Exam 1: Pt.3 Ch. 14** Flashcards
Ch. 14: Infection, Infectious Diseases, and Epidemiology
What are organisms that colonize the body’s surfaces without normally causing disease?
normal microbiota–> AKA normal flora and indigenous microbiota
What are the two kinds of normal flora?
- Resident microbiota
2. Transient microbiota
What are resident microbiota vs transient microbiota?
resident –> remain part of normal microbiota of a a person for life
Transient –> remain in body for few hours, days, months, before disappearing
What are sites that are free of any microbes and are never colonized by normal flora called?
Axenic
List the 5 sites that are Axenic in the human body.
- Alveoli of lungs
- CNS
- Circulatory System
- Upper Urogenital Regions
- Uterus
When in utero, is there exposure to microbiota?
NO! b/c uterus is axenic
When do humans begin to develop their normal microbiota?
during birthing process
- mouth and nose through birth canal
- first breath
- handling by staff, family
When is most of one’s resident microbiota established?
during first months of life
What are normal microbiota that cause disease under certain circumstances called?
opportunistic pathogens
What are three conditions that provide opportunities for opportunistic pathogens?
- intro of normal microbiota into unusual site in body
- immune suppression
- changes in the normal microbiota
Give an example of a how intro of normal microbiota into unusual site in body may be an opportunity for an opportunistic pathogen.
E. coli mutualistic in colon, but if enters urethra becomes opportunistic
Give an example of a how immune suppression may be an opportunity for an opportunistic pathogen.
AIDS and cancer patients often die from opportunistic infections
Give an example of a how changes in the normal microbiota may be an opportunity for an opportunistic pathogen.
take antibiotics, kills normal flora also, allows opportunistic yeast infection
T/F. Most pathogens cannot survive for long outside of their host; they must survive in some particular location.
true
What are sites where pathogens live until they can infect a new host?
reservoirs of infection
What are three types of reservoirs?
- Animal reservoirs
- human carriers
- nonliving reservoirs
What do we call disease that naturally spread from animal host to humans?
zoonoses
How do humans acquire zoonoses?
- direct contact with animal or its waste
- eating animals
- bloodsucking arthropods (ticks, mosquitoes)
T/F. Humans are usually not dead-end host
False–humans are usually dead end hosts–> humans get disease from animals, animals do not get diseases from humans (usually)
What is the reservoir for the zoonose, malaria?
monkeys
What is the reservoir for the zoonose, toxoplasmosis?
cats
What is the reservoir for the zoonose, anthrax?
livestock
What is the reservoir for the zoonose, bubonic plaque?
rodents (rats, mice, squirrels, prairie dogs)
What is the reservoir for the zoonose, lyme disease?
deer
What is the reservoir for the zoonose, rabies?
bat
What is the reservoir for the zoonose, yellow fever?
monkeys
What are human carriers as a reservoir?
infected inds who are asymptomatic but invective to others
What do we refer to humans that have eventually develop the illness?
a case
What do we refer to humans that never get sick?
a carrier
What is the term that is used to separate ill persons who have a communicable disease?
isolation
What is it called to separate and restrict the movement of well persons who may have been exposed to a communicable disease
quarantine
What are some non-living reservoirs? What is the presence of microorganisms here often due to?
soil, water, and food; often due to contamination by feces or urine
What is the mere presence of microbes in or on the body?
contamination
What is it called when an organism evades body’s external defense, multiples, and becomes established in the body?
infection
Does infection result in disease?
is MAY or MAY NOT results in disease
What are portals of entry?
sites through which pathogens enter the body
What are three major pathways of portal of entry?
- skin
- mucous membranes
- placenta
What route is technically not a portal of entry, but a way to circumvent the usual portals of entry?
Parenteral route
What are ways a pathogen may get through the skin as its way of portal of entry?
- openings or cuts
- hair follicles or sweat glands
- burrowing into or digesting outer layers of skin
T/F. The skin is the most common portal of entry for a microb.
False. Mucous membranes are. The skin’s outer layer of dead skin cells acts as a barrier to most pathogens (good at what it does)
What is the most common portal of entry, general and specifically?
mucous membranes; specifically respiratory tract (nose, mouth, eyes)
Describe the mucous membranes, and maybe why they are a good portal of entry?
- line body cavities that are open to env.
