Chapter 14- Infection and Epidemiology Flashcards
The microorganisms that happen to live with us (without normally causing disease) OR colonize the surface of our body are called our
normal flora / normal microbiota
2 main groups of normal flora
- Resident microbiota
- Transient microbiota
Resident microbiota
- Been there since we were born
- Harmless under normal conditions (non-pathogenic)
Resident microbiota only lives on the ____ of our body (external and internal surfaces like upper resp.). On the other hand, our internal tissues are _____ which means it’s ___/__ ___ ____
Resident microbiota only lives on the surface of our body (external and internal surfaces like upper resp.). On the other hand, our internal tissues are microbe-free which means it’s axenic (pure) / no bacteria exist
External body surfaces, where our Resident Microbiota can be found, include our ___ and _____ (the mucous membrane that covers the exposed surface of the eye and the interior of eyelid).
External body surfaces, where our Resident Microbiota can be found, include our skin and conjunctiva (the mucous membrane that covers the exposed surface of the eye and the interior of eyelid).
Internal body surfaces, where our Resident Microbiota can be found, include the linings of our…
Internal body surfaces, where our Resident Microbiota can be found, include the linings of our nose, mouth, throat, intestinal tract, vagina, and the urethra
Transient Microbiota are only _____ and do not persist in body due to 3 things:
temporary
1. Elimination by body’s defense cells
2. Hygiene
3. Competition from other microbe
Most microbial species that form our Transient Microbiota are harmless, but a few of them are ______ making transient microbiota potentially dangerous
pathogenic
Eyes/skin
Staph
Nose/throat
Strep
G.I (gastrointestinal tract)
E.coli, Lactobacillus
Most of our Resident Microbiota can actually benefit us by a phenomenon called ______ ______(1)
_____ _____(1) is a way for the members of our Resident Microbiota to protect us from these intruders. Microbial antagonism involves _____ between our Resident Microbiota and the invading pathogens. One consequence of such competition is that our Resident Microbiota can protect the host by ______ any invading pathogens coming from outside the human body from establishing their ______
Microbial antagonism is a way for the members of our Resident Microbiota to protect us from these intruders. Microbial antagonism involves competition between our Resident Microbiota and the invading pathogens. One consequence of such competition is that our Resident Microbiota can protect the host by preventing any invading pathogens coming from outside the human body from establishing their residence
What effect might broad-spectrum antibiotics have>
They could kill the beneficial resident microbiota
Example of a Microbial antagonist
Lactobacillus
(These bacteria are also known as lactic acid bacteria. Lactic acid bacteria are nonpathogenic and are usually referred as beneficial bacteria in the human body.)
Resident Microbiota normally __ ___ cause disease.
But under certain conditions, some members of our Resident Microbiota can become harmful and cause disease when the proper “_______” arises. These microorganisms are known as _______ _____
Resident Microbiota normally do not cause disease.
But under certain conditions, some members of our Resident Microbiota can become harmful and cause disease when the proper “opportunity” arises. These microorganisms are known as opportunistic pathogens.
What conditions turn our Resident Microbiota to an opportunistic pathogen?
- Immune suppression
- Stressful conditions
- Introduction of resident microbiota into unusual location
The relationship between Resident Microbiota AND the human host is called
Symbiosis
Symbiosis is when
two organisms live together
3 kinds of symbiotic relationships:
commensalism, mutualism, and parasitism
Commensalism
Benefits microbe, no harm to host
Ex: mites on eyelashes
Mutualism
Benefits microbe, benefits the host
Ex: E.coli
Parasitism
Benefits microbe, harms the host
Ex: tapeworm
There’s an offset of parasitism called _____ in which there is..
Amensalism: no benefit to microbe, but the host is still harmed
If the pathogenic microorganism is not a normal microbiota the question is where is the pathogen normally found?
