1. Investigation of a Legionella Cluster
Somu Chatterjee, MD, MPH.
Regional Epidemiologist,
Wheeling-Ohio County Health Department
Ph:
Cell:
This presentation will highlight the issues and the sequence of events associated with investigation of a Legionella cluster.
Investigated by CDC, state and the LHD, in the Northern panhandle of WV

2. Investigation of a Legionella Cluster
Disclaimer:
Few slides in this presentation have content similar to, or same as, the report presented by Epidemiology–Aid Team of Center of Disease Control and Prevention, on this particular event.
The idea is to share with you the Epidemiology and the process of field investigation in case of suspected Legionella cluster or outbreak.

3. Objectives of Presentation
Epidemiology of Legionellosis
Field Investigation in Legionella Outbreak/Cluster
Environmental Assessment
Importance of Multidisciplinary approach
Importance of Multi-state Cooperation
This is what we hope you will take back with you after the presentation
Epi – 5 Ws and 1 How
The process of a field investigation
Environment assessment which forms the axis around which major part of the investigation revolves
Dynamics of a field Investigation – cannot stress enough the dividends of cooperation between various agencies and across states.

4. Outline Background of Event Epidemiology of Legionellosis
Objectives of Investigation
Investigation
Findings
Summary
Recommendations
The event will be covered as outlined
Background – how it started
Salient points on Legionnaire's disease
Objectives of investigation
The actual investigation
And others
Additional inputs by OEHS*
*Office of Environmental Health and Prevention Services

5. Background What happened? Where did it take place?
CDC observed a common factor
State & LHD notified
Help of OEHS enlisted
Where did it take place?
Northern Panhandle WV
Facility “A”
One of the many examples of how an investigation is initiated.
What & Where
CDC noticed an unusual cluster of Legionella cases associated with travel to Facility A in Northern Panhandle of West Virginia
In this case CDC notified the state and information passed on to the LHD
A parallel investigation was also initiated by the office of environmental health services

6. Background cont… Who & When? CDC
July 19/2011- case reported with travel to
Facility A
Aug 24/ nd case reported with travel to Facility A
Aug 31/ rd case reported with travel to Facility A
LHD reported Legionellosis Death on
Aug 28/2011
Who were investigated and who were the investigators?
CDC reported 3 cases with travel to facility A
LHD reported death from the disease
Note the clusters around end of August and one in July

7. Background cont… Why did it happen? How did it happen?
The Epidemiological Triad
Characteristic of Host
Characteristic of Agent
Characteristic of Environment
So there were many questioned that were being asked like - Should we be concerned?, why/why not
If we should be concerned, we have to ask why and how it happened,
But before we reach the Why and How, we had to look into:
characteristics of those infected - Host
characteristics of the organism involved -Agent
Conditions favorable for infection of legionella - Env
This is going back to the to the basics of host-env-agent triangle otherwise known as the epi triad

8. Epidemiological Triad
Looking for common causes of exposures where all the three came together to manifest disease
Source: Snieszko (1974), Blackwell Publishing Ltd. Copyright 1974

9. Epidemiology - Legionellosis
Agent: Legionella pneumophila
80-90% of human infections
Atypical gram – negative bacillus
Symbiotic organisms
Algae
Amoeba
Ciliated protozoa - invades
Bacteria
Habitat : Aquatic bodies
Salient points about the agent:
All patients had urine Ag + for legionella Pneumophila serotype 1
Atypical b’cos need special media BCYE (buffered charcoal yeast extract) media
Clinically - Relative lack of sputum
Count is low in naturally occuring aquatic bodies

10. Epidemiology -Legionellosis
Causes 2 clinical syndromes:
Legionnaires Disease (pneumonia)
Pontiac fever (flu like illness)
Incidence of Legionnaire’s Disease depends on:
Degree of contamination of aquatic reservoir
Immune status of persons exposed
Intensity of exposure
2 syndromes
Infection and manifestation of disease (Legionnaire’s disease) depends on
Degree of contamination of aquatic reservoir
Immunity status of individual
Intensity – volume of exposure

11. Epidemiology -Legionellosis
CDC estimates only 3% of sporadic community acquired Legionnaire’s disease in US are correctly diagnosed
Host risk factors:
Cigarette smoking
Chronic lung disease
Advanced age
Discharge from hospital within 10 days
Immunosuppressive conditions
Which means what we have is 3% of the iceberg -- call it the tip.
All the more reason to investigate
Host factors predisposing to illness –community acquired vs nosocomial

12. Epidemiology -Legionellosis
Environment:
Natural bodies – small number
Survive for years in refrigerated water
Proliferate in:
Warm temperatures (250 – 420 C)
Scale
Sediment
Modes of transmission:
Aerosolisation
Aspiration
Anything that can lead to aerosolisation like:
mist machine grocery store
cooling tower
Whirlpools
air conditioners
lawn sprayers
etc

13. Epidemiology -Legionellosis
How prevalent has legionella been?
West Virginia Department of Health and Human Resources

14. Epidemiology -Legionellosis
It is in tune with the national trend.
West Virginia Department of Health and Human Resources

15. Epidemiology -Legionellosis
2008
2009
2010
Hancock 1
Brooke
Ohio
Marshall
Tyler
Pendleton
Hancock
Tyler counties have the highest incidence in the state.
West Virginia Department of Health and Human Resources

