and Dengue Hemorrhagic Fever
is caused by any one of four closely related viruses that
do not provide cross-protective immunity; a person can be
infected as many as four times, once with each serotype.
Dengue viruses are transmitted from person to person by
the Aedes aegypti mosquito in the domestic environment.
Classic dengue fever is characterised by acute onset of
high fever, frontal headache, retro-orbital pain, myalgias,
arthralgias, nausea, vomiting, and often a maculopapular
rash. In addition, many patients may notice a change in
taste sensation. Symptoms tend to be milder in children
than in adults, and the illness may be clinically indistinguishable
from influenza, measles, or rubella. The disease manifestations
can range in intensity from inapparent illness to the symptoms
described. The acute phase of up to one week is followed
by a one- to two-week period of convalescence which is characterised
by weakness, malaise and anorexia. Treatment emphasises
relief of these symptoms.
Hemorrhagic Fever/Dengue Shock Syndrome
During the first few days of illness, dengue hemorrhagic
fever (DHF), a severe and sometimes fatal form of dengue,
may resemble classic dengue or other viral syndromes. Patients
with DHF may have fever lasting two to seven days and a
variety of nonspecific signs and symptoms. At about the
time the fever begins to subside, the patient may become
restless or lethargic, show signs of circulatory failure,
and experience hemorrhagic manifestations. The most common
of these manifestations are skin hemorrhages but may also
include epistaxis, bleeding gums, hematemesis, and melena.
The condition of these patients may rapidly evolve into
dengue shock syndrome (DSS), which, if not immediately corrected,
can lead to profound shock and death. Advance warning signs
of DSS include severe abdominal pain, protracted vomiting,
marked change in temperature (from fever to hypothermia),
or change in mental status (irritability or obtundation).
Early signs of DSS include restlessness, cold clammy skin,
rapid weak pulse, and narrowing of pulse pressure and/or
hypotension. Fatality rates among those with DSS may be
as high as 44 per cent. DHF/DSS can occur in children and
Fortunately, DHF/DSS can be effectively managed by fluid
replacement therapy, and if diagnosed early, fatality rates
can be kept below one per cent. Once a person acquires dengue,
the key to survival is early diagnosis and appropriate treatment.
the pain and fever, patients suspected of having a dengue
infection should be given acetaminophen preparations rather
than aspirin, because the anticoagulant effects of aspirin
may aggravate the bleeding tendency associated with some
A dengue epidemic requires the presence of 1) the vector
mosquito (Aedes aegypti), 2) the virus, and 3)
a large number of susceptible human hosts. Outbreaks may
be explosive or progressive, depending on the density and
susceptibility of the vector, the strain of dengue virus,
the immune level in the human population, and the amount
of vector-human contact. Dengue should be considered as
the possible etiology where influenza, rubella, or measles
is suspected in a dengue-receptive area.
epidemics of dengue and DHF is difficult but, as noted previously,
the frequency of epidemic disease has increased significantly
in the past 20 years. This is likely due to increased air
travel, which provides the ideal mechanism for dengue viruses
to be carried around the world into areas where Aedes
aegypti occurs. This rapid movement of travelers around
the world is also the reason that dengue infections may
be detected in virtually any part of the world.
Source: Yahoo Health
(R) thedailystar.net 2004