BIO205 Chapter 2
The human protein transferrin sequesters iron away from bacteria. Transferrin attempts to interfere with which fundamental attribute of a successful pathogen?
nutrient acquisition FEEDBACK: Iron is an essential nutrient for all organisms. Preventing pathogens from acquiring iron limits their nutrient acquisition. Invasiveness is not a fundamental attribute of successful pathogens
Symptoms develop rapidly in which type of infection? o Disseminated infection o Latent infection o Acute infection o Chronic Infection
o Acute infection
Biosafety Level 3
o Agents may cause disease by inhalation route o Level 2 procedures plus ventilation providing directional airflow into room, exhaust air directed outdoors, restricted access o Pathogens produce a serious or lethal disease, but vaccines or therapeutic agents may be available. o Organisms are kept in negative pressure rooms
Biosafety Level 1
o Agents not known to cause disease o basic sterile technique, no mouth pipetting o Suitable for work involving well-characterized agents not known to consistently cause disease in healthy adult humans o Of minimal potential hazard to laboratory personnel and the environment
Biosafety Level 2
o Agents of moderate potential hazard o Required if personnel may have contact with human blood/tissues o Level 1 procedures plus limited access to lab, biohazard safety cabinets used, hepatitis vaccination recommended o Suitable for work involving agents of moderate potential hazard to personnel and the environment
In urban Brazil, outbreaks of leptospirosis can be predicted by heavy rain and flooding, which bring increased risk of human contact with waterborne Leptospira, a zoonotic bacterium. A longer or more prevalent rainy season is a result of which of the following? o Climate change o Human settlement sprawl o Deforestation
o Climate change
Biosafety Level 4
o Dangerous and exotic pathogens with high risk of aerosol transmission(only 11 labs in US) o Level 3 procedures o Positive pressure lab suits connected to a separate air supply o Lab is completely isolated from other areas present in the same building or is in separate building
Successful pathogens must do which of the following(SATA)? o Readily infect various animals o Grow and multiply within a host o Enter and exit a host o Avoid the host's immune system o Cause rapid death in the host
o Grow and multiply within a host o Enter and exit a host o Avoid the host's immune system
Infections that normally afflict animals but can be transmitted to humans are called zoonotic diseases. Which of the following are examples of zoonotic diseases(SATA)? o H1N1 influenza, also called "swine flu," affected many people in a 2009 outbreak. o Cats can contract feline immunodeficiency virus (FIV) and humans can contract human immunodeficiency virus (HIV). o Borrelia burgdorferi, the bacterium that causes Lyme disease (which usually infects deer, dogs, horses, and cattle), can cause disease in humans via the bite of a tick. o Rabies, a virus that causes a deadly and painful neurological disease, is transmitted from dogs to humans by dog bite.
o H1N1 influenza, also called "swine flu," affected many people in a 2009 outbreak. o Borrelia burgdorferi, the bacterium that causes Lyme disease (which usually infects deer, dogs, horses, and cattle), can cause disease in humans via the bite of a tick. o Rabies, a virus that causes a deadly and painful neurological disease, is transmitted from dogs to humans by dog bite.
Among a population of people exposed to influenza virus, those who frequently wash their hands or use hand sanitizers are less likely to contract the flu. This is an example of which factor that plays a role in whether a host will contract an infectious disease? o Nutrition and exercise o Immune status o Host hygiene o Occupation o Age
o Host hygiene
What is an infection transmitted from a health care worker to a patient called? o Mixed infection o Iatrogenic infection o Community-acquired infection o Focal infection
o Iatrogenic infection
The fungus Pneumocystis jirovecii easily infects people, but rarely causes disease in healthy people. What is this type of pathogen called? o Primary pathogen o True pathogen o Opportunistic pathogen o Virulent pathogen
o Opportunistic pathogen
Agents transmitted by mosquitoes or other insects enter their human hosts via what portal of entry? o Parenteral route o Urogenital route o Oral route o Fecal-oral route o Respiratory route
o Parenteral route
Which of the following organisms would be considered the most virulent, based on their infectious dose (ID50)? o Rickettsia rickettsii, ID50 = 1 o Vibrio cholerae, ID50 = 1,000,000,000 o Mycoplasma tuberculosis, ID50 = 10
o Rickettsia rickettsii, ID50 = 1
Why are very young children (under the age of 3) highly susceptible to infection? o Their immune systems are waning. o Their exercise levels are low. o They are continually exposed to infectious agents. o Their immune systems are still developing.
o Their immune systems are still developing.
