Exam 2 SA

Question 1

Immune surveillance refers to processes that take place while the human body is in the “ready” state, waiting to encounter pathogens.
A)Which cells bring antigens to naïve lymphocytes to initiate an adaptive immune
response?

Answer 1

dendritic cells

Question 2

Immune surveillance refers to processes that take place while the human body is in the “ready” state, waiting to encounter pathogens.

B)Where in the body do naïve lymphocytes encounter non-self antigens for the
first time?

Answer 2

Lymph nodes

Question 3

Immune surveillance refers to processes that take place while the human body is in the “ready” state, waiting to encounter pathogens.

C)Briefly outline where in the body each of the following cell types are found
during the “ready” state of immune surveillance: naïve B- and T-lymphocytes, neutrophils, and macrophages.

Answer 3

Naïve B- and T-lymphocytes circulate in blood/efferent lymphatics and are “strained through lymph nodes
Neutrophils circulate in the blood, waiting for call to action from tissues
Macrophages act as sentries in tissues, waiting to encounter pathogens

Question 4

Legionella pneumophila is a species of Gram-negative bacterium that is found ubiquitously in fresh-water. It also is a facultative intracellular pathogen that blocks phagolysosome fusion after being taken up by macrophages.
(a) What is the reservoir for L. pneumophila? [2 points].

Answer 4

Enviromental (fresh water)

Question 5

Legionella pneumophila is a species of Gram-negative bacterium that is found ubiquitously in fresh-water. It also is a facultative intracellular pathogen that blocks phagolysosome fusion after being taken up by macrophages

B) On which class of major histocompatibility complex will L. pneumophila antigens be presented by macrophages?

Answer 5

MHC II

Question 6

Legionella pneumophila is a species of Gram-negative bacterium that is found ubiquitously in fresh-water. It also is a facultative intracellular pathogen that blocks phagolysosome fusion after being taken up by macrophages

C) Briefly outline the sequence of events that begin after macrophages first take up L. pneumophila in the tissues and culminate in clearance of the infection by an adaptive immune response.

Answer 6

1. Dendritic cells (DCs) in tissues take up L. pneumophila antigens and migrate to local lymph node.
2. DCs present L. pneumophila antigens to naïve CD4+ T-cells.
3. CD4+ T-cells are activated [by binding their antigen and receiving co-stimulation from the DC] and differentiate into TH1 cells [caused by cytokines from the DC].
4. TH1 cells divide (clonal expansion), enter circulation, and extravasate at site of infection.
5. TH1 cells recognize L. pneumophila antigens presented by tissue macrophages, and specifically activate the antigen-presenting [infected] macrophages.
6. activation of macrophage allows it to kill intracellular L. pneumophila [by increasing oxidative burst, and forcing phagolysosome fusion].

Question 7

MCV4 is a conjugate vaccine that can provide protection against meningococcal disease caused by encapsulated Neisseria meningitidis of serotypes A, C, Y, and W-135.

A)What kind of N. meningitidis antigens are present in MCV4?

Answer 7

Antigens taken from the polysaccharide capsule

Question 8

MCV4 is a conjugate vaccine that can provide protection against meningococcal disease caused by encapsulated Neisseria meningitidis of serotypes A, C, Y, and W-135.

B) Does MCV4 protect against infection with N. meningitidis serotype B? Explain your reasoning.

Answer 8

doesn’t have any antigen because B doesn’t provoke and immune response

Question 9

MCV4 is a conjugate vaccine that can provide protection against meningococcal disease caused by encapsulated Neisseria meningitidis of serotypes A, C, Y, and W-135.

C) Briefly outline the steps that lead to activation of a naïve B cell after its B-cell receptor binds to one of the Neisseria meningitidis antigens present in MCV4.

Answer 9

1. The B cell receptor recognized the polysaccharide and endocytosed
2. TH2 cells recognize peptide fragments from carrier protein are presented on MHC II
3. TH2 cells stimulate the B cell, activating it to produce antibodies and undergo isotype switching.

Question 10

Treatment for infectious diseases can take several forms, which include surgery in certain cases, as well as the widespread application of antimicrobial chemotherapy.

A) For what types of infection would surgical intervention be an appropriate treatment?

Answer 10

Infections that involve the removal of dead tissue or drainage of abscesses.

1. Virulent infections
2. Necrotic infections

Question 11

Treatment for infectious diseases can take several forms, which include surgery in certain cases, as well as the widespread application of antimicrobial chemotherapy.

B) How is it that non-microbicidal drugs (“-statics”) nevertheless can form the basis of a curative treatment for an infectious disease?

