Salmonella in Japan’s Green Anoles

When I hear or read Salmonella, I think of my mom explaining to my 7-year-old self why I shouldn’t eat raw chicken (to be clear, I never expressed interest in doing this, but lesson learned nonetheless). According to the U.S. Centers for Disease Control and Prevention, most instances of Salmonella bacteria making people sick do in fact result from transmission by food. But Salmonella infection can come from other sources, including direct contact with living animals, particularly reptiles (including birds which, in case you haven’t heard, are reptiles). So I was only a little surprised when I came across a recent paper in the Journal of Veterinary Medical Science, based in Japan, documenting the prevalence of Salmonella in the green anole, Anolis carolinensis, on Okinawa Island, Japan.

Of the 706 green anoles from Okinawa Island whose intestinal contents were analyzed for Salmonella presence between 2009 and 2014, only 2.1% tested positive. That number is low compared with published results for green anole populations in Florida (7.5%), Chichi Island in Japan (34.2% – this study was highlighted here on Anole Annals when it came out in 2013), and Guam (76.2%). I’m struck by how much these percentages vary. Green anoles have been in Florida for millions of years, whereas populations in the other locations have only been established for tens of years. The authors hypothesize that infection rate in recently introduced populations should correlate with how long the population has been established. Testing this hypothesis will require data from more populations. It also appears that we know little about whether anoles are affected by carrying Salmonella, although a quick search did reveal this study involving the brown anole, Anolis sagrei.

All told, we have a lot to learn about anoles and Salmonella. In the meantime, please protect yourself from Salmonella infection by following basic food safety precautions: refrigerate foods adequately, wash fruits and vegetables and cook meat and eggs thoroughly, and clean potentially contaminated cookware and utensils with soap and water. Most importantly, WASH YOUR HANDS, although I assume that like me, you are already doing this approximately a hundred times per day (for those of you reading this in the future, I’m not a weirdo. We’re in the middle of a pandemic).

For those who may be interested, green anoles became established in and around Japan several decades ago and are considered an ecologically disruptive pest. If you want to read more, here are links to some old Anole Annals posts on various topics related to the region’s green anoles: trapping efforts, population age structure, range expansion. Enjoy!