Reservoir
Every pathogen must have at least one reservoir. A reservoir is the ___ of a pathogen or the____ ____ of a pathogen. A reservoir is a place for the pathogen to survive, multiply (reproduce), and to stay before and after infecting a host. Some pathogens have more than one reservoir.
Every pathogen must have at least one reservoir. A reservoir is the source of a pathogen or the primary habitat of a pathogen. A reservoir is a place for the pathogen to survive, multiply (reproduce), and to stay before and after infecting a host. Some pathogens have more than one reservoir.
3 primary reservoirs:
Human reservoir
Animal reservoir
Nonliving/environmental reservoir
The majority of infections are from ____ ____ due to
Human reservoirs due to temp. and species specificity
There are also people who are apparently healthy but are carrying the pathogen and capable of transmitting it to others. They are classified as _______ _____
Asymptomatic carriers
There are three types of asymptomatic carriers:
- Incubation carriers: not yet showing signs
- Convalescent carriers: active stages of recovery
- Chronic carriers: recovered but still shedding
Zoonoses
Diseases that spread from another animal host to humans
Zoonoses is acquired through various routes:
- Direct contact with animals or their waste
- Eating affected animals
- Blood-sucking anthropods
Both wild and domestic animals can also be reservoirs for some human pathogens. The animal may or may not be affected by the microorganism. Typically the human is considered a _____ ___ ____. This means that once in the human it will not be spread from human to human or even back to the animal from which it contacted the pathogen.
Dead End Host
Dead End Host basically means that we’re
not going to transmit it after contracting the disease
Examples of animal reservoirs
Influenza
Rabies
Salmonellosis
Influenza (ex. animal reservoirs and symptomatic or not)
Pigs, birds, horses
Symptomatic
Rabies (animal reservoirs and symptomatic or not)
Bats, skunks, coyotes, etc.
Symptomatic
Salmonellosis
Poultry and reptiles
Asymptomatic
Environmental Reservoirs-
Some human pathogens are able to survive and reproduce for long periods of time in ______reservoirs such as…
Environmental Reservoirs-
Some human pathogens are able to survive and reproduce for long periods of time in nonliving reservoirs such as soil, water, and food
Environmental Reservoirs-
Keep in mind, the condition in the soil is not as ideal as the human body. Some human pathogens can survive in the soil for years by forming ______
Keep in mind, the condition in the soil is not as ideal as the human body. Some human pathogens can survive in the soil for years by forming endospores
A critical stage of any disease development process is for the pathogen to be able to leave its reservoir and enter the body of a host, this is known as the _______
Human pathogens can enter the body of the host at particular locations called the ____ ___ ____
A critical stage of any disease development process is for the pathogen to be able to leave its reservoir and enter the body of a host, this is known as the transmission
Human pathogens can enter the body of the host at particular locations called the portals of entry
Common portals of entry
Skin, Mucous Membranes, Placenta, and Parenteral (blood)
3 major modes of transmission
contact, vehicle, and vector transmissions
Types of contact transmission
Direct contact transmission
Indirect contact transmission
Droplet transmission
Direct contact transmission
spread by direct physical contact between one person and another person such as by touching, kissing, or sexual intercourse (horizontal transmission)
Another kind of direct contact transmission would be the _____ transmission where the pathogens are directly transmitted from the ____ to ____
Another kind of direct contact transmission would be the vertical transmission where the pathogens are directly transmitted from the mother to fetus or infant
Indirect contact transmission:
Indirect contact transmission occurs when the pathogen is transmitted or spread from the reservoir to the human host through a ______ _____. Any nonliving object involved in the spread of an infection is known as a ____
Indirect contact transmission
Indirect contact transmission occurs when the pathogen is transmitted or spread from the reservoir to the human host through a nonliving object. Any nonliving object involved in the spread of an infection is known as a FOMITE
Examples of fomites:
Desk, door handle, fork/straw/glass
Droplet transmission-
Droplets of respiratory secretions are discharged into the air by…
These respiratory droplets can last only for a brief time and travel for a ___ distance (less than one meter) from the reservoir to the host because the droplets tend to get dry easily and killing the pathogens they contain.
