DENGUE IN ENGLISH
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DENGUE-
Dengue is a viral disease
caused by infection with dengue virus (an arbovirus) and transmitted to man by
infected aedes mosquito.
Dengue fever (DF)
and its severe forms dengue haemorrhagic fever (DHF) and dengue shock syndrome
(DSS) have become major international public health concerns. Dengue is endemic
in more than 100 countries. In India, the risk of dengue has shown an increase
in recent years due to rapid urbanization, lifestyle changes and deficient
water management
CAUSATIVE AGENT-
The dengue is
caused by a virus Which is form genus flavivirus. based on antigenic and biological
characteristics, here are four virus serotypes which are designated as DENV-1,
DENV-2, DENV-3 and DENV-4. All four serotypes are equally responsible for
epidemics of dengue fever (with or without DHF) with varying degree of
severity.
MODE OF
TRANSMISSION –
VECTOR
TRANSMISSION:
Dengue is
transmitted by the bite of aedes aegypti and aedes albopictus mosquitoes. The
Aedes mosquito becomes infective by feeding on a patient from the day before
onset to the 5th day of illness. After an extrinsic incubation period of 8 to
10 days, the mosquito becomes infective, and is able to transmit the infection.
Once the mosquito becomes infective, it remains so for life.
The population of
Aedes aegypti fluctuates with rainfall and water storage. Its life span
is influenced by temperature and humidity, survives best between 16°C-30°C and
a relative humidity of 60-80 per cent. It breeds even in the containers in and
around the houses. The mosquito is recognized by white markings on it’s body
SIGN AND S YMPTOMS-
Dengue virus
infection may be asymptomatic or may have following symptoms-
Fever with our
without maculopapular rash.
Chills and high
fever,
Intense headache,
Muscle and joint
pains.
Retro-orbital pain,
particularly on eye movements or eye pressure and photophobia develops. Other
common symptoms include extreme weakness, anorexia, constipation, altered taste
sensation, colicky pain and abdominal tenderness, pain in inguinal region, sore
throat and general depression. Fever is usually between 39°C and 40°C.
Fever lasts for
about 5 days, rarely more than 7 days after which recovery is usually complete.
Complications-
1. Dengue
haemorrhagic fever
Dengue haemorrhagic
fever (DHF) is a severe form of dengue fever.
DHF have three
stage-
1.Febrile
phase- In this stage there is high fever
accompanied by facial flushing and headache. Anorexia, vomiting, epigastric
discomfort, tenderness at the right costal margin and generalized abdominal
pain are common. Occasionally, the temperature may be 40°C to 41°C and febrile
convulsions may occur particularly in infants.
2. Critical
phase- this phase starts usually on
third dasy of illness. There is an increase in capillary permeability. The
period of clinically significant plasma leakage usually lasts 24-48 hours. The degree of plasma leakage varies.
Pleural effusion mostly on right side. and ascites may be clinically detectable
depending on the degree of plasma leakage and the volume of fluid therapy.
Severe haemorrhage may occur into internal organs.
3. Recovery
phase- if the patient is able to survive
the critical phase than recovery phase may start. A gradual reabsorption of extravascular
compartment fluid takes place. General well-being improves, appetite returns,
gastrointestinal symptoms improves, blood pressure stabilizes and diuresis
occurs. Some patients may experience
generalized pruritus and bradycardia.
2. Dengue shock
syndrome
Dengue shock
syndrome (DSS) is a very severe form of dengue. In DSS plasma leakage that may
lead to shock along with severe bleeding and severe organ impairment. The
patient may have hypoxia and acidosis, can lead to multiple organ failure and death
may occur.
DIAGNOSTIC INVESTIGATIONS-
1. RTPCR- The dengue virus
consists of RNA, that can be detected by reverse transcriptase polymerase chain
reaction (RT -PCR) from blood sample of the patient.
2. ELISA - ELISA and dot blot assays directed against the
envelop/membrane (EM) antigens and nonstructural protein 1 (NSl) can be
detected in both patients with primary and secondary dengue infection
3. Rapid diagnostic
test (RDT)- A number of commercial
rapid format serological test-kits for anti-dengue IgM and IgG antibodies have
become available in the market. These kits provide result only in 15 minutes.
4. Platelet count-
blood platelet count is also important in determinging the severity of disease
and need for platlet transfusion.
TREATMENT-
Treatment depends
upon the severity of dengue. For normal dengue fever only symptomatic treatment
is needed along with adequate hydration. Encourage intake of oral rehydration
solution (ORS), fruit juice and other fluids containing electrolytes and sugar
to replace losses from fever and vomiting. Paracetamol is given to control the
fever.
For DHF and DSS the
patient should be admitted in the hospital. Close observation is must to detect
shock at early stage. Fever and dehydration management should be continue
paracetamol, ORS and other oral fluids. IV fluid may be administered if the
patient is vomiting persistently or refusing to feed. Plasma expanders or Blood
/ platelet transfusion may be given as per need.
PREVENTION-
Ø Health education regarding prevention and control of
dengue is very important step to prevent it.
Ø Control of mosquitos is another very important measure to
prevent malaria.
Ø Insecticide-treated mosquito nets (ITNs) are the most
universally useful measure for the prevention of dengue
Ø Control of larval stages by elimination of mosquito
breeding sites, for example by filling and draining the water collection site.
Ø The use of larvivorous fish especially Gambusia is well
known in mosquito control
Ø General cleanliness is also helpful in eliminating
breeding places of aedes mosquito.
Ø Isolation of patient and preventing him from mosquito
bite until fever subsites also help in preventing further transmission of
dengue.
Ø Vector control also involves the application of
pesticides in the form of fog or mist using special equipment. The
ultra-low-volume method of pesticide dispersion by air or by ground equipment
has proved to be effective.
Ø Wear long sleeved clothing and long trousers when going
out to protect ourselves from mosquito bite.
Ø Apply mosquito repellent cream to exposed skin.
Ø Use screens/net over doors and windows; if no screens are
available, close windows and doors at night.
Ø Use anti mosquito coil or electric mosquito killer to
reduce number of vector.
