The use of medicinal herbs and plants against infections caused by streptococcus species in farmed fish
The use of medicinal herbs and plants against infections caused by streptococcus species in farmed fish
Mehdi Soltani,1,*Rozhin Farshgar,2
1. Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran. 2. Department of Clinical Sciences, Faculty of Veterinary Medicine, University Razi, Kermanshah.
Introduction: Streptococcus disease, especially caused by Streptococcus iniae, Streptococcus agalactia, Streptococcus dysagalactia, Streptococcus uberis, and Streptococcus parauberis, is one of the most important re-emerging infectious diseases in the global aquaculture industry, so that it has become one of the obstacles to the sustainable development of this industry.
Methods: Few studies have been conducted on the antagonistic effects and effectiveness of medicinal herbs and plants against the agents of bacterial zoonotic disease. We reviewed the available data through the scientific-related journals and analyses data since 1970 up to date. We focused on the antagonistic properties of extracts or essential oils of medicinal herbs and plants against all reported streptococcal species that can invade fish causing septicemia under in vitro condition. Also, we analyzed the clinical efficacy of medicinal herbs and plants used against pathogenic streptococcus species under in vivo condition.
Results: Most of the studies have been conducted on the antagonistic properties of plant and herb extracts or essential oils against two species of S. iniae and S. agalactiae under in vitro condition. Also, the findings show that the essential oils of the studied plant/herb exhibited better efficacy than the extracts. In addition among the studied-essential oils those containing eugenol, carvacrol, and thymol revealed a higher anti-streptococcal activity than others. Further, the results of clinical studies (experimental disease treatment) show a moderate effectiveness of the studied-medicinal plants and herbs.
Conclusion: Validating the clinical efficacy of these oils or extracts requires dosage standardization, accurate information of the effective ingredients in the essential oil/extract, their mechanism of action. Thus, in aquaculture practice, use of medicinal herbs and plants as the alternative of antibiotics toward aquaculture streptococcosis warranted further investigations.