The pathogens that are transmitted this way through droplet transmission CANNOT be considered as the airborne pathogens since they can only last for a brief time in the air and must be in _____ _____
Droplet transmission-
Droplets of respiratory secretions are discharged into the air by coughing, sneezing, laughing, or talking. These respiratory droplets can last only for a brief time and travel for a short distance (less than one meter) from the reservoir to the host because the droplets tend to get dry easily and killing the pathogens they contain.
The pathogens that are transmitted this way through droplet transmission CANNOT be considered as the airborne pathogens since they can only last for a brief time in the air and must be in close proximity.
Some examples of human diseases that can be transmitted by ___ ____ are common cold, influenza, pinkeye, and sexually transmitted diseases.
Some examples of human diseases that can be transmitted by direct contact are common cold, influenza, pinkeye, and sexually transmitted diseases.
Examples of diseases that can be transmitted from ____ __ ___ are rubella, hepatitis B, and sexually transmitted diseases.
Examples of diseases that can be transmitted from mother to infant are rubella, hepatitis B, and sexually transmitted diseases.
Disease that can be transmitted through ____ ____ would be, for example, common cold. Contaminated needles can also serve as the fomites for transmitting human pathogens that cause AIDS or hepatitis B.
Disease that can be transmitted through indirect contact would be, for example, common cold. Contaminated needles can also serve as the fomites for transmitting human pathogens that cause AIDS or hepatitis B.
Examples of diseases that can be transmitted by ____ _____ are influenza and pneumonia.
Examples of diseases that can be transmitted by droplet transmission are influenza and pneumonia.
Vehicle Transmission-
Vehicle transmission is the spread of pathogen from its reservoir to the host by a _____, such as..
Vehicle Transmission-
Vehicle transmission is the spread of pathogen from its reservoir to the host by a vehicle, such as water, food, or air.
If the vehicle is water, then the type of transmission is known as ______ transmission; if the vehicle is food, then it is known as _____ transmission; if the vehicle is air, then it is known as ______transmission.
If the vehicle is water, then the type of transmission is known as waterborne transmission; if the vehicle is food, then it is known as foodborne transmission; if the vehicle is air, then it is known as airborne transmission.
In waterborne transmission, pathogens are spread by..
contaminated water
In foodborne transmission, pathogens are spread by..
foods that are undercooked or prepared under unsanitary conditions.
In airbone transmission, pathogens travel more than __ meter via an _____ trapped in ___ ____
In airbone transmission, pathogens travel more than 1 meter via an aerosol trapped in dust particles
Besides the vehicles that we mentioned above (water, food, or air), blood and other ___ ____ can also serve as a vehicle.
bodily fluids
Vector Transmission-
Vectors are referred to animals that carry pathogens from the _____ to the ___. The most important group of disease vectors are _____, such as flies, mosquitoes, fleas, ticks…etc. Some of these arthropods are ______vectors whereas others are ______vectors.
Vector Transmission-
Vectors are referred to animals that carry pathogens from the reservoir to the host. The most important group of disease vectors are arthropods, such as flies, mosquitoes, fleas, ticks…etc. Some of these arthropods are mechanical vectors whereas others are biological vectors
Mechanical vectors pick up pathogens on their body parts, such as their feet, and carry them from one place to another. They ____ transmit pathogens present on their body to new hosts. Basically, the pathogens are ___ the bug, not __ it.
Mechanical vectors pick up pathogens on their body parts, such as their feet, and carrying them from one place to another. They passively transmit pathogens present on their body to new hosts. Basically, the pathogens are on the bug, not in it.
