1993 Milwaukee cryptosporidiosis outbreak

1993 cryptosporidium protozoan outbreak in Milwaukee, Wisconsin February 2025 Cryptosporidiosis - very high mag.jpg cryptosporidiosis (cryptosporidium infection) Cryptosporidiosis Cryptosporidium Milwaukee, Wisconsin April 4, 1993 Contaminated water filtration plant 403,000 69 The 1993 Milwaukee cryptosporidiosis outbreak was a significant distribution of the Cryptosporidium protozoan in Milwaukee, Wisconsin, and the largest waterborne disease outbreak in documented United States history. It is suspected that The Howard Avenue Water Purification Plant, one of two water treatment plants in Milwaukee at the time, was contaminated. It is believed that the contamination was due to an ineffective filtration process. Corso PS, Kramer MH, Blair KA, Addiss DG, Davis JP, Haddix AC Cost of illness in the 1993 waterborne Cryptosporidium outbreak, Milwaukee, Wisconsin Emerging Infectious Diseases 9 4 426–431 April 2003 12702221 2957981 10.3201/eid0904.020417 Approximately 403,000 residents were affected, and 4,400 were hospitalized. Immediate repairs were made to the treatment facilities along with continued infrastructure upgrades during the 25 years since the outbreak. The total cost of the outbreak, in productivity loss and medical expenses, was $96 million. Attendance at schools were severely affected, and schools had to throw away 68,000 servings of Jell-O due to the possibility that it was contaminated.Pulido Michael Cryptosporidium https://emke.uwm.edu/entry/cryptosporidium/ emke.uwm.edu 31 January 2025 At least 69 people died as a result of the outbreak. The city of Milwaukee has spent upwards to $510 million in repairs, upgrades, and outreach to citizens. Epidemiology Cryptosporidium are a chlorine-resistant enteric pathogens that cause gastrointestinal illness (cryptosporidiosis) with symptoms such as diarrhea. Other symptoms include stomach cramps, dehydration, nausea, vomiting, fever, or weight loss. Symptoms can be more severe for people who are immunocompromised, for whom diarrhea can lead to death. Enteric pathogens are microorganisms that humans ingest, typically through contaminated food or water.Division of Foodborne, Waterborne, and Environmental Diseases (DFWED) Home. (2023). Enteric Diseases Epidemiology Branch. Washington, D.C.: Centers for Disease Control and Prevention. Since Cryptosporidium is a coccidian parasite, it has oocysts.2024-06-03 CDC - DPDx - Cryptosporidiosis https://www.cdc.gov/dpdx/cryptosporidiosis/index.html 2026-09-10 www.cdc.gov en-us An oocyst is a period in the life cycle of a coccidian parasite. The oocysts in Cryptosporidium are the transmissible stage for cryptosporidiosis.2019-02-25 CDC - Parasites - Glossary https://www.cdc.gov/parasites/glossary.html https://web.archive.org/web/20240405062122/https://www.cdc.gov/parasites/glossary.html 2024-04-05 2026-09-10 www.cdc.gov en-us Most reports do not specify the species of Cryptosporidium involved in the outbreak. Several species cause cryptosporidiosis in humans, with most caused by Cryptosporidium parvum and Cryptosporidium hominis.MORGAN-RYAN UNA M. FALL ABBIE WARD LUCY A. HIJJAWI NAWAL SULAIMAN IRSHAD PAYER RONALD THOMPSON R. C. ANDREW OLSON M. LAL ALTAF LIHUA XIAO Cryptosporidium hominis n. sp. (Apicomplexa: Cryptosporidiidae) from Homo sapiens Journal of Eukaryotic Microbiology November–December 2002 49 6 433–440 10.1111/j.1550-7408.2002.tb00224.x 12503676 https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1550-7408.2002.tb00224.x 25 June 2024 en 1550-7408 4630522305 25 June 2024 https://web.archive.org/web/20240625153537/https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1550-7408.2002.tb00224.x live subscription However adding to the confusion, these two species were only split from each other in 2002. In 2003, Phaedra S. Corso et al. imply without evidence that it was C. parvum. In 2001, Alicia C. McDonald et al. clearly state that C. parvum is the cause,McDonald Alicia C. Mac Kenzie William R. Addiss David G. Gradus M. Stephen Linke George Zembrowski Elizabeth Hurd Margaret R. Arrowood Michael J. Lammie Patrick J. Priest Jeffrey W. Cryptosporidium parvum–Specific Antibody Responses among Children Residing in Milwaukee during the 1993 Waterborne Outbreak The Journal of Infectious Diseases 1 May 2001 183 9 1373–1379 10.1086/319862 11294669 https://academic.oup.com/jid/article/183/9/1373/931377 25 June 2024 en 1537-6613 118846463 20 January 2022 https://web.archive.org/web/20220120045545/https://academic.oup.com/jid/article/183/9/1373/931377 live subscription