The ___________ of an organism is its ability to cause disease.
pathogenicity
Immunopathology is defined as
the symptoms caused by the host immune system in response to the pathogen. FEEDBACK: Immunopathologies are signs and symptoms caused by the host immune system in response to the pathogen, but they do not necessarily include death.
microbiota
the term for the microbes that are normally present in and on the human body; usually beneficial
Some pathogens can have more than one portal of entry. Pick the pair of words that will make the following sentence correct. HIV can be transmitted via the _______________ route during sexual contact or via the ________________ route during needle sharing.
urogenital; parenteral FEEDBACK: In the urogenital route, the pathogen enters the body through the urethra or vagina. In the parenteral route, the pathogen enters the body via injection into the bloodstream (such as via a needle or insect bite).
Which of the following would be an effective means of limiting a disease spread via a respiratory route?
wearing a mask that covers the nose and mouth FEEDBACK: Pathogens using the respiratory route enter the body during the act of breathing, which uses the nose and mouth. Therefore, placing a mask over the nose and mouth to filter out pathogens may limit the spread of respiratory route pathogens. The other precautions listed would not help against respiratory route infections
ARE YOU A GOOD HOST FOR A DISEASE? WELL, THAT DEPENDS ON A NUMBER OF FACTORS(8)
1. Age 2. Genetic makeup 3. Host hygiene and social behavior 4. Nutrition/Diet 5. Exercise 6. Underlying health conditions 7. Occupation 8. Immune (System) Health/Status
portals of exit for disease
1. Respiratory Tract 2. Gastrointestinal Tract 3. Urogenital Tract 4. Open Wounds
What might allow disease vectors such as mosquitoes to increase their global geographic range?
An expansion of suitable habitat due to climate change. FEEDBACK: Climate change is causing expansion of mosquitoes into previously unsuitable habitats. For example, tropical species are expanding their range northward. A reduction in food or water sources would not allow increases in geographic range
pathogen
An organism that causes disease (bacterium, virus, fungus, protozoan, worm/helminth)
zoonoses
Animal, living reservoirs
What distinguishes biosafety level 2 agents from biosafety level 3 agents?
Both biosafety levels contain pathogenic agents: biosafety level 2 agents are not transmitted via inhalation, but biosafety level 3 agents can be transmitted via inhalation. FEEDBACK: Biosafety level 3 agents may cause disease via inhalation (unlike the pathogens in biosafety level 2). A positive-pressure suit is only required for work with biosafety level 4 agents.
What is the underlying factor that explains how age and nutrition can affect disease susceptibility?
Both can affect host immune status. FEEDBACK: Both the very young and the very old have weaker immune systems as the immune system is still developing in the very young and is declining in the very old. Poor nutrition negatively affects immune status.
What is the most likely way that expansion of human civilization leads to new human disease outbreaks?
Expansion brings humans into contact with disease reservoirs from which they were previously isolated. FEEDBACK: Humans must be exposed to an etiologic agent in order to contract an infectious disease. As humans expand into previously uninhabited regions, they are exposed to new pathogen reservoirs
nonliving reservoirs
Soil and water
Pathogen A has an LD50 of 1,000, and pathogen B has an LD50 of 75. Which of the following statements is true?
Pathogen B is more virulent than pathogen A. FEEDBACK: LD50 means lethal dose 50% and is the number of pathogens required to cause death in 50% of an experimental group of hosts. Ultimately, it is a measure of virulence. A lower LD50 indicates a higher virulence because fewer pathogens are required to cause the same amount of mortality
You and your immunocompromised neighbor both consume undercooked meat containing a pathogenic strain of Escherichia coli. Your neighbor becomes ill (but eventually recovers), whereas you never experience any symptoms. Which of the following statements is true?
The E. coli strain ingested was an opportunistic pathogen. FEEDBACK: An opportunistic pathogen is one that only causes disease in compromised hosts. You were infected with the E. coli (an infection occurs anytime a pathogen enters or starts to grow on a host), but with a healthy immune system you fought off the infection before it led to disease symptoms.
mortality
a measure of how many died from the disease.
morbidity
a measure of how many people are sick from an infectious disease
opportunistic pathogen
a microbe that causes disease only when introduced into a host with a weak immune system
Re-emerging infectious diseases
diseases that have existed but are exhibiting a recent increase in incidence or geographic location(WNV, Co MRSA, Mad Cow).
