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Dengue

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Dengue

  1. 1. Junhel Dalanon, DDM, MAT
  2. 2. Contents <ul><li>What is dengue fever </li></ul><ul><li>Symptoms of dengue fever </li></ul><ul><li>Characteristics of the A edes mosquito </li></ul><ul><li>Life cycle of the Aedes mosquito </li></ul><ul><li>How the Aedes mosquito transmit diseases </li></ul><ul><li>How to prevent the spread of dengue fever </li></ul><ul><li>The 10-Mininute Mozzie Wipe-out Exercise </li></ul><ul><li>Quiz </li></ul>
  3. 3. What is dengue fever? Dengue Fever is an illness caused by infection with a virus transmitted by the Aedes mosquito .
  4. 4. Symptoms of Dengue Fever Example of a skin rash due to dengue fever
  5. 5. Do you know… <ul><li>Dengue Fever (DF) and Dengue Haemorrhagic Fever (DHF) are the most common mosquito-borne viral disease in the world. </li></ul><ul><li>It can be fatal. </li></ul>
  6. 6. Characteristics of the Aedes Mosquito <ul><li>One distinct physical feature – black and white stripes on its body and legs. </li></ul><ul><li>Bites during the day. </li></ul><ul><li>Lays its eggs in clean, stagnant water. </li></ul>Close-up of an Aedes mosquito
  7. 7. <ul><li>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. </li></ul><ul><li>On average, a female Aedes mosquito can lay about 300 eggs during her life span of 14 to 21 days. </li></ul>Do you know…
  8. 8. Life cycle of the Aedes Mosquito 1-2 days Stagnant water Pupae 4-5 days Larvae Eggs 2-3 days
  9. 9. 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.
  10. 10. This is what you can do to help…
  11. 11. Prevent Aedes from Breeding! Remove ALL sources of stagnant water. Deny the Aedes mosquito of any chance to breed.
  12. 12. 10-Minute Mozzie Wipe-Out Exercise
  13. 13. Do the 10-Minute Mozzie Wipe-out everyday. Change water in vases on alternate days.
  14. 14. Do the 10-Minute Mozzie Wipe-out everyday. Remove water from flowerpot plates on alternate days.
  15. 15. Do the 10-Minute Mozzie Wipe-out everyday. Turn over all pails and water storage containers.
  16. 16. Do the 10-Minute Mozzie Wipe-out everyday. Cover bamboo pole holders when not in use.
  17. 17. Do the 10-Minute Mozzie Wipe-out everyday. Clear blockages and put Bti insecticide in roof gutters monthly.
  18. 18. Unwanted items Do not litter. Rubbish such as cups and bottles can collect rain water and breed mosquitoes.
  19. 19. Before you leave for holidays…
  20. 20. <ul><li>Cover all toilet bowls in your home. </li></ul><ul><li>Seal off the overflow pipe of the flushing cistern. </li></ul><ul><li>Cover all gully/floor traps. </li></ul><ul><li>Add sand granular insecticide to places that mosquitoes could potentially breed, such as flower vases and places where stagnant water could not be removed. </li></ul>Before you leave for holidays…
  21. 21. <ul><li>Clear blockages and add Bti insecticide in roof gutters. </li></ul><ul><li>• Turn over all water storage containers. </li></ul><ul><li>Ask a relative or close friend to check your home regularly for stagnant water if you are going away for a long period of time. </li></ul><ul><li>Leave your contact with your neighbours or the neighbourhood police post/ centre so that you can be reached easily. </li></ul>Before you leave for holidays…(Cont’d)
  22. 22. Spread the dengue prevention message to others… Let your family , friends and neighbours know about the dangers of breeding Mozzies!!
