Presentation

Environmental Engineering
in Disease Outbreaks
Rick Gelting, Ph.D., P.E.
Emergency Response and Recovery Branch
CDC/Center for Global Health
Center for Global Health
Global Water, Sanitation, and Hygiene
Outline

Introduction/background

Specific examples
 Environmental investigations
• E. coli O157:H7 in spinach
 Prevention/Treatment
• Ebola in West Africa: Decommissioning Ebola Treatment
Units

Conclusion/Q& (hopefully) A
What questions are we asking (and not
asking) in disease outbreaks?

Who is sick?
When did they get sick?
Where did they get sick?

What caused illness? (Epi, Lab analysis)

Why did exposure occur?


Epidemiology
(i.e., why was the agent present in the environment in
such a way that host was exposed?)
 Environmental investigation
Example 1: 2006 E. coli O157:H7 Outbreak
associated with Spinach
• September 2006: E. coli O157:H7 infection reported from
several states to CDC
• Fresh spinach identified as the vehicle
• More than 500 cases (>200 hospitalizations including 4
deaths) in 26 states
• PFGE led to genetic matches of E. coli O 157:H7 strains
from patients and bagged spinach to environmental
samples at a single farm (referred to as Farm A hereafter)
TM
TM
Ground water elevation in Paicines Well #2
(San Benito County Water District Water Level Measurement Well Ridgemark 5)
Paicines Well 2
¼ mile
San Benito River
March 2006
652’
650’
Riverbed Elevation
TM
River
TM
Ground water elevation in Paicines Well #2
(San Benito County Water District Water Level Measurement Well Ridgemark 5)
Paicines Well 2
¼ mile
San Benito River
March 2006
652’
July 2006
650’
650’
Riverbed Elevation
October 2006
646’
Outbreak August-Sept
TM
River
TM
Example 1: Spinach Outbreak
• 4 dimensional (including time) watershed scale
analysis revealed risk factors
• Groundwater levels can vary over:
– Short periods (seasonally from pumping and recharge)
– Long periods (often from decades of overpumping)
• Affects groundwater/surface water interaction
– Potential contamination from interaction
Example 2: Decommissioning Ebola Treatment Units
Guidance on Decommissioning ETUs
Decommissioning: Sanitation
Temporary Latrines:
 Superstructure:



Disinfect
Dismantle
Dispose: incineration, burn or
deep burial
 Substructure:



Backfill with packed soil or solid
debris
Demarcate with signs and GPS
Note: red zone pits often also
treated with lime before
backfilling
Decommissioning: Sanitation
Septic/holding tanks
 Temporary


Seal and backfill
Demarcate with signs and GPS
 Permanent



Empty only if > 2/3 full
Desludging/disposal should follow
national guidelines; otherwise
transport/disposal should be
assessed and risks minimized as
close to zero as possible
Refer to Infection Prevention and
Control guidelines (Full PPE for red
zone waste)
Decommissioning: Grey Water Facilities
 Superstructure:



Disinfect
Dismantle
Dispose: incineration, burial or
deep burial
 Substructure:



Disinfect soakaway, drainage
channels with 0.5% chlorine
Backfill
Demarcate with signs and GPS
Decommissioning: Water Infrastructure
 Dismantling




Piping can be reused
Chlorinated water pipes: no
additional disinfection
Non-chlorinated water: disinfect
with 0.5% chlorine before reuse
Crush/bury red zone piping in
some locations
 Reuse of water points (wells)





Sanitary survey
Recommend microbiological
testing according to WHO
standards
Shock chlorinate
Inform community
Reuse depends on location:
some wells capped for future use
Decommissioning: Solid Waste
 Incineration, burning or deep
burial
 Decontaminate prior to disposal
 Avoid environmental
contamination and occupational
risks
 Burn pits: cover with 1 m soil
 Sharps/organic pits: backfill, cover
with concrete
 Ash pits: backfill, compact
 Record GPS coordinates and share
with partners (Ministry of Health,
etc)
Decommissioning: Solid Waste
 Recommended deep burial for large quantities of plastic sheeting
Solid Waste: Medical Waste Management
Decommissioning ETUs that had no Ebola patients
Septic tank/drainfield
Monrovia Medical Unit
Perimeter
Light
Morgue
Staff Latrine
Low Risk Zone
Perimeter
Light
Perimeter
Light
Generator Farm
Covered
Storage
Patient Latrines
& Shower
Patient Latrine
High-Risk
Zone
Logistics
Supply
Entrance to Generator Farm Corridor
MED
OPS/ADMIN
Guard
Shack
Laboratory
Survivor
Wall
Intake
Container
Storage
Intake
Patient
Shower
Ambulance
Parking
Storage Tent
0% 05% 5%
Chlorine
Mixing
Laundry/Scrub
Changing
Station
Water
Tanks
Incinerators
(4)
Perimeter
Light
Perimeter
Light
Chlorine
storage
MMU
Discharge
Exit
High-Risk Zone
Low Risk Zone
Hand Washing /
Temp. Check
Porta Pottys (4)
Station
Family
Visitor
Booth
Perimeter
Light
Behavior
Health
Donning
Doffing
MWR
Dumpster
Patient
Patient
Visitor
Visitor
Booth
Booth
Confirmed
(Ward 3)
Probable
(Ward 2)
Corridor
Pharmacy
Perimeter
Light
Suspected
(Ward 1)
Emergency Decon
Fuel Tank
Command
Observation
Ward
Catwalk
0% .05% .5%
Perimeter
Light
Suspect
Patient Exit
Tent City
Employee Entrance
Ambulance Entrance
Guard Tent
Decommissioning the MMU
Conclusion

Environmental engineering is a critical element
of outbreak responses
 Contributes to better understanding of
environmental influences on outbreaks, and
improved procedures/guidelines

Need to institutionalize engineering into
prevention and response programs
 Sanitation/waste management
 Not dependent on individuals
Thank you for
your attention!
For more information please contact Centers for Disease Control and Prevention
1600 Clifton Road NE, Atlanta, GA 30333
Telephone, 1-800-CDC-INFO (232-4636)/TTY: 1-888-232-6348
E-mail: cdcinfo@cdc.gov
Web: www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official
position of the Centers for Disease Control and Prevention.
Center for Global Health
Division of Emergency and Environmental Health Services