Ebola epidemics occasionally occur. Where does the virus that causes Ebola "hide" in between epidemics? It is thought that bats naturally harbor the virus, and thus bats are:
a reservoir. FEEDBACK: A reservoir is a site where an infectious agent survives and is thus a source of infection. Bats are not known to be active disease vectors, at least not in the traditional sense of the word
pathogenicity
ability to cause disease
Nosocomial infection
acquired as a result of a hospital stay only in individuals with compromised mmune system
How do bacteria, such as Escherichia coli, stay attached to body cells, tissues, or other surfaces?
adhesins
Emerging infectious diseases
diseases that have not previously been recognized and are the result of newly evolved organisms or organisms that have made the leap from animal to human (HIV/AIDS, SARS, H1N1).
transmission of infectious disease (5 types)
droplets(mucus), arthropod(bugs), contaminated water, injections, human to human
Organisms in which group require only routine laboratory practices and standard sterile technique for biological safety containment?
biosafety level 1 FEEDBACK: Biosafety level 1 organisms have little to no pathogenic potential and thus require the lowest level of containment. Biosafety level 4 organisms are the most dangerous and require the most rigorous containment efforts
What determines whether an individual will contract a particular infectious disease?
both the host's susceptibility to the pathogenic agent and the virulence of the pathogenic agent FEEDBACK: Humans must be exposed to a pathogen in order to be infected by the pathogen. Whether the infection leads to a disease depends on many host factors that influence how quickly and effectively the host can fight off the infection
patient/medical history consists of:
chief complaint, history of present illness, medical history, social history, family history
indirect transmission(aka fomites)
nonliving objects (tissues, money, etc)
virulence
degree of pathogenicity
direct transmission
direct contact/person to person
primary pathogen
disease causing microbes with the ability to breach or break through the immune defenses occurs dispute the strength of the host's immune system
A disease that is always present at low levels in a restricted area of the world is known as a ______ disease
endemic FEEDBACK: An epidemic disease is one in which the number of patients rapidly rises above the background endemic level. A pandemic is a worldwide epidemic. Endemic diseases need not be transmitted from animals (i.e. zoonoses).
A particular flu strain spreads easily from person to person and also has high mortality. This flu strain has:
high infectivity and high virulence. FEEDBACK: Infectivity is a measure of how easily the organism causes disease. Because this flu strain spreads easily, its infectivity is high. Virulence is a measure of the severity of the disease, so high mortality indicates high virulence.
carriers
human, living reservoirs
Which of the following has the stages of infectious disease in the correct order?
incubation phase, prodromal phase, illness phase, decline phase, convalescent phase FEEDBACK: The incubation phase-the time from initial infection but before the first symptoms-is first. Second is the prodromal phase, characterized by general malaise, followed by the illness phase where the typical signs and symptoms of the disease are apparent. Symptoms subside during the decline phase, which is followed by a return to full health during the convalescent phase.
MERS, a respiratory illness first reported in 2012, is caused by a virus that is shed by infected camels and can spread to humans. In this example, camels served as a:
incubator. FEEDBACK: Only "incubator" makes sense here. In vertical transmission, the pathogen is passed directly from parent to offspring. Fomites are inanimate objects on which pathogens can be passed from one host to another. Incubators are animals that harbor microbes that can ultimately be passed to humans
Walter defecates in the company restroom, does not wash his hands thoroughly, and then uses the office coffee pot, transferring bacteria onto the handle of the pot. Maria pours some coffee, and then goes to her desk to eat a muffin, ingesting some of the bacteria she picked up from the coffee pot. Maria's bacterial infection occurred via
indirect contact. FEEDBACK: Walter did not have direct contact with Maria to infect her-the coffee pot served as an intermediary, in this case a fomite-so the infection was indirect. This is an example of horizontal transmission (from an infected to an uninfected individual) and not vertical transmission, in which the pathogen is passed directly from parent to offspring.
infection
invasion of the body by a pathogenic organism
A mutualistic relationship exists between human hosts and:
microbiota. FEEDBACK: In a mutualistic relationship, both partners benefit. Pathogens and parasites harm the human host. Fomites are inanimate objects on which pathogens can be passed from one host to another
Pick the pair of words that will make the following sentence correct. A _________ is a disease manifestation that can be observed and measured by clinicians, whereas a __________ is a disease manifestation that can only be felt or experienced by the patient
sign; symptom FEEDBACK: Signs (such as rashes) can be observed by others and usually can be objectively measured. Symptoms (body aches) cannot be directly observed by others but are felt by the patient. A syndrome is a collection of signs and symptoms that occur together, ultimately signifying a particular disease
syndrome
signs and symptoms thich signifies a specific disease
reservoirs of infection
sites where pathogens are maintained as a source of infection
symptom
something that can be felt only by the patient
sign
something that can be observed by a person examining a patient
invasiveness
the ability of a bacterial pathogen to spread through tissue
invasion
the ability of the pathogen to enter/invade and live inside a host
infectious dose 50%
the infectious dose needed to colonize 50% of experimental group
lethal dose 50%
the number of bacteria or virus particles required to kill 50% of an experimental group of animal hosts
