dengue presentation final by dr.sohail sarwar
TRANSCRIPT
DENGUEMuhammad SOHAIL
SARWARUNIVERSITY OF LHR
Introduction to Dengue
Dengue is a mosquito-borne infection that in recent decades has become a major international public health concern. Dengue is found in tropical and sub-tropical regions around the world, predominantly in urban and semi-urban areas.
It is caused by a virus which is transmitted to the humans by mosquito known as ”Aedes aegypti & Aedes albopictus”
Dengue According to the World Health Organization (WHO), Dengue is a mosquito-borne infection that causes a severe flu-like illness, and sometimes a potentially lethal complication called dengue hemorrhagic fever. The incidence of dengue has grown dramatically around the world in recent decades. Some 2.5 billion people – two fifths of the world's population – are now at risk from dengue. WHO currently estimates there may be 50 million dengue infections worldwide every year.
The causative agent
Dengue Virus
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Introduction to Dengue Virus Dengue virus is know as DENV. DENV is an single stranded RNA positive-strand virus of the family Flaviviridae, genus Flavivirus. DENV causes a wide range of diseases in humans, from a self limited Dengue Fever (DF) to a life-threatening syndrome called Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS)
There are four antigenically different serotypes of the virus: a.DENV-1 b.DENV-2 c.DENV-3 d.DENV-4
The vector
Aedes aegypti and Aedes albopictus
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The Mozzies
3,500 mosquito species
Culex Anopheles Aedes
West Nile
Virus
MalariaYellow Fever,
Dengue
Question
What does “aedes” mean?
“Unpleasant” (Greek) by Meigen in 1818
AEDES AEGYPTI Egyptian tiger
mosquito Origin: Africa Primary vector for:
Yellow fever Dengue fever
Prefers to breed in water storage containers (in and out)
Day biter humans
AEDES ALBOPICTUS Asian Tiger mosquito Origin: Africa/S.E.
Asia Vector for:
Same as aegypti Prefers to breed in
trash (out) Outdoor day biter
humans, livestock, amphibians, reptiles, and birds
Life Cycle
All in all, it takes 8-10 days.
Two phases: terrestrial and aquatic
Eggs are resistant to environmental stress.
Eggs larva (feeder) in presence of water
Larva pupa (non-feeder)
Pupa young adult (still water)
Characteristics of theAedes Mosquito
One distinct physical feature – black and white stripes on its body and legs.
Bites during the day.
Lays its eggs in clean, stagnant water
Only the female Aedes mosquito feeds on blood. This is because they need the protein found in blood to produce eggs. Male mosquitoes feed only on plant nectar.
On average, a female Aedes mosquito can lay about 300 eggs during her life span of 14 to 21 days.
How Do Aedes Mosquitoes Transmit Diseases...
Mosquito bites and sucks blood containing the virus from an infected person.
Virus is carried in its body.
And passes the virus to healthy people when it bites them.
Feeding
Mosquitoes sense the presence of: Genetics – 85% Chemicals
(respiratory, skin) Carbon dioxide (activity,
using candle) Lactic acid (exercise,
after eating salty foods, high-potassium)
Steroids Uric acid Cholesterol
Body temperature Dark-colored
materials clothing's, garbage
cans Movement Floral/fruity
fragrances Moisture
Breeding
Mosquitoes will practically breed anywhere where there is a collection of
water that stands longer than five to seven days. Some prefer lighted areas and
some shady areas. Some prefer fresh water and some stagnant water.
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Ponds
Streams Swamps
Rock holes
DitchesTree holes
Common natural breeding grounds
Common man-made breeding grounds
Wells
Rain barrel
Cans
Roof gutter
Old tires Road gutter
Vases
The disease
Dengue Fever, Dengue Hemorrhagic Fever
Question
Where did the word “dengue” come from?
Spanish, “dengue” for “fever”Swahili, “Ka-dinga pepo” for
“sudden cramp-like illness caused by an evil spirit.”
Historical Reports Chronology
265-420 AD in China; called “water poison”
Slaves in Caribbean, “Dandy fever”
1780 in Madras, India 1780, Benjamin Rush coined
the term “breakbone fever” 1799 in Cairo and Alexandria,
Egypt; Jakarta, Indonesia1943: Japanese scientists first identified the virus
1953: First report of Dengue Hemorrhagic Fever in Manila
1956: Four types of dengue 1994, Karachi , Pakistan
Number of cases vs. number of countries1955-2007
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Dengue virus infection
With sympto
ms
No symptom
s
Dengue Fever (DF) Syndrome
No different
from other fever
With unusual hemorrhageSymptoms: high
fever; severe headache; pain
behind the eyes; muscle, bone and
joint pains; nausea, vomiting, and rash.