Answer 11

non-microbial drugs are able to inhibit microbial growth long enough for humoral or cell mediated immunity to be activated and respond

Question 12

Treatment for infectious diseases can take several forms, which include surgery in certain cases, as well as the widespread application of antimicrobial chemotherapy.

C) Briefly outline the four mechanisms used by pathogens to evade or counteract antimicrobiall drugs, and indicate to which class(es) of pathogens each mechansim applies.

Answer 12

drug inactivation (B)- acquired drug resistance by enzymes made by the pathogen by chemically cleaving the drug 
reduced access to drug targets (B, F, P)-unmodified penicillin: outer envelope shields peptidoglycan

multidrug efflux pumps (B, F, P)-pumps are involved in expelling drugs from the cytoplasm of the pathogen. Found in the cytoplasmic membrane

target alterations (B, V, F, P)- The microbial enzyme undergoes mutations that block the binding of the drug and the normal function of the enzyme will remain.

Question 13

Vaccination is intended to generate immunity, via immunological memory and circulating specific antibody, before a person encounters a specific, virulent pathogen for the first time.

A)During a primary immune response, a process occurs that results in changes to the antigen-binding site of the antibody encoded by an activated B cell. What is the name given to this process?

Answer 13

Somatic hypermutation- effect on coded antibody- affinity hypermaturation

Question 14

Vaccination is intended to generate immunity, via immunological memory and circulating specific antibody, before a person encounters a specific, virulent pathogen for the first time.

B) What effect(s) are booster vaccinations intended to have on immunity?

Answer 14

Increase or maintain levels of immunity bus simulation of memory B cells to differentiate into plasma b cells to produce antibody with same specificity as primary immune response

Question 15

Vaccination is intended to generate immunity, via immunological memory and circulating specific antibody, before a person encounters a specific, virulent pathogen for the first time.

C) List the different types of vaccine currently used for routine immunization of the general public in the United States, and give one specific example vaccine of each type.

Answer 15

(1) live-attenuated virus (MMR, Varicella, Rotavirus, LAIV, Zoster) [any one for credit]
(2) inactivated virus (IPV, HepA, IIV) [any one for credit]
(3) polysaccharide (PPSV)
(4) polysaccharide-conjugate (MCV4, PCV, Hib) [any one for credit]
(5) toxoid (DTaP, Tdap, Td) [any one for credit]
(6) subunit (HepB, HPV)

Question 16

Post-exposure prophylaxis (PEP) refers to a medical intervention that is carried out after exposure, or potential exposure, to a pathogen with the intent to prevent disease.

A) What factors determine whether PEP is feasible for any given pathogen?

Answer 16

The disease must have a relatively long incubation period and effective protocol must be available as well.

Question 17

Post-exposure prophylaxis (PEP) refers to a medical intervention that is carried out after exposure, or potential exposure, to a pathogen with the intent to prevent disease.

B)Upon what two principles are current PEP protocols based?

Answer 17

• passive and/or active immunization

- chemotherapy (antibacterial or antiviral drugs)

Question 18

Post-exposure prophylaxis (PEP) refers to a medical intervention that is carried out after exposure, or potential exposure, to a pathogen with the intent to prevent disease.

C) Give three examples of diseases for which PEP is employed as a public health control measure and describe a specific protocol used for each one. Include at least one example from each kind of protocol identified in part (b).

Answer 18

Hepatitis A: caused by hepatitis A virus. PEP is active immunization with HepA vaccine, or passive immunization with immune globulin (depending on age). PEP prevents person to person transmission

Invasive meningococcal meningitis disease- caused by Neisseria meningitides. PEP is course of antibiotics. PEP prevents person to person transmission.

Rabies: caused by rabies virus. PEP is passive immunization with immune goblin and active immunization with rabies virus. PEP does not prevent person to person transmision

Question 19

Herd immunity can protect a population against infectious disease even though not all of the individuals in the population are immune.

A) What pathogen-specific characteristics determine the proportion of the population that must be immune in order for herd immunity to operate?

Answer 19

The duration of shedding and ease of transmission.

Question 20

Herd immunity can protect a population against infectious disease even though not all of the individuals in the population are immune.

B) Against what type of epidemics would herd immunity be effective?

Answer 20

Propagated epidemics

Question 21

Herd immunity can protect a population against infectious disease even though not all of the individuals in the population are immune.

C) Briefly explain the mechanism through which herd immunity operates.

