People for the Ethical Treatment of Animals (PETA) is battling Ringling Brothers and Barnum and Bailey Circus because of Karen, an elephant with tuberculosis (TB). The animal rights group is claiming that the elephant poses a public health risk because she has TB, and it appears that their appeal had initially convinced Baltimore city council to bar the animal from performing.
However, while Karen does have TB (along with about 12% of all Asian elephants in captivity in North America) she does not have active disease. This means she is not known to be shedding Mycobacterium tuberculosis, the cause of TB. Standard protocols are for captive elephants to be tested each year for TB shedding through culture of trunk washes, whereby the elephant essentially sucks some fluid into its trunk and blows it back into a collection bag. If TB is grown from that sample, the elephant has active disease and needs to be quarantined. Since Karen does not have active disease (and because close and prolonged contact are needed for transmission of TB), she is not believed to pose any public health risk.
Recently, I wrote about an outbreak of TB in people that worked with infected elephants at a sanctuary. That was a totally different situation from this one. The major differences, particularly with regard to the risk of transmission, are perhaps best explained by one of the authors of that report, Dr. William Schaffner, who said "If you’re at a circus, you’re at a great distance from the elephants. You do not have genuinely prolonged contact with them. You’re there for 2 hours of the show. That sort of exposure should not put people at risk. I would let my grandchildren attend."