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Dengue fever is a relatively common problem in Indonesia and periodically
reaches epidemic proportions in Jakarta and other parts of Indonesia,
usually every 4-5 years. Rarely fatal in fit adults, the patient is often
left debilitated and requires considerable time for convalescence. Dengue
Fever is most common during the rainy season (November - May) as the mosquito
requires clean standing water to reproduce.
Dengue occurs due to infection by a flavivirus which is transmitted
by the bite of the Aedes mosquito. (Unlike malaria, this disease
occurs in greater Jakarta - urban dengue occurs in nearly all tropical
countries).
SYMPTOMS
Certainly in the first stages of illness, dengue fever is difficult
if not impossible to clinically distinguish from the many other possible
causes of similar symptoms and signs.
IN ADULTS:
Following the deposit of the dengue virus in the skin by the bite,
there is a an incubation period of 2 - 14 (usually 4 - 8) days.
Thereafter onset of symptoms is usually abrupt, coinciding with viremia (the virus multiplying in the bloodstream) with chills, headache, backache,
weakness, pain behind the eyes, flushing of the face, muscle and joint
pain, and lassitude. The joint and back pains can be very bad indeed;
hence the older name 'breakbone fever'.
The temperature rapidly rises, often to 40°C (104°F), and there is a low heart rate (compared to the degree of,
and other causes of, high fever). The blood pressure is often low also.
A transient rash which blanches under pressure may be seen during the
first 24 hours of fever.
During the 2nd to 6th day of fever, nausea and
even vomiting may occur, and the patient may develop one or more of the
following; skin hypersensitivity, generalized swelling of regional lymph
nodes, swelling of the palms, changes in taste sensation, loss of appetite,
constipation, anxiety and depression.
Within 2 to 4 days a temporary improvement can occur with a sudden
drop in temperature and subjective improvement - for 24 hours until there
is a second rapid temperature rise. A generalized morbilliform (“measles-like”) rash appears a characteristic rash on the
trunk, limbs, palms and soles especially. (This second febrile phase does
not invariably occur). This rash usually disappears in 1-5 days, the skin
in these areas turns bright red and may peel. The temperature should fall
back to normal and the infectious episode is effectively over.
Epistaxis (“nose bleeds”), petechiae (“red skin
spots”) and purpuric skin lesions (“purple skin spots / bruises”)
can occur at any stage of the disease, varying with age, sex, and type
of dengue virus. Bleeding from the gastrointestinal tract, and excessive
vaginal bleeding if menstruating can also occur, but do not usually occur
in the majority of cases.
IN CHILDREN:
A fever occurs in nearly all dengue infections in children; the other
most common symptoms are a red throat, a (usually mild) runny nose, cough,
and mild gastrointestinal symptoms which of course may present similar
to pharyngitis, influenza, and upper respiratory infections.
The presentation of dengue in the younger child is much less characteristic
than in the older child and adult as above.
CONFIRMING THE DIAGNOSIS
There are no immediately useful tests for dengue fever which are unequivocally
accurate. However the laboratory can be used to aid confirmation of a
clinically suspicious case:
- The white cell count is often low unlike in bacterial causes of
fever.
- The dengue blot test can give both false positive and false negative
results, especially in the first week of the disease.
- The diagnosis will in a large proportion of cases be based on clinical
presentation and a characteristic
drop of platelets in the blood (platelets are often low - normal is
150,000 - 400,000).
Definite confirmation of the diagnosis of dengue infection can be
made by sophisticated tests, but the results are not available for two
weeks or more after the onset of the illness (because two separate blood
samples need to be tested (by the same lab) for dengue antibody levels,
the first as soon as possible after the onset of the illness, the second
10-14 days later).
Convalescence can take weeks, and bed rest and antipyretics and analgesics
are required. An attack produces immunity for a year or more, but only
to the one of the four flavivirus strains responsible for the intial
illness.
DENGUE HAEMORRHAGIC FEVER / DENGUE SHOCK SYNDROME
A rare complication of dengue fever, dengue haemorrhagic fever, can
occur, most often in small children and elderly adults. This can sometimes
be a serious illness. If DHF / DSS occurs it will usually do so by day
3-5 of the fever.