but the 1994 source they cite does not specify the species. McDonald et al. do find positive results testing blood samples with antigens derived from C. parvum, but a 2018 paper from Sumeeta Khurana and Preeti Chaudhary indicate that antigen tests are not species-specific and that molecular methods are needed to differentiate other species.Khurana Sumeeta Chaudhary Preeti Laboratory diagnosis of cryptosporidiosis Tropical Parasitology January–June 2018 8 1 2–7 10.4103/tp.TP_34_17 free 29930899 en 2229-5070 5991046 7704802362 A 2003 study by Ling Zhou et al. specifically addresses these issues and clearly identifies the pathogen in this outbreak as C. hominis.Zhou Ling Singh Ajaib Jiang Jianlin Xiao Lihua Molecular Surveillance of Cryptosporidium spp. in Raw Wastewater in Milwaukee: Implications for Understanding Outbreak Occurrence and Transmission Dynamics Journal of Clinical Microbiology 1 November 2003 41 11 5254–5257 10.1128/jcm.41.11.5254-5257.2003 14605176 262506 en 0095-1137 9173124979 History On April 4, 1993, pharmacist Jeff Langer contacted a local television station after the Milwaukee Health Department did not respond to his calls regarding substantial increase in gastrointestinal complaints. Sunday evening, April 4, the station came out to interview Jeff Langer regarding the substantial increase in requests for anti-diarrhea medications. Following that television interview, April 5, 1993, Milwaukee Health Department received additional reports of gastrointestinal illness at their local hospitals and calls of complaints related to reduced water-quality aesthetic. Water aesthetics include taste, color, odor, hardness/softness, and turbidity. They are considered a secondary standard under the EPA National Primary Drinking Water Regulations (NPDWR). Although these drinking aesthetics are under the EPA NPDWR, they are not federally enforced but are standard regulations that states may choose to adopt and enforce themselves. In the spring of 1993, turbidity was the main complaint. This was corroborated by Milwaukee Water Works records of Maximal Turbidity for both water treatment plants from March through April 1993. Causes The root cause of the epidemic was never officially identified; however, it was most likely the result of human error at the Howard Avenue Water Treatment Plant. Initially it was suspected to be caused by runoff from upstream cattle pastures.A Massive Outbreak in Milwaukee of Cryptosporidium Infection Transmitted through the Public Water Supply William R. Mac Kenzie Neil J. Hoxie Mary E. Proctor M. Stephen Gradus Kathleen A. Blair Dan E. Peterson James J. Kazmierczak David G. Addiss Kim R. Fox Joan B. Rose Jeffrey P. Davis July 21, 1994 New England Journal of Medicine 331 3 161–167 free 10.1056/NEJM199407213310304 7818640 It was also thought that melting ice and snowmelt carrying Cryptosporidium may have entered the water treatment plants through Lake Michigan. Botkin DB, Keller EA Environmental Science: Earth as a Living Planet 2005 978-0-471-48816-3 5th 441 Wiley Mac Kenzie et al. and the CDCJanuary 2025 showed that this outbreak was caused by Cryptosporidium oocysts that passed through the filtration system of one of the city's water-treatment plants, arising from a sewage treatment plant's outlet two miles upstreamJanuary 2025 in Lake Michigan. This abnormal condition at the water purification plant lasted from March 23 through April 8, after which the plant was shut down. The increased turbidity of the treated water was mitigated by the added flocculant polyaluminum chloride, but peaked again on April 5 after the plant changed to alum three days prior. Over the span of approximately two weeks, 403,000 Hoxie NJ, Davis JP, Vergeront JM, Nashold RD, Blair KA Cryptosporidiosis-associated mortality following a massive waterborne outbreak in Milwaukee, Wisconsin American Journal of Public Health 87 12 2032–2035 December 1997 9431298 1381251 10.2105/ajph.87.12.2032 of an estimated 1.61 million residents in the Milwaukee area (of which 880,000 were served by the malfunctioning treatment plant) became ill with the stomach cramps, fever, diarrhea and dehydration caused by the pathogen. After the outbreak, cryptosporidiosis antibody rates among Milwaukee children reached 80%, compared to only 10% prior to the outbreak.Cryptosporidium in Milwaukee's water supply caused widespread illness https://www.healio.com/news/infectious-disease/20120225/i-cryptosporidium-i-in-milwaukee-s-water-supply-caused-widespread-illness 22 February 2021 Infectious Disease News September 2007 Healio