Past Outbreaks in Wisconsin

Archived Outbreaks and Investigations

Below is a list of past outbreaks and investigations with wide impact in Wisconsin.

For current outbreaks and investigations, please visit our Outbreaks in Wisconsin page.

Stack of folders full of paper documents

2018 Outbreaks

Salmonellosis Linked to Kellogg's Honey Smacks Cereal
Final Update 6/19/19

Bowl of dry breakfast cereal

Cyclosporiasis Linked to Salads Sold at McDonald's
Final Update 6/19/19

Salmonellosis Linked to Cut Melons
Final Update 6/19/19

Fresh melon cut up and ready to eat

  • The Wisconsin Department of Health Services (DHS) and the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) alerted Wisconsin consumers to a multistate outbreak of Salmonella Adelaide infections linked to the consumption of pre-cut melons. No cases were identified in Wisconsin residents, but the recalled products were sold at locations in the state.
  • The FDA identified Costco stores in the following Wisconsin cities as having distributed the recalled pre-cut melon: Bellevue (Green Bay), Grafton, Grand Chute, Menomonee Falls, Middleton, New Berlin, Pewaukee, Pleasant Prairie, and Sun Prairie.
  • The full list of stores where this product was distributed is available on the FDA’s website.
  • No cases were reported in Wisconsin. Nationally, 77 people infected with the Salmonella strain have been reported.
  • Additional information can be found on the following websites:

Synthetic Cannabinoids (K2, Spice)
Final Update 6/19/19

  • Case counts in Wisconsin can be found on our synthetic cannabinoid webpage.
  • The CDC is investigated this outbreak across the nation.
  • Share our one-page fact sheet on synthetic cannabinoids (PDF) . Now available in English and Spanish.
  • If you have used any of these products, and start experiencing severe, unexplained bleeding or bruising, please have someone take you to the hospital immediately or call 911. Image of Synthetic Cannabinoids fact sheet "K2, Spice, Black Mamba, Fake Weed, Green Giant"

Acute Flaccid Myelitis (AFM) Investigation
Final Update 6/4/19

Digital illustration of a neuron

  • The Wisconsin Department of Health Services (DHS) and local health departments (LHDs) are actively working to identify potential cases of acute flaccid myelitis (AFM). DHS is working with health care providers and the Centers for Disease Control and Prevention (CDC) during this developing situation.
  • There were nine confirmed and three probable cases of AFM in Wisconsin.
    • AFM is also called “acute flaccid paralysis with anterior myelitis” or “polio-like syndrome.” It is rare and mainly found in children. It affects the body’s nervous system, specifically the spinal cord. AFM can be caused by some viruses, environmental toxins, and genetic disorders.
    • Viruses that can cause AFM include enteroviruses (polio and non-polio) and flaviviruses, such as West Nile Virus, Japanese Encephalitis virus, or St. Louis encephalitis virus. Other viruses that may cause AFM are herpesviruses (e.g., cytomegalovirus, Epstein-Barr virus) and adenoviruses.
  • See the DHS AFM webpage for more information on common symptoms and treatment of AFM. Seek medical care as soon as possible if you notice any symptoms of AFM in you or your child, for example if your child is not using their arm or leg normally.
  • Additional information can be found on the following websites:
    • AFM Fact Sheet, P-01298 (Multiple Languages): Educational fact sheet for the general public on AFM covering signs and symptoms, treatment, and prevention.
    • About AFM: CDC webpage including information on symptoms, diagnosis, possible causes of AFM, treatment, and prevention.

E. coli O157:H7 Linked to Romaine Lettuce - Fall 2018
Final Update 1/10/19

  • Romaine Lettuce on white backgroundThe Wisconsin Department of Health Services (DHS), Centers for Disease Control and Prevention (CDC), U.S. Food and Drug Administration (FDA), and numerous other states investigated a multistate outbreak of E. coli O157:H7 infections.
  • This outbreak was not related to the multistate outbreak of E. coli O157:H7 infections linked to romaine lettuce that occurred earlier in 2018 (see below for Wisconsin-specific information).
  • Nationwide, 62 people from 16 states were infected with the outbreak strain of E. coli O157:H7. Illnesses started on dates ranging from Oct. 7 to Dec. 4, 2018.
  • There were 25 people hospitalized, with no deaths reported. One Wisconsin E. coli O157:H7 infection was linked to the outbreak.
  • This outbreak appears to be over as of January 9, 2019.
    • Contaminated lettuce that made people sick in this outbreak should no longer be available.
    • Epidemiologic, laboratory, and traceback evidence from the United States and Canada indicated that romaine lettuce harvested from the Central Coastal growing regions of northern and central California was the likely source of the outbreak.
  • Additional information on the following websites:

