Outbreak of Cryptosporidiosis Associated with a Private Lake Tarrant County, 2008 Anita Kurian, MBBS, DrPH Chief Epidemiologist & Epidemiology Division Manager Tarrant County Public Health June 02, 2009

Detection of Outbreak and Timeline July 8, 2008  Initial notification of potential food-borne illness among several persons who attended a church picnic at the privately- owned, chlorinated Lake A July 9, 2008  A second group of Lake A attendees reported similar illnesses  Detailed history shifted the focus from food borne to water borne illness July 10, 2008  ~ 200+ calls with similar history  1 st lab confirmed case reported

Timeline (continued) July 11, 2008  5 lab-confirmed cases  Five different groups had been identified with similar illness/history  An Epi-Aid was requested  Lake A was visited by TCPH officials

Aerial View of Lake A

Lake A

Updated Equipment

Timeline (continued) July 16, 2008  Different exposure dates emerge  Approximately calls  TCPH recommended Lake A closure  8 Lab-confirmed cases of Cryptosporidiosis identified

Cryptosporidiosis  Etiologic agent – Chlorine resistant protozoa of the genus Cryptosporidium  Cryptosporidium is spread through the fecal-oral routewater  Has been associated with more than two-thirds of reported recreational water illness (RWI) outbreaks in the United States

Background (cont’d)  Nationally reported crypto outbreaks associated with treated recreational water venues: –7 in 2004 –19 in 2005 –26 in 2007  Number of crypto cases in Tarrant County: –6 in 2006 –6 in 2007 –7 from Jan 2008 – June 2008

Epidemiological Investigation  Descriptive and Hypothesis Generating Study  Matched Case-Control Study

 Confirmed cases - persons who developed gastrointestinal illness following a visit to Lake A after June 20, 2008 and whose stool tested positive for Cryptosporidium  Probable cases - persons who developed diarrhea, defined as at least 3 watery stools per day, lasting at least 3 days within 2-10 days of visiting Lake A after June 20, Case Definitions

 The purpose of the environmental study was 3-fold: 1) To determine if there was evidence of Cryptosporidium contamination of Lake A 2) To determine if a possible source of the contamination could be identified on the property surrounding Lake A 3) To determine the feasibility of remediating or hyperchlorinating Lake A. Environmental Study

Laboratory Results Microbiology Well #1 Total coliform /100ml sample Negative for fecal coliform Well #2 Negative for total coliform & fecal coliform Well #3 Sample 1 feeding the lakeTotal coliform - 6.3/100ml sample Negative for fecal coliform Sample 2 from the restrooms sinkNegative for total coliform & fecal coliform Well #4 Negative for total coliform & fecal coliform Well #5 Sample 1 from the wellNegative for total coliform & fecal coliform Sample 2 at the snack barNegative for total coliform & fecal coliform Composite sample from the lake Cryptosporidium-~0.5 to 1 oocyst per 10 L of lake water Backwash from 2 sand filters Cryptosporidium-~0.5 to 1 oocyst per 10 L of lake water Wells feeding Lake A

*1 parts per million (ppm) or mg/L free chlorine at ph 7.5 or less and a temperature of 77 o F (25 o C) or higher. Germ Inactivation Time for Chlorinated Water

Crypto Inactivation Time for a Diarrheal Fecal Incident

Hyperchlorination – July 24, 2008

Hyperchlorination  Lake A was reopened on July 27, 2008

 ~1,400 called in sick after swimming in Lake A  113 confirmed cases  142 probable cases, and  182 persons with gastrointestinal illness epidemiologically linked to a confirmed or probable case and the lake. Results

 The median age of cases was 12 years (range: 3 months – 62 years),  52% were male  92% were white  C. hominis identified by RT-PCR in stool samples from cases  2 genotypes identified - IaA28R4 (56.1%) and IaA15R3. Results (cont’d)

Lake A Crypto Cases – Visit Dates /6/08 6/11/086/16/086/21/086/26/08 7/1/087/6/08 7/11/087/16/087/21/087/26/087/31/08 8/5/08 8/10/088/15/08 Visit Date Confirmed (n=113) * Probable (n=135) * 06/28/08 07/05/08 Number of Crypto Cases *Cases for Tarrant County and Non-Tarrant County Residents

/15/086/19/086/23/086/27/08 7/1/087/5/087/9/08 7/13/087/17/087/21/087/25/087/29/08 8/2/088/6/08 8/10/088/14/088/18/088/22/088/26/088/30/08 Onset of Illness Date Number of Crypto Cases Confirmed (n=113) * Probable (n=135) * 07/04/08 07/11/08 Lake A Crypto Cases – Onset of Illness *Cases for Tarrant County and Non-Tarrant County Residents

Frequency of Symptoms Percent Diarrhea98.8 Abdominal Cramps88.3 Vomiting62.1 Fever51.2( ) Weight Loss46.1 Fatigue7.0 Headache5.1 Bloody Diarrhea3.5

Univariate Analysis for Factors Associated with Cryptosporidium Infection VariableOR*Wald 95% CI Age in years (continuous) – 0.98 Male gender – 5.74 Went into water** – Infinity Put head under water** – Infinity Swallowed water** – Infinity Brought own food‡ Ate at concession stand – 42.8 Ate sno-cone**1.000 – 39.0 Drink from water fountain‡‡ Contact with pet – 28.8 * Odds ratios are matched odds ratios. ** Exact matched odds ratios and confidence intervals. ‡ No odds ratio possible as there are no discordant pairs. ‡‡ No one drank from the water fountain.

Multivariate Logistic Regression Analysis for Factors Associated with Cryptosporidium Infection VariableExact OR*Exact 95% CI Went into water – Infinity Put head under water – Infinity Swallowed water – Infinity *All OR’s are matched OR’s.

Crypto Case Timeline /13/20085/20/20085/27/2008 6/3/2008 6/10/20086/17/20086/24/2008 7/1/20087/8/2008 7/15/20087/22/20087/29/2008 8/5/2008 8/12/20088/19/20088/26/2008 9/2/20089/9/2008 9/16/20089/23/20089/30/200810/7/ /14/200810/21/2008 Onset of Illness Date Number of Crypto Cases Outbreak detected by TCPH TCPH Visits Lake A Initial Press Release (AM) & Lake A Closed (PM) Recommend Hyper-Chlorination of Lake A Lake A Hyper-Chlorinated Lake A Re-Opened 2 nd Alert Sent to Day Cares Recommend Weekly Hyper- Chlorination of All Rec-Water Facilities Press Conference & Alert to Health Care Providers, Day Cares, Public Pool Owners Lake A (n=83) * Non-Lake A (n=356) * 07/10/0807/11/0807/16/0807/17/0807/22/0807/23/0807/27/0808/01/0808/13/08 *Cases for Tarrant County Residents Only

In Conclusion  First documented outbreak of cryptosporidiosis associated with a chlorinated lake  First documented hyperchlorination of a lake  Multi-disciplinary investigation  Multi-disciplinary approach is needed to reduce the risk of future RWI outbreaks.

 Paul Cantey, MD, MPH  Jimee Hwang, MD, MPH  Rebecca Hall, MPH  Michele Hlavsa, RN, MPH  Vince Hill, PhD  Charles Otto, MPA  Jeff Taylor, MPH  Rita Espinoza, MPH  Jade Dukes, MPH  Jawaid Asghar, MBBS  TCPH staff Acknowledgments