Vector surveillance involves the ongoing collection, analysis, and dissemination of mosquito data to inform appropriate public health actions. The key objectives are to monitor mosquito populations and breeding sites to determine infection risk levels and recommend prevention/control measures. Common surveillance methods include adult mosquito collection, pupal surveys, larval surveys, and ovitrapping. Larval surveys inspect water containers to calculate larval indices like House Index, Container Index, and Breteau Index. Analysis of findings considers vector characteristics, community factors, and prioritizes areas for intervention and monitoring based on mosquito density levels. The information benefits various stakeholders for public health decision-making and research.

1. Norma DC Joson
Entomologist III
Department of Health
DENGUE VECTOR
SURVEILLANCE

2. What is Vector Surveillance
 an on-going systematic process of
collection
analysis
interpretation
dissemination
of information about the vector for appropriate
action.

3. MOSQUITO VECTORS
Aedes
CulexAnopheles
Mansonia

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. What life stage
of the
mosquito is
used in vector
surveillance?

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. 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. 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. What are the
common
breeding
sites of
Aedes
mosquitoes?

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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Thank you!!!