16. Objectives of Investigation
To conduct case finding to identify possible common exposures among cases
To conduct environmental sampling of potential common sources
To recommend environmental remediation strategies to prevent additional cases of Legionellosis
Starting the inv: main aims
Identify common factors among the host, agent and the environment
Environmental sampling to identify sources
Remediation strategies

17. Investigation Sept 2/2011 Investigation team:
Conference call with local, regional, state (WV, OH) Public health and CDC. Epi-Aid initiated
Investigation team:
CDC (Lab, EIS officers)
LHD, Regional Epi
OEPS/Infectious Disease Epidemiology
OEHS/District engineers/District Sanitarians
We did not have enough experience with Legionella investigation at the LHD level
State sought help from CDC
Multidisciplinary approach
Team comprised of:

18. Investigation – Case Finding
Case Definition
Facility Associated
Signs and symptoms of pneumonia
AND lab confirmed with: culture positive OR urine antigen positive OR fourfold rise in titers
AND visit to Facility A during incubation period, and onset of symptoms between June 15 and September 7
Community Associated
AND present in the WV Northern Panhandle or adjacent counties during the incubation period, and onset of symptoms between June 15 and September 7
In order to start the investigation; we needed to define what we are investigating
Case def – into 2 areas: facility associated / community associated
With Onset of symptoms: June 15 to Sep 7

19. Investigation – Case finding
Nationally Notifiable Disease Surveillance System / Travel Associated LD
Epi-X posting by West Virginia on Aug 25th
Health advisories in OH and WV
For Laboratory Confirmed cases:
Contacted hospitals in catchment areas of WV Northern Panhandle/OH adjacent counties to search for LD discharge dx, or lab dx.
For Non Lab confirmed:
Obtained Resort A staff absences ≥ 4d
Scouting for other cases:
History of travel to or through state of Ohio was present
Multidisciplinary  Multistate investigation under guidance of CDC
Other conference calls with State of PA and OH on active case finding.
Other cases of community acquired Legionella infection uncovered
Health advisory: lab, other state, absentee report
and EPI-X (notification system of event by CDC)

20. Findings Northern Panhandle Legionnaire’s Cluster
9 cases- (3 Resort Associated , 6 Community Associated)
Median age = 60 years
5/9 male
9/9 hospitalized
1 died
5/9 with known travel through Hancock Co.
All were hospitalized

21. Investigation – Distribution of Cases4 3 2 1
By onset 21
CDC Epi-Aid team 21

22. Investigation Map of the facility All cases Interviewed extensively
DIDE surveillance questionnaire
Patient’s residence (LTCF, Nursing home)
Travel or stay overnight other than usual residence
Dental work
Hospital visit
Among 3 cases that visited the facility:
Inv water sources and possible exposures\
No common baths – b’cos some didn’t stay/ some stayed but didn’t use the aquatic facilities
So no common link of exposure to water bodies 22 22

23. Investigation Inspected exposures potential in: Drinking water Spa
Pools
Hot water tubs
Race track
Showers/baths
Among 3 cases that visited the facility:
Inv water sources and possible exposures\
No common baths – b’cos some didn’t stay/ some stayed but didn’t use the aquatic facilities
So no common link of exposure to water bodies 23 23

24. Findings - Facility associated cases
3 cases visited Facility A (1-2 days)
3/3 visited the Facility
Potential sources of exposure near entrance (fountain), parking lot and other places noted.
3/3 entered via that particular entrance (5-60min)
2/3 report 5-20 min in parking lot, 1/3 reported >20min
No exposure to other fountains
No common exposures found.
Among 3 cases that visited the facility:
Inv water sources and possible exposures\
No common baths – b’cos some didn’t stay/ some stayed but didn’t use the aquatic facilities
So no common link of exposure to water bodies

25. Environmental Assessment
District, State Engineers and Environmental Health professionals
Inspection of water sources in Facility A
Room to Room
All aquatic bodies
Meteorological considerations
Cooling towers
Data on wind direction, velocity and humidity from nearest airport
What we did:
Went from rooms where the patients stayed
Assessed the water supply system
Inspected all water bodies
Occurred to us the presence of cooling towers in the area:
Data from nearest Met dept – Airport
Wind speed
Humidity

26. Map of Cases, Facility A & Cooling Towers in Area
Blue dots – cooling towers
Red dots -- cases
Judith Vallandingham and J.D. Doughlas, OEHS, DHHR, WV, 2011.

27. Environmental Assessment
Over to:
Judy Vallandingham,
Chief, Public Health Sanitation
Office of Environmental Health Services, WV
For description of environmental assessment and final recommendations

28. ACKNOWLEDGEMENT: CDC - Epidemiology Team - Lab Team Hancock Co HD
CDC
 - Epidemiology Team
 - Lab Team
Hancock Co HD
- Jackie Huff, Jolene Zuros, Michelle Truax, Carolyne Baker
WV State/ Regional/District
- Dee Bixler
- Sherif Ibrahim, Jonah Long
- Mark Uraco
- JD Douglas, Judy Vallandingham, Bob Smith, Brad Hess
EIS Officer WV OEPS: Tegwin Taylor
Ohio HD
Pennsylvania HD
Facility A Staff

29. Thank You