IN CHILDREN
In children, the progression of disease is not always characteristic.
A relatively mild first phase with an abrupt onset of fever, malaise,
vomiting, headache anorexia and cough is succeeded 2-5 days later by weakness
and, sometimes, physical collapse. Frequently, spots appear on the forehead,
arms and legs, along with spontaneous bruises and bleeding from punctures
where blood was taken. The more ill child may breathe rapidly and often
effortfully; the pulse may be weak, rapid, and thready. Almost always
patients have a positive “tourniquet test” (where a tourniquet
i.e. a blood pressure cuff is applied and the skin demonstrates petechiae
and / or bruising).
The WHO criteria for DHF are a platelet count of less than 100,000 and a haematocrit 20% greater then normal. Such children need to
be hospitalized and watched for potential DSS. Such shock can be a mortal
illness and requires rapid and careful in-hospital management with assiduous
correction and replacement of fluid, electrolytes, plasma and sometimes
fresh blood / platelet transfusions. The most useful laboratory test in
suspected DHF is estimation of thrombocytes (platelets) which will be
very low. In contrast to uncomplicated dengue fever the white cell count
is more often high. Mortality ranges from 5 - 30% (in untreated native
populations) and the highest risk is to infants under 1 year.
TREATMENT
There is no specific treatment for the infectious cause - the
dengue virus - in either dengue fever or DHF / DSS. The symptoms can and
should be treated, and in the rare cases of DSS, treatment for shock as
well as a low platelet count is both essential and available - including
fresh blood and / or platelet transfusion -but there is no medicine or
vaccine anywhere available that can act specifically against the virus.
It has been suggested that DHF is more likely if the patient
has previously had an attack of dengue within the last calendar year (generally
within the last 8-12 months), and that the occurrence of DHF relates to
this previous "sensitization". Previous exposure may raise the
incidence of subsequent DHF, presumably (as experiments have shown) by
the antibody elicited in response to the first infection, being capable
of enhancing the infection due to the virus found in the second episode.
Uncontrolled bleeding distinguishes this from uncomplicated dengue
fever. Bleeding can occur from the gums, nose, intestine, or under the
skin as bruises or spots of blood especially under a tourniquet - this
test should be employed if there is any suspicion. The liver is often
enlarged.
TO AVOID GETTING DENGUE YOU MUST AVOID BEING BITTEN
In an epidemic, the emergency control measure is insecticide applied
outside by vehicle-mounted or portable ultra-low-volume generators for
a minimum 2 applications at 10 day intervals. The uncontrolled use of
residual and space insecticides especially where inappropriate and possibly
toxic materials are used, is to be avoided.
Do not allow indiscriminate use of insecticides around work sites
or dwellings unless possible risks of their use are clearly understood.
Know what you are doing and / or what chemical is being used.
PREVENTIVE MEASURES AGAINST MOSQUITOES
All varieties of mosquitoes breed in or near water that is stagnant
or slow moving. The importance of mosquitoes in transmission of disease
makes adequate control of mosquito-breeding sites very important, especially
those close to human habitation.
In the long term community education and participation are necessary
to eliminate mosquito breeding sites, especially those close to human
habitation as mosquitoes usually fly less than one kilometer from where
they are hatched. Over 50 important diseases can be transmitted by the
bite of infected female mosquitoes - among these are malaria, dengue,
Japanese B encephalitis, yellow fever, and a variety of forest and jungle
fevers. Urban mosquitoes breed in any pools of standing water such as
empty tin cans, old tires and water filled tire tracks, coconut shells,
and the saucers under domestic pot plants. Rural mosquitoes breed in rice
paddies, stagnant ponds and slow moving streams. So destroy mosquitoes
and their larvae (young) by:
- Clearing the neighborhood of ponds and pits.
- Covering all water containers and any objects that can trap rain
water (tires, pots, etc.). Invert any used buckets and containers that
can trap water, and ensure roof gutters are not clogged.
- Filling in or draining areas of stagnant water except for swimming
pools and ornamental pools if they are aerated by a pump or fountain
or similar.
