No abstract

Spirorchiid trematodes are implicated as an important cause of stranding and mortality in sea turtles worldwide. However, the impact of these parasites on sea turtle health is poorly understood due to biases in study populations and limited or missing data for some host species and regions, including the southeastern United States. We examined necropsy findings and parasitological data from 89 loggerhead Caretta caretta and 59 green turtles Chelonia mydas that were found dead or moribund (i.e. stranded) in Florida (USA) and evaluated the role of spirorchiidiasis in the cause of death. High prevalence of infection in the stranding population was observed, and most infections were regarded as incidental to the cause of death. Spirorchiidiasis was causal or contributory to death in some cases; however, notable host injury and/or large numbers of parasites were observed in some animals, including nutritionally robust turtles, with no apparent relationship to cause of death. New spirorchiid species records for the region were documented and identified genera included Neospirorchis, Hapalotrema, Carettacola, and Learedius. Parasites inhabited and were associated with injury and inflammation in a variety of anatomic locations, including large arteries, the central nervous system, endocrine organs, and the gastrointestinal tract. These findings provide essential information on the diversity of spirorchiids found in Florida sea turtles, as well as prevalence of infection and the spectrum of associated pathological lesions. Several areas of needed study are identified with regard to potential health implications in the turtle host, and findings caution against over-interpretation in individual cases.

Marine turtle fibropapillomatosis is associated with chelonid fibropapilloma-associated herpesvirus (C-FP-HV) and commonly affects juvenile green turtles (Chelonia mydas) in neritic (nearshore) habitats. Green turtles have a complex life history, characterized by shifts in trophic level as well as habitat during ontogeny. Thus, several hypotheses can be proposed for when turtles become infected with C-FP-HV. They may acquire the virus at an early stage in the life cycle, including prenatal, hatchling, or the posthatchling pelagic stages. Alternatively, they may become infected later in life after they emigrate from the open ocean to neritic habitats. Each hypothesis generates predictions about the spatial distribution of genetic variants of C-FP-HV among nearshore sites within a region. Sequencing of polymerase chain reaction-amplified viral DNA from fibropapillomas of individual turtles was used to genotype the viral variants present in marine turtles from different coastal areas in Florida. We found four distinct virus variants (A, B, C, and D), two of which (A and C) were present in multiple turtle species. Green turtles in Florida were infected with variants A, B, and C. Variant A was found in green turtles from all three areas. Outside the Indian River Lagoon, variant A was most commonly detected and was found in >94% of diseased green turtles and 70% of loggerhead sea turtles (Caretta caretta) in the Florida Bay/Florida Keys. However, in the Indian River Lagoon, variant B was found in >94% of affected green turtles. Variant B was not detected outside of the Indian River system. Chi-square analysis strongly supported (P<0.001) an association between viral variant distribution in green turtles and location. On the basis of the assumption that juvenile green turtles found in Florida's west-central coast, Florida Keys, and Indian River Lagoon areas represented recruits from a mixed pelagic population, we expected that the distribution of viral variants in these turtles would be relatively homogeneous among locations; this would correspond to infection in the earlier phases of their life cycle. The heterogeneous distribution of viral variants in green turtle tumors from different Florida coastal locations strongly supports the hypothesis that, during epizootics, turtles are infected with specific C-FP-HV variants after they arrive as juveniles in neritic habitats. The conclusion that C-FP-HV is acquired after turtles recruit to nearshore habitats should help focus further research efforts on understanding the mechanisms of transmission and raises the possibility that the effect of fibropapillomatosis on turtle populations might be reduced by management strategies designed to break the cycle of transmission in these locations.

