Preventing dengue
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Preventing dengue

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Presentation done last October 8, 2010 at Fairchild Semiconductor, EPZA 1, Lapu-Lapu City, Cebu, Philippines. Some data reflects regional situation. Data from statistics presented does not reflect ...

Presentation done last October 8, 2010 at Fairchild Semiconductor, EPZA 1, Lapu-Lapu City, Cebu, Philippines. Some data reflects regional situation. Data from statistics presented does not reflect current situation; however, links are provided for further information.

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Preventing dengue Preventing dengue Presentation Transcript

  • Preventing Dengue
    The Vector, The Virus, and The Fever
    Prepared & Designed by:
    Raphael D. Fernandez, M.D.
    Website: www.raphaelfernandez.com
    10/12/2010
    1
  • Question
    Why should we be concerned about Dengue?
    10/12/2010
    2
  • Dengue
    Worldwide, WHO estimates 2.5 billion people are at risk with 50 million cases annually.
    Fatality rate: <1% to 20% depending on health care
    DHF develops in 1/100 cases
    Nationwide, 90,771 cases were recorded from January to Sept 29, 2010
    Case fatality rate: 1%
    10/12/2010
    3
  • Dengue Update
    A total of 9,284 cases seen in Region 7 from January 1 to October 2, 2010
    65 deaths (CFR=0.7%)
    2009, 4,961/67 (CFR=1.4%)
    Ages: 1-89 y.o. (↑6-10 y.o)
    Sex: Male = Female
    Areas: Cebu City > Tagbilaran > Dumaguete > Lapulapu > Toledo
    10/12/2010
    4
    “Dengue Update,” 39th Morbidity Week
  • Dengue Update, Central Visayas
    10/12/2010
    5
  • We Are Not AloneFrom 07 Sept to 07 Oct 2010
    10/12/2010
    6
    DengueMap, HealthMap.
  • 10/12/2010
    7
    KNOW
    DO
    GOAL
  • Aedes aegypti and Aedes albopictus
    The vector
    10/12/2010
    8
  • The Mozzies
    Yellow Fever
    Dengue
    Chikungunya
    West Nile Virus
    Malaria
    10/12/2010
    9
  • Question
    10/12/2010
    10
    What does “aedes” mean?
    “Unpleasant” (Greek) by Meigen in 1818
  • 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)
    “The Mosquito Life-cycle,” Centers for Disease Control and Prevention
    10/12/2010
    11
  • 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
    Pregnancy
    Body temperature
    Dark-colored materials
    clothings, garbage cans
    Movement
    Floral/fruity fragrances
    Moisture
    10/12/2010
    12
  • Question
    10/12/2010
    13
    Why do female mosquitoes need blood?
    For egg development. The amino acid isoleucine is important.
  • Breeding
    10/12/2010
    14
    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.
  • 10/12/2010
    15
    Ponds
    Streams
    Swamps
    Common natural breeding grounds
    Rock holes
    Tree holes
    Ditches
  • 10/12/2010
    16
    Rain barrel
    Cans
    Wells
    Common man-made breeding grounds
    Vases
    Roof gutter
    Old tires
    Road gutter
  • Comparison
    Aedes aegypti
    Aedes albopictus
    10/12/2010
    17
    “Invasion biology of Aedes albopictus,” University of Florida.
  • Aedes aegypti
    Aedes albopictus
    Egyptian tiger mosquito
    Origin: Africa
    Primary vector for:
    Yellow fever
    Dengue fever
    Chikungunya fever
    Prefers to breed in water storage containers (in and out)
    Day biter  humans
    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
    “Larval habitats and distribution patterns of Aedes aegypti and Aedes albopictus in Thailand,” Chareonviriyaphap, et al., 2003. PDF
    Aedes albopictus, Global Invasive Species Database.
    10/12/2010
    18
  • Question
    10/12/2010
    19
    In the Philippines, which of the two is the predominant mosquito specie?
    Aedes aegypti
  • Dengue Virus
    The causative agent
    10/12/2010
    20
  • The Dengue Virus
    10/12/2010
    21
    Flavivirus (Yellow virus)
    Only transmitted by mosquito bites
    It takes 8 days for a mosquito to be a vector but remains infected for life.
    Dengue 1 Virus and Dengue Hemorrhagic Fever, French Polynesia, 2001, Hubert and Halstead, Emerging Infectious Diseases, August 2009
  • Historical
    Dengue viruses originally came from monkeys.
    It jumped to humans 100 to 800 years ago.
    It was a minor disease until World War 2
    10/12/2010
    22
  • Question
    10/12/2010
    23
    Why has dengue became a significant health problem after World War 2?
    Due to increased travel and active transport industry
  • The Four Types
    Dengue has four closely related types or serotypes: DENV-1 to 4
    Each serotype gives specific lifetime immunity and short-term cross-immunity.
