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VIRAL INFECTIONS
A viral infection is a disease that can be caused by different kinds
of viruses, of which the influenza-virus is best known
...


VIRAL HEPATITIS
Introduction
Hepatitis means inflammation of the liver
...

Important forms of hepatitis to be discussed include hepatitis A
(HAV), hepati- tis B (HBV), hepatitis C (HCV)
...

The only one of these viruses that poses a potential threat is
hepatitis E, a virus that clinically looks like HAV, causes an acute
infection, and is spread by the fecal-oral route
...
Infectious
outbreaks occur where there is exposure to infected water or food
(e
...
, shellfish, com- mercial food preparation where an employee
does not follow standard food handling guidelines)
...
Risk
groups include those who use intravenous drugs, individuals
sexually active with multiple partners, homosexual men, infants
born to infected mothers, hemodialysis patients, and healthcare
workers
...


Epidemiologic Information

The Centers for Disease Control and Prevention estimates that
between 125,000 and 200,000 infections occur annually in the
United States, of which about 70 percent of adults are symptomatic
...

Hepatitis B is more common among lower socioeconomic groups;
however, it is observed among all economic strata
...

Hepatitis C virus is responsible for the majority of cases of what
was previously called non-A, non-B viral hepatitis
...

An estimated four million Americans are infected with HCV
...


Clinical features:
The main clinical features of the three types of viral hepatitis are
similar with the most common features being,
• fatigue
• abdominal discomfort
• jaundice (yellowing of the skin and whites of the eyes), and loss of
appetite
...

Patients may have intermit- tent diarrhea and nausea
...

Hepatitis B infections present with similar symptoms usually several
weeks following infection
...
However, there are between
8,000 and 32,000 new chronic infections per year resulting in

between 5,000 and 6,000 deaths annually from liver failure and liver
cancer
...

Hepatitis C has a similar presentation to the other viruses; however,
the risk of chronic infection is much higher with this virus (at least
85 to 90 percent)
...


Diagnosis:
Diagnosis of the common hepatitis infections is easily made through
laboratory tests
...


Treatment and Prevention:
Treatment for HAV is primarily supportive because of its self-limited
nature
...
For patients who develop
end-stage liver disease, surgical interventions can reduce the
morbidity of disease
...

Prevention of those hepatitis infections transmitted by the fecaloral route in- volves standard hygiene and sanitation
techniques
...
Recently, a hepatitis A vaccine became
available that reduces the risk of HAV disease
...
Vaccines
for HBV have been available since 1982 and have been
instrumental in reducing the risk of infec- tion from this virus
...


DENGUE

Introduction
Dengue fever is caused by a virus that is part of the Flaviviridae
family
...
The most common infection in humans is
caused by the dengue virus, of which there are four types
...
Infection with these viruses does not
produce a unique clinical picture
...

Dengue and dengue hemorrhagic fever (DHF) are caused by
infection with one of four antigenically distinct, virus serotypes
(DEN-1, DEN-2, DEN-3, and DEN- 4)
...
This mosquito, a domestic, day-biting mosquito, prefers to
feed on humans
...
5 billion people are living in areas at risk for
epidemic transmission
...


Clinical Presentations :
• Fever and Chills
• Myalgias
• Headache
• Retro-orbital
• Pain rash
•
•
•
•
•

Pharyngitis
Cough
Conjunctivitis
Joint and bone pain may also occur
...


• The fever usually breaks after three to six days, followed by a
maculopapular or morbilliform rash on the trunk, spreading to the
limbs and face and resolving after a few days
...
Patients then recover over several
weeks although the convalescent period may extend a few more
weeks
...
Laboratory tests
available include isolation of the virus, demonstrating the presence
of the
viral antigen using immunoassay tests, or amplification of the viral
nucleic acids using the polymerase chain reaction process
...


Treatment and Prevention
Dengue is treated by managing the patient’s symptoms, rather than
a specific treatment such as an antiviral agent
...

No vaccines currently available protect against dengue
...
Although the virus has been classically associated with
dogs and dog bites, rabies can affect a large number of wild and
domesticated animal species
...
The likelihood of contracting rabies
varies with the type of exposures
...


Clinical Presentation :
•
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•
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•
•
•
•
•
•
•
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•
•

severe fever
headache
malaise
myalgias
easy fatigability
cough
apprehension
anxiety
agitation
irritability
nervousness
insomnia
psychiatric abnormalities
depression

Diagnosis :
The laboratory findings are generally either normal or nonspecific
...


