Dengue vector surveillance final

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Dengue vector surveillance final

  1. 1. Norma DC Joson Entomologist III Department of Health DENGUE VECTOR SURVEILLANCE
  2. 2. What is Vector Surveillance  an on-going systematic process of collection analysis interpretation dissemination of information about the vector for appropriate action.
  3. 3. MOSQUITO VECTORS Aedes CulexAnopheles Mansonia
  4. 4. General : To obtain information about the mosquito for proper action. Specific : •To establish presence/absence of the vector. •To determine major mosquito breeding sites. •To monitor high risk areas. •To monitor seasonal population fluctuations. •To monitor mosquito population w/c will serve as a warning for an impending outbreak. •To recommend immediate prevention & control measures when necessary. •To assess impact of interventions. Objectives
  5. 5. What life stage of the mosquito is used in vector surveillance?
  6. 6. A. ADULT MOSQUITO COLLECTION • collection of adult mosquito as they land on a human bait B. PUPAL SURVEY • collection of pupae from the breeding sites C. LARVAL SURVEY • collection of mosquito larvae from the breeding sites D. OVITRAP/LARVITRAP • collection of mosquito eggs using an oviposition trap where adult mosquitoes lay their eggs • if the eggs emerged into larval stage before collection, the method is called Larvitrap Methods of Vector Surveys Adult collection
  7. 7. A. PREPARATORY PHASE 1. Organize & mobilize a Dengue Watch Team/Task Force/Brigade. 2. Prepare a spot map of the barangay. 3. Prepare entomological supplies needed 4. Group the team into 4 to cover 25 houses per group. 5. Coordinate with local officials prior to the activity. Strategies / Activities
  8. 8. B. FIELD COLLECTION 1. Inspect all houses w/in 300m radius of index house 2. Inspect all water-holding containers • artificial : drums, tires, tin cans, bottles, flower vase, roof gutter, coconut shell • natural : leaf axils, tree holes, bamboo stumps 3. Label as to kind, location & type of container 4. Indicate containers w/o larvae in the survey form 5. Collect adult mosquitoes, if any. 6. Conduct on the spot health education to the household/owner. Strategies / Activities
  9. 9. What are the common breeding sites of Aedes mosquitoes?
  10. 10. C. LABORATORY 1. Prepare laboratory materials, equipment & other supplies 2. Mount & identify the larvae under the microscope 3. Identify adult mosquitoes, if any, using a stereoscope or magnifying lens 4. Determine larval indices. 5. Analyze & interpret findings. Strategies / Activities
  11. 11. Strategies / Activities RAPID MOUNTING OF MOSQUITO LARVAE 1. Kill the larvae in 600C hot water. 2. Transfer larvae into 70% alcohol solution. 3. Transfer larvae into 95% alcohol solution. 4. Clear larvae using xylene. 5. Put larvae on clean slides, wipe excess water w/ filter or tissue paper. 6. Mount the larvae using a mounting medium. 7. Examine specimen under the microscope.
  12. 12. A. ADULT MOSQUITO ADULT BITING INDEX (ABI) or HUMAN LANDING RATE (HBR)  used to determine adult mosquito density through human bareleg catches ABI = no. of Aedes sp. collected x 60 no. of human baits Interpretation : ADULT DENSITY >2/human/hr = high risk <2/human/hr = low risk Mosquito Indices
  13. 13. B. PUPAL SURVEY PUPAL INDEX  used to calculate adult mosquito production  used for special assessment & studies, not for routine surveys PI = no. of Aedes sp. collected x 100% no. of houses inspected Mosquito Indices
  14. 14. B. LARVAE B.1 LARVAL INDICES – from larval surveys House Index Container Index Breteau Index B.2 LARVITRAP INDEX (LI) – from traps LI = no. of traps (indoor/outdoor) (+) for Aedes sp x 100 total no. of traps set Interpretation : LI (rural) >20% & LI (urban) >10% = dengue sensitive areas Mosquito Indices
  15. 15. C. EGG – survey is conducted in areas where Aedes density is low; useful for early detection of new Aedes infestations OVITRAP DENSITY INDEX (ODI) – from traps ODI = no. of Aedes eggs x 100 no. of positive traps Mosquito Indices BLACK TIN CAN PADDLE (Lawanit) ¾ full of H2O
  16. 16. A. HOUSE/PREMISE INDEX (HI) HI = no. of houses (+) for Aedes sp. x 100% no. of houses inspected B. CONTAINER INDEX (CI) CI = no. of containers (+) for Aedes sp. X 100% no. of containers inspected C. BRETEAU INDEX (BI) BI = no. of positive containers x 100 total no. of houses inspected Larval Survey COMPUTATION OF RESULTS
  17. 17. A. Vector  presence/absence - primary/secondary vectors, geographic distribution  larval indices - high/low indices based on WHO figure, mosquito density vs. cases, area dengue sensitive or not, color code, etc.  breeding sites - kind of container (i.e. drum, tire, etc.), type (artificial/natural), location (indoor/outdoor), size (large/small), most common container, etc. B. Community  socio-economic factors & behavioral practices, lifestyle, beliefs, presence/absence of legislations on dengue prevention & control, etc. Larval Survey ANALYSIS OF FINDINGS
  18. 18. Priority 1 - localities where an outbreak of DF/DHF had occurred Priority 2 - localities w/ high larval indices HI >5% and/or BI >20 Priority 3 - localities w/ relatively low larval indices HI <5% and/or BI <20 Priority 4 - localities where there are no dengue cases and low Aedes densities. Priotization of Areas
  19. 19. w/in 24 hrs of the 1st case from an outbreak locality following an outbreak based on priority classification of the locality high risk areas (Priority 1 & 2) = monthly/ quarterly in 100% of houses low risk areas (Priority 3 & 4) = monthly/ quarterly in at least 20% of houses before and after interventions when there is suspect of insecticide resistance When to Conduct Larval Surveys
  20. 20. COLOR CODES : Dengue Vector Surveillance CODE INTERPRET ATION WHAT TO DO WHITE HOUSE INDEX is<5% and/or BRETEAU INDEX is <20 •Continue IEC campaign on prevention & control •Continue clean-up activities •Continue monthly entomological survey by local health authorities •Maintain the Code WHITE in the community
  21. 21. COLOR CODES : Dengue Vector Surveillance CODE INTERPRE TATION WHAT TO DO RED HOUSE INDEX is >5% and/or BRETEAU INDEX is >20 •Intensify IEC campaign on prevention & control •Mobilize residents of affected barangay to start clean-up campaign w/ the help of the Dengue Brigade •Continue monthly entomological survey by local health authorities •Improve environmental sanitation •Start community vigilance; search for more areas w/ HI >5% and/or BI >20 •Apply larvicide.
  22. 22. Who will benefit from the Information Program Planners & Managers Field Health Workers Local Government Units Community Researchers Media Other Sectors of Society Funding agencies
  23. 23. Thank you!!!

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