Page 189 - Concise Pathology for Exam Preparation ( PDFDrive )

174 SECTION I General Pathology

Multinucleate
giant cell

FIGURE 7.8. Herpes-infected enlarged keratinocytes with multinucleated syncytial cells.

Cytomegalovirus (CMV)
Pathogenesis
• CMV can produce a variety of disease manifestations, depending on the age of the host,
and, more important, on the host’s immune status.
• The major glycoprotein envelope of CMV binds to epidermal growth factor receptor
(EGFR) to gain entry into different cells.
• CMV infects and remains latent in white blood cells, and can be reactivated in the event
of depressed cell-mediated immunity (CMI). In immunocompromised patients, CMV
can cause life-threatening illness.

Morphology
CMV produces cellular and nuclear enlargement true to its name. A large intranuclear
inclusion surrounded by a clear halo (owl’s eye) is its morphological hallmark.

Dengue Fever
Pathogenesis
• Dengue (‘break-bone’) fever is an infectious disease common in tropics. It occurs in
epidemic form from time-to-time.
• Dengue is transmitted by several species of mosquitoes within the genus Aedes, princi-
pally A. aegypti.
• Dengue fever virus (DENV) is an RNA virus of family Flaviviridae; genus Flavivirus.
• The virus has four different types; infection with one type usually gives life-long im-
munity to that type, but only short-term immunity to others. Subsequent infection with
a different type increases the risk of severe complications.

Clinical Features
• The World Health Organization’s 2009 classification divides dengue fever into two
groups: uncomplicated and severe.
• Most people infected with dengue virus are asymptomatic or only have mild symptoms
such as an uncomplicated fever. Others present with a more severe illness, which in a
small proportion of cases may be life threatening.
• The incubation period ranges from 3 to 14 days, but most often is about 4–7 days.
• The characteristic symptoms of dengue are sudden-onset fever, headache (typically lo-
cated behind the eyes), muscle and joint pains and rash. The course of infection is di-
vided into three phases: febrile, critical and recovery. The febrile phase involves high
fever, often over 40°C (104°F), and severe generalized aches and pains; this usually lasts
2–7 days. This is followed by a maculopapular rash, after which the disease proceeds to

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