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 current situation; however, links are provided for further information.

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Preventing dengue

  1. 1. Preventing Dengue<br />The Vector, The Virus, and The Fever<br />Prepared & Designed by:<br />Raphael D. Fernandez, M.D.<br />Website:<br />10/12/2010<br />1<br />
  2. 2. Question<br />Why should we be concerned about Dengue?<br />10/12/2010<br />2<br />
  3. 3. Dengue<br />Worldwide, WHO estimates 2.5 billion people are at risk with 50 million cases annually.<br />Fatality rate: <1% to 20% depending on health care<br />DHF develops in 1/100 cases<br />Nationwide, 90,771 cases were recorded from January to Sept 29, 2010<br />Case fatality rate: 1%<br />10/12/2010<br />3<br />
  4. 4. Dengue Update<br />A total of 9,284 cases seen in Region 7 from January 1 to October 2, 2010<br />65 deaths (CFR=0.7%)<br />2009, 4,961/67 (CFR=1.4%)<br />Ages: 1-89 y.o. (↑6-10 y.o)<br />Sex: Male = Female<br />Areas: Cebu City > Tagbilaran > Dumaguete > Lapulapu > Toledo<br />10/12/2010<br />4<br />“Dengue Update,” 39th Morbidity Week<br />
  5. 5. Dengue Update, Central Visayas<br />10/12/2010<br />5<br />
  6. 6. We Are Not AloneFrom 07 Sept to 07 Oct 2010<br />10/12/2010<br />6<br />DengueMap, HealthMap.<br />
  7. 7. 10/12/2010<br />7<br />KNOW<br />DO<br />GOAL<br />
  8. 8. Aedes aegypti and Aedes albopictus<br />The vector<br />10/12/2010<br />8<br />
  9. 9. The Mozzies<br />Yellow Fever<br />Dengue<br />Chikungunya<br />West Nile Virus <br />Malaria<br />10/12/2010<br />9<br />
  10. 10. Question<br />10/12/2010<br />10<br />What does “aedes” mean?<br />“Unpleasant” (Greek) by Meigen in 1818<br />
  11. 11. Life Cycle<br />All in all, it takes 8-10 days.<br />Two phases: terrestrial and aquatic<br />Eggs are resistant to environmental stress.<br />Eggs  larva (feeder) in presence of water<br />Larva  pupa (non-feeder)<br />Pupa  young adult (still water)<br />“The Mosquito Life-cycle,” Centers for Disease Control and Prevention<br />10/12/2010<br />11<br />
  12. 12. Feeding<br />Mosquitoes sense the presence of:<br />Genetics – 85%<br />Chemicals (respiratory, skin)<br />Carbon dioxide (activity, using candle)<br />Lactic acid (exercise, after eating salty foods, high-potassium)<br />Steroids<br />Uric acid<br />Cholesterol<br />Pregnancy<br />Body temperature<br />Dark-colored materials<br />clothings, garbage cans<br />Movement<br />Floral/fruity fragrances<br />Moisture<br />10/12/2010<br />12<br />
  13. 13. Question<br />10/12/2010<br />13<br />Why do female mosquitoes need blood?<br />For egg development. The amino acid isoleucine is important.<br />
  14. 14. Breeding<br />10/12/2010<br />14<br />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.<br />
  15. 15. 10/12/2010<br />15<br />Ponds<br />Streams<br />Swamps<br />Common natural breeding grounds<br />Rock holes<br />Tree holes<br />Ditches<br />
  16. 16. 10/12/2010<br />16<br />Rain barrel<br />Cans<br />Wells<br />Common man-made breeding grounds<br />Vases<br />Roof gutter<br />Old tires<br />Road gutter<br />
  17. 17. Comparison<br />Aedes aegypti<br />Aedes albopictus<br />10/12/2010<br />17<br />“Invasion biology of Aedes albopictus,” University of Florida.<br />
  18. 18. Aedes aegypti<br />Aedes albopictus<br />Egyptian tiger mosquito<br />Origin: Africa<br />Primary vector for:<br />Yellow fever<br />Dengue fever<br />Chikungunya fever<br />Prefers to breed in water storage containers (in and out)<br />Day biter  humans<br />Asian Tiger mosquito<br />Origin: Africa/S.E. Asia<br />Vector for:<br />Same as aegypti<br />Prefers to breed in trash (out)<br />Outdoor day biter  humans, livestock, amphibians, reptiles, and birds<br />“Larval habitats and distribution patterns of Aedes aegypti and Aedes albopictus in Thailand,” Chareonviriyaphap, et al., 2003. PDF<br />Aedes albopictus, Global Invasive Species Database.<br />10/12/2010<br />18<br />