- provide a moist, warm env. hospitable to pathogens
- GI tract may be route of entry (must survive acidic pH of stomach
How common is the placenta as a portal of entry for pathogens? If they do cross, what can occur?
typically forms effective barrier to pathogens
Pathogens may cross placenta and infect fetus:
- spontaneous abortion
- birth defects
- premature birth
What are the 7 pathogens that can cross the placenta?
- Toxoplasma gondii
- Treponema pallidum
- Listeria monocytogenes
- Cytomegalovirus
- Erythrovirus
- Lentivirus (HIV)
- Rubivirus
What are the 7 conditions in adults that can cross the placenta?
- Toxoplasmosis
- Syphilis
- Listeriosis
- (—Cytomegalovirus is asymptomatic)
- Erythema infectiosum
- AIDS
- German measles
What is the Parenteral Route?
NOT a true portal of entry
- means by which portal of entry can be bypassed
- pathogens deposited directly into tissues beneath the skin or mucous membranes
What are some examples of a pathogen entering the body via the parenteral route of “portal of entry”?
- Needles
- tattoos
- piercings
The invasion of the host by a pathogen.
infection
Results if the invading pathogen alters normal body functions (aka morbidity).
disease
Ability of a microorganism to cause disease.
pathogenicity
Degree of pathogenicity (how easy it is for the organism to cause disease).
virulence
T/F. Pathogenicity and Virulence refer to the severity of the disease.
False– they do NOT refer to the severity of the disease
The ability of a substance to stimulate the production of antibodies or cell-mediated immune responses.
antigenicity
What are symptoms?
Subjective characteristics of disease felt only by the patient
What are signs?
Objective manifestation of disease observed or measured by others (what we as a DC would observe)
What is a group of symptoms and signs that characterize a disease or abnormal condition?
syndrome
Pain, nausea, headache, chills, sore throat, fatigue, malaise, itching, abdominal cramps…are all signs or symptoms?
symptoms (sensed by the patient)
Swelling, rash or redness, vomiting, diarrhea, fever, pus, anemia, leukocytosis/leukopenia, bubo (swollen lymph node), tachycardia/bradycardia…are all signs or symptoms?
signs (detected or measured by an observer)
What are virulence factors and can you name the 5?
contribute to virulence (degree of pathogenicity)
- Adhesion factors
- Biofilms
- Extracellular ezymes
- Toxins
- Antiphagocytic factors
If an infectious agent has more virulent factors, what does that mean?
increase in virulence of the pathogen (how easy it is for it to cause disease)
What aids in adhesion for microorganisms?
attachment proteins
What renders a microorganism avirulent?
inability to make attachment proteins or adhesins
What do we call it when some bacterial pathogens attach to each other?
biofilm
Ex: dental plaque
(not always the same species)
Describe what extracellular enzymes do for a microorganism to increase its virulence?
are secreted by the pathogen
- dissolve structural chemicals in the body
- help pathogen maintain inf, invade, and avoid body defenses
Ex: hyaluronidase and collagenase break down tissue and allow bacteria to penetrate deeper
What are hyaluronidase and collagenase examples of, that help break down tissue and allow bacteria to penetrate deeper?
the virulence factor, Extracellular enzymes
What type of virulence factor are chemicals that harm tissues or trigger host immune responses that cause damage?
Toxins
What are the two types of toxins that pathogens can release as a virulence factor? Give examples of each.
- Exotoxins (cytotoxins, neurotixins, enterotoxins)
2. Endotoxins (aka lipid A)
What are protective molecules (antibodies) formed by the host or may be administered artificially?
antitoxins
What type of virulence factor prevents phagocytosis by the host’s phagocytic cells??
Antiphagocytic factors
What are two kinds of antiphagocytic factors?
- Bacterial Capsule
2. Antiphagocytic chemicals
What does a bacterial capsule do for the pathogen?
(type of Antiphagocytic factor)
- not recognized as foreign
- slippery, difficult for phagocytes to engulf
What do antiphagocytic chemicals do for a pathogen?
(type of antiphagocytic factor)
- allow bacteria to survive inside phagocytes
- produce leukocidins which destroy phagocytic WBCs
What are the 5 stages of Infectious Disease?
- Incubation period
- Prodromal period
- Illness
- Decline
- Convalescence
What stage of infectious disease is when the patient recovers from illness, and the tissues are repaired and returned to normal?
Stage 5: Convalescence
What stage of infectious disease is considered the most severe stage and signs/symptoms are most evident?
