Eustrongylides spp. parasite risk management in Atherina boyeri from Lake Trasimeno

Atherina boyeri is the primary source of fishing profit in Lake Trasimeno and a common host for Eustrongylides spp. larvae. The presence of Eustrongylides in fish is a public health concern, and effective risk management procedures are necessary to guarantee that infected products do not reach the market. Currently, in the European Union, there is no official sampling plan for fresh fish that defines sample size, inspection methods, and criteria for accepting or rejecting the product. An approach to Eustrongylides risk management is proposed in this study. A total of 270 batches of A. boyeri, each consisting of 29 specimens, were collected and examined visually in 3 years (2020-2023). The prevalence of the parasite was 20% in 2020, and in the first months of 2021, it grew up to similar to 40%, then dropped to 12.50% in December 2021 and settled at 16% in February 2022. In January and February 2023, the prevalence fell below 1%. The mean abundance was calculated and used to establish a threshold value to determine fish marketability. In 2020 and 2021, several batches were judged not marketable, and in some batches, a freezing treatment was implemented to ensure the inactivation of the parasite. In the last months of 2022 and in January and February of 2023, the presence of parasites in captured fish was negligible, and this allowed the marketability of fish as fresh. The proposed sampling plan was effective in preventing the commercialization of potentially hazardous products.