  23. 23. <ul><li>Dengue is an arthropod-borne disease caused by any one of four closely related viruses, ( Arbovirus ). </li></ul><ul><li>Characterized by fever, severe headache, backache joint pains nausea and vomiting, eye pain and rash </li></ul><ul><li>Occasionally produces shock and hemorrhage, leading to death. </li></ul><ul><li>Also called breakbone fever , dandy fever or dengue fever. </li></ul>Dengue fever
  24. 24. Epidemiology <ul><li>Globally, there are an estimated 50 to 100 million cases of dengue fever (DF) and several hundred thousand cases of dengue hemorrhagic fever (DHF) per year. </li></ul><ul><li>2.5 billion people are at risk world-wide </li></ul><ul><li>In the last 20 years, dengue transmission and the frequency of dengue epidemics has increased greatly in most tropical countries </li></ul><ul><li>It is a resurgent (re-emergent) disease worldwide in the tropics </li></ul>
  25. 25. <ul><li>Major global demographic changes (urbanization and population growth) </li></ul><ul><li>These demographic changes have resulted in sub-standard environmental sanitation that facilitates transmission of Ae. aegypti -borne disease; (Overcrowding in cities with poor sanitation) </li></ul>Factors contribute to the emergence and re-emergence of arthropod-borne diseases
  26. 26. <ul><li>Increased travel by airplane resulting in a frequent exchange of dengue viruses and other pathogens. </li></ul><ul><li>Inadequate mosquito control services; the use of insecticide space sprays for adult mosquito proved ineffective approach for controlling Ae. aegypti . (Domestic habitat) </li></ul><ul><li>The emergence of resistance to insecticides linked to their increased misuse. </li></ul>
  27. 28. Mean Annual Number of DHF Cases Thailand, Indonesia and Vietnam, by Decade * Provisional data through 1998
  28. 29. Reported Cases of DHF in the Americas, 1970 - 1999 * Provisional data through 1999
  29. 32. Distribution of suspected and confirmed Dengue fever in KSA Year N. of suspected cases N. of confirmed cases 1994 1995 1996 1997 1998 1999 2000 2001 2002 673 136 57 62 31 26 17 07 11 289 6 2 15 00 3 0 0 4 Total 1020 319
  30. 33. Virus, Vector and Transmission
  31. 34. Dengue Viruses <ul><li>Four closely related single-stranded RNA Dengue viruses (DEN-1, DEN-2, DEN-3 and DEN-4) </li></ul><ul><li>Each serotype provides specific lifetime immunity, and short-term cross-immunity (A person can be infected as many as four times, once with each serotype) </li></ul><ul><li>All serotypes can cause severe and fatal disease </li></ul>
  32. 35. Transmission of Dengue Virus by Aedes aegypti Viremia Viremia Extrinsic incubation period DAYS 0 5 8 12 16 20 24 28 Human #1 Human #2 Illness Mosquito feeds / acquires virus Mosquito refeeds / transmits virus Intrinsic incubation period Illness
  33. 36. Replication and Transmission of Dengue Virus (Part 1) 1. Virus transmitted to human in mosquito saliva 2. Virus replicates in target organs 3. Virus infects white blood cells and lymphatic tissues 4. Virus released and circulates in blood 3 4 1 2
  34. 37. Replication and Transmission of Dengue Virus (Part 2) 5. Second mosquito ingests virus with blood 6. Virus replicates in mosquito midgut and other organs, infects salivary glands 7. Virus replicates in salivary glands 6 7 5
  35. 38. Aedes aegypti Mosquito
  36. 39. Aedes aegypti <ul><li>Dengue transmitted by infected female Aedes aegypti mosquito </li></ul><ul><li>Primarily, it is a daytime feeder </li></ul><ul><li>Highly domesticated tropical mosquito, lives around human habitation </li></ul><ul><li>Lays eggs and produces larvae preferentially in artificial water containers inside and around the houses for example; plastic containers, flower vases, buckets, used automobile tires,.. </li></ul>