Biological vectors not only carry pathogens from reservoir to the host, but they themselves have also been _____ with the pathogens. Therefore, the pathogens are ___ the bug, not ___ it. Biological vectors usually transmit pathogens by ____
Biological vectors not only carry pathogens from reservoir to the host, but they themselves have also been infected with the pathogens. Therefore, the pathogens are in the bug, not on it. Biological vectors usually transmit pathogens by biting
Example- West Nile disease
Reservoir:
Mode of Transmission:
Example- West Nile disease
Reservoir: Birds
Mode of Transmission: Vector- Mosquito
Example- Lyme disease
Reservoir:
Mode of Transmission:
Example- Lyme disease
Reservoir: Deer
Mode of Transmission: Vector- Tick
Now that the microorganism has gained access to the body and assuming survived the body’s defenses, the pathogen can begin to multiply and cause disease. _____ means that the microbe has invaded whereas _____ means that the microbe is affecting the host causing disease. A pathogen that has invaded and caused disease will result in symptoms and signs.
Now that the microorganism has gained access to the body and assuming survived the body’s defenses, the pathogen can begin to multiply and cause disease. Infection means that the microbe has invaded whereas MORBIDITY means that the microbe is affecting the host causing disease. A pathogen that has invaded and caused disease will result in symptoms and signs.
Infection basically means
exposure to pathogens
_______ basically means the exposure to pathogens have now led to an _______ in ________
Morbidity basically means the exposure to pathogens have now led to
an imbalance in homeostasis
Symptoms are ____ characteristics of disease that are ___ by the patient
Symptoms are subjective characteristics of disease that are felt by the patient
Signs are ____ manifestations of disease ____ or ____ by others
Signs are objective manifestations of disease observed or measured by others
Examples of symptoms
pain, headache, fatigue, nausea
Examples of signs
fever, vomiting, a rash
If the microbe has a high _______ that means it has a high likelihood of not just _____ but also causing ____. The _____ of pathogenicity is described as ______. The pathogens with high virulence exhibit traits that improve the ability of the pathogen to enter and attach to host cells and subsequently cause disease.
If the microbe has a high pathogenicity that means it has a high likelihood of not just invading but also causing disease. The degree of pathogenicity is described as VIRULENCE. The pathogens with high virulence exhibit traits that improve the ability of the pathogen to enter and attach to host cells and subsequently cause disease.
The three most common virulence factors are:
Extracellular enzymes
Toxins
Antiphagocytic factors
Extracellular Enzymes-
Some pathogenic bacteria _____ extracellular enzymes like _____ and ______. These _____ the normal protective layers allowing for _____transmission.
Extracellular Enzymes-
Some pathogenic bacteria produce extracellular enzymes like keratinase and mucinase. These disrupt the normal protective layers allowing for easier transmission.
Bacterial Toxins-
Toxins are poisonous substances that are ______ by certain microorganisms. There are two general types of toxins produced by microorganisms: ______ and_____
Bacterial Toxins-
Toxins are poisonous substances that are produced by certain microorganisms. There are two general types of toxins produced by microorganisms: exotoxins and endotoxins.
Exotoxins are ____ _____by the microbe that are released to _____ the ___/_____. They include cytotoxins, neurotoxins, and enterotoxins. There are ______ called _____ that are against the exotoxin.
Exotoxins are proteins produced by the microbe that are released to damage the cells/tissues. They include cytotoxins, neurotoxins, and enterotoxins. There are vaccines called TOXOID that are against the exotoxin.
endotoxin:
Some pathogenic bacteria ____ another toxin, called endotoxins. Endotoxin is actually part of the ___(____) membrane of ____ ____ bacteria called ___ ___. Currently, there is ___ _____for endotoxins.
endotoxin:
Some pathogenic bacteria contain another toxin, called endotoxins. Endotoxin is actually part of the outer (cell) membrane of gram-negative bacteria called LIPID A. Currently, there is no vaccine for endotoxins.
Diseases caused by bacteria that produce ______ are Typhoid fever, salmonellosis.
