Introduction

CDC collaborated with public health officials in many states and the U.S. Food and Drug Administration to investigate an outbreak of human Salmonella Typhimurium infections linked to contact with frozen feeder rodents used to feed pet reptiles.

Public health investigators used the PulseNet system to identify cases of illness that were part of this outbreak. PulseNet, the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC, obtains DNA “fingerprints” of Salmonella bacteria through diagnostic testing with pulsed-field gel electrophoresis, or PFGE, to identify cases of illness that were part of this outbreak. This PFGE pattern had been seen before in PulseNet and in the past had typically caused 4 to 8 cases per month during the outbreak period.

A total of 41 persons infected with the outbreak strain of Salmonella Typhimurium were reported from 21 states since January 11, 2014. The number of ill persons reported from each state was as follows: Alabama (1), Arizona (2), California (7), Colorado (1), Illinois (1), Kentucky (1), Maryland (1), Michigan (2), Minnesota (1), Missouri (3), Montana (3), New Jersey (3), New Mexico (1), North Carolina (1), Ohio (4), Oregon (2), Pennsylvania (3), South Carolina (1), South Dakota (1), Texas (1), and Virginia (1).

Among 35 persons with available information, dates that illnesses began ranged from January 11, 2014 to May 17, 2014. Ill persons ranged in age from younger than 1 year to 69 years, with a median age of 21 years. Fifty-four percent of ill persons were female. Among 37 persons with available information, 6 (16%) were hospitalized. No deaths were reported.

This outbreak of Salmonella Typhimurium infections was not related to an outbreak of Salmonella infections related to snakes and feeder rodents in CanadaExternal .

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback investigations conducted by officials in local, state, and federal public health, veterinary, agriculture, and regulatory agencies indicated that contact with frozen feeder rodents used to feed pet reptiles was a likely source of this outbreak of human Salmonella Typhimurium infections. Frozen feeder rodents may include mice, rats, or other rodents of different sizes and ages. Frozen feeder rodents are used to feed some pet reptiles, amphibians, and birds of prey.

In interviews, ill persons answered questions about foods eaten and animal contact during the week before becoming ill. Twenty-two (61%) of 36 ill persons interviewed reported contact with multiple types of reptiles, including snakes and lizards. Seventeen (77%) of the 22 ill persons reporting reptile exposure were able to provide information about what the reptile was fed. Fifteen (88%) of these 17 ill persons reported exposure to frozen feeder rodents.

The Oregon State Public Health Laboratory isolated the outbreak strain of Salmonella Typhimurium in one sample of unused frozen mice, packaged by Reptile Industries, Inc. and sold under the brand name Arctic Mice at PetSmart, collected by the Oregon Department of Public Health from an ill person’s home.

Testing conducted by FDA isolated the outbreak strain in two samples of frozen feeder rodents collected during an FDA investigation at the Reptile Industries facility.

On May 20, 2014, as Reptile Industries, Inc. was unable to conclusively identify and withdraw from the market all possibly contaminated products, FDAExternal issued a warning to pet owners who purchased frozen rodents packaged by Reptile Industries, Inc. since January 11, 2014, that they had the potential to be contaminated with Salmonella. Reptile Industries, Inc. packages frozen rodents for PetSmart stores nationwide and they are sold under the brand name Arctic Mice.

FDA currently advises pet owners who have Reptile Industries Inc.’s Arctic Mice brand frozen rodents purchased from PetSmart from January 11, 2014 through May 21, 2014, to dispose of the product by placing it in a sealed container in the trash so that no children, pets, or other animals, such as wildlife, may be able to reach it.

CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory conducted antibiotic resistance testing on Salmonella Typhimurium isolates collected from three ill persons infected with the outbreak strain; all isolates were pansusceptible (susceptible to all antibiotics on the NARMS panel). NARMS is a U.S. public health surveillance system that tracks antibiotic resistance in foodborne and other enteric bacteria found in people, raw meat and poultry, and food-producing animals. NARMS is an interagency partnership among CDC, FDA, the U.S. Department of Agriculture (USDA), and state and local health departments. The NARMS human surveillance program at CDC monitors antibiotic resistance in Salmonella and several other bacteria isolated from clinical specimens and submitted to NARMS by public health laboratories.