Chronic debilitation in stranded loggerhead sea turtles (<i>Caretta caretta</i>) in the southeastern United States: Morphometrics and clinicopathological findings

<div><p>Chronically debilitated loggerhead sea turtles (<i>Caretta caretta</i>) (DT) are characterized by emaciation, lethargy, and heavy barnacle coverage. Although histopathological findings associated with this condition have been reported, only limited data is available on health variables with clinical application. The objectives of this study were to 1) to compare morphometrics, clinicopathological variables, and immune functions of DTs to a group of apparently healthy loggerhead turtles to better understand the pathophysiology of the condition and 2) to assess health parameters in live debilitated turtles as they recovered during rehabilitation in order to identify potential prognostic indicators. We examined and sampled 43 DTs stranded from North Carolina to Florida for 47 health variables using standardized protocols to further characterize the condition. DTs were grouped into categories of severity of the condition, and those that survived were sampled at four time points through rehabilitation. All groups and time points were compared among DTs and to clinically healthy loggerhead turtles. Compared to healthy turtles, DTs had significantly lower body condition index, packed cell volume (PCV), total white blood cell (WBC) count, lymphocytes, glucose (Glc), total protein, all protein fractions as determined by electrophoresis, calcium (Ca), phosphorus (P), Ca:P ratio, potassium (K), lymphocyte proliferation, and greater heterophil toxicity and left-shifting, uric acid (UA), aspartate aminotransferase, creatine kinase, lysozyme, and respiratory burst. From admission to recovery, hematology and plasma chemistry data improved as expected. The most informative prognostic indicators, as determined by correlations with a novel severity indicator (based on survival times), were plastron concavity, P, albumin, total solids, UA, lymphocyte proliferation, WBC, K, Glc, Ca:P, and PCV. The results of this study document the wide range and extent of morphometric and metabolic derangements in chronically debilitated turtles. Monitoring morphometrics and clinicopathological variables of these animals is essential for diagnosis, treatment, and prognosis during rehabilitation.</p></div

Comparison of variables measured in debilitated loggerhead sea turtles (DTs) before and during rehabilitation and compared to healthy loggerhead turtles (means and one standard deviation).

<p>Each turtle group on the x-axis was significantly different (p<0.05 or p<0.00883 for repeated measures) from groups represented by letters above data. (A) glucose; (B) total protein by biuret method at U. Miami; (C) albumin by plasma electrophoresis; (D) phosphorus. Lines represent an individual turtle through rehabilitation. For samples sizes in each diagram, please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200355#pone.0200355.s006" target="_blank">S3 Table</a>.</p

Diagram of severity indicator with five case examples of debilitated loggerhead sea turtles.

<p>Images show turtles at time of admission.</p

Health variables that significantly correlated with the severity indicator in debilitated loggerhead sea turtles (DTs).

<p>Spearman rank correlation coefficients and p-values are shown. (A) plastron concavity; (B) packed cell volume (PCV); (C) glucose; (D) phosphorus; (E) albumin by bromocresol green method; (F) albumin by plasma electrophoresis; (G) B-lymphocyte proliferation.</p

Comparison of immune function variables measured in debilitated loggerhead sea turtles (DTs) before and during rehabilitation and compared to healthy loggerhead turtles (means and one standard deviation).

<p>Each turtle group on the x-axis was significantly different (p<0.05 or p<0.00883 for repeated measures) from groups represented by letters above data. (A) lymphocyte proliferation with ConA; (B) lymphocyte proliferation with PHA; (C) respiratory burst with Ca ionophore; and (D) lysozyme activity. Lines represent an individual turtle through rehabilitation. For samples sizes in each diagram, please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200355#pone.0200355.s007" target="_blank">S4 Table</a>.</p

Comparison of plastron concavity measured in debilitated loggerhead sea turtles (DTs) before and during rehabilitation and compared to healthy loggerhead turtles (means and one standard deviation).

<p>Lines represent an individual turtle through rehabilitation. Each turtle group on the x-axis was significantly different (p<0.05 or p<0.00883 for repeated measures) from groups represented by letters above data. Sample size for each group: 15 [X], 9 [Y], 6 [A]–[D], 1[H].</p

Sample sizes and characteristics of debilitated (DT) and healthy loggerhead turtles sampled in the current study.

<p>Sample sizes and characteristics of debilitated (DT) and healthy loggerhead turtles sampled in the current study.</p

Fibropapillomatosis and chelonid alphaherpesvirus 5 infection in kemp’s ridley sea turtles (lepidochelys kempii)

Fibropapillomatosis (FP), a debilitating, infectious neoplastic disease, is rarely reported in endangered Kemp’s ridley sea turtles (Lepidochelys kempii). With this study, we describe FP and the associated chelonid alphaherpesvirus 5 (ChHV5) in Kemp’s ridley turtles encountered in the United States during 2006–2020. Analysis of 22 case reports of Kemp’s ridley turtles with FP revealed that while the disease was mild in most cases, 54.5% were adult turtles, a reproductively valuable age class whose survival is a priority for population recovery. Of 51 blood samples from tumor-free turtles and 12 tumor samples from turtles with FP, 7.8% and 91.7%, respectively, tested positive for ChHV5 DNA via quantitative polymerase chain reaction (qPCR). Viral genome shotgun sequencing and phylogenetic analysis of six tumor samples show that ChHV5 sequences in Kemp’s ridley turtles encountered in the Gulf of Mexico and northwestern Atlantic cluster with ChHV5 sequences identified in green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles from Hawaii, the southwestern Atlantic Ocean, and the Caribbean. Results suggest an interspecific, spatiotemporal spread of FP among Kemp’s ridley turtles in regions where the disease is enzootic. Although FP is currently uncommon in this species, it remains a health concern due to its uncertain pathogenesis and potential relationship with habitat degradatio