VIBRIO AND MAJOR COMMERCIALLY IMPORTANT VIBRIOSIS DISEASES IN DECAPOD CRUSTACEANS


Vibriosis is among the major bacterial diseases in crustaceans all over the world aquaculture. They can be present in the water column and form parts of the biofilm on submerged surfaces. All aquatic crustaceans are susceptible to Vibrio infection and the diseases associated with this pathogen that caused mass mortalities in hatcheries and grow-out ponds. These bacteria will associate not only in animal tissues but also in healthy animal and aquaculture systems. Vibrio bacteria can be devastating, particularly during the crustacean larval production stage. When these bacterial outbreaks happen it will cause huge economic losses.



Vibrio is Gram-negative in rod shaped, facultatively aerobic, oxidase-positive genus of bacteria having a fermentative and respiratory metabolism. Some species have polar flagella, whereas others have flagella that are dispersed throughout the cell. Flagella are necessary for host cell colonisation, biofilm formation, motility and pathogenicity. Vibrio spp. will colonise or accumulate in a number of organs and tissues of crustaceans, including the hepatopancreas, gut, hemolymph, hearts, gills, lymphoid organ, somatic muscle, cuticle and carapace. Vibrio harveyi, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio alginolyticus are recognized as the main agents that cause disease in shrimp aquaculture. These bacteria species can be isolated easily using culture medium with added NaCl or thiosulfate-citrate-bile salts-sucrose (TCBS) agar, chromogenic vibrio (CV), marine agar and trypticase soy agar (TSA). In addition, to improve the isolation of marine Vibrio species need modified TCBS medium by dissolved it with filtered seawater or artificial seawater. Besides, CV agar is a suitable use when to detect, select, differentiate and isolate Vibrio cholera, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio alginolyticus. Meanwhile, the other three agars can be used to observe Vibrio bioluminescence. However, different mediums will have different targets for growth of vibrio species and different indicators for results. Thus, we need to choose the right agar when to do an experiment on Vibrio species based on what kind the result of Vibrio species we targeted.




Vibriosis can affect crustaceans such as shrimp, lobsters, and crabs in all stages of their lives. Especially early stage larvae, post larvae and juvenile of these animals. This is usually related to the fact that the immune system does not fully develop until the crustacean postlarval substages. The severity of infection not only depends on the stage of the animal, but it also involves Vibrio species and strain, and environmental conditions (Jayasree et al., 2006). Illnesses like acute hepatopancreatic necrosis disease (AHPND) have been reported in Penaeus vannamei and Penaues monodon shrimps caused by Vibrio spp. outbreaks and danger to shrimp farming. However, Macrobrachium rosenbergii have been resistant to this disease. Shell disease also known as brown spot occurs due to poor water quality, presence of contaminants and organic load and high stocking densities. These two diseases commonly occur in aquaculture that leads to economic expenses. Luminous vibriosis, tail necrosis, zoea ΙΙ syndrome, limp lobster illness, red body disease, Vibrio-cause bacteremia and summer syndrome are some of the other vibriosis infections that have been documented in hatchery crustaceans. This happens in all farmed shrimp such as Penaeus vannamei, Penaeus monodon, Penaeus merguiensis and Macrobrachium rosenbergii. Thus, we need to ensure, monitor and control our aquaculture conditions are in good or suitable conditions to control the Vibrosis outbreaks that will risk food security and socio-economic losses.




In addition, controlling vibriosis on a farm requires an integrated health management plan. This to ensure that biosecurity is maintained, and good animal welfare practices are being carried out. For example, a health management plan would include aspects of how to prevent mixing of animal cohorts, including sharing the same water body or sharing of equipment, and a protocol for eliminating diseases that include safely eliminating carcasses of animals suspected to harbour disease. Maintaining good water quality within normal tolerances, reducing stocking density and acute stress such as temperature shocks, and meeting the nutritional requirement of the farmed animals helps to prevent or limit vibriosis and outbreaks of other diseases. Adequate pond preparation and maintenance is associated with the prevention of vibriosis such as AHNP. Thus, shrimp and crab discourage the use of antibiotics or disinfectants to control vibriosis. Besides, by suggested use of production systems such as green water or biofloc technologies, there are also other alternatives to prevent the occurrence of vibrosis. So, by applying these recommended prevention methods in our aquaculture we can prevent and minimize vibriosis disease and also increase our economy in aquaculture since some of our crustaceans species are a food source to humans.


With a vast number of aquatic crustacean species and some of them are food sources to humans that can be affected by vibriosis, it is necessary to understand Vibrio biocomplexity, disease characteristics, epidemiology, microbial ecology, and how to manage the impact of vibriosis. To reduce or limit vibrio infection we can use some prevention management or treatment options as mentioned before. Despite extensive research to date, there has been no comprehensive study on Vibrio and their associated vibriosis diseases relevant to decapod crustacean aquaculture. Therefore, we need to address this knowledge gap, with a focus on commercially important crustaceans, such as shrimps, lobsters, and crabs.



References

  1. de Souza Valente, C., & Wan, A. H. (2021). Vibrio and major commercially important vibriosis diseases in decapod crustaceans. Journal of Invertebrate Pathology, 107527.

  2. Jayasree, L., Janakiram, P., & Madhavi, R. (2006). Characterization of Vibrio spp. associated with diseased shrimp from culture ponds of Andhra Pradesh (India). Journal of the world aquaculture society, 37(4), 523-532.

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