Anita Kurian, MBBS, DrPH Chief Epidemiologist & Epidemiology Division Manager

1. 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

2. 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 Detection of Outbreak and Timeline 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 • 1st lab confirmed case reported

3. 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

4. Aerial View of Lake A

5. Lake A

6. Lake A

7. Updated Equipment

8. Timeline (continued) July 16, 2008 • Different exposure dates emerge • Approximately 500 + calls • TCPH recommended Lake A closure • 8 Lab-confirmed cases of Cryptosporidiosis identified

9. 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

10. 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

11. Descriptive and Hypothesis Generating Study Matched Case-Control Study Epidemiological Investigation

12. 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, 2008. Case Definitions

13. Environmental Study • 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.

14. Laboratory Results Wells feeding Lake A Microbiology Well #1 Total coliform - 23.1/100ml sample Negative for fecal coliform Well #2 Negative for total coliform & fecal coliform Well #3 Sample 1 feeding the lake Total coliform - 6.3/100ml sample Negative for fecal coliform Sample 2 from the restrooms sink Negative for total coliform & fecal coliform Well #4 Negative for total coliform & fecal coliform Well #5 Sample 1 from the well Negative for total coliform & fecal coliform Sample 2 at the snack bar Negative for total coliform & fecal coliform Cryptosporidium- ~0.5 to 1 oocyst per 10 L of lake water Composite sample from the lake Cryptosporidium- ~0.5 to 1 oocyst per 10 L of lake water Backwash from 2 sand filters

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

16. Crypto Inactivation Time for aDiarrheal Fecal Incident

17. Hyperchlorination – July 24, 2008

18. Hyperchlorination • Lake A was reopened on July 27, 2008

19. Results • ~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.    

20. Results (cont’d) • 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.

21. Confirmed (n=113)* Probable (n=135)* Lake A Crypto Cases – Visit Dates 70 06/28/08 60 07/05/08 50 40 Number of Crypto Cases 30 20 10 0 6/6/08 7/1/08 7/6/08 8/5/08 6/11/08 6/16/08 6/21/08 6/26/08 7/11/08 7/16/08 7/21/08 7/26/08 7/31/08 8/10/08 8/15/08 Visit Date *Cases for Tarrant County and Non-Tarrant County Residents

22. Confirmed(n=113)* Probable (n=135)* Lake A Crypto Cases – Onset of Illness 40 07/11/08 35 30 07/04/08 25 Number of Crypto Cases 20 15 10 5 0 7/1/08 7/5/08 7/9/08 8/2/08 8/6/08 6/15/08 6/19/08 6/23/08 6/27/08 7/13/08 7/17/08 7/21/08 7/25/08 7/29/08 8/10/08 8/14/08 8/18/08 8/22/08 8/26/08 8/30/08 Onset of Illness Date *Cases for Tarrant County and Non-Tarrant County Residents

23. Frequency of Symptoms Percent Diarrhea 98.8 Abdominal Cramps 88.3 Vomiting 62.1 Fever 51.2 (99.0 - 104.0) Weight Loss 46.1 Fatigue 7.0 Headache 5.1 Bloody Diarrhea 3.5

24. Univariate Analysis for Factors Associated with Cryptosporidium Infection Variable OR* Wald 95% CI Age in years (continuous) 0.95 0.92 – 0.98 Male gender 2.67 1.24 – 5.74 Went into water** 8.17 1.18 – Infinity Put head under water** 21.14 3.59 – Infinity Swallowed water** 39.90 7.10 – Infinity Brought own food ‡ Ate at concession stand 5.00 0.58 – 42.8 Ate sno-cone** 1.00 0 – 39.0 Drink from water fountain ‡‡ Contact with pet 3.00 0.31 – 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.

25. Variable Exact OR* Exact 95% CI Went into water 4.11 0.46 – Infinity Put head under water 16.5 2.44 – Infinity Swallowed water 29.5 4.75 – Infinity *All OR’s are matched OR’s. Multivariate Logistic Regression Analysis for Factors Associated with Cryptosporidium Infection

26. Lake A (n=83)* Non-Lake A (n=356)* Crypto Case Timeline 18 2nd Alert Sent to Day Cares 16 07/11/08 07/10/08 07/27/08 07/23/08 08/01/08 07/17/08 07/16/08 07/22/08 08/13/08 Initial Press Release (AM) & Lake A Closed (PM) 14 12 TCPH Visits Lake A Press Conference & Alert to Health Care Providers, Day Cares, Public Pool Owners 10 Number of Crypto Cases Recommend Hyper-Chlorination of Lake A 8 Outbreak detected by TCPH Lake A Hyper-Chlorinated 6 Lake A Re-Opened 4 Recommend Weekly Hyper-Chlorination of All Rec-Water Facilities 2 0 6/3/2008 7/1/2008 7/8/2008 8/5/2008 9/2/2008 9/9/2008 5/13/2008 5/20/2008 5/27/2008 6/10/2008 6/17/2008 6/24/2008 7/15/2008 7/22/2008 7/29/2008 8/12/2008 8/19/2008 8/26/2008 9/16/2008 9/23/2008 9/30/2008 10/7/2008 10/14/2008 10/21/2008 Onset of Illness Date *Cases for Tarrant County Residents Only

27. 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.

28. 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