Treatment and Prevention:
Because rabies is virtually 100 percent fatal without intervention,
prevention is critical
...
Pre- and postexposure prophylaxis is also important in
preventing the devastating consequences of this disease
...
The disease is caused by the phleboviruses
that are part of the Bunyaviridae family
...
Of these five

types, two (Sicilian virus and Naples virus) are endemic in the
Middle East
...
sandfly fever is a serious threat, since a large number of
individuals can become infected and ill within a short period of time
...
The female fly transmits the
disease, starting about a week after she acquires the infection from
an infected human host
...
Most natives ac- quire the infection early in life
and remain immune
...

Serologic tests are also avail- able for diagnosis of the infection
...

Prevention centers on avoidance of sandfly bites
...


SINDBIS
Introduction
Sindbis is a vector-borne alphavirus that produces a disease
characterized by fever, rash, and polyarthritis
...
The most recognized member of the
Togaviridae family is the virus that causes rubella
...


Epidemiologic Information
Because of this common vi- ral vector, in the Middle East it is
common to find individuals who are positive for exposure to Sindbis
to also be positive for exposure to West Nile virus
...
Swollen joints do
not show significant fluid accumulation
...
Nonspecific laboratory tests include
mild leukopenia and elevation of acute phase reactants, and the
identification of a rising specific anti- body titer
...

Prevention, as with other arboviruses, centers on decreased
exposure to the potentially infective mosquito through the use of
repellants and the wearing of clothing that covers the body,
particularly when the mosquito population is abundant
...
g
...
Rift Valley fever is most commonly associated with
mosquito-borne epidemics during years of heavy rainfall
...
People get Rift Valley fever from the bites of
mosquitoes (Aedes mcintoshi, Culex pipiens, Eretmapodites
chrysogaster, Aedes caballus, Aedes circumluteolus, Culex theileri)
and possibly other blood-sucking insects that serve as vectors
...
Therefore, increased
risk of infection is seen in farm- ers, veterinarians, and others who
handle infected animals and carcasses
...


Clinical Presentations
•
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•
•

fever and chills
malaise
headache
retroorbital pain
backache
nausea
vomiting

Diagnosis
Rift Valley fever can be diagnosed easily through laboratory testing
...


Treatment and Prevention
Treatment of patients is symptomatic; there are no specific
treatments for Rift Valley fever
...


WEST NILE FEVER
Introduction
West Nile fever is caused by a virus that is part of the Flaviviridae
family
...
The World Health Organization defines
arboviruses (arthropod-borne viruses) as a group as those “which
are maintained in nature principally, or to an important extent,
through biological transmission between susceptible vertebrate
hosts by hematophagous arthropods; they multiply and produce
viremia in the verte- brates, multiply in the tissues of arthropods,
and are passed on to new verte- brates by the bites of arthropods
after a period of extrinsic incubation” (Sanford, 1991)
...
Louis encephalitis, and
tick-borne encephalitis viruses
...

Infection with these viruses does not produce a unique clinical
picture
...

West Nile virus is a mosquito-borne virus found most commonly in
Africa, France, India, Indonesia, the Middle East, and Soviet
countries
...
The bird is the primary host
and the principal vector is Culex univitta- tus
...
Other animal
reservoirs are not part of the virus’s normal life cycle
...
Children experience a nondescript viral illness
with fever that is rarely diagnosed
...
Spread oc- curs

primarily in the summer months when the mosquito population
increases
...
Viral isolation (during infection) or the
identification of a rising specific antibody titer
...
There are
no specific treatments for West Nile fever
...

LEISHMANIAVIRUS

Introduction
Leishmaniavirus is a double-stranded RNA virus that infects some
strains of Leishmania
...
However, in a study of human
biopsy tissues collected in 1996 as part of a drug treatment
program in Cuzco, Peru, viral RNA was identified in two of 11
samples studied by molecular diagnostic techniques

Clinical Presentation
Much more evaluation needs to be completed to understand
whether infection of Leishmania with Leishmaniavirus alters the
pathogenesis of the protozoa in humans
...
However, this diagnostic technique is currently per- formed
only in specialized research laboratories
...


CRIMEAN-CONGO HEMORRHAGIC FEVER
Introduction
Crimean-Congo hemorrhagic fever is caused by a virus that is part
of the Bun- yaviridae family, genus Nairovirus
...

The disease is transmitted from the bite of the Hyalomma tick,
although noso- comial and household transmission to humans has
been observed
...

Epidemiologic Information
The virus has been identified in outbreaks in the Soviet Union,
Bulgaria, Pakistan, Iraq, Dubai, Kuwait, and the United Arab
Emirates
...


Clinical Presentations
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Headaches
Fever and chills
muscle aches sore throat
photophobia

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