EPIDEMIOLOGY OF YELLOW FEVER AND ITS PREVENTION AND.pptx
Dengue
1. DENGUE
B Y
M E L C H I Z E D E K M I C H A E L J I M B A I
T R A I N E E M E D I C A L L A B O R A T O R Y T E C H N O L O G Y
A T
H O S P I T A L K A J A N G
2. Objective
Distribution
Epedimiology
Statistic
What is Dengue
Dengue clinical Symptoms
Sign and symptoms
Vector of Dengue
Transmision of Dengue
Laboratory Diagnosis
Prevention
3. Distribution
Endemic in more than
100 tropical and
subtropical countries
Pandemic began in
South East Asia after
WW II with
subsequent global
spread
Several epidemics
since 1980s
Distribution is
comparable to malaria
4. Epidemiology
In India first outbreak of dengue was recorded in 1812
A double peak hemorrhagic fever epidemic occurred in
India for the first time in Calcutta between July 1963 &
March 1964
In New Delhi, outbreaks of dengue fever reported in
1967,1970,1982, &1996
7. What is Dengue
• Dengue is a viral disease
• It is transmitted by the infective bite of female Aedes Aegypti mosquito
• Man develops disease after 5-6 days of being bitten by an infective mosquito
• It occurs in two forms: Dengue Fever and Dengue Haemorrhagic Fever(DHF)
• Dengue Fever is a severe, flu-like illness (Influenza)
• Dengue Haemorrhagic Fever (DHF) is a more severe form of
disease, which may cause death
• Person suspected of having dengue fever or DHF must see a doctor at once
8. Sign and Symptoms of Dengue fever
• Abrupt onset of high fever
• Severe frontal headache
• Pain behind the eyes which worsens with eye movement
• Muscle and joint pains
• Loss of sense of taste and appetite
• Measles-like rash over chest and upper limbs
• Nausea and vomiting
9. Vector of Dengue
Dengue is transmitted by the bite of female Aedes mosquito.
Female Aedes mosquito deposits eggs singly on damp surfaces just above the
water line. Under optimal conditions the life cycle of aquatic stage of Ae.
Aegypti (the time taken from hatching to adult emergence) can be as short as
seven days
The eggs can survive one year without water. At low temperature, however, it
may take several weeks to emerge. Ae. aegypti has an average adult survival
of fifteen days. During the rainy season, when survival is longer, the risk of
virus transmission is greater. It is a day time feeder and can fly up to a limited
distance of 400 meters. To get one full blood meal the mosquito has to feed on
several persons, infecting all of them.
10. Transmission of Dengue
1.The virus is inoculated into humans with the
mosquito saliva.
2.The virus localizes and replicates in various
target organs, for example, local lymph nodes and
the liver.
3.The virus is then released from these tissues and
spreads through the blood to infect white blood
cells and other lymphatic tissues.
4.The virus is then released from these tissues and
circulates in the blood.
5.The mosquito ingests blood containing the virus.
6.The virus replicates in the mosquito midgut, the
ovaries, nerve tissue and fat body. It then escapes
into the body cavity, and later infects the salivary
glands.
7.The virus replicates in the salivary glands and
when the mosquito bites another human, the cycle
continues.
12. Dengue IgM ELISA : Principle
Serum antibodies of the IgM class, when present, combine with anti-
human IgM antibodies attached to the polysterene surface of the
microwell test strips, a concentrated pool of dengue 1-4 antigens is
diluted to the correct working volume with antigen diluent. The
antigens are produced using an insect cell expression system
immnopurified utlising a specific monoclonal antibody ( MAB) is added
to the diluted antigen which allows the formation of antigen – MAB
complexes. Risidual serum is removed from the assay plate . After
incubation, the microwell are washed and a colourless substrate system
tetramethlbenzidine / hydrogen peroxide ( TMB chromogen ) is added
the substrate is hydrolysed by the enzyme and chromogen changes to a
blue colour. After stopping , the reaction with acid the TMB becomes
yellow and the colour development is indicative of the presence of anti-
dengue IgM antibodies in the test sample.
13. Dengue rapid test IgG / IgM
Detect the presence of antibodies to the Dengue virus. This test is
the newer generation lateral flow immunochromatographic type
assay. The test can be used either with serum or whole blood and
employs the use of an antibody binding protein conjugated to a
colloidal gold particle and a unique combination of Dengue antigens
immobilized on the membrane.
Once the sample is added to the test cassette along with the
diluents, the mixture passes through the antibody binding/gold
complex, which then binds the immunoglobulins in the sample. As
this complex passes over the immobilized antigens on the
membrane, if any antibodies to Dengue (IgG or IgM) are present,
the antigens capture them in turn. This produces a pink/purple
band in the T (Test) zone of the test strip. The remaining complex
continues to migrate to a control area in the test strip and produces
a pink/purple band in the C area. This control band indicates that
the test has been performed properly.
14. Dengue NS1 Ag
The Dengue NS1 Detect Rapid Test is a qualitative, membrane
based immunoassay for the detection of NS1 antigen in human
serum. The rapid test membrane is pre-coated with a NS1 specific
antibody on the test line region and utilizes a separate control to
assure assay flow and performance. During testing, the test sample
is added directly to the sample region and the test is placed into a
well containing 3 drops of buffer.
The buffer and serum mix and interact with NS1-specific
monoclonal antibodies conjugated to gold nanoparticles. The
solution migrates upward on the membrane (via capillary action) to
react with the anti-NS1 antibody on the membrane. If NS1 antigen is
present, a red line will appear at the test line. The red line at the
control region should always appear if the assay is performed
correctly. The presence of this red line verifies that proper flow has
occurred and catastrophic failure of the conjugate has not occurred.
The entire procedure takes approximately 30 minutes.
16. Prevention
Using insect repellent to avoid being bitten,
especially around dawn and dusk – products containing N-
diethylmetatoluamide (DEET) are effective, but products containing
this ingredient should not be used in babies younger than two
months and in lower concentrations in younger children (20-30%
DEET)
wearing loose-fitting but protective clothing – mosquitoes
are able to bite through tight-fitting clothes; trousers, long-sleeved
shirts, and socks and shoes (not sandals) are ideal
sleeping under a mosquito net to avoid being bitten at night
be aware of your environment – mosquitoes that cause dengue
breed in standing water in crowded urban environments; this can
range from communal toilets to water that gathers inside a stack of
old tyres
17. Preventing dengue
There is no vaccine to prevent dengue. The best way to
prevent getting the disease is to avoid being bitten by an
infected mosquito.
When there is a severe symptoms immediately go for
laboratory diagnosis for early detection