September 2007 21 February 2021 https://web.archive.org/web/20210221093625/https://www.healio.com/news/infectious-disease/20120225/i-cryptosporidium-i-in-milwaukee-s-water-supply-caused-widespread-illness live Deaths have been attributed to this outbreak, mostly among the elderly and immunocompromised people, such as people with AIDS. Social impact Reports of gastrointestinal illness began in April 1993; however, studies occurring after the outbreak confirmed that there were echoes of the epidemic beyond initial contamination as the population contracted the illness through secondary transmission. This resulted in negative public sentiment toward Milwaukee Water Works. Carrie Lewis, superintendent of Milwaukee water works in 2015, explained that "people had been hurt, they felt let down by their drinking water and it took a long time for them to believe that we knew what we were doing again,"Lewis, C. (2015, January 9). Superintendent of Milwaukee Water Works. (M. Gonzalez, & B. Gonzalez, Interviewers) It took ten years for Milwaukee citizens to begin to trust the public water supply again with the help of frequent community outreach by the utility. Current treatment in Milwaukee In the 2020s, Milwaukee consistently scored as one of the highest drinking water qualities in the state.Water Quality https://city.milwaukee.gov/water/WaterQuality https://web.archive.org/web/20260519140946/https://city.milwaukee.gov/water/WaterQuality May 19, 2026 2026-09-10 city.milwaukee.gov This is due to $508 million invested in water treatment and monitoring improvements since the outbreak.Ceraso, M. (2013). 20 years after fatal outbreak, Milwaukee leads on water testing. Wisconsin Water Watch. Improvements in treatment include: Activated charcoal filtration (Actiflo Carb) removes certain drugs, disinfectants, antibiotics.Water treatment process https://city.milwaukee.gov/water/customer/FAQs/qualityandhealth/Water-treatment-process.htm https://web.archive.org/web/20230413075617/https://city.milwaukee.gov/water/customer/FAQs/qualityandhealth/Water-treatment-process.htm April 13, 2023 2026-09-10 city.milwaukee.gov Monitoring on each stream of flow (8 streams) – previously, streams were only monitored before and after branching off (no way to monitor individual streams). Collection pipe for water was moved further out in the lake to draw higher quality water. Ozone treatment (treatment of chlorine-resistant microorganisms, such as Cryptosporidium)US Environmental Protection Agency (EPA) September 1999 Ozone Disinfection; Wastewater Technology Fact Sheet https://www3.epa.gov/npdes/pubs/ozon.pdf https://web.archive.org/web/20240125022604/https://www3.epa.gov/npdes/pubs/ozon.pdf 2024-01-25 Online monitoring/automation See also 1987 Carroll County cryptosporidiosis outbreak Pryor Avenue Iron Well Drinking water quality in the United States References Further reading Osewe P, Addiss DG, Blair KA, Hightower A, Kamb ML, Davis JP Cryptosporidiosis in Wisconsin: a case-control study of post-outbreak transmission Epidemiology and Infection 117 2 297–304 October 1996 8870627 2271709 10.1017/s0950268800001473 Gradus S 10 January 2014 Milwaukee, 1993: The Largest Documented Waterborne Disease Outbreak in US History. Water Quality and Health Council https://waterandhealth.org/safe-drinking-water/drinking-water/milwaukee-1993-largest-documented-waterborne-disease-outbreak-history/ 3 December 2020 11 November 2022 https://web.archive.org/web/20221111173619/https://waterandhealth.org/safe-drinking-water/drinking-water/milwaukee-1993-largest-documented-waterborne-disease-outbreak-history/ dead External links Parasites - Cryptosporidium - US Centers for Disease Control and Prevention Water Quality - Milwaukee Water Works Surface Water Treatment Rules - EPA Milwaukee Health Department Laboratory Cryptosporidium and Public Health (1995) - Milwaukee Health Department Corso Phaedra S. Kramer Michael H. Blair Kathleen A. Addiss David G. Davis Jeffrey P. Haddix Anne C. Costs of Illness in the 1993 WaterborneCryptosporidiumOutbreak, Milwaukee, Wisconsin Emerging Infectious Diseases Centers for Disease Control and Prevention (CDC) 9 4 2003 1080-6040 10.3201/eid0904.020417 426–431 12702221 2957981 https://wwwnc.cdc.gov/eid/article/9/4/02-0417_article none Category:Cryptosporidiosis Category:1993 disasters in the United States Milwaukee Cryptosporidiosis outbreak Milwaukee Cryptosporidiosis outbreak Category:1993 disease outbreaks Category:March 1993 in the United States Category:April 1993 in the United States Category:Disease outbreaks in the United States