Skin hemorrhage (tiny purplish-red spots on skin) sometimes seen
Without hemorrhag
e
Dengue Hemorrhage Fever (DHF)
(plasma leakage)
Symptoms: Sudden rise in temperature,
facial flush, DF symptoms like
vomiting, headache, etc., sore throat, gum
bleeding, breathlessness, elevated blood
hematocrit
No shock
Dengue Shock Syndrome
Symptoms: Occurs at the end of fever on 3rd
to 7th day, skin becomes cool and
blotchy, pulse weak and rapid, lethargy, restlessness, acute
abdominal pain frequently felt just
before onset of shockDengue Fever
Dengue Hemorrhage
Fever
Signs and Symptoms of Dengue Fever
Recognition of Dengue fever - Sudden onset of high fever - Severe headache (mostly in the forehead) - Pain behind the eyes which worsens with eye movement - Body aches and joint pains - Nausea or vomiting
Dengue or not?
Diagnosis: Medical history Physical examination Tourniquet test
Lab: Low platelet count
(<150,000) Complete blood
count/hematocrit Blood test for
antibodies
Managing Dengue
WHAT TO DO
Bring the fever down. Sponge bath and paracetamol.
Maintain hydration using oral fluids.
Keep mosquitoes away. Use mosquito nets.
WHAT NOT TO DO
Avoid certain drugs like aspirin, NSAIDs (ibuprofen, mefenamic acid)
Avoid IV fluids. Use oral fluids if child is able to drink. Fluids in the lungs Water retention
Warning Signs of DHF
Refuse fluids or vomiting.
Sleepy or restless child. Gastrointestinal
bleeding Abdominal pain Skin mottling, cold
sweaty skin, cold hands and feet
No urine for the past 6 hours.
Critical Period: Risk for DHF is high 5-7 days after fever subsides.
Mottled skin
Abdominal pain
dehydration
GI bleeding
Dengue Hemorrhagic Fever (DHF)
Odds of getting DHF? DHF is a second infection.
90% of DHF patients has previous infection.
Getting a second infection does not mean you’re going to get DHF
Risk of dying from DHF with inadequate treatment is 10%-15%
Risk of dying from DHF with adequate treatment is < 1%
Causes of death Shock due to
dehydration Severe hemorrhage Encephalitis Liver failure
Preventing dengue
Barriers Against Mosquito Bites and Infection
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Mosquito Repellents
DEET Apply insect repellent
DEET (20-30%) If repellent is aerosol,
open air If child, don’t apply to
hands Apply on clothing. Mosquito net if room
is non-air-conditioned or screened
Natural Need frequent
application Citronella, lemon
eucalyptus, castor oil, peppermint oil.
Multiple repellents tend to be more effective due to mosquito differences.
Prevent Breeding
Cover water containers, wells, and water tanks
tightly
Let’s Act to Prevent Dengue
1 Keep drains free from blockage2
Change the water in vases and for aquatic plants at least once a
week and leave no water in the saucers
underneath the plants
3 Cover up tires before disposal to prevent
water from collecting.4
Dispose of unwanted containers where water
may collect such as lunch boxes and soft drink cans
into covered bins5 Repair uneven surfaces
of the ground to prevent water from
collecting6
Check whether there is water collecting on the tray under an air-conditioner and in the drainage system, and
remove stagnant water
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Prevent Bites
Wear light-coloured and long-sleeved clothing
and pants1Apply mosquito repellents
containing DEET to exposed parts of the body2
Use mosquito nets or screens when the room is not air-conditioned
3
Avoid visiting scrubby areas4
Install screens on windows and doors, or place mosquito coils /electric mosquito
mats /anti-mosquito liquid near the
windows
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Vaccines?
At present, there are no approved vaccines.
At the US National Institute of Health, 11 vaccines are undergoing testing.
Difficulties with vaccine development: Four serotypes with no
cross-immunity. No good animal model for
testing. Vaccines should be
tetravalent against the DENV-1 to 4
References
Mandell’s Book of Infectious Disease, Seventh Edition
Davidson’s Book Medicine
Books
websites
www.medicinenet.com www.denguevirusnet.com www.drugbank.ca www.who.org
THANK YOU!
Muhammad Asif Mahmood
(Pharmacist)
www.facebook.com/Best.Pharmacist
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