Streptococcosis

- Control of disease

Preventive measures

◾  Application of Standard operating procedures (SOPs) and biosecurity measurements are an effective strategy for limiting disease spread.

◾  Vaccine application in aquaculture is also effective for disease prevention. Formalin killed Strept. agalactiae vaccine via different routes (Linh et al., 2022), DNA vaccines and live attenuated Strept. iniae vaccine (Heckman et al., 2022) were applied. Also, oral delivery of nanoemulsion Streptococcus agalactiae vaccine with bile salt coated by chitosan in Nile tilapia (Suwanbumrung et al., 2023).

◾  In Egypt, there was limited research towards generating a streptococcal commercial vaccine. Montanide adjuvant Strept. agalactiae (Abu-Elala et al., 2019) and polyvalent formalin and autoclaved inactivated vaccine (El-daim et al., 2023b) were used as a trial for protecting Nile tilapia against streptococcosis.

◾  Immunostimulants such as herbal, prebiotics and probiotics have protective effects against Streptococcus sp. infection (Van Doan et al., 2022).

Treatment

◾  Sensitivity test should be done to select the most effective antibiotic to use.

◾  The approved antibiotics that have been used to control streptococcal infection, are oxytetracycline (75 and 100 mg/ kg), 1.5 g erythromycin/ kg diet for fed for 10 to 14 days (Darwish and Hobbs, 2005), and Aquaflor (florfenicol) (15 mg/kg fish per day for 10 consecutive days) (Oliveira et al., 2018).

Zoonotic importance

◾ Strept. agalactiae, and Strept. dysgalactiae, and Strept. iniae were known to be zoonotic for immunocompromised people who handled live fish (Gauthier, 2015).

◾ In humans, handling of infected live and dead fish can result in development of cellulite, endocarditis, meningitis, severe systemic infections, suppurating ulcers, septicemia, arthritis, lymphadenitis (Haenen et al., 2013), and rarely death.