Page 342 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com mebooksfree.com 3. Regarding measles virus and the disease measles, which one of mebooksfree.com
CHAPTER 39 RNA Enveloped Viruses
331
Quarantine of individuals thought to be exposed for 21 days
is also important. There is no vaccine. Several candidate
the following statements is most accurate?
vaccines are being tested as of this writing.
(A) The measles vaccine contains killed virus as the immunogen.
(B) One of the main sequelae of measles is autoimmune glomeru-
lonephritis and kidney failure.
MARBURG VIRUS
(C) Measles is unlikely to be eradicated because there is a signifi-
cant animal reservoir for this virus.
Marburg virus and Ebola virus are similar in that they both
(D) Fecal–oral transmission during the diaper stage is the main
cause hemorrhagic fever and are members of the filovirus
mode of acquisition of measles virus.
family; however, they are antigenically distinct. Marburg 4. Regarding respiratory syncytial virus (RSV), which one of the
(E) This virus has only one antigenic type, and lifelong immunity
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virus was first recognized as a cause of human disease in
occurs in patients who have had measles.
1967 in Marburg, Germany. The common feature of the
following statements is most accurate?
infected individuals was their exposure to African green
monkeys that had recently arrived from Uganda. As with
(A) RSV is an important cause of bronchiolitis in infants.
(B) RSV causes tumors in newborn animals but not in
Ebola virus, the natural reservoir of Marburg virus is
humans.
unknown, although bats are suspected.
(C) The RSV vaccine is recommended for all children prior to
The clinical picture of this hemorrhagic fever is as
entering school.
described for Ebola virus (see earlier). In 2005, an outbreak
(D) Amantadine should be given to elderly nursing home resi-
of hemorrhagic fever caused by Marburg virus killed hun-
dents to prevent outbreaks of disease caused by RSV.
dreds of people in Angola. No cases of disease caused by
(E) RSV forms intranuclear inclusion bodies within neutrophils
Marburg virus occurred in the United States prior to 2008.
that are important in diagnosis by the clinical laboratory.
However, in that year, a U.S. traveler became ill after visit-
ing a cave in Uganda inhabited by fruit bats. He returned to 5. Regarding rubella virus, which one of the following statements is
most accurate?
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the United States, where he was diagnosed with Marburg
(A) Systemic infection with rubella virus often causes severe liver
hemorrhagic fever. He recovered without sequelae.
damage resulting in cirrhosis.
The diagnosis is made by PCR assay or detecting a rise in
(B) If a pregnant woman is infected during the first trimester,
IgM antibody titer. No antiviral therapy or vaccine is available.
significant fetal abnormalities typically result.
(C) The main source of virus is adults who have recovered from
As with Ebola virus, secondary cases among medical per-
the disease but are chronic carriers of the virus.
sonnel have occurred; therefore, stringent infection control
(D) Immunization of both male and female health care workers
practices must be instituted to prevent nosocomial spread.
with the formalin-inactivated vaccine is recommended.
(E) The significant changes in the antigenicity of this virus are
SELF-ASSESSMENT QUESTIONS
attributed to reassortment of the segments of its genome.
1. Regarding influenza virus, which one of the following statements
following statements is most accurate?
is most accurate?
(A) Finding intranuclear inclusion bodies within macrophages is
(A) The virion contains an RNA-dependent DNA polymerase. 6. Regarding rabies virus and the disease rabies, which one of the
presumptive evidence of rabies virus infection.
(B) Its surface proteins, hemagglutinin and neuraminidase, have
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(B) Lamivudine is used to treat rabies because it inhibits the
multiple serologic types.
RNA-dependent DNA polymerase in the virion.
(C) The protein that undergoes antigenic variation most often is
(C) In the United States, skunks and bats are more likely to trans-
the internal ribonucleoprotein.
mit rabies virus to people than are dogs and cats.
(D) Antigenic drift involves major changes in antigenicity that
(D) The incubation period of the disease is usually 2 to 4 days,
result from reassortment of the segments of its RNA genome.
leading to the rapid progression of the encephalitis and
(E) The neuraminidase on the virion surface mediates the inter-
death.
action of the virus with the receptors on the respiratory tract
(E) After the animal bite, rabies virus enters the bloodstream,
epithelium.
replicates in internal organs such as the liver, and then
2. Regarding influenza virus and the disease influenza, which one
reaches the central nervous system during the secondary
of the following statements is most accurate?
viremia.
(A) Both the killed and the live, attenuated vaccines induce life-
and bit her on the leg. She now presents to your emergency room
long immunity.
about an hour after the bite. Which one of the following is the
(B) Influenza A virus causes more severe disease and more wide- 7. A woman was hiking in an isolated area when a skunk appeared
most appropriate thing to do?
spread epidemics than does influenza B virus.
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(C) The genome of influenza A virus has eight segments, but the
(A) Give rabies vaccine and hyperimmune globulin immediately.
genome of influenza B virus is in one piece.
(B) Reassure her that rabies is not a problem because skunks do
(D) The classification of influenza viruses into A, B, and C viruses
not carry rabies.
is based on antigenic differences in their hemagglutinin.
(C) Quarantine the animal for 10 days and only treat her if signs
(E) Chronic carriers (i.e., patients from whom influenza virus is
of rabies appear in the animal.
isolated at least 6 months after the acute disease) are an
(D) Test the patient’s serum for antibodies now and in 10 days to
important source of human infection.
see if there is a rise in antibody titer before treating her.
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