When it comes to handling microorganisms, there are 4 biosafety levels.
- Biosafety level 1 (BSL-1) organisms are harmless.
- BSL-2 organisms include most of the commonly encountered bugs, including things like E. coli, Salmonella and Staphylococcus aureus. They can cause serious disease but infections are often treatable and they can be handled safely with standard lab protocols.
- BSL-3 organisms are a relatively small group of bad guys that require more extensive facilities and protocols to handle them. These include Coxiella burnetii (the cause of Q-fever) and Francisella tularensis, the cause of tularemia.
- BSL-4 organisms are the really bad guys that require high level containment like you see in the movies. There are a limited number of BSL-4 facilities in the world and they deal with bugs like Ebola virus.
One of the BSL-3 pathogens I mentioned was a bug called Francisella tularensis, the bacterium that causes tularemia, which is also listed as a potential bioterrorism agent. Tularemia is a very nasty disease. It’s uncommon but human infections occur sporadically in many regions, typically associated with wildlife exposure. It’s often associated with contact with rabbits, but the bacterium can be found in a wide range of animals (including insects) and in the environment.
Recently, people in Bell and Coryell counties in Texas (between Dallas and San Antonio) were warned about the potential for tularemia exposure from wild hogs, since 15-50% of tested feral hogs in those areas had evidence of current of past infection. While evidence of past infection (the presence of antibodies against the bacterium in their blood) does not mean that they are actively infectious, it indicates that the bacterium is circulating in the area and that hogs are being exposed. If a hog was actively infected, it could be a source of human infection if there was direct contact (i.e. hunting and butchering).
Because of the potential risk of exposure, the following recommendations have been made:
- Always wear rubber gloves and eye protection when dressing (i.e. skinning & gutting) wild game.
- Ensure that game meats are handled carefully and thoroughly cooked.
- Use insect repellent to keep ticks, biting flies and other insects at bay.
- Look for rabbit nests in tall grasses before mowing. (As unusual as it sounds, running over rabbits with a lawnmower has been associated with development of tularemia).
The risk of tularemia is pretty low, but it’s a very serious disease and you don’t want it. Using these basic precautions should help reduce the risk.