- Local infection: Pathogens are limited to a small area of the body.
- Systemic infection: An infection spreads throughout the body, usually in the bloodstream.
- Focal infection: A systemic infection that began as a local infection and can have multiple sites of infection.
What are the different methods that microbes will spread throughout the blood?
- Sepsis is a toxic inflammatory condition that arises from the spread of microbes, especially bacteria or their toxins, from a focus of infection.
- Bacteremia refers to bacteria in the bloodstream,
- Septicemia, also known as blood poisoning, is characterized by the growth of bacteria in the blood.
- Toxemia indicates the presence of toxins in the bloodstream
- Viremia means the presence of viruses in the blood.
What is the differene between a primary infection and a secondary infection? Provide examples of each.
- A primary infection is an acute infection that causes the initial illness, such as strep throat.
- A secondary infection is an opportunistic infection that occurs after a primary (predisposing) infection. Examples include Pneumocystis infection and sinus infection.
What is a subclinical disease, and can you provide examples of it?
Subclinical disease is a condition with no noticeable signs or symptoms, often referred to as an inapparent infection.
Examples include Streptococcus pyogenes carriers, individuals carrying the polio virus, or the hepatitis A virus without displaying symptoms.
What are some factors that can make the body more susceptible to disease?
Various factors can increase susceptibility to disease, including gender, inherited traits (like the sickle cell gene), climate and weather conditions, lack of vaccination, fatigue, age, lifestyle choices, nutrition, and the effects of chemotherapy.
Describe the typical sequence of events that occur during infection and disease. List the five periods of infection.
- Incubation period: Interval between the initial infection and any signs or symptoms.
- Prodromal period: Early mild symptoms of disease, often characterized by general aches and malaise.
- Illness period: The most severe phase of the disease with pronounced signs and symptoms.
- Decline period: Signs and symptoms subside, and the patient may recover.
- Convalescence period: The patient regains strength.
Able to spread illness at any stage. You are subject to reinfection at the Decline period.
Explain the concept of reservoirs in the context of disease transmission. What are some examples of reservoirs?
Reservoirs are continual sources of infection. They include:
* Human reservoirs, where carriers may have inapparent infections or latent diseases.
* Animal reservoirs, contributing to zoonoses (diseases transmitted from animals to humans).
* Nonliving reservoirs, such as soil and water, that can carry disease agents.
