Page 351 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com mebooksfree.com vaccine recipients. Hygienic measures such as proper sew- mebooksfree.com
340
PART IV Clinical Virology
this watery diarrhea is caused primarily by stimulation of
the enteric nervous system.
age disposal and handwashing are helpful. There is no
The virulence of certain reoviruses in mice has been
antiviral therapy.
localized to the proteins encoded by several specific genome
segments. For example, one gene governs tissue tropism,
SELF-ASSESSMENT QUESTIONS
whereas another controls the inhibition of cell RNA and
protein synthesis.
Immunity to rotavirus infection is unclear. It is likely
the following is most accurate?
that intestinal IgA directed against specific serotypes pro- 1. Regarding poliovirus and the disease poliomyelitis, which one of
(A) Poliovirus is transmitted primarily by the fecal–oral route.
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tects against reinfection and that colostrum IgA protects
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mebooksfree.com mebooksfree.com mebooksfree.com (D) Poliovirus has single-stranded RNA as its genome and a poly- mebooksfree.com
(B) New antigenic variants arise by coinfection with animal strains
newborns up to the age of 6 months.
of poliovirus.
(C) Paralytic poliomyelitis is the most common manifestation of
Clinical Findings
poliovirus infection.
Rotavirus infection is characterized by nausea, vomiting,
merase in the virion that synthesizes its mRNA.
and watery, nonbloody diarrhea. Gastroenteritis is most
(E) The current vaccine recommendation is to give the live, attenu-
serious in young children, in whom dehydration and elec-
ated vaccine for the first three immunizations to prevent the
trolyte imbalance are a major concern. Adults usually have
child from acting as a reservoir, followed by boosters using the
minor symptoms.
killed vaccine.
organization to build houses in a developing country where polio
Laboratory Diagnosis
is still endemic. He plans to be there about 9 months. He thinks he
Although the diagnosis of most cases of viral gastroenteri- 2. A 70-year-old retired carpenter has signed up with a volunteer
has never been immunized against polio. Which one of the follow-
ing is the most appropriate thing to do?
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mebooksfree.com mebooksfree.com mebooksfree.com 3. Regarding rhinoviruses, which one of the following is most accurate? mebooksfree.com
tis does not involve the laboratory, a diagnosis can be
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made by detection of rotavirus in the stool by using
(A) Give immune serum globulins (ISG).
(B) Give the killed vaccine containing only type 3.
radioimmunoassay or enzyme-linked immunosorbent
(C) Give the killed vaccine containing types 1, 2, and 3.
assay (ELISA). This approach is feasible because there are
(D) Give the live vaccine containing only type 3.
large numbers of virus particles in the stool. The original
(E) Give the live vaccine containing types 1, 2, and 3.
demonstration of rotavirus in the stool was done by
immunoelectron microscopy, in which antibody aggre-
(A) Rhinoviruses are an important cause of viral meningitis and
gated the virions, allowing them to be visualized in the
myocarditis.
electron microscope. This technique is not feasible for
(B) The rhinovirus vaccine is recommended for all children over
routine clinical use. In addition to antigen detection, the
2 years of age.
diagnosis can be made by observation of a fourfold or
greater rise in antibody titer. Although the virus can be
many infections caused by these viruses.
cultured, this procedure is not routinely done. (C) Rhinoviruses have many serologic types, so a person can have
(D) Rhinoviruses are not inactivated by stomach acid, so they
infect the upper gastrointestinal tract and are one of the causes
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mebooksfree.com mebooksfree.com mebooksfree.com 4. Regarding norovirus, which one of the following is most accurate? mebooksfree.com
Treatment & Prevention
of viral diarrhea.
(E) An important feature of the laboratory diagnosis of rhinovi-
There are two rotavirus vaccines available. Both contain
ruses is finding cytopathic effect in cell culture consisting of
live virus and are given orally. One is a live, attenuated
multinucleated giant cells.
vaccine (Rotarix), which contains the single most common
rotavirus serotype (G1) causing disease in the United
(A) The diarrhea is caused by an exotoxin that increases cyclic
States. The other is a live reassortant vaccine (Rotateq),
adenosine monophosphate (cyclicAMP).
which contains five rotavirus strains. An increased risk of
(B) There are no neutrophils or red cells in the stool.
(C) Ritonavir, a protease inhibitor, is the drug of choice for chronic
intussusception has been reported with both vaccines.
diarrhea caused by norovirus.
Patients with a history of intussusception should not
(D) Ingestion of undercooked hamburger is a common mode of
receive either vaccine.
acquisition of norovirus as cattle are a major reservoir of the
The five rotaviruses in the Rotateq vaccine are reassor-
virus.
tants in which the gene for the outer surface protein of a 5. Regarding rotavirus, which one of the following is most accurate?
(E) The diagnosis of norovirus-induced diarrhea is typically made
human rotavirus is inserted into a bovine strain of rotavirus.
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mebooksfree.com mebooksfree.com mebooksfree.com (A) Rotavirus is a major cause of nosocomial diarrhea in intensive mebooksfree.com
by the detection of a fourfold or greater rise in antibody titer to
(Recall that rotavirus has a segmented genome.) The
the virus.
bovine strain is nonpathogenic for humans, but the human
outer surface protein in the vaccine virus elicits protective
(IgA) immunity in the gastrointestinal tract.
care units.
A previously approved vaccine (Rotashield) was with-
(B) The vaccine against rotavirus contains live, attenuated virus as
drawn when a high rate of intussusception occurred in
the immunogen.
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