Abstract
A Caribbean spiny lobster, Panulirus argus was received for necropsy after increased fatalities in a local public aquarium. Mortalities spanned multiple tanks connected to the same life support system. There was an absence of clinical signs and post-mortem decomposition limited investigation to an arbitrary individual, which was euthanized and submitted immediately for diagnostics. The Caribbean spiny lobster is named for the protective spines that span their body.1 According to the IUCN Red List P. argus is labeled Data Deficient but the population is considered decreasing.2 The Caribbean spiny lobster fishery is exceptionally valuable generating over $450 million per year.3 Wild populations are largely affected by overfishing, but disease outbreaks have also been reported, including Panulirus argus Virus 1 (PaV1) which has a predilection for juveniles.4,5
At necropsy there was no external shell disease or trauma, the hemolymph was mildly opaque and did not clot, and the hepatopancreas was tan to green with multifocal small, firm white foci. The lobster’s gonads were immature and was sexed a female. Microscopic findings revealed significant multifocal necrosis of the hepatopancreas centered on myriad gram-negative bacteria. PaV1 polymerase chain reaction (PCR) was negative, but Vibrio harveyi was cultured from multiple organs, identified initially by MALDI-TOF MS and confirmed by MLSA gene sequencing. Susceptibility testing was attempted. The genus Vibrio is salt-tolerant, found in temperate climates and commonly associated with human illness through the consumption of seafood.6 Vibrio spp. infections result in morbidity for many aquaculture animals and are the most frequently encountered pathogen of cultured shrimp.7 Vibrio harveyi causes necrosis of the striated tail muscle in shrimp, while several other Vibrio spp. are implicated in limp lobster disease and luminous vibriosis.7,8 In addition, toxins produced by the family Vibrionaceae produce clinical manifestations, such as hepatopancreatic necrosis disease (AHPND/EMS) in aquacultured shrimp, which is caused by plasmid mediated PirA and PirB genes carried by certain strains of Vibrio parahaemolyticus.9 Since it has been reported that Vibrio harveyi isolates from marine organisms can have virulence-variation and genetic diversity with the production of toxins such as haemolysin and protease toxin, a PCR was performed but negative for the CTX gene.10
In conclusion, this lobster had significant hepatopancreas necrosis, likely associated with Vibrio harveyi, which may produce toxins resulting in clinical morbidity similar to AHPND/EMS. As Caribbean spiny lobsters continue to be used for consumption and aquariums, it is prudent to expand diagnostic techniques and to develop management strategies to reduce the incidence of infectious diseases.
Acknowledgments
The authors wish to thank BADDL, the University of Florida and Mississippi State University, College of Veterinary medicine for their contributions to this study.
*Presenting author
+Student presenter
Literature Cited
1. Caribbean Spiny Lobster | NOAA Fisheries. NOAA Fisheries. https://www.fisheries.noaa.gov/species/caribbean-spiny-lobster. [accessed December 30, 2020]
2. Butler M, Cockcroft A, MacDiarmid A, Wahle R. 2011. Panulirus argus. The IUCN Red List of Threatened Species 2011:e.T169976A6697254. [accessed December 30, 2020].
3. Higgs ND, Newton J, Attrill MJ. 2016. Caribbean spiny lobster fishery is underpinned by trophic subsidies from chemosynthetic primary production. Curr Biol 26(24):3393–3398.
4. Li C, Shields J, Small H, Reece K, Hartwig C, Cooper R, Ratzlaff R. 2006. Detection of Panulirus argus virus 1 (PaV1) in the Caribbean spiny lobster using fluorescence in situ hybridization (FISH). Dis Aquat Org 72(3):185–192.
5. Terio KA, McAloose D, Leger JS, editors. 2018. Pathology of Wildlife and Zoo Animals. London: Academic Press, Elsevier.
6. Raissy M, Moumeni M, Ansari M, Rahimi E. 2012. Occurrence of Vibrio spp. in lobster and crab from the Persian Gulf. J Food Saf 32(2):198–203.
7. Zhou J, Fang W, Yang X, Zhou S, Hu L, Li X, Qi X, Su H, Xie L. 2012. A nonluminescent and highly virulent Vibrio harveyi strain is associated with “bacterial white tail disease” of Litopenaeus vannamei shrimp. PLoS ONE. 7(2):e0029961.
8. Tall BD, Fall S, Pereira MR, Ramos-Valle M, Curtis SK, Kothary MH, Chu DMT, Monday SR, Kornegay L, Donkar T, Prince D, Thunberg RL, Shangraw KA, Hanes DE, Khambaty FM, Lampel KA, Bier JW, Bayer RC. 2003. Characterization of Vibrio fluvialis-like strains implicated in limp lobster disease. Appl Environ Microbiol 69(12):7435–7446.
9. Han J, Tang K, Tran L, Lightner D. 2015. Photorhabdus insect-related (Pir) toxin-like genes in a plasmid of Vibrio parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND) of shrimp. Dis Aquat Org 113(1):33–40.
10. Nakayama T, Nomura N, Matsumura M. 2006. Study on the relationship of protease production and luminescence in Vibrio harveyi. J Appl Microbiol 101(1):200–205.