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Preventing dengue
 

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