A Multi‐stateSalmonellaTyphimurium Outbreak Associated with Frozen Vacuum‐packed Rodents used to Feed Snakes

Abstract

Summary From December 2005 through January 2006, the Minnesota Department of Health (MDH) identified four human clinical isolates of Salmonella Typhimurium that were indistinguishable by pulsed‐field gel electrophoresis (PFGE). During routine interviews, three of the cases reported attending the same junior high school and two handled snakes in the science classroom. MDH collected environmental samples from the school’s science classroom for Salmonella culturing; these included environmental samples and frozen vacuum‐packed mice purchased over the internet to feed the classroom snakes. Through PulseNet, a national molecular subtyping surveillance network for enteric bacteria, 21 human S. Typhimurium isolates with indistinguishable PFGE patterns were identified in the United States since December 2005. Each state determined whether these human cases had recent exposure to snakes fed vacuum‐packed rodents. Texas state officials conducted tracebacks of the vacuum‐packed mice and collected samples at the breeding facility. Nineteen of 21 cases were interviewed, and seven reported contact with frozen vacuum‐packed rodents from the same internet‐based supplier in Texas. In Minnesota, the outbreak PFGE subtype of S. Typhimurium was isolated from the snakes, frozen feed rodents, and the classroom environment. Three human cases were identified in Michigan, Pennsylvania, and Wyoming. The outbreak PFGE subtype of S. Typhimurium was isolated from the Pennsylvania case’s frozen rodents and the Michigan case’s pet snake. The outbreak PFGE subtype of S. Typhimurium was also isolated from the supplier’s rodent facility. This was a S. Typhimurium outbreak associated with frozen rodents. Human transmission likely occurred through direct contact with snakes and contaminated environmental surfaces. This report represents the second recent multi‐state salmonellosis outbreak associated with commercially distributed rodents. Stronger oversight of the commercial rodent industry is warranted.

Free-living snakes as a source and possible vector of Salmonella spp. and parasites

“…The observed differences also can result from different habitats and prey preferences of both snakes species. Influence of food intake on Salmonella prevalence is hard to estimate, but some studies indicate on this route as a way of transmission of new serovars for an individual (Fuller et al 2008).…”

Prevalence of Salmonella in Australian Reptiles

“…Salmonella Typhimurium has been isolated from snakes fed vacuum-packed frozen rodents infected with the same serotype (Fuller et al, 2008). Although Salmonella was not isolated from Healesville Sanctuary rodents, more research is needed to assess the risks that mice and rats pose to Salmonella colonization in Australian reptiles.…”

The Burden of Salmonellosis in the United States

“…For example, in 2008 there was a multi-state outbreak of Salmonella Typhimurium associated with frozen vacuum-packed rodents that are used to feed snakes (Fuller et al, 2008). This occurrence represents a rare, but wide-spread outbreak associated with commercially distributed rodents.…”