WHAT YOU SHOULD
KNOW ABOUT DENGUE?
Q. What is dengue?
A. Dengue (pronounced den'
gee) is a disease caused by any one of four closely related dengue viruses (DENV
1, DENV 2, DENV 3, or DENV 4). The viruses are transmitted to humans by the
bite of an infected mosquito. In the Western Hemisphere, the Aedes
aegypti mosquito is the most
important transmitter or vector of dengue viruses, although a 2001 outbreak in
Hawaii was transmitted by Aedes
albopictus. It is estimated that there are over 100 million cases of
dengue worldwide each year.
Q.What is dengue hemorrhagic fever (DHF)?
A.DHF is a more severe form of dengue infection. It can be fatal if
unrecognized and not properly treated in a timely manner. DHF is caused by
infection with the same viruses that cause dengue fever. With good medical
management, mortality due to DHF can be less than 1%.
Q.How are dengue and dengue
hemorrhagic fever (DHF) spread?
A. Dengue is transmitted
to people by the bite of an Aedes mosquito
that is infected with a dengue virus. The mosquito becomes infected with
dengue virus when it bites a person who has dengue virus in their blood. The
person can either have symptoms of dengue fever or DHF, or they may have no
symptoms. After about one week, the mosquito can then transmit the virus while
biting a healthy person. Dengue cannot be spread directly from person to
Q.What are the symptoms of the
A. The principal symptoms
of dengue fever are high fever, severe headache, severe pain behind the eyes,
joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums
bleed, easy bruising). Generally, younger children and those with their first
dengue infection have a milder illness than older children and adults.
Dengue hemorrhagic fever is characterized by a fever that lasts from 2 to 7
days, with general signs and symptoms consistent with dengue fever. When the
fever declines, symptoms including persistent vomiting, severe abdominal pain,
and difficulty breathing, may develop. This marks the beginning of a 24- to
48-hour period when the smallest blood vessels (capillaries) become
excessively permeable (“leaky”), allowing the fluid component to escape from
the blood vessels into the peritoneum (causing ascites) and pleural cavity
(leading to pleural effusions). This may lead to failure of the circulatory
system and shock, followed by death, if circulatory failure is not corrected.
In addition, the patient with DHF has a low platelet count and hemorrhagic
manifestations, tendency to bruise easily or other types of skin hemorrhages,
bleeding nose or gums, and possibly internal bleeding.
Q.What is the treatment for dengue?
A. There is no specific
medication for treatment of a dengue infection. Persons who think they have
dengue should use analgesics (pain relievers) with acetaminophen and avoid
those containing aspirin. They should also rest, drink plenty of fluids, and
consult a physician. If they feel worse (e.g., develop vomiting and severe
abdominal pain) in the first 24 hours after the fever declines, they should go
immediately to the hospital for evaluation.
Q.Is there an effective treatment
for dengue hemorrhagic fever (DHF)?
A. As with dengue fever,
there is no specific medication for DHF. It can however be effectively treated
by fluid replacement therapy if an early clinical diagnosis is made. DHF
management frequently requires hospitalization. Physicians who suspect that a
patient has DHF may want to consult the Dengue Branch at CDC, for more
Q. Where can outbreaks of dengue
A.Outbreaks of dengue occur primarily in areas where Ae.
aegypti (sometimes also Ae.
albopictus) mosquitoes live. This includes most tropical urban areas of
the world. Dengue viruses may be introduced into areas by travelers who become
infected while visiting other areas of the tropics where dengue commonly
Q.What can be done to reduce the
risk of acquiring dengue?
A.There is no vaccine for preventing dengue. The best preventive
measure for residents living in areas infested with Ae.
aegypti is to eliminate the
places where the mosquito lays her eggs, primarily artificial containers that
Items that collect rainwater or to store water (for example, plastic
containers, 55-gallon drums, buckets, or used automobile tires) should be
covered or properly discarded. Pet and animal watering containers and vases
with fresh flowers should be emptied and cleaned (to remove eggs) at least
once a week. This will eliminate the mosquito eggs and larvae and reduce the
number of mosquitoes present in these areas.
Using air conditioning or window and door screens reduces the risk of
mosquitoes coming indoors. Proper application of mosquito repellents
containing 20% to 30% DEET as the active ingredient on exposed skin and
clothing decreases the risk of being bitten by mosquitoes. The risk of dengue
infection for international travelers appears to be small. There is increased
risk if an epidemic is in progress or visitors are in housing without air
conditioning or screened windows and doors.
Q.How can we prevent epidemics of
dengue hemorrhagic fever (DHF)?
A.The emphasis for dengue prevention is on sustainable,
community-based, integrated mosquito control, with limited reliance on
insecticides (chemical larvicides, and adulticides). Preventing epidemic
disease requires a coordinated community effort to increase awareness about
dengue fever/DHF, how to recognize it, and how to control the mosquito that
transmits it. Residents are responsible for keeping their yards and patios
free of standing water where mosquitoes can be produced.