Dengue Fever
Dengue fever (DF), a benign acute febrile syndrome, has been called the most vital
mosquito-transmitted viral disease. It is caused by one
of four closely related virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the
genus Flavivirus. Each serotype is antigenically
distinct, so there is no cross-protection, and epidemics caused by
multiple serotypes (hyperendemicity) can occur. The infectious disease is transmitted to
humans by the bite of mosquitoes, most commonly Aedes aegypti. Dengue
disease is sometimes called break-bone fever because it causes severe
joint and muscle pain that feels like bones are breaking.
In some cases of dengue, the virus may cause increased vascular permeability
that leads to a bleeding diathesis (unusual susceptibility to bleeding) or disseminated intravascular coagulation
(clots) (DIC)
known as dengue hemorrhagic fever (DHF). DHF is characterised by hemorrhage and shock called dengue shock syndrome (DSS).
The first outbreak of
Dengue fever epidemics occurred in 1779-1780 in Asia, Africa, and North America.
Its viral etiology and mode of transmission through mosquitoes were
not established until the early 20th century. A pandemic
of dengue began in Southeast Asia in 1950s
after World War II and has
spread around the globe since then. By 1975, this mosquito-borne
disease had become a
frequent cause of hospitalization and child mortality in several Asian
and South American countries.
During the past few decades, epidemics of dengue fever are causing concern in
several South-East Asian countries including India. In India, the dengue virus was first isolated in 1945. Delhi had outbreaks of
dengue virus infection due to different dengue virus types in 1967, 1970, 1982
and 1988. During these epidemics no cases of DHF/DSS were reported except some
cases in 1988. In 1996, a major outbreak of dengue hemorrhagic fever was
reported in Delhi.
Signs & Symptoms
Dengue infection can cause a spectrum of illness ranging from mild,
undifferentiated fever often to
104-105 degrees Fahrenheit. There may be severe headache, retro-orbital
(behind the eye) pain, joint
and muscle pains. A
flat, bright red rash
may appear first on the lower limbs and the chest and it spreads
to cover most of the body early during the fever. A second
rash, measles-like in appearance, appears later in the disease. There may
also be gastritis
with some combination of associated abdominal pain, nausea,
vomiting or
diarrhea. Infected
people may have increased skin sensitivity and are very uncomfortable. Some
cases develop much milder symptoms, which can, when no rash is present, be
misdiagnosed as a flu or other viral infection. Generally, younger children
have a milder illness than older children and adults. The classic dengue fever lasts about six to seven days,
with a smaller peak of fever at the trailing end of the fever. Dengue fever should not
be confused with Dengue hemorrhagic fever (DHF), which is a separate disease and
frequently fatal.
The symptoms of the deadly complicated Dengue Haemorrhagic Fever (DHF) includes
bleeding from the nose, gums, or under the skin, causing purplish bruises, thrombocytopenia
(reduced platelet count) and plasma leakage. In Dengue Shock Syndrome (DSS) all the above
signs will appear plus circulatory failure, hypotension for age
and low pulse pressure. DHF and DSS are potentially deadly but patients with
early diagnosis and appropriate therapy can recover. DHF requires continuous
monitoring of vital signs and urine output. DSS is a medical emergency that
requires intensive care unit hospitalisation
The increase in dengue mortality is considered
to be a reflection of the increase in the proportion of DF patients who develop
DHF/DSS.
Treatment
Once a person acquires dengue, the key to survival is early diagnosis and
appropriate treatment. The mainstay of treatment is supportive therapy. Risk
factors for dengue hemorrhagic fever include age, immune status, as well as the
type of infecting virus. Persons who were previously infected with one or more
types of dengue virus, if infected again, are thought to be at greater risk for
developing DHF.
There is no specific treatment for dengue. Patients must take rest, drink
plenty of fluids and are encouraged to
keep up oral intake, especially of oral fluids. If they are unable to
maintain oral intake, supplementation with intravenous
fluids may be necessary to prevent dehydration and significant hemoconcentration
(decrease of the fluid content of the blood, with resulting increase in its
concentration). They should be kept away from mosquitoes for the protection of
others. Dengue hemorrhagic fever is treated by replacing lost fluids. Some
patients need transfusions to control bleeding.
.
Prevention
The best way to prevent dengue fever is to
take special precautions to avoid contact with mosquitoes.
Using personal
protection like mosquito repellents on skin and clothing, wearing long-sleeved
shirts and long pants etc will help to prevent mosquito bites. Mosquito abatement programs
may reduce the risk of infection, but vaccination is the only sure method of
prevention.
Eliminate mosquito
breeding sites around homes. Discard items like buckets, tyres, food cans etc
that can collect rain or run-off water. Regularly change the water in outdoor
bird baths and pet and animal water containers.
|