  37. 40. Dengue Clinical Syndromes <ul><li>Undifferentiated fever (87% of Patients are asymptomatic or mild fever) </li></ul><ul><li>Classic dengue fever (DF) </li></ul><ul><li>Dengue hemorrhagic fever (DHF) </li></ul><ul><li>Dengue shock syndrome (DSS) </li></ul>
  38. 41. Clinical Characteristics of Dengue Classic Fever <ul><li>Incubation period 3-14 days (commonly 4-7 days) </li></ul><ul><li>Fever </li></ul><ul><li>Headache </li></ul><ul><li>Muscle and joint pain </li></ul><ul><li>Nausea/vomiting </li></ul><ul><li>Rash </li></ul><ul><li>Hemorrhagic manifestations </li></ul>
  39. 42. Dengue Hemorrhagic Fever (DHF) <ul><li>Fever, or recent history of acute fever </li></ul><ul><li>Hemorrhagic manifestations </li></ul><ul><li>Low platelet count (100,000/mm 3 or less) </li></ul><ul><li>Objective evidence of “leaky capillaries:” </li></ul><ul><ul><li>elevated hematocrit (20% or more over baseline) </li></ul></ul><ul><ul><li>low albumin </li></ul></ul><ul><ul><li>pleural or other effusions </li></ul></ul>4 Necessary Criteria:
  40. 43. Dengue Shock Syndrome (DSS) <ul><li>4 criteria for DHF </li></ul><ul><li>Evidence of circulatory failure. </li></ul>
  41. 44. Risk Factors Reported for DHF <ul><li>Virus serotype </li></ul><ul><ul><li>DHF risk is greatest for DEN-2 , followed by DEN-3, DEN-4 and DEN-1 </li></ul></ul><ul><li>Pre-existing anti-dengue antibody </li></ul><ul><ul><li>previous infection </li></ul></ul><ul><ul><li>maternal antibodies in infants </li></ul></ul><ul><li>Host genetics </li></ul><ul><li>Age (fatal cases are among children and young adult). </li></ul><ul><li>Higher risk in secondary infections </li></ul><ul><li>Higher risk in locations with two or more serotypes circulating simultaneously at high levels (hyper-endemic transmission) </li></ul>
  42. 45. Increased Probability of DHF Hyperendemicity Increased circulation of viruses Increased probability of secondary infection Increased probability of occurrence of virulent strains Increased probability of immune enhancement Increased probability of DHF Gubler & Trent, 1994
  43. 46. Common Misconceptions about Dengue Hemorrhagic Fever <ul><li>Dengue + bleeding = DHF </li></ul><ul><ul><li>Need 4 WHO criteria & capillary permeability </li></ul></ul><ul><li>DHF kills only by hemorrhage </li></ul><ul><ul><li>Patient dies as a result of shock </li></ul></ul><ul><li>Poor management turns dengue into DHF </li></ul><ul><ul><li>Poorly managed dengue can be more severe, but DHF is a distinct condition, which even well-treated patients may develop </li></ul></ul><ul><li>DHF is a pediatric disease </li></ul><ul><ul><li>All age groups are involved </li></ul></ul><ul><li>DHF is a problem of low income families </li></ul><ul><ul><li>All socioeconomic groups are affected </li></ul></ul>
  44. 47. Treatment of Dengue Fever <ul><li>Antipyretics (Acetaminophen) preparations to manage the pain and fever. </li></ul><ul><li>Avoid Aspirin and non-steroidal anti-inflammatory. </li></ul><ul><li>Rest and drink plenty of fluids </li></ul><ul><li>Monitor blood pressure, hematocrit, platelet count,... </li></ul><ul><li>Keep patient in screened sickroom or under a mosquito net </li></ul><ul><li>Mosquito barriers are only needed until fever subsides, to prevent Aedes aegypti mosquitoes from biting patients and acquiring virus. </li></ul>
  45. 48. Prognosis <ul><li>Dramatic clinical response to aggressive fluids and electrolytes. </li></ul><ul><li>Convalescence may be prolonged, with weakness and mental depression </li></ul><ul><li>Survival is related directly to early hospitalization and aggressive supportive care </li></ul><ul><li>Treated DHF is associated with a 3% mortality rate </li></ul><ul><li>Un-treated DHF is associated with a 50% mortality rate. </li></ul>
