Two trichina outbreaks in Alaska; it was the walrus

There’s not a lot of trichina in the U.S. food supply anymore. It used to be a much more important pathogen. In the 1940s, when the US Public Health Service started tracking the illness, there was around 400 cases a year. Now there’s about 20.

A couple of the more notable incidents were reported in MMWR last week – two outbreaks in Alaska linked to raw walrus.

During July 2016–May 2017, the Alaska Division of Public Health (ADPH) investigated two outbreaks of trichinellosis in the Norton Sound region associated with consumption of raw or undercooked walrus (Odobenus rosmarus) meat; five cases were identified in each of the two outbreaks. These were the first multiple-case outbreaks of walrus-associated trichinellosis in Alaska since 1992.

The walrus consumed during the implicated meal in the second outbreak had been harvested and butchered by patients F and I during the previous 1–3 months, and the meat had been stored frozen in unlabeled bags in their respective household chest freezers. The meat was prepared by patient H, who reported that she boiled it for approximately 1 hour, after which the exterior was fully cooked, but the interior remained undercooked or raw, which was the desired result; interviewed persons reported that many community members prefer the taste and texture of undercooked or raw walrus meat to that of fully cooked meat.

These outbreaks also highlight the importance of culturally sensitive public health messaging. In areas where wild game species are harvested for subsistence, traditional methods of collecting, handling, preparing, storing, and consuming meat often have great cultural significance; however, some of these methods can be inconsistent with public health best practices. Rather than promoting or proscribing specific methods, public health messages that focus on communicating risks and explaining the manner and magnitude of risk reduction that can be achieved using different approaches (e.g., alternative methods of preparing meat for consumption) enable members of the target population to make informed decisions that integrate their traditional practices with their awareness and tolerance of risks.