Caribou and reindeer, especially in northern Alaska, are known to be infected with a bacteria, Brucella suis biovar 4, that causes a disease known as rangiferine brucellosis. These bacteria are mainly spread amongst caribou from contact with birthing fluids during calving. Exposure to contaminated parts such as fluids from enlarged joints can cause illness in people but is preventable through hygienic butchering and safe meat handling practices.
In people, brucellosis often causes a high fever that frequently comes and goes. People that experience symptoms and are concerned about infection should tell their health care provider that they may have been exposed to Brucella. If signs of the disease are seen in wildlife, it should be reported to ADF&G.
The Alaska Department of Fish and Game monitors the health of caribou which includes periodic testing specifically for brucellosis in animals handled by staff as well as harvested wildlife with signs of potential disease. Recently, routine surveillance of serum samples from Mulchatna caribou found a higher prevalence rate of antibodies to Brucella compared to other herds. Along with observations of caribou with the typical swollen front knee or enlarged scrotum, and detection of bacteria in tissues of two dead caribou, these findings indicate an increase of brucellosis in this herd.
Hunters may be aware of the constant, low-level presence and potential risk of brucellosis in other herds including Western Arctic, Teshekpuk, Central Arctic and Porcupine. The higher rates recently observed in the Mulchatna herd are notable, warranting a notice to hunters and their family members who have harvested a Mulchatna caribou.
Department wildlife health veterinarian Dr. Kimberlee Beckmen advises these precautions: “Do not cut into enlarged or abnormally appearing organs or meat, and do not cut into the womb. Smoking, drying, or pickling may not kill all potential pathogens in game meat so cook all meat thoroughly (minimum internal temperature of 165˚ F). Wash your hands, knives, and food processing surfaces with hot soapy water after handling game meat. Do not consume raw bone marrow, as this is a high risk for infection with Brucellosis. Do not feed diseased parts to pets.”
The Mulchatna caribou are harvested under the state registration permit RM503 and the season ended in September under both state and federal regulations. There is currently no open season for Mulchatna caribou. The Mulchatna caribou population is currently under the population objective set by wildlife managers.
Biologists are researching several possible factors including health and disease that may be contributing to the population decline. For best practices to prevent infections, and how to report diseased caribou, please visit the Division’s Wildlife Parasites and Diseases webpage at www.adfg.alaska.gov/index.cfm?adfg=disease.general3 and refer to the bulletin Brucellosis: Answers to Frequently Asked Questions, issued by the Alaska Native Health Consortium (https://anthc.org/wp-content/uploads/2016/01/CCH-Bulletin-No-6-Brucellosis.pdf).