Vector-borne Disease Surveillance in Southeast Asia

1
Vector-borne Disease Surveillance in Southeast
Asia Challenges and Opportunities in Vector
Collection and Pathogen Detection MAJ Brian
Evans, Ph.D. Jim McAvin Alongkot Ponlawat, PhD
Ratree Takhampunya, PhD LTC Jason Richardson,
PhD
2
Agenda

• Mission
• Intelligence requirements
• PM detachment capabilities
• Detection capabilities (JBAIDS)
• Value of pathogen assays
• Where is the gap?
• Conclusion

3
Mission

• To accurately asses the risk of vector-borne
  disease in an AO and to recommend/ implement
  measures that reduce the disease threat among
  soldiers.

4
Intelligence Requirements

• Human case data
• Vector data (presence/absence)
• Pathogen data (presence/absence)
• Environmental data

5
PM Detachment Capabilities

• Pre-deployment intelligence
• Gather case data (non-specific/specific)
• Limited vector surveillance
• Limited or no pathogen detection capability.

6
Detection Capability
JBAIDS Assay GRI Rank Activities Underway Comments
       
Dengue virus 5 Deployed Vector Surveillance AFPMB Approved
Chikungunya virus 6 Wet Assay Optimization Funded Pending FY10 Award
Aedes aegypti mosquitoes not ranked Deployed Vector Surveillance AFPMB Submission Planned
       
Leishmania spp 50 Deployed Vector Surveillance AFPMB Approved
Leishmania visceral genotype 20 Deployed Vector Surveillance AFPMB Approved
Leishmania human pathogenic spp Various Wet Assay Optimization Funded Pending FY10 Award
       
Plasmodium spp, P. f and P. v 1 Wet Assay Optimization Funded Pending FY10 Award
       
Flavivirus spp Various Wet Assay Optimization Funded Pending FY10 Award
Japanese enchephalitis virus 24 Wet Assay Optimization Funded Pending FY10 Award

7
Value of Pathogen Assays
Relative impact of information availability on risk accuracy, control efficacy, and on the added value of a pathogen detection assay
Information Availability Cases Vector Pathogen Information Availability Cases Vector Pathogen Information Availability Cases Vector Pathogen Risk accuracy Control efficacy Pathogen assay (value added) Example
X X X Accurate Effective Limited Dengue - Thailand
X X   Accurate Efffective NA  
X     Accurate Partial NA Malaria - Thailand
  X   Inaccurate Ineffective NA  
  X X Partially Partial Significant Dengue Thailand
    X NA NA NA  
X   X NA NA NA  
Assumptions Case data is specific in number and
location. Vector surveillance, pathogen detection
tools, and control tools are effective.
8

• Case data
• is valuable!

9
Where is the gap?

• Adult mosquito/sand fly collection devices
  minimally effective taxonomic keys
• 1 or 2 Ae. aegypti /house (15 mins/house)
  countless man-hours and houses needed for
  sufficient sample sizes (1 in 1000 infected)
  this is an area where there is transmission of
  dengue year-round.

10
Where is the gap?
BG Sentinel (BG Lure)
Bed net trap - NAMRU-2
11
Where is the gap?

• Rodent-baited traps as a tool for collecting
  chigger mites, vectors of scrub typhus.

12
Other Challenges?

• Low densities seasonality?
• How does pathogen/vector data translate into
  risk?
• What does it mean to have 6 in 1000 infected
  should I be concerned?
• Even when we know the vector locations and where
  the pathogen is most prevalent in the vector, do
  we understand the biology?
• Not one-size fits all solutions same species
  from different locations may have evolved
  independently different vector ecology

13
Conclusion

• Bottom-line Pathogen detection has greatest
  added value for risk determination and control
  efficacy in instances where there is limited or
  no case data. If disease is seasonal, a valuable
  forecasting tool.
• Challenge Relevancy of pathogen detection data
  is highly-dependent on the vector surveillance
  tool.
• Pathogen surveillance should be a critical part
  of the PM mission need more effective
  surveillance tools to complement this mission
  need trained soldiers who can interpret
  information/data.
• Where time/resources/money are limited, should be
  very selective about when and where to use
  pathogen detection assays.