  19. 19. Question<br />10/12/2010<br />19<br />In the Philippines, which of the two is the predominant mosquito specie?<br />Aedes aegypti<br />
  20. 20. Dengue Virus<br />The causative agent<br />10/12/2010<br />20<br />
  21. 21. The Dengue Virus<br />10/12/2010<br />21<br />Flavivirus (Yellow virus)<br />Only transmitted by mosquito bites<br />It takes 8 days for a mosquito to be a vector but remains infected for life.<br />Dengue 1 Virus and Dengue Hemorrhagic Fever, French Polynesia, 2001, Hubert and Halstead, Emerging Infectious Diseases, August 2009<br />
  22. 22. Historical<br />Dengue viruses originally came from monkeys.<br />It jumped to humans 100 to 800 years ago.<br />It was a minor disease until World War 2<br />10/12/2010<br />22<br />
  23. 23. Question<br />10/12/2010<br />23<br />Why has dengue became a significant health problem after World War 2?<br />Due to increased travel and active transport industry<br />
  24. 24. The Four Types<br />Dengue has four closely related types or serotypes: DENV-1 to 4<br />Each serotype gives specific lifetime immunity and short-term cross-immunity.<br />A second, third or fourth infection results in a worse infection than the first.<br />Infants can have a severe first infection if the mother has previous dengue infection.<br />10/12/2010<br />24<br />“Molecular Evolutionary Pathogenesis of Dengue Virus Infection,” Shannon Bennett<br />
  25. 25. Why is the next infection worse?When Good Antibodies Go Bad<br />10/12/2010<br />25<br />Antibody-dependent Enhancement<br />In ADE, two things will happen:<br />The virus is still active and will continue infecting cells and replicating in them.<br />The dengue virus will initiate a complement cascade activation that leads to blood vessel breakdown  bleeding and shock<br />ADE can be found in:<br /><ul><li>Dengue patients with previous dengue infections.
  26. 26. Infants and toddlers of mothers with previous dengue infection.</li></li></ul><li>Dengue Spread<br />Possible factors<br />Inadequate housing and public health systems (water, sewage, waste management)<br />Poor vector control<br />Climate change<br />Increased international travel<br />10/12/2010<br />26<br />
  27. 27. Dengue Fever, Dengue Hemorrhagic Fever<br />The disease<br />10/12/2010<br />27<br />
  28. 28. Question<br />10/12/2010<br />28<br />Where did the word “dengue” come from?<br />Spanish, “dengue” for “fever”<br />Swahili, “Ka-dinga pepo” for “sudden cramp-like illness caused by an evil spirit.”<br />
  29. 29. Historical Reports<br />Chronology<br />265-420 AD in China; called “water poison”<br />Slaves in Caribbean, “Dandy fever”<br />1780 in Madras, India and Philadelphia, USA<br />1789, Benjamin Rush coined the term “breakbone fever”<br />1799 in Cairo and Alexandria, Egypt; Jakarta, Indonesia1943: Japanese scientists first identified the virus<br />1953: First report of Dengue Hemorrhagic Fever in Manila<br />1956: Four types of dengue<br />10/12/2010<br />29<br />Number of cases vs. number of countries<br />1955-2007<br />
  30. 30. 10/12/2010<br />30<br />Dengue virus infection<br />With symptoms<br />No symptoms<br />Dengue Fever (DF) Syndrome<br />No different from other fever<br />Dengue Hemorrhage Fever (DHF) (plasma leakage)<br />Symptoms: Sudden rise in temperature, facial flush, DF symptoms like vomiting, headache, etc., sore throat, gum bleeding, breathlessness, elevated blood hematocrit<br />With unusual hemorrhage<br />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<br />Without hemorrhage<br />No shock<br />Dengue Shock Syndrome<br />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<br />Dengue Fever<br />Dengue Hemorrhage Fever<br /><br />
  31. 31. Dengue or not?<br />Diagnosis:<br />Medical history<br />Physical examination<br />Tourniquet test<br />Lab:<br />Low platelet count (<150,000)<br />Complete blood count/hematocrit<br />Blood test for antibodies<br />10/12/2010<br />31<br />
