Turtle fibropapillomatosis
Chelonid alphaherpesvirus 5 | |
---|---|
Hawaiian green turtle with severe fibropapilloma tumors. Cleaner wrasses avoid feeding on the tumours. | |
Virus classification | |
(unranked): | Virus |
Realm: | Duplodnaviria |
Kingdom: | Heunggongvirae
|
Phylum: | Peploviricota |
Class: | Herviviricetes |
Order: | Herpesvirales |
Family: | Orthoherpesviridae
|
Genus: | Scutavirus |
Species: | Chelonid alphaherpesvirus 5
|
Turtle fibropapillomatosis (FP) is a disease of sea turtles. The condition is characterized by benign but ultimately debilitating epithelial tumours on the surface of biological tissues.[1] FP exists all over the world, but it is most prominent in warmer climates, affecting up to 50–70% of some populations.[1]
The causative agent of the disease is believed to be Chelonid alphaherpesvirus 5 (ChHV-5), a species of virus in the genus
Description
Fibropapillomatosis is a benign tumour disease of marine turtles, predominantly in the
FP incidence is highest among immature and juvenile green turtles, while it is rare in adults.[8] The suggestions for this pattern include the tumours can regress and be cured, which has been documented in some individuals, even when tumours were severe.[9] However, the responses that cause these tumour regressions is unknown. Secondly, the juvenile individuals with FP might die before reaching adulthood.[9]
Prognosis
The tumours appear to be benign and can be present for many years, but if large, can mechanically hamper sight, swallowing, and swimming, which may ultimately be fatal.
Other species
Fibropapillomas are present in other animal groups, but are caused by different viruses, for example the bovine papillomavirus.[7]
History
The first documented case of the disease was in 1938 in Key West, Florida.[1] Long-term studies found no signs of the disease on Florida's Atlantic coast in the 1970s, but during the 1980s FP was recorded in incidences varying from 28 to 67%.[1] Today, incidences as high as 92% have been reported in Kaneohe Bay, Oahu, Hawaii. Generally, FP is most prominent in warmer climates. Recent research has found that FP is caused by stress and tumours have been observed in turtles that are part of turtle tourism tours. It is thought that the presence of tourists causes the turtles stress [1]
Cause
The FP is an infectious disease with horizontal transmission.[1] An alphaherpesvirus initially called fibropapilloma-associated turtle herpesvirus (FPTHV), and now called Chelonid alphaherpesvirus 5, is believed to be the causative agent of the disease. The reason for this belief is because nearly all tissue samples tested from turtles with lesions carry genetic material of this herpesvirus, varying between 95 and 100% depending on different studies and locations.[1][4][6] The DNA loads of the herpesvirus in tumour tissue are 2.5–4.5 logarithms higher than in uninfected tissue.[10] The FPTHV herpesvirus has been found in turtles free from FP and this suggest that the FP progression is multifactorial and might even involve some sort of tumour-promoting phase.[6] The global prevalence of the disease also suggests a multifactorial cause, rather than single factors or agents.[6][11] Possible factors include some parasites, bacteria, environmental pollutants, UV-light, changing water temperatures and biotoxins. Even physiological factors such as stress and immunologic status appear to be associated with FP.[1]
The leech genus
Treatment
Surgical removal of tumors caused by FP is the most common treatment method. Photodynamic therapy and electrochemotherapy are also used,[13] as is CO2 laser surgery.[14]
Epidemiology
FP affects green sea turtle populations all over the world, making it a panzootic.[1] It is especially found in warmer climates, such as the Caribbean, Hawaii, Japan, and Australia, where up to 70% of individuals in a population have FP.[1]
Epidemiological links are seen between FP rates, nitrogen footprints, and invasive macroalgae.[15] The strongest association with FP is with habitat type, especially increased anthropogenic activity causing high-nitrogen footprints in a surrounding environment where green sea turtles are found.[6][8][15] Sea turtles do live in very complex ecosystems, with both near-shore habitats and several years in the open ocean, which makes study of ecosystem associations difficult.[8] Even so, observations support the hypothesis that near-shore habitats have a strong correlation with the disease, as newly recruited individuals from the pelagic life phase have never been found with tumours,[6] and when migrating to more shallow ocean zones, such as the neritic zone, individuals still remain free from FP, but when entering lagoon systems, turtles may become infected.[15] The high prevalence of FP is also associated with habitats’ poor quality, while FP is absent in some habitats of good quality.[15]
Turtles are known to be robust to physical damage, but are surprisingly very susceptible to biological and chemical contaminants caused by anthropogenic activity.[15] As the turtles forage on invasive macroalgae in nutrient-rich waters, they can ingest environmental nitrogen in the form of arginine, which is known to regulate immune activity, promote herpesviruses, and contribute to tumorigenesis.[15]
References
- ^ a b c d e f g h i j k l m n o p q r s t u
Aguirre, A. A.; Lutz, P.L. (2004). "Marine turtles as Sentinels of Ecosystem Health: Is fibropapillomatosis an indicator?". Ecohealth. 1 (3): 275–283. S2CID 42838117.
