B. suis is an extremely infectious bacteria that’s usually found in pigs. The most common symptom in pigs is reproductive losses, such as stillbirths, though they can also develop other symptoms, such as abscesses and arthritis. In humans, it causes an insidious, hard-to-detect infection called brucellosis, which describes an infection from any Brucella species: B. suis, B. melitensis, B. abortus, and B. canis.
In the US, there are only about 80 to 140 brucellosis cases reported each year, and they’re mostly caused by B. melitensis and B. abortus. People tend to get infected by eating raw (unpasteurized) milk and cheeses. B. suis, however, is generally linked to hunting and butchering feral pigs and hogs.
Until recently, the Brucella species were designated as select agents by the US government, a classification to flag pathogens and toxins that can potentially be a severe threat to public health, such as if they’re used in a bioterror attack. The current list includes things like anthrax and Ebola virus. Brucella species were originally listed because they can be easily aerosolized, and only a small number of the bacterial cells are needed to spark an infection. In humans, infections can be both localized and systemic and have a broad range of clinical manifestations. Those include brain infections, neurological conditions, arthritis, anemia, respiratory involvement, pancreatitis, cardiovascular complications, like aneurysms, and inflammation of the spinal cord, among many other things.
In January, federal officials removed Brucella species from the select agents list—a designation that limits the types and amount of research that can be done on a pathogen. According to the US Department of Agriculture, the reason for the removal was to ease those limits, thereby making it easier for researchers to conduct veterinary studies and develop vaccines for animals.
Perilous present
After finding B. suis, the doctors gathered more information about how the man could have contracted this rare species. The man said he wasn’t a hunter but recalled receiving a gift of feral swine meat from a local hunter on several occasions in 2017. Though he couldn’t recall the specific hunter who gave him the biohazardous bounty, he remembered handling the raw meat and blood with his bare hands—a clear transmission risk—before cooking and eating it.