    A second, third or fourth infection results in a worse infection than the first.
    Infants can have a severe first infection if the mother has previous dengue infection.
    10/12/2010
    24
    “Molecular Evolutionary Pathogenesis of Dengue Virus Infection,” Shannon Bennett
  • Why is the next infection worse?When Good Antibodies Go Bad
    10/12/2010
    25
    Antibody-dependent Enhancement
    In ADE, two things will happen:
    The virus is still active and will continue infecting cells and replicating in them.
    The dengue virus will initiate a complement cascade activation that leads to blood vessel breakdown  bleeding and shock
    ADE can be found in:
    • Dengue patients with previous dengue infections.
    • Infants and toddlers of mothers with previous dengue infection.
  • Dengue Spread
    Possible factors
    Inadequate housing and public health systems (water, sewage, waste management)
    Poor vector control
    Climate change
    Increased international travel
    10/12/2010
    26
  • Dengue Fever, Dengue Hemorrhagic Fever
    The disease
    10/12/2010
    27
  • Question
    10/12/2010
    28
    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 and Philadelphia, USA
    1789, 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
    10/12/2010
    29
    Number of cases vs. number of countries
    1955-2007
  • 10/12/2010
    30
    Dengue virus infection
    With symptoms
    No symptoms
    Dengue Fever (DF) Syndrome
    No different from other fever
    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
    With unusual hemorrhage
    Symptoms: 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 hemorrhage
    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 shock
    Dengue Fever
    Dengue Hemorrhage Fever
    http://thestar.com.my/archives/2008/9/14/health/sf_pg06manifestation.jpg
  • Dengue or not?
    Diagnosis:
    Medical history
    Physical examination
    Tourniquet test
    Lab:
    Low platelet count (<150,000)
    Complete blood count/hematocrit
    Blood test for antibodies
    10/12/2010
    31
  • 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
    10/12/2010
    32
  • Warning Signs of DHF
    10/12/2010
    33
    Critical Period: Risk for DHF is high 1-2 days after fever subsides.
    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.
    Mottled skin
    dehydration
    GI bleeding
    Abdominal pain
  • Dengue Hemorrhagic Fever (DHF)
    Causes of death
    Shock due to dehydration
    Severe hemorrhage
    Encephalitis
    Liver failure
    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%
    10/12/2010
    34
    Advice to former dengue patients
    Don’t get bitten again!
  • Barriers Against Mosquito Bites and Infection
    Preventing dengue
    10/12/2010
    35
  • 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.
    10/12/2010
    36
  • Prevent Breeding
    10/12/2010
    37
    4
    Cover up tires before disposal to prevent water from collecting.
    1
    2
    Change the water in vases and for aquatic plants at least once a week and leave no water in the saucers underneath the plants
    Keep drains free from blockage
    Cover water containers, wells, and water tanks tightly
    3
    Check whether there is water collecting on the tray under an air-conditioner and in the drainage system, and remove stagnant water
    Dispose of unwanted containers where water may collect such as lunch boxes and soft drink cans into covered bins
    5
    7
    6
    Repair uneven surfaces of the ground to prevent water from collecting
    Let’s Act to Prevent Dengue, Hong Kong Housing Authority
  • Prevent Bites
    10/12/2010
    38
    3
    Use mosquito nets or screens when the room is not air-conditioned
    1
    Wear light-coloured and long-sleeved clothing and pants
    2
    Apply mosquito repellents containing DEET to exposed parts of the body
    Install screens on windows and doors, or place mosquito coils /electric mosquito mats /anti-mosquito liquid near the windows
    5
    4
    Avoid visiting scrubby areas
  • 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
    10/12/2010
    39
  • 10/12/2010
    40
    Dengue Hemorrhagic Fever: Early Recognition, Diagnosis and Hospital Management
    Click the image below to view video from your browser.
  • Websites of Interest
    dengue References
    10/12/2010
    41
  • Wikipedia
    10/12/2010
    42
    http://en.wikipedia.org/wiki/Dengue_fever
  • Centers for Disease Control and Prevention
    10/12/2010
    43
    http://www.cdc.gov/Dengue/
  • Dengue Map
    10/12/2010
    44
    http://www.healthmap.org/dengue/index.php
  • Center for Health DevelopmentCentral Visayas
    10/12/2010
    45
  • This Week in Virology
    10/12/2010
    46