Green turtle fibropapillomatosis (GTFP), characterized by multiple benign fibroepithelial tumors on the skin and eyes, has become a growing threat to green turtle Chelonja mydas populations worldwide. The cause of GTFP 1s unknown, but a viral etiology is suspected. This study investigated whether GTFP could be experimentally transmitted to young captive-reared green turtles using cell-free fibropapilloma extracts prepared from free-ranging turtles with spontaneous disease Turtles raised from eggs collected from 4 separate clutches in the wild were assigned to 4 expenmental groups and 1 control group. For each experiment a crude homogenate (33 % w/v) was prepared from fibropapillomas removed from a free-ranging turtle with spontaneous disease. The crude tumor homogenates were freeze-thawed and centrifuged to yield cell-free extracts that were used (both filtered and unaltered) for inoculation. Recipients were inoculated by intradermal injection or by scarification; control turtles were not treated but \yere housed with treated turtles. Fibropapillomas developed in all 12 turtles receiving 3 of the 4 tumor extracts, and were first detected between 15 and 43 wk post inoculation. Both filtered and unfiltered tumor extracts successfully induced tumor development. During the 10 and 12 mo monitoring periods. fibropapillomas did not develop in control turtles or in any turtles inoculated with the fourth tumor extract. Although 2 sets of experiments were performed 8 wk apart, most of the tumors in both sets became evident simultaneously after water temperatures rose Experimental tumors were h~stologically i n d~s -tinguishable from spontaneous fibropapillomas found In free-living turtles but lacked evidence of endoparasites. Scattered foci of epidermal degeneration were found in most sections of experimentally induced fibropapillomas and within some sections taken from donor turtles. Electron rnicroscopy revealed virus-like particles conforming in size, morphology, and intranuclear location with herpesvirus. Negativestaining electron microscopy of transmission-positive tumor extracts failed to demonstrate intact virus particles. This study demonstrates that the etiology of GTFP is an infectious filterable subcellular agent. The herpesvirus identified in this study is 1 possible candidate for the etiology of GTFP.

Sea turtle fibropapillomatos~s (FP) is a disease marked by proliferat~on of b e n~g n but debilitating cutaneous fibropapillomas and occasional visceral fibromas Transmission experiments have implicated a chloroform-sensltlve transforming agent present in filtered cell-free tumor homogenates in the etiology of FP In t h~s study, consensus pnmer PCR methodology was used to test the a s s o c~a t~o n of a chelonian herpesvirus with f~bropapillomatosis Fibiopap~lloma and skin samples were obtalned f~o m 17 green and 2 loggerhead turtles affected iwth FP stranded along the Flor~da coastline Ninety-three cutaneous and vlsceral tumors fiom the 19 turtles, and 33 skln samples from 16 of the turtles, were tested All turtles affected with FP had herpesvlrus associated w t h thelr tumors as detected by PCR N~nety-six percent (89/93) of the tumors but only 9 % (3/33) of the skin samples from affected turtles contained detectable herpesvirus The skin samples that contained herpesvirus were all within 2 cm of a flbropapillo~na Also. 1 of 11 scar tissue samples from sites where fibropapillomas had been removed 2 to 51 wk earlier from 5 green turtles contalned detectable herpesvirus None of 18 normal skln samples from 2 green and 2 loggerhead turtles stranded without FP contained herpesvirus The data indicated that heipesvlrus was detectable only withln or close to tumors To determine if the same vlrus infected both turtle specles, partial nucleotide sequences of the herpesvlrus DNA polymerase gene were determined from 6 loggerhead and 2 green turtle samples The sequences predicted that herpesviius of loggerhead turtles dlffered from those of green turtles by only 1 of 60 a m~n o acids In the sequence examined, Indicating that a chelonlan herpesvlrus exhibltlng minor intratyplc vanation was the only helpesvlrus present in tumors of both green and loggerhead turtles The FP-assoc~ated herpesvlrus reslsted cultlvat~on on chelonian cell hnes whlch support the replicat~on of other chelonian herpesvlruses These results lead to the conclus~on that a chelonian herpesvirus IS regularly associated with f~bropap~llomatosis and 1s not merely an ~ncldental flndlng in affected turtles