I+R+D

Is Artemia a potential carrier of EHP affecting shrimp?

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By Milthon Lujan

Artemia franciscana. Source: Biodiversity Institute of Ontario
Artemia franciscana. Source: Biodiversity Institute of Ontario

The global shrimp industry faces a growing threat: Ecytonucleospora hepatopenaei (EHP), originally called Enterocytozoon hepatopenaei, a microscopic parasite that stunts shrimp growth and increases susceptibility to deadly bacterial infections.

Artemia is commonly used as a nutritional source for shrimp, crab, and fish larvae. However, Artemia’s vulnerability to marine bacterial pathogens, such as Vibrio anguillarum, V. parahaemolyticus, and V. harveyi, etc., raises concerns regarding the potential transmission of pathogenic bacteria to fish and shrimp larvae. Additionally, recent studies have detected EHP in Artemia samples through PCR testing.

A team of scientists from the Yellow Sea Fisheries Research Institute (China), Shanghai Ocean University (China), and the Network of Aquaculture Centres in Asia-Pacific (Thailand) exposed juvenile Artemia franciscana to EHP inoculation through immersion and oral administration to address the question: Can the small crustaceans called Artemia, commonly used as shrimp feed, act as silent carriers of EHP?

EHP: A Growing Threat to Shrimp Farms

EHP infection affects the hepatopancreas and gastrointestinal tract, weakening shrimp and leading to slow growth and higher mortality rates. This parasite has been reported in some countries including China, Vietnam, Brunei, Malaysia, Indonesia, India, and Venezuela, posing a significant risk to shrimp aquaculture sustainability and profitability.

While EHP primarily targets shrimp such as Penaeus vannamei and P. monodon, its scope may extend further. Studies suggest the presence of EHP in other crustaceans such as Procambarus clarkii, P. japonicus, and Macrobrachium nipponense, but confirmation through detailed examinations is needed.

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Artemia: A Possible Culprit?

Artemia is a staple food for shrimp larvae and provides essential nutrients for healthy growth. However, concerns persist about its potential role in transmitting pathogens such as Vibrio anguillarum, V. parahaemolyticus, V. harveyi, and EHP.

Previous studies using PCR (genetic testing) detected EHP in Artemia samples, raising alarms. This research delves deeper, utilizing advanced techniques to determine if EHP can indeed infect Artemia.

Exploring Artemia’s Susceptibility

Determining a species’ susceptibility to a pathogen is crucial for disease control and commercial regulations. While some reports suggest Artemia’s susceptibility to EHP, evidence requires further exploration.

The study rigorously challenged juvenile Artemia franciscana with EHP, through immersion in a homogenized suspension of hepatopancreas from EHP-infected Penaeus vannamei and oral administration with Chlorella soaked in a homogenized hepatopancreatic suspension infected with EHP to determine susceptibility, using protocols accepted by the World Organisation for Animal Health (OIE). Scientists employed techniques such as PCR and ISDL to detect EHP presence in exposed Artemia.

The Verdict: Artemia is not a host for EHP

While scientists found some initial traces of EHP in Artemia shortly after exposure, they quickly disappeared. There was no evidence of sustained infection or multiplication of EHP within Artemia.

According to the study, Artemia exposed to EHP through immersion in water and contaminated food showed minimal parasite presence after 3 days. By day 7, no detectable EHP remained in the exposed Artemia.

Conclusion

“The results indicated that exposure to EHP caused invasion of Artemia into intestinal epithelial cells, but the infection could not persist, confirming that Artemia is not susceptible to EHP. Thus, the research contradicts the claim that Artemia is a potential reservoir of EHP,” concludes the researchers.

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This research confirms that Artemia is not a host for EHP, alleviating concerns about its role in EHP transmission. This finding allows shrimp producers to continue using Artemia with confidence, ensuring a vital food source for their shrimp.

The study was funded by the Joint Research Fund of the National Natural Science Foundation of China (NNSFC)-Shandong Province; the CAS-NSTDA Joint Research Program; and the Agriculture Research System of China.

Contact
Jie Huang
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences
No. 106, Nanjing Road, Qingdao 266071, China.
Email: huangjie@ysfri.ac.cn

Reference
Guo, X., Gao, W., Chen, X., Wang, H., Zhao, R., Xie, G., & Huang, J. (2024). Is Artemia susceptible to the microsporidium Ecytonucleospora hepatopenaei (EHP) infection? Aquaculture, 741014. https://doi.org/10.1016/j.aquaculture.2024.741014