Dr. Norton demonstrating drawing blood on an
Olive Ridley during a workshop in Costa Rica.
Abnormal kidney from an Olive Ridley.
The kidney is riddled with cysts and
By Dr. Terry Norton, GSTC Director and Veterinarian
The Disney Conservation Fund (DCF) supported a variety of the Jekyll Island Authority’s Georgia Sea Turtle Center (GSTC) activities in Costa Rica. One project was to investigate a syndrome involving abnormal kidneys in Olive Ridley sea turtles. As part of our capacity building in Costa Rica, we hosted several workshops on sea turtle rehabilitation and health. Training veterinarians and biologists how to do a necropsy (animal autopsy) on a sea turtle was part of this effort. Most of the turtles that were necropsied had very abnormal kidneys which were often riddled with abscesses and cysts.
In 2011, there was a large die-off of Olive Ridley sea turtles in the Osa Peninsula in Costa Rica. Most of these turtles had the same abnormal kidneys. The individuals investigating the cause of this event thought the turtles had kidney stones. Years later, our team was able to evaluate some of these cases and determined it was the same disease. We decided to investigate this disease further by involving a number of our Costa Rican partners and eventually several organizations in the US. The results of this investigation are now complete and have been submitted to Plos One for a peer reviewed publication. The manuscript has 21 authors from 15 institutions, one being the GSTC.
The investigating team was able to determine that the underlying cause of the kidney disease in these turtles is a type of Salmonella - S. Typhimurium. This disease is much wider spread than we originally realized, occurring in the Pacific coast of several Central American countries, continental US, and Hawaii. It has been found in stranded sick turtles and apparently healthy turtles that died from long line fisheries related causes. The disease ranged from mild to severe.
Genetic testing showed that the isolates from the Olive Ridleys formed a single clade distinct from other strains of S. Typhimurium. Although S. Typhimurium is known in coastal environments, its presence in Olive Ridleys within the oceanic environment was unexpected. Further study is warranted to determine the origin and host specificity of the Olive Ridley S. Typhimurium strain as well as the potential role of salmonellosis in Olive Ridley conservation. In addition, S. Typhimurium is one of the more common non-typhoidal Salmonella in humans, and Olive Ridley eggs are commonly harvested for human consumption in Central America (https://www.seeturtles.org/olive-ridley-turtles/). Thus, a potential for human exposure exists.
We would like to thank the DCF for their financial support and the Jekyll Island Foundation for managing the funds from this DCF award.