Answer 21

In order to transmit the pathogen to a new host, an infected person would need to encounter a susceptible, non-immune person while they are still shedding the pathogen. As the number of non-immune people in the population decreases, the probability of an infected person encountering a non-infected person while they are shedding gradually decreases. When the probability reaches zero, herd immunity has operated.

Question 22

Some groups of people are at higher risk than others for contracting certain kinds of diseases. Information gathered by a physician is intended to identify patients in such groups, and will be used to arrive at a differential diagnosis.

A) What is a differential diagnosis?

Answer 22

A short-list of diseases/pathogens consistent with clinical presentation and patient history.

Question 23

Some groups of people are at higher risk than others for contracting certain kinds of diseases. Information gathered by a physician is intended to identify patients in such groups, and will be used to arrive at a differential diagnosis.

B) What is the general name for the type of disease for which veterinarians are at increased risk in comparison to members of the general public?

Answer 23

Zoonoses

Question 24

Some groups of people are at higher risk than others for contracting certain kinds of diseases. Information gathered by a physician is intended to identify patients in such groups, and will be used to arrive at a differential diagnosis.

C) Briefly outline the steps taken by a physician in the process of diagnosing an infectious disease.

Answer 24

Take patient history.
Perform physical exam.
Establish differential diagnosis.
Order tests (if necessary) and begin treatment.
Review test results and patient response to treatment.

Question 25

In October 2004 there was an outbreak of infection by Escherichia coli O157:H7 among people who had attended the North Carolina State Fair. This outbreak was investigated by a team of epidemiologists from the North Carolina Division of Public Health (NCDPH) and the Centers for Disease Control and Prevention (CDC).

A) In general, what is the most common way for people to be exposed to E. coli O157:H7?

Answer 25

Contaminated food

Question 26

In October 2004 there was an outbreak of infection by Escherichia coli O157:H7 among people who had attended the North Carolina State Fair. This outbreak was investigated by a team of epidemiologists from the North Carolina Division of Public Health (NCDPH) and the Centers for Disease Control and Prevention (CDC).

B) The fair already was over before the E. coli O157:H7 outbreak was recognized. Why did NCDPH decide to investigate the outbreak?

Answer 26

It was investigated due to the severity of the disease and the number of people potentially exposed. Also, to prevent the outbreak from happening again.

Question 27

In October 2004 there was an outbreak of infection by Escherichia coli O157:H7 among people who had attended the North Carolina State Fair. This outbreak was investigated by a team of epidemiologists from the North Carolina Division of Public Health (NCDPH) and the Centers for Disease Control and Prevention (CDC).

C) List the components of a generic outbreak investigation, and indicate which one of them was not employed by the NCDPH–CDC team during this investigation?

Answer 27

Verify diagnosis and confirm outbreak
Define case and conduct case findings
Tabulate and orient data
Take immediate control measures
Test and formulate hypothesis
Plan and execute additional studies
Evaluate control measures
Communicate findings

Control measures was not done!

Question 28

The disease tuberculosis (TB) is caused by infection with Mycobacterium tuberculosis. Infections with this organism can result in either active TB, in which mycobacteria are shed and can be detected in a patient’s sputum (coughed-up mucus), or in clinically latent TB, which is characterized by a lack of mycobacterial shedding.

A) What combination of diagnostic tests would allow a clinician to determine whether a patient is infected with M. tuberculosis, and distinguish whether they have active or latent TB?

Answer 28

skin test (PPD), sputum sample, and chest x ray.
latent - no symptoms and cannot be spread
active - symptoms and can spread

Question 29

The disease tuberculosis (TB) is caused by infection with Mycobacterium tuberculosis. Infections with this organism can result in either active TB, in which mycobacteria are shed and can be detected in a patient’s sputum (coughed-up mucus), or in clinically latent TB, which is characterized by a lack of mycobacterial shedding.

B) If the patient is determined to have active TB, what kind of public health control measure would be necessary to prevent them from exposing members of the general public?

Answer 29

isolation orders

Question 30

The disease tuberculosis (TB) is caused by infection with Mycobacterium tuberculosis. Infections with this organism can result in either active TB, in which mycobacteria are shed and can be detected in a patient’s sputum (coughed-up mucus), or in clinically latent TB, which is characterized by a lack of mycobacterial shedding.

C)List, and briefly describe, each of the infection control precautions that should be employed if an active TB patient requires hospitalization. Include the elements of standard precautions as well as those of the appropriate transmission-based precautions.

Answer 30

hand hygiene, PPE (including N95 respirator), safe handling of equipment and items, respiratory hygiene/cough etiquette, individual patient room (negative pressure isolation room)