Outbreak Investigation Updates by Date

Final Update

Published on April 15, 2021

This investigation is over. CDC continues to work with state public health officials to monitor for new illnesses. Although the investigation is over, people can still get a Campylobacter infection from dogs. Always take steps to stay healthy around your dog.

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December 17, 2019

CDC and public health officials in several states are investigating a multistate outbreak of multidrug-resistant human Campylobacter jejuni infections linked to contact with puppies from pet stores.

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 and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on Campylobacter bacteria isolated from ill people by using a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria from people infected with Campylobacter were related genetically to each other. This means that people in the outbreak are more likely to share a common source of infection. WGS also showed that bacteria from people infected with Campylobacter in the current outbreak are related genetically to a 2016–2018 outbreak of multidrug-resistant Campylobacter infections linked to pet store puppies.

As of December 17, 2019, a total of 30 people infected with Campylobacter have been reported from 13 states. A list of the states and the number of confirmed cases in each state can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from January 6, 2019, through November 10, 2019. Ill people range in age from 8 months to 70 years, with a median age of 34; 52% of ill people are female. Of 26 people with information available, 4 hospitalizations have been reported. 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.

WGS analysis of 26 isolates from ill people predicted antibiotic resistance to tetracycline (26 isolates), ciprofloxacin (25), nalidixic acid (25), azithromycin (23), erythromycin (23), clindamycin (23), telithromycin (23), and gentamicin (18). Testing of one outbreak isolate using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory confirmed these results.

Investigation of the Outbreak

Epidemiologic and laboratory evidence indicate that puppies purchased from pet stores are the likely source of this outbreak. Many of the cases had contact with puppies or were employees at pet stores, including Petland.

CDC included ill people in this outbreak if

  • their stool (poop) sample grew Campylobacter jejuni in the laboratory (called a culture-confirmed infection) and they also had a link to puppies, or
  • they had a culture-confirmed Campylobacter jejuni infection that was closely related genetically to a confirmed puppy-linked case by WGS.

In interviews, ill people answered questions about dog, puppy, and other exposures they had in the week before they became ill. Of 24 people interviewed, 21 (88%) reported contact with a puppy in the week before illness started, and 15 (71%) of those 21 people reported contact with a puppy from a pet store. When asked about the specific pet store, 12 (80%) of those 15 people reported either having contact with a puppy or working at a Petland store.

Investigators reported eight more ill people who had contact with a puppy at Petland and had a diagnostic test showing they were infected with Campylobacter bacteria. However, CDC did not include these people in the outbreak case count because no bacterial samples were available for WGS. Public health investigators use WGS to identify illnesses that are part of multistate outbreaks.

A single, common supplier of puppies has not been identified. This investigation is ongoing. CDC will provide updates if more information becomes available.