  46. 49. Prevention <ul><li>Personal protection against mosquito biting by: </li></ul><ul><ul><li>Screening doors and windows </li></ul></ul><ul><ul><li>Protective clothing </li></ul></ul><ul><ul><li>Application of mosquito repellents on exposed skin </li></ul></ul><ul><li>However, the best preventive measure is vector control. </li></ul>
  47. 50. Vector Control Methods: <ul><li>Biological control </li></ul><ul><ul><li>Largely experimental </li></ul></ul><ul><ul><li>Option: place fish in containers to eat larvae </li></ul></ul><ul><li>Environmental control </li></ul><ul><ul><li>Elimination of larval habitats; Cover water holding containers, Discard artificial containers,… </li></ul></ul><ul><ul><li>It is the most likely method to be effective in the long term. </li></ul></ul>
  48. 51. Vector Control Methods: <ul><li>Chemical Control </li></ul><ul><li>Larvicides may be used to kill immature aquatic stages </li></ul><ul><li>Ultra-low volume fumigation is ineffective against adult mosquitoes as Aedes aegypti is fully domesticated </li></ul><ul><li>Mosquitoes may have resistance to commercial aerosol sprays. </li></ul>
  49. 52. Dengue Vaccine? <ul><li>No licensed vaccine at present </li></ul><ul><li>Effective vaccine must be tetravalent </li></ul><ul><li>Field testing of an attenuated tetravalent vaccine currently underway </li></ul><ul><li>Effective, safe and affordable vaccine will not be available in the immediate future. </li></ul>
  50. 53. Community Participation <ul><li>Active community involvement and participation to reduce larval breeding sources is the key for prevention and control. </li></ul><ul><li>Educate the public in the basics of dengue, such as: </li></ul><ul><ul><li>Where the mosquito lays her eggs </li></ul></ul><ul><ul><li>The link between larvae and adult mosquitoes </li></ul></ul><ul><ul><li>General information about dengue transmission, symptoms and treatment </li></ul></ul>
  51. 54. Public Education <ul><li>Dengue fever is NOT contagious through person-to-person contact </li></ul><ul><li>Early hospitalization is important. </li></ul><ul><li>Reduce A aegypti vector populations </li></ul><ul><li>Reduce exposure to A aegypti . </li></ul><ul><ul><li>Use insect repellent. </li></ul></ul><ul><ul><li>Sleep under a mosquito net in affected areas. </li></ul></ul><ul><ul><li>Wear protective clothing. </li></ul></ul><ul><li>Vaccine is NOT available. </li></ul>
  52. 55. Quiz
  53. 56. Why is the Aedes mosquito dangerous to us?
  54. 57. ANSWER: It can carry the dengue virus and infect a healthy person with dengue fever.
  55. 58. Name the 5 steps in the 10-Minute Mozzie Wipe-out Exercise
  56. 59. ANSWER: <ul><li>Change water in vases on alternate. </li></ul><ul><li>Remove water from flowerpot plates on alternate days. </li></ul><ul><li>Turn over all pails and water storage containers. </li></ul><ul><li>Cover bamboo pole holders when not in use. </li></ul><ul><li>Clear blockages and put in Bti insecticide in roof gutters monthly. </li></ul>
  57. 60. What are the things that you should do before going for a holiday?
  58. 61. ANSWER: <ul><li>Cover all toilet bowls in your home. </li></ul><ul><li>Seal off the overflow pipe of the flushing cistern. </li></ul><ul><li>Cover all gully/floor traps. </li></ul><ul><li>Add sand granular insecticide to places that mosquitoes could potentially breed, such as flower vases and places where stagnant water could not be removed. </li></ul><ul><li>Clear blockages and add Bti insecticide in roof gutters. </li></ul><ul><li>• Turn over all pails and water storage containers. </li></ul><ul><li>Ask a relative or close friend to check your home regularly for stagnant water if you are going away for a long period of time. </li></ul><ul><li>Leave your contact with your neighbours or the neighbourhood police post/ centre so that you can be reached easily. </li></ul>

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