Investigation of a Giardia Cluster Associated with a Private Club, Cook County, 2011 Alicia M. Siston, PhD, MPH, MS Chicago Department of Public Health
Giardia Background Most common intestinal human parasite Often associated with contaminated water exposure Outbreaks not frequently identified but have been linked to both treated and untreated recreational water. Giardiasis is a reportable disease in Illinois
Giardiasis Characteristics Symptoms: Diarrhea, abdominal cramps, bloating, Transmission: Fecal-oral Incubation period: Median (7-10 days), range (3-25 days)
Outbreak Identification September 2011, Cook County Department of Public Health (CCDPH) determined that: 5 individuals diagnosed with Giardia resided in 2 households (same block). Household members belonged to private sports club (Club A) with recreational water facilities October, 2 additional Giardia cases reported from 2 different households; also Club A members
Satellite Image of Club A Lake
Outbreak Investigation Objective and dcollaboration CCDPH, in collaboration with Illinois Department of Public Health (IDPH) and Centers for Disease Control and Prevention (CDC), initiated an investigation to determine source and extent of outbreak.
Methods: Case Finding Letter sent to all Club A members and staff requesting: any yperson experiencing diarrheal illness for three days or longer since August 1 contact CCDPH
Methods: Environmental Health CCDPH Environmental Health inspected: whirlpool spa indoor pool kitchen facilities CCDPH and IDPH collected water specimens: the pool (backwash) lake (bathing beach) whirlpool filter lake (swimming buoy) water fountain CDC tested water specimens using real-time PCR and fluorescence microscopy
Confirmed and Probable Case Definitions Confirmed Case person experiencing diarrhea or bloating since August 1, and contact with Club A lake, and tested positive for Giardia by microscopy or EIA antigen Probable Case a person experiencing diarrhea or bloating since August 1, and contact with the Club A lake (without laboratory confirmation)
Results: Cases Identified 8 confirmed and 2 probable cases identified 1 confirmed and 2 probable cases not previously diagnosed with giardiasis, but were identified through active case finding 2 of these case-patients remained symptomatic during the investigation and reported intermittent gastrointestinal symptoms the previous 4-6 weeks Both experienced extensive gastrointestinal workups that included colonoscopy and severe dietary restrictions, but were not tested
Epidemic Curve of Confirmed (n=8) and Probable (n=2) Cases, by Family
Case-patient Characteristics (N=10) 70% Female 35 years (median age) ; 2-60 years (range) Signs and symptoms 80% Bloating 70% Diarrhea 60% Abdominal cramps 20% Vomiting
Results: Epidemiologic Investigation In the month prior to illness onset: All case-patients reported Club A lake water exposure 1 case-patient t reported pool exposure 1 case-patient reported spa exposure
Results: Environmental CCDPH inspection results: Whirlpool spa contained turbid water Pool had a malfunctioning drain Kitchen facilities passed the CCDPH inspection. IDPH water sample results Giardia was not detected in any of the water samples tested by CDC
IDPH E. coli Testing History of Water Samples Taken from Club A Lake Bathing Beach
Epidemic Curve of Confirmed (n=8) and Probable (n=2) Cases, by Family
Limitation Although Giardia was not detected from collected water samples, the samplings occurred approximately one month after the last case s s onset of illness.
Conclusions Possible that transient fecal contamination episode introduced Giardia into lake Finding of three additional cases during investigation demonstrates the value of active case-finding when investigating Giardia clusters This outbreak investigation highlights the importance of Giardia surveillance and supports rationale for keeping giardiasis as a reportable disease in Illinois.
Acknowledgments CCDPH Communicable Disease Control Program Environmental Health IDPH Infectious Disease Division Environmental Health CDC