Page 296 - Review of Medical Microbiology and Immunology ( PDFDrive )

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PART IV CLINICAL VIROLOGY

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mebooksfree.com mebooksfree.com mebooksfree.com Poxviruses mebooksfree.com mebooksfree.com

Most of the clinically important viral pathogens can be catego-
rized into groups according to their structural characteristics
Poxviruses are the largest and most complex of the viruses.
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(i.e., DNA enveloped viruses, DNA nonenveloped viruses,
The disease smallpox has been eradicated by effective use
RNA enveloped viruses, and RNA nonenveloped viruses)
of the vaccine. Molluscum contagiosum virus is the only
(see Chapters 37–40 and Table IV–1).
mebooksfree.com mebooksfree.com mebooksfree.com poxvirus that causes human disease in the United States at mebooksfree.com
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However, some viruses (e.g., arboviruses, tumor viruses,
this time. (See Chapter 37.)
and slow viruses) (see Chapters 41–45) are described best
in terms of their biologic features. Several clinically less
DNA NONENVELOPED VIRUSES
prominent viruses (e.g., parvoviruses and coronaviruses)
are described in Chapter 46. An overview of the viruses in
Adenoviruses
the four structural categories follows.
These viruses are best known for causing upper and lower
respiratory tract infections, including pharyngitis and
pneumonia. (See Chapter 38.)
DNA ENVELOPED VIRUSES
Papillomaviruses
Herpesviruses
These viruses cause papillomas on the skin and mucous
These viruses are noted for their ability to cause latent
infections. This family includes (1) herpes simplex virus
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implicated as a cause of cancer (e.g., carcinoma of the cer-
types 1 and 2, which cause painful vesicles on the face and
vix). (See Chapter 38.)
genitals, respectively; (2) varicella-zoster virus, which
causes varicella (chickenpox) typically in children and,
Parvovirus B19
when it recurs, zoster (shingles); (3) cytomegalovirus, an
important cause of congenital malformations; (4) Epstein–
This virus causes “slapped cheeks” syndrome, hydrops feta-
Barr virus, which causes infectious mononucleosis; and
lis, and severe anemia, especially in those with hereditary
(5) human herpesvirus 8, which causes Kaposi’s sarcoma.
anemias such as sickle cell anemia. (See Chapter 38.)
(See Chapter 37.)
RNA ENVELOPED VIRUSES
Hepatitis B Virus
This virus is one of the important causes of viral hepatitis.
(1) Influenza A and B viruses. Influenza A virus is the
In contrast to hepatitis A virus (an RNA nucleocapsid Respiratory Viruses
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major cause of recurrent epidemics of influenza.
virus), hepatitis B virus causes a more severe form of hepa-
(2) Parainfluenza viruses. These viruses are the leading
titis, results more frequently in a chronic carrier state, and
cause of croup in young children and an important cause
is implicated in the induction of hepatocellular carcinoma,
the most common cancer worldwide. (See Chapter 41.)
(3) Respiratory syncytial virus. This virus is the leading
cause of bronchiolitis and pneumonia in infants. (See
Chapter 39.)
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Nonenveloped viruses are also called naked nucleocapsid viruses.
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