Dengue is an arbovirus consisting of 4 serotypes (DEN 1,2,3,4) all
of which can cause severe and fatal disease. After an infection
with one subtype an individual will gain lifelong immunity to that
Dengue infection involves a spectrum of different symptoms, which
range from a non-specific fever, classical dengue fever, dengue
hemorrhagic fever, and dengue shock.
fever may begin suddenly.
are estimated 50-100 million cases of Dengue fever/year. 250-500,000
cases of Dengue hemorrhagic fever worldwide.
deaths are in children 5-15 years.
to travelers is estimated 1/1,000 in countries where it is present
but could be worse in outbreaks.
transmission by mosquito:
Dengue is transmitted by infectious mosquitoes- Aedes egypti which
is a mosquito adapted to city life and typically feeds in early
morning and late afternoon.
Adults lay eggs as floating egg rafts in puddles. These mosquitoes
thrive on small puddles.
Aedes egypti has a tropical and subtropical distribution.
single mosquito will feed many times so that many people could become
infected at the same time.
mosquitoes are found active in the daytime and are found in and
around human habitation.
lay eggs in shallow containers that rainwater has collected in.
the mosquito Ades albopictus has been recognized as a disease causing
Albopictus (Asian Tiger mosquitoes) were recently introduced to
Hawaii and Texas.
the dengue virus is also introduced into these areas as well then
dengue transmission could occur.
mosquito also causes Eastern Equine Encephalitis and Cack Valley
viruses, but not Yellow Fever.
Mild disease Symptoms include high fever, severe headache, and joint
and muscle pain.
vomiting and anorexia may also occur.
A rash may also appear 3-4 days after the onset of fever spreading
from the torso to the arms, legs and face.
Dengue hemorrhagic fever is usually defined as having a rash, haemorrhage
should be checked for evidence of bleeding, their hydration status,
and their blood pressure.
is evidenced by petechiae, purpura, increased bleeding from gums
and increased menstrual flow.
The W.H.O criteria for diagnosis are:
These include fever, bleeding, platelets less than 100,000; and
evidence of ' leaky capillaries'.
that will worsen the severity of dengue include having a prior infection
with one or more of the other 3 serotypes (and how long ago, and
how severe); age; and host genetics.
strain of serotype is also important with the lethality ranked:
complications of dengue are encephalopathy, liver and heart damage;
and gastrointestinal bleeds.
Clinical tests for dengue fever:
CBC- WBC, Hb, and platelets; albumen, liver function tests, urinalysis
(to check for hematuria), and direct tests to look for virus isolation
Blood serology should be taken during the acute phase (less than
5 days after start of fever) to check for acute serology and virus
isolation; and again after 6-21 days to check for convalescent serology
and confirm the diagnosis.
rapid diagnostic test for dengue fever is at present not approved.
the fever starts greater than 2 weeks after the end of travelling
then this is not dengue fever, as dengue will present within 2 weeks.
Differential diagnosis includes influenza, rubella, measles, malaria,
typhoid, leptospirosis, meningococinemia, rickettsia, bacterial
sepsis, and other viral hemorrhagic illnesses.
Treatment for Dengue
Treatment of dengue hemorrhagic fever includes fluids, rest, anti-pyretics
(acetaminophen but no ASA or NSAIDS), and to check blood pressure,
hemoglobin and platelets.
may be treated at home if there is no bleeding and well hydrated.
is warranted if sicker and ICU admission if bleeding.
hemoglobin and platelets are done until afebrile for 1-2 days.
treatments include IV fluids and avoidance of invasive procedures.
and gammaglobulin are unproven treatments.
Personal protection against Dengue:
Because there is no vaccination or specific treatment for dengue
prevention is the best way of managing the possibility of dengue
DEET 20-30%, spray clothing with permethrin, and spray insecticide
long sleeved pants and shirts.
may also decrease risk by spending less time in areas where dengue
areas are the most affected while industrialized or commercial areas
(like beaches, forests, and tennis courts) have less Aedes mosquitoes.
conditioning helps remove mosquitoes.
Prevention of Dengue Fever - destroy mosquito breeding
grounds by eliminating unused containers, stock small fish that
will eat mosquito larvae and vaccines are being developed.
Dengue Fever Links on the internet
Center for Disease Control CDC http://www.cdc.gov/ncidod/dvbid/dengue/
Armchair Medicine (A personal testimony) http://www.armchair.com/info/spira7.html
Medline Plus http://www.nlm.nih.gov/medlineplus/ency/article/001374.htm