Cyclosporiasis Linked to Vegetable Trays
Final Update 9/7/18

Store bought vegetable tray

  • The Department of Health Services (DHS), the Wisconsin Department of Agriculture, Trade, and Consumer Protection (DATCP), and local health departments are working with the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) to investigate an outbreak of cyclosporiasis linked to the consumption of Del Monte vegetable trays sold at Kwik Trip.
    • 177 cases report consuming a Del Monte vegetable tray purchased at a Kwik Trip location in Wisconsin. Most ill persons reported purchasing the tray on or after May 16, 2018. Kwik Trip voluntarily removed the trays from sale in their stores on June 8, 2018.
    • Consumers should not eat 6 oz. or 12 oz. Del Monte vegetable trays (containing broccoli, cauliflower, carrots, and dill dip) purchased at a Kwik Trip location.
    • Del Monte issued a recall of 6 oz, 12 oz, and 24 oz vegetable trays with dip. See the FDA website for full details.
  • As of Sept. 5, 2018, CDC was notified of 250 laboratory-confirmed cases of Cyclospora infection in people from 4 states who reported consuming pre-packaged Del Monte Fresh Produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip.
  • Based on epidemiological data or traceback evidence, it was not possible to determine if an individual component of the vegetable trays was the likely vehicle of infection. Read the related statement from the FDA for additional information.
  • See the DHS cyclosporiasis fact sheet for more information on common symptoms and treatment of cyclosporiasis. If you have any symptoms of cyclosporiasis, please contact your doctor.
  • Additional information can be found on the following websites:

Multistate Outbreak of Salmonella Infections Linked to Contact with Backyard Poultry
Final Update 6/14/19

  • Chickens feeding on the grassDuring 2018, the Wisconsin Department of Health Services (DHS) and local health departments worked with the Centers for Disease Control and Prevention (CDC) to investigate multistate outbreaks of Salmonella infections linked to contact with backyard poultry.
    • The CDC reported that 334 people from 47 states became ill with a strain of Salmonella linked to backyard poultry during 2018. 
    • In Wisconsin, 33 laboratory-confirmed cases of Salmonella were linked to the 2018 national backyard poultry outbreak. 
    • Nationally, illness onset dates ranged from Feb. 15, 2018 to Aug. 10, 2018. Children younger than 5 years accounted for 21% of illnesses.
  • Outbreaks of Salmonella infections linked to contact with backyard poultry happen every year in the U.S. Many of these infections are preventable.  
  • More information about outbreaks associated with live poultry can be found at CDC's webpage U.S. Outbreaks of Zoonotic Diseases Spread between Animals and People.
  • More information about backyard poultry and safe handling can be found at the DHS backyard poultry webpage.

E. coli O157:H7 Linked to Romaine Lettuce - Spring 2018
Final Update 6/28/18

  • The Wisconsin Department of Health Services (DHS), the Centers for Disease Control and Prevention (CDC), U.S. Food and Drug Administration (FDA), and numerous other states investigated a multistate outbreak of E. coli O157:H7 infections.
  • Epidemiologic, laboratory, and traceback evidence indicated that romaine lettuce from the Yuma growing region was the likely source of this outbreak.
  • Nationwide, 210 people from 36 states were infected with the outbreak strain of E. coli O157:H7. Illnesses started on dates ranging from March 13, 2018, to May 12, 2018.
  • As of 6/28/2018, 96 people were hospitalized, with five deaths reported. Three Wisconsin E. coli O157:H7 infections have been linked to the outbreak.
2017 Outbreaks

