What is dengue
fever? What is dengue hemorrhagic fever?
Dengue fever is a flu-like illness spread by the bite of an
infected mosquito.
Dengue hemorrhagic fever is a severe, often fatal, complication of
dengue fever.
What is the
infectious agent that causes dengue?
Dengue and dengue hemorrhagic fever are caused by any of the dengue
family of viruses. Infection with one virus does not protect a
person against infection with another.
How is dengue
spread?
Dengue is spread by the bite of an Aedes mosquito. The mosquito
transmits the disease by biting an infected person and then biting
someone else.
Where is dengue
found?
Dengue viruses occur in most tropical areas of the world. Dengue is
common in Africa, Asia, the Pacific, Australia, and the Americas.
It is widespread in the Caribbean basin. Dengue is most common in
cities but can be found in rural areas. It is rarely found in
mountainous areas above 4,000 feet.
The mosquitoes that transmit dengue live among humans and breed in
discarded tires, flower pots, old oil drums, and water storage
containers close to human dwellings. Unlike the mosquitoes that
cause malaria, dengue mosquitoes bite during the day.
What are the
signs and symptoms of dengue fever and dengue hemorrhagic
fever?
Dengue fever usually starts suddenly with a high fever, rash,
severe headache, pain behind the eyes, and muscle and joint pain.
The severity of the joint pain has given dengue the name "breakbone
fever." Nausea, vomiting, and loss of appetite are common. A rash
usually appears 3 to 4 days after the start of the fever. The
illness can last up to 10 days, but complete recovery can take as
long as a month. Older children and adults are usually sicker than
young children.
Most dengue infections result in relatively mild illness, but some
can progress to dengue hemorrhagic fever. With dengue hemorrhagic
fever, the blood vessels start to leak and cause bleeding from the
nose, mouth, and gums. Bruising can be a sign of bleeding inside
the body. Without prompt treatment, the blood vessels can collapse,
causing shock (dengue shock syndrome). Dengue hemorrhagic fever is
fatal in about 5 percent of cases, mostly among children and young
adults.
How soon after
exposure do symptoms appear?
The time between the bite of a mosquito carrying dengue virus and
the start of symptoms averages 4 to 6 days, with a range of 3 to 14
days. An infected person cannot spread the infection to other
persons but can be a source of dengue virus for mosquitoes for
about 6 days.
How is dengue
diagnosed?
Dengue is diagnosed by a blood test.
Who is at risk
for dengue?
Anyone who is bitten by an infected mosquito can get dengue fever.
Risk factors for dengue hemorrhagic fever include a person's age
and immune status, as well as the type of infecting virus. Persons
who were previously infected with one or more types of dengue virus
are thought to be at greater risk for developing dengue hemorrhagic
fever if infected again.
What is the
treatment for dengue and dengue hemorrhagic
fever?
There is no specific treatment for dengue. Persons with dengue
fever should rest and drink plenty of fluids. 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.
How common is
dengue?
In tropical countries around the world, dengue is one of the most
common viral diseases spread to humans by mosquitoes. Tens of
millions of cases of dengue fever and up to hundreds of thousands
of cases of dengue hemorrhagic fever occur each year.
In the United States, approximately 100 cases of dengue are
reported each year in travelers returning from tropical areas. Many
more cases probably go unreported. A few persons have become
infected with dengue while living in the United States. Aedes
mosquitoes are found in Texas, Florida, and other southern states,
and locally acquired dengue has been reported three times since
1980 in southern Texas.
Is dengue an
emerging infectious disease?
Yes. All types of dengue virus are re-emerging worldwide and
causing larger and more frequent epidemics, especially in cities in
the tropics. The emergence of dengue as a major public health
problem has been most dramatic in the western hemisphere. Dengue
fever has reached epidemic levels in Central America and is
threatening the United States.
Several factors are contributing to the resurgence of dengue
fever:
* No effective mosquito control efforts are underway in most
countries with dengue.
* Public health systems to detect and control epidemics are
deteriorating around the world.
* Rapid growth of cities in tropical countries has led to
overcrowding, urban decay, and substandard sanitation, allowing
more mosquitoes to live closer to more people.
* The increase in non-biodegradable plastic packaging and discarded
tires is creating new breeding sites for mosquitoes.
* Increased jet air travel is helping people infected with dengue
viruses to move easily from city to city.
Dengue hemorrhagic fever is also on the rise. Persons who have been
infected with one or more forms of dengue virus are at greater risk
for the more severe disease. With the increase in all types of
virus, the occurrence of dengue hemorrhagic fever becomes more
likely.
