A Multi-Jurisdictional Trichinellosis Cluster Investigation with Possible Association to Free-Range Pork Consumption

BACKGROUND: During a three-week period in early 2012, three confirmed cases of trichinellosis were identified in the National Capital Region(two cases were married Fairfax County residents and the other was a D.C. resident). Prior to their respective onset of illness, all three cases consumed free-range pork at two different D.C. restaurants. During 2008-2010, an annual average of 20 cases were reported to CDC; the vast majority of these cases reported consuming game meat. Prior to these recent reports, the last reported case of trichinellosis in Virginia was in 2008 in an adult with recent history of consuming wild elk.

METHODS: On 2/1/12, the Fairfax County Health Department received a positive Trichinella commercial lab report of a male Fairfax County resident. Once identified, the reported case prompted further investigation to characterize the case and identify any additional cases. An additional case investigation was performed on the case's spouse, who presented with similar symptoms. The couples’ serologic specimens were forwarded to CDC for testing on 2/16/12(Scimedx kit). On 2/15/2012, the D.C. Department of Health also received a positive Trichinella commercial lab report on a male D.C. resident (specimen forwarded to the CDC). Environmental health inspections were conducted at all restaurants where the three cases consumed pork. The geographic and temporal clustering of cases and commonalities in type of undercooked pork consumed at two D.C. restaurants prompted a USDA traceback of the pork and the CDC testing of pork samples from one restaurant.

RESULTS: All three cases met the CDC confirmed case definition for trichinellosis as the CDC laboratory confirmed the lab results. The onset dates of the three cases ranged from 1/7/2012- 1/13/2012. The environmental health focus was on two separate D.C. restaurant exposures(consumption dates of 12/25/11 & 1/5/12). All three cases consumed free-range pork chops cooked to “chef's specifications.” On 2/7/12, the D.C. Department of Health acquired the distributor of the pork at the two restaurants as well as the brand. The USDA traceback did not identify common suppliers of pork and the CDC ruled out Trichinella larvae in the pork sample.

CONCLUSIONS: Although these investigations did not yield a definitive source of infection, the three cases likely source of infection was undercooked free-range pork. While the overall number of trichinellosis cases reported has decreased because of improved pig-raising practices in the pork industry and freezing of pork, the increasing popularity of free-range pork could result in an increase trichinellosis cases in America.