Endotoxins
Diseases caused by bacteria that produce _____are tetanus, botulism
Exotoxins
Antiphagocytic Factors-
Factors that prevent phagocytosis by the host’s phagocytotic cells
Some microbes produce _______ which disrupt the function of host _______ cells allowing them to ______ the immune response. They basically…
Some microbes produce leukocidins which disrupt the function of host phagocytic cells allowing them to evade the immune response. They basically directly destroy pathogenic cells
Now that the pathogen has gained access to the host and is capable of causing disease there is a typical progression of disease in the host.
List the 5 stages of infectious disease
- Incubation period
- Prodromal period
- Illness
- Decline
- Convalescence
Describe the incubation period
no signs or symptoms (infected but not affected)
Describe the prodromal period
vague, general symptoms
Illness
most severe signs and symptoms
Decline
declining signs and symptoms
Convalescence
no signs or symptoms
For the stages of infectious disease, keep in mind that
every disease progresses through the stages in variable amounts of time
_____ testing can be done to determine if the symptoms displayed by a person can be attributed to a specific ______ The etiology is the ____of the ____/______. experienced by the person. Microbes are categorized as an infectious etiology.
Diagnostic testing can be done to determine if the symptoms displayed by a person can be attributed to a specific ETIOLOGY. The etiology is the cause of the disease/symptoms experienced by the person. Microbes are categorized as an infectious etiology.
Microbes are categorized as an infectious etiology. Others include:
Hereditary
Iatrogenic
Nosocomial
Idiopathic
Congenital
Infectious
Hereditary
Caused by genetics
Iatrogenic
Caused by a medical procedure
Nosocomial
Caused by the hospital (hospital aquired)
Idiopathic
Unknown cause
Congenital
Present at birth
Infectious
Caused by a pathogen, bacteria, etc.
Virulence
The degree of pathogenicity
When the pathogenic microorganism is ready to leave the body of the host, it will either return back to its reservoir or enter a new host. The route through which a pathogen leaves the body of its host is called the ____ __ ___
portal of exit
Most common portals of exit on the human body are:
- Respiratory tract
- Gastrointestinal tract
- Genitourinary tract
- Skin
- Infected blood
Communicable disease
an infectious disease that spreads from one person to another
Communicable diseases can also be considered a ____ ____ if ____ ___
a contagious disease if it is easily spread
Non-communicable disease
NOT spread from one person to another
Endemic disease
Disease is constantly present (stable)
Epidemic disease
Larger number of people affected in a short period of time
Pandemic disease
Occurring in multiple countries within a short period of time
The CDC (Center for Disease Control) provides weekly reports listing the ______and _________ for numerous diseases. Incidence is the _____ of ____ ____ whereas Prevalence is the _____ ____ of cases. One of the most important diseases in these reports is for ____- ______ _____ _____.
The CDC (Center for Disease Control) provides weekly reports listing the INCIDENCE and PREVALENCE for numerous diseases. Incidence is the number of new cases whereas Prevalence is the total number of cases. One of the most important diseases in these reports is for HAI’s- Healthcare Associated Infections.
The most important way to prevent Healthcare Associated Infections (HAI) is by
handwashing
HAI =
Nosocomial
Which would increase virulence?
- F plasmid
- Keritinase
- Envelope
- Slime layer
- Leukocidin
- Endospore
- Catalase
- Keritinase
- Envelope
- Slime layer
- Leukocidin
Which would increase virulence?
- Mucinase
- Penicillinase
- Spirilla
- Neurotoxin
- Lipoteichoic acid
- Acidophile
- Lipid A
- Mucinase
- Neurotoxin
- Lipid A
How diseases affect the population in general is the work of an
Epidemiologist
If a person coughs and transmits a microbe through a ventilation system it’s ____. However, if they coughed within 3 ft of you, it’s _____
Vehicle
Contact
(droplet vs aerosol)
Examples of exotoxins
cytotoxins, neurotoxins, and enterotoxins