Stage 3: illness
What stage of infectious disease is between infection and first symptoms or signs?
Stage 1: Incubation period
What stage of infectious disease is the short period of generalized, mild symptoms?
Stage 2: prodromal period
What stage of infectious disease consists of immune response/treatment vanquishes pathogens, and the body slowly returns to normal?
Stage 4: Decline
What do we call the ways pathogens leave the host?
Portals of Exit
relatively same as portals of entry, but these contain FLUIDS
What are the five portals of exit?
- bodily secretions (earwax, tears, nasal secretions, saliva, sputum, respiratory droplets
- blood
- vaginal secretions or semen
- breast milk
- bodily wastes (urine, excrement, sweat)
Transmission is from a _____ or a ______ to another host’s ______.
reservoir or a portal of exit; to portal of entry
What are the four Modes of Transmission?
- Contact transmission
- Vehicle transmission
- Vector transmission
- Perinatal
What is an inanimate object called that is involved in indirect transmission?
fomite
What are the three subcategories of Contact transmission?
direct, indirect, or droplet
What type of mode of transmission is airborne, waterborne, foodborne, fecal-oral, or bodily fluids considered?
Vehicle transmission
What kind of transmission is it when an arachnid or insect trasfers it? What are the two subcategories?
Vector transmission
- biological vector
- mechanical vector
What do you call an arachnid/insect that carries the pathogen and drops it off?
mechanical vector (picks up pathogen but is never infected)
What do you call an arachnid/insect that serves as a host and transfers pathogen that way?
biological vector (must infect the host and then be carried)
What is the mode of transmission called when it is transmitted from mom to baby?
Perinatal
DO NOT confuse with Parenteral
What are the two ways that perinatal transmission can occur?
placenta
breast milk
What are animals that carry pathogens called?
arthropod vectors
What do we call the type of arthropod vector only carries the pathogen?
mechanical vector
What do we call the type of arthropod that serves as a host for the pathogen and transfers it that way?
biological vector
What are the two classes of arthropod?
Arachnids (ticks and mites)
Insects (fleas, lice, flies, mosquitoes, true bugs)
What are the types of arachnids that are disease vectors? How many legs?
4 pairs of legs
- ticks
- mites
(NOT SPIDERS)
What are the most important arachnid vectors?
ticks
What are the insect vectors? How many legs?
3 pairs of legs
- fleas
- lice
- flies
- mosquitoes
- kissing bugs (true bugs or reduriid)
What are true bugs also called?
kissing bugs or reduriid
are an insect vector
What are the most important insect vector?
mosquitoes
What are the most important and common vector of all?
mosquitoes (even over ticks)
What are the 6 steps in the chain of an infection?
- agent
- reservoir
- portal of exit
- mode of transmission
- portal of entry
- the new host
What two words are used when we talk about the frequency (occurrence) of disease?
Incidence
Prevalence
What is the term for the number of new cases of a disease in a given area during a given period of time?
indidence
What is the term for the number of total cases of a disease in a given area during a given period of time?
Prevalence
What do we call a disease that normally(commonly) occurs at regular intervals at a relatively stable incidence w/in a give population of geographical area?
endemic
What do we call a disease where only a few scattered cases are within an area or population?
sporadic
random
What do we call a disease that occurs at a greater frequency than is usual for an area or population?
epidemic
no specific number attached
What do we call an epidemic that occurs simultaneously on more than one continent?
pandemic
What two things does descriptive epidemiology involve?
- careful tabulation of data concerning a disease (location, time, patient info)
- index case
What is the first case of the disease called?
index case
What is included in careful tabulation of data concerning a disease?
- record location and time of the cases of disease
- collect patient information
What are infections acquired in a health-care setting called?
Nosocomial infections
could be patients or employees
What are the three subtypes of Nosocomial infections?
- Exogenous
- Endogenous
- iatrogenic
What do we call a pathogen that is acquired from the healthcare environment?
exogenous
outside body
What do we call a pathogen that arises from normal microbiota due to factors in the healthcare setting?
Endogenous
inside body
What do we call an infection that results from modern medical procedures?
iatrogenic
ex: surgery
What is the most effective way at reducing nosocomial infections?
hand washing
What is the term for diseases which any healthcare professional is required to report cases of to the state health department? Where does it go from there?
Notifiable diseases
then to CDC
What is the scheme for reporting notifiable diseases?
Doctors, clinics, hospitals –> local health department—> state health department —-> CDC