Seoul Hantavirus
Final Update 05/26/2017

  • Three ratsDuring 2017, the Wisconsin Department of Health Services (DHS), Wisconsin local health departments, the Centers for Disease Control and Prevention (CDC), and other state health departments investigated an outbreak of illnesses caused by the Seoul virus, a rare type of hantavirus carried by Norway and black rats.
  • The outbreak was detected in January 2017 when two Wisconsin residents were diagnosed with Seoul hantavirus (SHV), which can cause hemorrhagic fever with renal syndrome. Norway and black rats are the only known reservoir. The investigation determined the affected individuals were in routine contact with pet rats, either owning rats as pets or operating a rattery where they regularly sold and exchanged rats with individuals and other ratteries.
  • The response efforts included tracking movement of rats between locations (ratteries, pet homes) with infected rats, coordination of hantavirus testing for rats linked to the outbreak, and follow-up with people exposed to infected rats or ratteries.
  • Nationwide, 17 laboratory-confirmed recent human cases of SHV infection were reported as part of this outbreak, including three cases in Wisconsin. Two additional Wisconsin residents were identified with evidence of past infection.
    • The outbreak investigation led to the identification of 31 infected ratteries in 11 states and Canada. This indicated that Seoul virus should be considered endemic in the U.S., and that pet rats in the U.S., including Wisconsin, can be carrying Seoul virus at any time.
    • Rat owners and breeders may wish to determine if a rat is infected prior to introducing it into their home or rattery. Commercial testing for Seoul virus is available through several laboratories. Contact your veterinarian for testing information.
  • See the DHS hantavirus fact sheet, P-42053 for more information on common symptoms and prevention of SHV. If you have any symptoms of SHV and a history of rat contact, please contact your doctor.
  • Additional information can be found on the following websites:
2016 Outbreaks

Multidrug-resistant Campylobacter Outbreak
Final Update 01/18/2018

Sleepy puppy rests in his owner's arm

  • The Wisconsin Department of Health Services (DHS), the Centers for Disease Control and Prevention (CDC), several other states, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) investigated a multistate outbreak of multidrug-resistant (MDR) Campylobacter infections.
  • Nationwide, 113 people from 17 states were infected with the outbreak strain of MDR Campylobacter, including eight people in Wisconsin. Illnesses started on dates ranging from Jan. 12, 2016, to Jan. 7, 2018.
    • Of the 103 ill people with information available, 23 (22%) were hospitalized.
    • This outbreak was linked to contact with pet store puppies. Of those who became ill, 90% had a link to puppies at, or from, a Petland store, or had contact with with a person who became sick after contact with a puppy from a Petland store.
  • In Wisconsin, eight people became sick and two were hospitalized.
  • All puppies and dogs can carry Campylobacter bacteria. Because of this, it is especially important to wash your hands thoroughly with running water and soap for at least 20 seconds every time you touch dogs, their poop, or their food. Adults should supervise handwashing for young children. Please see our Handwashing After Animal Contact flyer, P-01699 for more information about how to prevent these infections.
  • See the DHS campylobacteriosis fact sheet, P-42045 for more information on common symptoms and treatment of campylobacteriosis. If you have any symptoms of campylobacteriosis, please contact your doctor.
  • Additional information can be found on the following websites:

Elizabethkingia anophelis
Final Update 05/03/2016

Elizabethkingia Anophelis - culture plate

  • The Wisconsin Department of Health Services (DHS) and the Centers for Disease Control and Prevention (CDC) investigated an outbreak of bacterial infections caused by Elizabethkingia anophelis.
  • There were 67 total cases reported to DHS during this outbreak. Of those cases, 63 were confirmed, and four tested positive for Elizabethkingia but will never be confirmed as the same strain of Elizabethkingia anophelis because the specimens were not available for testing.
  • The majority of patients who acquired these infections were over 65 and all patients had a history of at least one underlying serious illness.
  • Counties with confirmed cases include Columbia, Dane, Dodge, Fond du Lac, Jefferson, Milwaukee, Ozaukee, Racine, Sheboygan, Washington, Waukesha, and Winnebago.
  • There were 18 deaths among individuals with confirmed Elizabethkingia anophelis infections and an additional one death among possible cases for a total of 19 deaths. It was not determined if these deaths were caused by the infection or other serious, pre-existing health problems. Counties where deaths occurred are: Columbia, Dodge, Fond du Lac, Milwaukee, Ozaukee, Racine, Sheboygan, Washington, and Waukesha.
  • DHS quickly identified effective antibiotic treatment for Elizabethkingia, and alerted health care providers, infection preventionists, and laboratories statewide. Initial guidance was sent on January 15, 2016, and there was a rapid identification of cases and health care providers were able to treat and improve outcomes for patients.
  • Additional information can be found on the following websites:
2015 Outbreaks

Salmonella Heidelberg
Final Update 02/12/2018

Calf laying on hay

Last Revised: June 20, 2019