  32. 32. Managing Dengue<br />What to do<br />Bring the fever down. Sponge bath and paracetamol. <br />Maintain hydration using oral fluids.<br />Keep mosquitoes away. Use mosquito nets.<br />What Not to do<br />Avoid certain drugs like aspirin, NSAIDs (ibuprofen, mefenamic acid)<br />Avoid IV fluids. Use oral fluids if child is able to drink.<br />Fluids in the lungs<br />Water retention<br />10/12/2010<br />32<br />
  33. 33. Warning Signs of DHF<br />10/12/2010<br />33<br />Critical Period: Risk for DHF is high 1-2 days after fever subsides.<br />Refuse fluids or vomiting.<br />Sleepy or restless child.<br />Gastrointestinal bleeding<br />Abdominal pain<br />Skin mottling, cold sweaty skin, cold hands and feet<br />No urine for the past 6 hours.<br />Mottled skin<br />dehydration<br />GI bleeding<br />Abdominal pain<br />
  34. 34. Dengue Hemorrhagic Fever (DHF)<br />Causes of death <br />Shock due to dehydration<br />Severe hemorrhage<br />Encephalitis<br />Liver failure<br />Odds of getting DHF?<br />DHF is a second infection.<br />90% of DHF patients has previous infection.<br />Getting a second infection does not mean you’re going to get DHF<br />Risk of dying from DHF with inadequate treatment is 10%-15%<br />Risk of dying from DHF with adequate treatment is < 1%<br />10/12/2010<br />34<br />Advice to former dengue patients<br />Don’t get bitten again!<br />
  35. 35. Barriers Against Mosquito Bites and Infection<br />Preventing dengue<br />10/12/2010<br />35<br />
  36. 36. Mosquito Repellents<br />DEET<br />Apply insect repellent<br />DEET(20-30%)<br />If repellent is aerosol, open air<br />If child, don’t apply to hands<br />Apply on clothing.<br />Mosquito net if room is non-air-conditioned or screened<br />Natural<br />Need frequent application<br />Citronella, lemon eucalyptus, castor oil, peppermint oil.<br />Multiple repellents tend to be more effective due to mosquito differences.<br />10/12/2010<br />36<br />
  37. 37. Prevent Breeding<br />10/12/2010<br />37<br />4<br />Cover up tires before disposal to prevent water from collecting.<br />1<br />2<br />Change the water in vases and for aquatic plants at least once a week and leave no water in the saucers underneath the plants<br />Keep drains free from blockage<br />Cover water containers, wells, and water tanks tightly<br />3<br />Check whether there is water collecting on the tray under an air-conditioner and in the drainage system, and remove stagnant water<br />Dispose of unwanted containers where water may collect such as lunch boxes and soft drink cans into covered bins<br />5<br />7<br />6<br />Repair uneven surfaces of the ground to prevent water from collecting<br />Let’s Act to Prevent Dengue, Hong Kong Housing Authority<br />
  38. 38. Prevent Bites<br />10/12/2010<br />38<br />3<br />Use mosquito nets or screens when the room is not air-conditioned<br />1<br />Wear light-coloured and long-sleeved clothing and pants<br />2<br />Apply mosquito repellents containing DEET to exposed parts of the body<br />Install screens on windows and doors, or place mosquito coils /electric mosquito mats /anti-mosquito liquid near the windows<br />5<br />4<br />Avoid visiting scrubby areas<br />
  39. 39. Vaccines?<br />At present, there are no approved vaccines.<br />At the US National Institute of Health, 11 vaccines are undergoing testing.<br />Difficulties with vaccine development:<br />Four serotypes with no cross-immunity. <br />No good animal model for testing.<br />Vaccines should be tetravalent  against the DENV-1 to 4<br />10/12/2010<br />39<br />
  40. 40. 10/12/2010<br />40<br />Dengue Hemorrhagic Fever: Early Recognition, Diagnosis and Hospital Management<br />Click the image below to view video from your browser.<br />
  41. 41. Websites of Interest<br />dengue References<br />10/12/2010<br />41<br />
  42. 42. Wikipedia<br />10/12/2010<br />42<br /><br />
  43. 43. Centers for Disease Control and Prevention<br />10/12/2010<br />43<br /><br />
  44. 44. Dengue Map<br />10/12/2010<br />44<br /><br />
  45. 45. Center for Health DevelopmentCentral Visayas<br />10/12/2010<br />45<br />
  46. 46. This Week in Virology<br />10/12/2010<br />46<br />