Salmonella, Turtles and Frogs...Oh My!
As many BioJobBlog readers may know by now, my PhD thesis focused on elucidating the underlying pathogenic mechanisms that contributed to the pathogenesis of Salmonella gastroenteritis. Salmonella gastroenteritis, which is primarily a food-borne illness, occurs in approximately 1.4 million Americans each year. Most people who develop Salmonella gastroenteritis recover without treatment within four to seven days. However, some people develop diarrhea so severe they are hospitalized and can become critically ill. According to a former lab mate, who accidentally infected himself, Salmonella gastroenteritis is much worse than the mild form of the disease described in many microbiology textbooks!
While I haven’t performed any research in this field for about 30 years, I still consider myself to be a Salmonella expert (go figure). Therefore, it should come as no surprise that a newspaper article entitled “Salmonella outbreak linked to pet frogs”— that appeared in the Salt Lake Tribune several weeks ago—caught my eye.
According to the article, a 31-state Salmonella outbreak (which was first detected in Utah was linked to pet frogs. The U.S. Centers for Disease Control and Prevention (CDC) in Atlanta started a national investigation to find the source of the outbreak this past summer, after five Utahans were infected by the strain of S. typhimurium a common cause of gastroenteritis (I knew getting a PhD would useful one day). In all, 85 people across several states developed gastroenteritis and nearly two-thirds had had some contact with frogs. Most of the patients were children and among those whose outcomes are known, almost a third required hospitalization. None died.
The source of the outbreak was eventually linked back to a single frog breeder in California that distributed the African dwarf frogs thought to be responsible for the multi-state outbreak. According to CDC officials, the bacteria were likely spread through contact with the tanks' water, not the frogs themselves. Of those who supplied information to the CDC, 30 percent said they cleaned the frog's aquarium in the kitchen sink and 35 percent used the bathroom basin.
While this last bit of information wasn’t remarkable, I finally—after almost 30 years as card carrying microbiologist—realized how the urban legend about Salmonella and turtles got started! Like many kids, I had a pet turtle. I remember my parents cautioning me about handling the turtle because I would get sick (of course I handled the turtle and never got sick). Later on, as a microbiology undergraduate student, I learned about the relationship between Salmonella and turtles and that turtle had been associated with Salmonella gastroenteritis outbreaks in the past. An interesting but inconsequential fact because I no longer owned a pet turtle.
Early on as a graduate student, I learned that it takes a minimum of about 108 salmonellae to cause gastroenteritis. At the time, I wasn’t thinking much about turtles and failed to realize that the large dose required for infection pretty much ruled out the likelihood that picking up a turtle would almost certainly result in Salmonella gastroenteritis. Although reptiles and amphibians harbor Salmonella in their gastrointestinal tracts, a child would have to suck on an infected turtle (or eat its poop) to get a large enough inoculum to initiate an infection—now this is where the PhD training become evident. However, if parents clean their children’s infected tanks in kitchen or bathroom sinks and then fail to wash their hands or the sinks with disinfectant, the number of salmonellae present in these environments would be sufficient to cause disease if infected food or water was ingested. And, this is what likely happened in the frog outbreak; based on the epidemiological data presented by CDC investigators
So, what is the lesson of this story? While it is true that turtles and frogs may carry Salmonella (in a separate study 21 percent of frogs from 16 retailers tested positive) the likelihood of developing gastroenteritis after touching or briefly handling frogs or turtles is extremely low. However, it is not a good idea to handle them for long periods of time without washing your hands before your next meal or cleaning their tanks in areas where food is prepared or people brush their teeth! Food borne illnesses are easy to prevent if appropriate personal hygiene is practiced and foods are prepared and cooked according to recommended standards.
Finally, it took a long time, but I can now feel comfortable around turtles. This is probably a good thing—my friend Pete is a turtle fanatic and he constantly wants me to pick up his pets!
Until next time...
Good Luck and Good Job Hunting!!!!!!!!!!
As we all know, the H1NI pandemic has been raging on for close too 10 ten days now. Curiously, “Fear & The Flu: The New Age of Pandemics” is the title this week’s cover story in Newsweek magazine. From an informational standpoint point, “this may be too little, too late”—as the old saying goes. While the Internet has been around for over twenty years now, government agencies, most notably the US Food and Drug Administration (FDA) and the Centers for Disease Control (CDC) continue to rely almost exclusively on old media to communicate with the American public during infectious disease outbreaks. Apparently, the administrators who run these government agencies haven’t been listening closely enough to President Obama’s assertion that “we live in the digital age.”.jpg)
I apparently made a few errors in the post about the recent Salmonella food poisoning outbreak at PU (pun intended). I want to thank the anonymous member of the Princeton Graduating Class of ’09 for pointing out the inconsistencies and errors in the post. First, the so-called “dining clubs” are actually called eating clubs. Second, fraternities and sororities are allowed at PU and I hear that they are alive and well. Finally, I inadvertently noted that the University has severed contracts with several of its produce suppliers which may have been the putative source(s) of the outbreak. In fact, the University didn’t cancel contracts but only temporarily closed a few of the eating stations at the Frist Campus Center. My local newspaper reported that contracts where severed–I guess you truly can’t believe everything that you read!.jpg)
Yes, even the Ivy League isn’t immune to food poisoning outbreaks from time-to-time. There are currently 10 confirmed cases of 
