Page 363 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com mebooksfree.com HEPATITIS G VIRUS (HGV) mebooksfree.com mebooksfree.com
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PART IV Clinical Virology
352
Clinical Findings
Because HDV can replicate only in cells also infected with
In 1996, hepatitis G virus (HGV) was isolated from patients
HBV, hepatitis delta can occur only in a person infected
with posttransfusion hepatitis. HGV is a member of the
with HBV. A person can either be infected with both HDV
flavivirus family, as is HCV. However, unlike HCV, which is
and HBV at the same time (i.e., be “coinfected”) or be previ-
clearly the cause of both acute hepatitis and chronic active
ously infected with HBV and then “superinfected” with HDV.
Hepatitis in patients coinfected with HDV and HBV is
HGV has not been documented to cause any of these clini-
more severe than in those infected with HBV alone, but the
cal findings. The role of HGV in the causation of liver dis-
incidence of chronic hepatitis is about the same in patients hepatitis and predisposes to hepatocellular carcinoma,
ease has yet to be established, but it can cause a chronic
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mebooksfree.com mebooksfree.com mebooksfree.com is carried in the blood of millions of people worldwide. In mebooksfree.com
infected with HBV alone. However, hepatitis in chronic
infection lasting for decades. Approximately 60% to 70% of
carriers of HBV who become superinfected with HDV is
those infected clear the virus and develop antibodies.
much more severe, and the incidence of fulminant, life-
HGV is transmitted via sexual intercourse and blood. It
threatening hepatitis, chronic hepatitis, and liver failure is
significantly higher.
the United States, it is found in the blood of approximately
2% of random blood donors, 15% of those infected with
HCV, and 35% of those infected with HIV. Patients coin-
Laboratory Diagnosis
fected with HIV and HGV have a lower mortality rate and
The diagnosis of HDV infection in the laboratory is made
have less HIV in their blood than those infected with HIV
by detecting either delta antigen or IgM antibody to delta
antigen in the patient’s serum.
replication of HIV. (HGV is also known as GB virus C.)
Treatment & Prevention alone. It is hypothesized that HGV may interfere with the
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mebooksfree.com mebooksfree.com mebooksfree.com 1. An outbreak of jaundice occurs in several young children who mebooksfree.com
Peginterferon alfa can mitigate some of the effects of the
SELF-ASSESSMENT QUESTIONS
chronic hepatitis caused by HDV but does not eradicate the
chronic carrier state. There is no specific antiviral therapy
against HDV. There is no vaccine against HDV, but a per-
attend the same day care center. If the outbreak was caused by a
son immunized against HBV will not be infected by HDV
virus, which one of the following is the most likely cause?
because HDV cannot replicate unless HBV infection also
(A) Hepatitis A virus
occurs.
(B) Hepatitis B virus
(C) Hepatitis C virus
(D) Hepatitis D virus
HEPATITIS E VIRUS (HEV)
statements is most accurate?
HEV is a major cause of hepatitis transmitted by the fecal–
(A) The HAV vaccine contains live, attenuated virus as the
immunogen.
oral route. It is thought to be more common than HAV in 2. Regarding hepatitis A virus (HAV), which one of the following
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mebooksfree.com mebooksfree.com mebooksfree.com 3. A woman who is hepatitis B surface antigen (HBsAg) positive and mebooksfree.com
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(B) The screening of blood for transfusion has greatly reduced the
many developing countries. It is a common cause of water-
spread of this virus.
borne epidemics of hepatitis in Asia, Africa, India, and
(C) The diagnosis is typically made by serologic tests rather than by
Mexico but is uncommon in the United States. HEV is a
culturing the virus.
nonenveloped, single-stranded RNA virus classified as a
(D) Multiple episodes of hepatitis A are common because it has
member of the hepevirus family.
three serotypes.
Clinically the disease resembles hepatitis A, with the
(E) It has a segmented, negative-polarity, single-stranded RNA
exception of a high mortality rate in pregnant women.
genome and an RNA polymerase in the virion.
Chronic infection resulting in chronic hepatitis and cirrho-
sis but not hepatocellular carcinoma, occurs in immuno-
hepatitis B surface antibody (HBsAb) negative has just given birth.
compromised individuals such as HIV-infected patients,
Which one of the following is the most appropriate thing to do for
those who are receiving cancer chemotherapy, and patients
the newborn?
(A) Nothing. The child is protected against hepatitis B.
who are receiving immunosuppressive drugs to prevent
(B) Immunize with the vaccine containing HBsAg (HBV vaccine).
rejection of solid-organ transplants. 4. Regarding hepatitis B virus (HBV) and the disease hepatitis B,
(C) Give hepatitis B hyperimmune globulin (HBIG).
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mebooksfree.com mebooksfree.com mebooksfree.com (A) The most reliable indicator that a person can transmit HBV is mebooksfree.com
The diagnosis is typically made by detecting IgM anti-
(D) Give both the HBV vaccine and HBIG.
body to HEV. A PCR assay that detects HEV RNA in
patient specimens is available. There is no antiviral drug
which one of the following is most accurate?
available for acute infection in immunocompetent patients.
In immunocompromised patients, ribavirin cleared HEV
the presence of HBsAg in the blood.
viremia in solid organ transplant recipients. There is no
(B) HBV has a circular, partially double-stranded DNA as its
vaccine.
genome and has a DNA polymerase in the virion.
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