Page 320 - Review of Medical Microbiology and Immunology ( PDFDrive )

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CHAPTER 38 DNA Nonenveloped Viruses
related arthritis include hepatitis B and rubella.

Chronic B19 Infection
People with immunodeficiencies, especially HIV-infected,
chemotherapy, or transplant patients, can have chronic
anemia, leukopenia, or thrombocytopenia as a result of
chronic B19 infection.
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Fifth disease and aplastic anemia are usually diagnosed by
detecting IgM antibodies. B19 virus can be isolated from
throat swabs, but this is not usually done. In immunocom-
promised patients, antibodies may not be detectable; there-
fore, viral DNA in the blood can be assayed by PCR
methods. Fetal infection can be determined by PCR analy-
sis of amniotic fluid.
Treatment & Prevention

There is no specific treatment of B19 infection. Pooled
immune globulins may have a beneficial effect on chronic
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is no vaccine or chemoprophylaxis.
POLYOMAVIRUSES
FIGURE 38–5
Slapped cheek syndrome—note erythematous
There are three members of the polyomavirus family that
macular rash on cheeks bilaterally caused by parvovirus B19.
cause disease in humans, Merkel cell polyomavirus, JC
(Reproduced with permission from Usatine, RP et al: The Color Atlas of Family
virus, and BK virus. One member, SV40 virus, is a monkey
Medicine, New York: McGraw-Hill, 2009. Courtesy of Richard P. Usatine, MD..)
virus that infected humans when it contaminated the
poliovirus vaccine but has not caused human disease.
Merkel cell polyomavirus causes carcinoma of the skin
Aplastic Anemia
Children with chronic anemia, such as sickle cell anemia,
gressive multifocal leukoencephalopathy and is discussed
thalassemia, and spherocytosis, can have transient but and is discussed in Chapter 43. JC virus is the cause of pro-
in Chapter 44. BK virus causes nephropathy in renal trans-
severe aplastic anemia (aplastic crisis) when infected with
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plant patients and is discussed in Chapter 46. SV40 virus
B19 virus. People with normal red blood cells do not have
causes no detectable disease in humans but does cause
clinically apparent anemia, although their red blood cell
precursors are infected.
a tumor virus in Chapter 43 and as a contaminant of the
poliovirus vaccine in Chapter 40.
Fetal Infections
If a woman is infected with B19 virus during the first or
second trimester of pregnancy, the virus may cross the
placenta and infect the fetus. Infection during the first
SELF-ASSESSMENT QUESTIONS
trimester is associated with fetal death, whereas infection
during the second trimester leads to hydrops fetalis.
most accurate?
Third-trimester infections do not result in important clini-
(A) Acyclovir is the drug of choice for life-threatening infections.
cal findings. B19 virus is not a common cause of congeni- 1. Regarding adenoviruses, which one of the following statements is
(B) They cause pharyngitis, pneumonia, and conjunctivitis (“pink
tal abnormalities, probably because the fetus dies when
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eye”).
infected early in pregnancy.
(C) They are often transmitted across the placenta and cause
hydrocephalus in the fetus.
Arthritis
Parvovirus B19 infection in adults, especially women, can
to entering first grade.
cause arthritis mainly involving the small joints of the
(E) Laboratory diagnosis depends on seeing multinucleated giant
hands and feet bilaterally. It resembles rheumatoid arthritis.
cells on biopsy as the virus has not been grown in cell culture.
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