Outbreak of Trichinella spiralis infections associated with a wild boar hunted at a game farm in Iowa

Abstract

Background: Rates of trichinellosis have declined significantly in the United States due to improved pork production practices and public awareness of the danger of eating raw or undercooked pork. In April 2011, the Minnesota Department of Health received a report of presumptive trichinellosis in a 50-year-old man with a history of wild boar consumption. A public health investigation was initiated.

Methods: Medical record reviews and patient and family interviews were conducted. Trichinella species serology was performed on patient and family serum samples, and larval identification was attempted on clinical specimens and meat samples.

Results: The index patient harvested a wild boar from an Iowa game farm; he processed the meat after returning home and developed gastrointestinal symptoms 2 days later. Four days after his illness onset, all 5 family members consumed a roast from the boar. The index patient sought healthcare 4 times after illness onset before being definitively diagnosed with trichinellosis. Following initiation of albendazole therapy, the index patient developed atrial fibrillation. One additional family member who processed the raw meat was diagnosed with trichinellosis. Trichinella spiralis larvae were identified in wild boar meat samples.

Conclusions: Trichinellosis has long been recognized as a potential hazard of consuming undercooked wild carnivore meat, and historically has been associated with consumption of pork from domestic swine, but may be unfamiliar to practicing clinicians in the United States. Education of hunters and the broader population on the potential for trichinellosis and the importance of proper handling and cooking meat from wild or free-range animals needs to be reinforced.

Keywords: Trichinella spiralis; human trichinellosis; outbreak; pork; wild boar.

Figure 1

Timeline of events preceding and during an investigation of a trichinellosis outbreak associated with wild boar consumption. Abbreviations: ER, emergency room; GI, gastrointestinal; MDH, Minnesota Department of Health.

Figure 2

Trichinella larvae encysted in sartorius muscle of index patient (hematoxylin and eosin stain, magnification 40×).

Figure 3

Computed tomographic imaging of the index patient’s head demonstrating swollen rectus muscles of the eye (as indicated by arrows).

Figure 4

Trichinella larvae encysted in muscle tissue from wild boar ham roast (wet mount, magnification 40×).