Whirling disease (Myxosoma cerebralis): control with ultraviolet irradiation and effect on fish

Area of Science:

• Aquatic parasitology
• Environmental microbiology
• Water treatment technologies

Background:

• Whirling disease, caused by the parasite Myxosoma cerebralis, significantly impacts fish populations.
• Contaminated water serves as the primary vector for Myxosoma cerebralis transmission.
• Effective disinfection methods are crucial for controlling the spread of whirling disease in aquaculture and natural ecosystems.

Purpose of the Study:

• To evaluate the efficacy of ultraviolet (UV) irradiation as a disinfection method for water containing Myxosoma cerebralis spores.
• To determine the optimal UV irradiation dosage for inactivating Myxosoma cerebralis infectivity.
• To assess the impact of silt on the effectiveness of UV disinfection against Myxosoma cerebralis.

Main Methods:

• Water samples experimentally contaminated with Myxosoma cerebralis were subjected to varying doses of UV irradiation.
• UV irradiation doses tested included 18,000 microwatt seconds/cm2 (MWS/cm2) and 27,650 MWS/cm2.
• Infectivity of Myxosoma cerebralis post-irradiation was assessed, with experiments conducted in both clean water and water containing a small amount of silt.

Main Results:

• UV irradiation at 18,000 MWS/cm2 reduced Myxosoma cerebralis infectivity by 31-86%.
• A higher dose of 27,650 MWS/cm2 achieved a more significant reduction in infectivity, ranging from 86-100%.
• Effective disinfection was observed even in the presence of a small amount of silt, indicating robustness of the method.

Conclusions:

• Ultraviolet irradiation is a viable and effective method for disinfecting water contaminated with Myxosoma cerebralis.
• Higher UV irradiation doses are more effective in reducing the infectivity of the whirling disease parasite.
• UV disinfection shows promise for controlling whirling disease transmission in aquatic environments, even under suboptimal conditions with silt presence.