- PMID 29479497.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ "ICTV Master Species List 2018b.v2". International Committee on Taxonomy of Viruses (ICTV). Retrieved 19 June 2019.[dead link]
- ^ a b
Ackermann, M.; Koriabine, M.; Hartmann-Fritsch, F.; de jong, P. J.; Lewis, T. D.; et al. (2012). "The Genome of Chelonid Herpesvirus 5 Harbours Atypical Genes". PLOS ONE. 7 (10): e46623. PMID 23056373.
- ^ a b
Greenblatt, R. J.; Work, T. M.; Balazs, G. H.; Sutton, C. A.; Casey, R. N.; et al. (2004). "The Ozobranchus leech is a candidate mechanical vector for the fibropapilloma-associated turtle herpesvirus found latently infecting skin tumors on Hawaiian green turtles (Chelonia mydas)". Virology. 321 (1): 101–110. PMID 15033569.
- ^ a b c d e f g h i j Arthur, K.; Limpus, C.; Balazs, G. H.; Capper, A.; Udy, J.; et al. (2008). "The Exposure of Green Turtles (Chelonia mydas) to Tumour Promoting Compounds Produced by the Cyanobacterium Lyngbya majuscula and their Potential Role in the Aetiology of Fibropapillomatosis". Harmful Algae. 7 (1): 114–125. .
- ^ a b Tan, M. T.; Yildirim, Y.; Sozmen, M.; Bilge-Dagalp, S.; Yilmaz, V.; et al. (2012). "A Histopathological, Immunohistochemical and Molecular Study of Cutaneous Bovine Papillomatosis". Kafkas Univ Vet Fak Derg. 18 (5): 739–744. .
- ^ S2CID 14386579.
- ^ a b
Foley, A. M.; Schroeder, B. A.; Redlow, A. E.; Fick-Child, K. J.; Teas, W. G. (2005). "Fibropapillomatosis in Stranded Green Turtles (Chelonia mydas) from the Eastern United States (1980–98): Trends and Associations with Environmental factors". Journal of Wildlife Diseases. 41 (1): 29–41. PMID 15827208.
- ^
Quackenbush, S. L.; Casey, R. N.; Murcek, R. J.; Paul, T. A.; Work, T. M.; et al. (2001). "Quantitative Analysis of Herpesvirus Sequences from Normal Tissue and Fibropapillomas of Marine Turtles with Real-Time PCR". Virology. 287 (1): 105–111. PMID 11504546.
- ^
Herbst, L. H.; Klein, P. A. (1995). "Green Turtle Fibropapillomatosis: Challenges to Assessing the Role of Environmental Cofactors". Environmental Health Perspectives. 103 (4): 27–30. PMID 7556020.
- ^ a b Lutz, P. L.; Cray, C.; Sposato, P. L. (2001). Studies of the association between immunosuppression and fibropapillomatosis within three habitats of Chelonia mydas (PDF) (Report). Southwest Fisheries Science Center.
- ^ "fibropapillomatosis of sea turtles". www.cabi.org. Retrieved 2018-08-13.
- S2CID 8090102.
- ^ a b c d e f
Van Houtan, K. S.; Hargrove, S. K.; Balazs, G. H. (2010). "Land Use, Macroalgae and a Tumour-Forming Disease in Marine Turtles". PLOS ONE. 5 (9): e12900. PMID 20927370.
External links
- Data related to Chelonid alphaherpesvirus 5 at Wikispecies
- Observations on iNaturalist