Outbreak Investigation Updates by Date

Published on July 31, 2019 at 1:00 PM ET

July 17, 2019

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA)external icon are investigating a multistate outbreak of Salmonella serotypes I 4,[5],12:i:-, Infantis, Newport, and London infections linked to contact with pig ear dog treats.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health laboratories coordinated by CDC. DNA fingerprinting is performed on Salmonella bacteria isolated from ill people by using standardized laboratory and data analysis techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE. WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of July 17, 2019, a total of 93 people infected with the outbreak strains of Salmonella have been reported from 27 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from October 1, 2018 to June 20, 2019. Ill people range in age from less than 1 year to 90 years, with a median age of 38 years. Forty-three (46%) ill people are female. Of 67 ill people with information available, 20 (30%) have been hospitalized. No deaths have been reported.

Illnesses might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Whole genome sequencing analysis of Salmonella isolates from 33 ill people predicted antibiotic resistance or decreased susceptibility to ampicillin, ciprofloxacin, gentamicin, nalidixic acid, streptomycin, sulfisoxazole, and tetracycline. Testing of one clinical isolate using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) provided comparable results. If antibiotics are needed, infections related to this outbreak may be difficult to treat with some commonly recommended antibiotics, and may require a different antibiotic choice.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback evidence indicates that contact with pig ear dog treats is the likely source of this outbreak.

In interviews, ill people answered questions about animal contact in the week before they became ill. 63 (90%) of 70 ill people reported contact with a dog before getting sick. Of 49 people with available information, 34 (69%) reported contact with pig ear dog treats or with dogs who were fed pig ear dog treats. Both of these proportions are significantly higher than the results from a survey pdf icon[PDF – 787 KB] of healthy people who reported contact with dogs (61%) or handling dog treats, such as pig ears (16%), in the week before interview.

During the investigation, officials from the Michigan Department of Agriculture and Rural Developmentexternal icon gathered pig ear dog treats at retail locations where ill people reported buying the products. They sampled pig ears for Salmonella. As additional strains of Salmonella were identified in pig ear products, a search of the CDC PulseNet database identified ill people infected with some of these strains, including Salmonella Infantis, Salmonella London, and Salmonella Newport. These ill people were added to the outbreak investigation.

On July 3, 2019, Pet Supplies Plus recalledexternal icon bulk pig ears stocked in open bins because they might be contaminated with Salmonella. Consumers should not feed recalled pig ears to their dog. Throw them away in a secure container so that your pets and other animals can’t eat them. Even if some of the recalled pig ears were fed to dogs and no one got sick, do not continue to feed them to pets. Wash containers, shelves, and areas that held the recalled pig ear dog treats with hot, soapy water.

A common supplier of pig ear dog treats has not been identified. Pet owners can take steps to keep their families healthy while feeding pets.

This investigation is ongoing, and CDC will provide updates when more information is available.

July 3, 2019

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are investigating a multistate outbreak of multidrug-resistant Salmonella I 4,[5],12:i:- infections linked to contact with pig ear dog treats.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health laboratories coordinated by CDC. DNA fingerprinting is performed on Salmonella bacteria isolated from ill people by using standardized laboratory and data analysis techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE. WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of July 2, 2019, a total of 45 people infected with the outbreak strain of Salmonella I 4,[5],12:i:- have been reported from 13 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from November 18, 2018, to June 13, 2019. Ill people range in age from less than 1 year to 81 years, with a median age of 23. Half (50%) of ill people are female. Of 39 ill people with information available, 12 (31%) have been hospitalized. No deaths have been reported.

Illnesses might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Whole genome sequencing analysis of Salmonella isolates from 30 ill people predicted antibiotic resistance or decreased susceptibility to ampicillin, ciprofloxacin, gentamicin, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole. Testing of one clinical isolate using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) provided comparable results. These antibiotic-resistant infections may be difficult to treat with commonly recommended antibiotics, and may require a different antibiotic choice.

Investigation of the Outbreak

Epidemiologic evidence indicates that contact with pig ear dog treats is the likely source of this outbreak.

In interviews, ill people answered questions about animal contact in the week before they became ill. Thirty-four (89%) of 38 ill people reported contact with a dog before getting sick. Of 24 people with available information, 17 (71%) reported contact with pig ear dog treats or with dogs who were fed pig ear dog treats. Both of these proportions are significantly higher than the results from a survey pdf icon[PDF – 787 KB] of healthy people who reported contact with dogs (61%) or handling dog treats, such as pig ears (16%), in the week before interview.

Officials from the Michigan Department of Agriculture and Rural Developmentexternal icon gathered pig ear dog treats at retail locations where ill people reported buying the products. They sampled pig ears for Salmonella. Although the outbreak strain was not identified, other strains of Salmonella were. Investigators are checking to see if any human illnesses are linked to those strains. Retail locations where sampling occurred have removed pig ears from shelves.

On July 3, 2019, Pet Supplies Plus recalledexternal icon bulk pig ears stocked in open bins because they might be contaminated with Salmonella. Consumers should not feed recalled pig ears to their dog. Even if some of the recalled pig ears were fed to dogs and no one got sick, do not continue to feed them to pets. Wash containers, shelves, and areas that held the recalled pig ear dog treats with hot, soapy water.

A common supplier of pig ear dog treats has not been identified. Pet owners can take steps to keep their families healthy while feeding pets.

This investigation is ongoing, and CDC will provide updates when more information is available.