- Use of larvicides or mosquito larvae-eating fish in waters that
cannot be drained.
- In endemic mosquito areas, insist owners, employers and landlords
supply screens on doors and windows and mosquito nets on beds.
- Changing water in flower pots once a week and washing them thoroughly.
Do not let plants stand in trays containing water. Scrub trays weekly
to get rid of any mosquito eggs.
- Fill tree holes with sand or cement and plug the tops of bamboo
fences.
- Remove and destroy old tires.
- Installing mosquito screens on doors and windows and mosquito
nets on beds.
- Avoid the uncontrolled use of residual and space insecticides,
and the use of toxic materials. Do not allow indiscriminate use of insecticides
unless possible risks of their use are clearly understood. Know what
you are doing and / or what chemical is being used.
Personal protective measures can greatly reduce the risk of being
bitten. The use of mosquito deterrents in bedrooms is effective to reduce
the number of mosquitoes in the room, but it does not prevent mosquito
bites all together. The chemical deterrent is released through an electronically
heated impregnated pad or gel, and its effectiveness depends largely on
the size and ventilation of the room.
Other personal protection methods include:
- Use of mosquito coils and "knockdown spray" (containing
pyrethoids)
- spray insecticide in cool dark places where mosquitoes lurk.
- Avoid use of dark colored clothing, perfumes and colognes
in the
evening and at night, as all these attract mosquitoes.
- Use of an effective mosquito repellent on exposed skin and
clothing.
DEET (diethylmethylbenzamide) is an effective safe component of good
repellents. The actual concentration of DEET varies widely between
different manufacturers, and can be as high as 90% (too high for safety).
Choose a repellent with between 30-45% DEET and take the following
precautions against adverse reactions:
a. apply sparingly and only to exposed skin
b. never apply high concentrations to skin (use those for clothing)
c. do not inhale / swallow repellent or get in eyes or mucous membranes
d. do not apply to hands that may touch eyes or mouth
e. do not apply to wounds, rashes, or abrasions
f. wash repellent off after coming indoors to stay
g. if skin starts to burn, wash repellent off and seek medical advice
DEET-based repellents should last for up to 4 hours.
TREATMENT OF MOSQUITO NETS WITH PERMETHRIN
Correct use of mosquito nets is essential if accommodation is not
air- conditioned. For added protection of up to 3 months or longer, a
safe and effective treatment which can be used on curtains and drapes
as well as mosquito nets is to soak the nets in 1% solution of PERMETHRIN
(or other repellent /insecticide). If resident in a malaria area, curtains
can be treated in a similar manner.
The chemical is available from SHELL as a 20% emulsifiable concentrate
(EC) and from ICI as 'AMBUSH' 50% EC. The application rate is 0.5g/sqm
of net. Therefore a net of 6 sqm using 25% permethrin EC will require
6m x 0.5g/sqm = 3g permethrin. This is contained in 3g x 100 / 20 = 15ml
of 20% EC or 3gx100 / 50 = 6ml of 50%. Experience has found that approximately
150ml of water is required as a wetting agent.
Suggested method:
1. Mix EC with water in measured quantities
2. Ruffle the net and place in a stout plastic sack
3. Pour the permethrin solution over the net in the plastic bag
4. Hold the plastic bag at the neck and work the bag to ensure the permethrin
solution is applied over the entire surface of the net.
5. Take out the damp net and place it on top of the plastic bag to dry.
6. If there is residual solution in the bag, repeat 2, 4 and 5 again.
A mosquito net treated in this way is effective for up to three months.
We trust this information will assist you to make correct choices
for your health and welfare. However it is not, and is not intended to
be, a substitute for personalized medical advice from your medical advisor.
Our appreciation to Dr. Uwe Stocker and Dr. Rene de Jongh of International
SOS, An AEA Company who has contributed this article in response
to a growing health threat faced by expatriates in Indonesia.
Additional Links on Dengue Fever:
US Center
for Disease Control, Atlanta, Georgia
Traveler's
Info on Dengue
World Health Organization
If you have medical-related questions about living
in Indonesia to ask of medical professionals, see Ask
the Experts.
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