The white spot syndrome virus (WSSV) belongs to the genus Whispovirus , family Nimaviridae. The virus was reported for the first time in Costa Rica in 2000 in shrimp production systems located in the Gulf of Nicoya, causing mortalities between 60%-70%. Enterocytozoon hepatopenaei (EHP) is an intracellular spore-forming microsporidium parasite that causes the hepatopancreatic microsporidiosis. Microsporidium has been reported in Asia and recently in Venezuela . There are no reports of EHP in Costa Rica. The objective of this study was therefore to detect the presence of these agents using molecular techniques (PCR and sequencing) in samples collected from shrimp farms located in the Gulf of Nicoya on the Pacific coast of Costa Ric a.
A non-systematic convenience, cross-sectional descriptive study was carried out. Between 2017 and 2018 water from the first pumping, postlarvae , and juvenile shrimp of Penaeus vannamei were collected during a productive cycle in 15 shrimp farms in the Gulf of Nicoya and Central Pacific from Costa Rica and were visited two times: at the beginning of the production cycle (between January 2017 and June 2018), and 6-7 weeks after stocking, which is when the literature reports that the highest mortalities caused by WSSV and EHP occur in farms. Samples were analyzed through the polymerase chain reaction (PCR) using primers and protocols to detect the VP41B gene in WSSV, and the small subunit ribosomal RNA gene of EHP. The amplifications yielded better results when DNA extractions were used without dilution or in 1/10 dilution. The presence of WSSV was detected in a farm, while EHP was not detected. Sequencing of the amplified segments of the VP41B gene showed 100% identity with sequences isolated from a shrimp in Taiwan and another from Mexico , this sequence was deposited in the GenBank database with access number MH553567. It is recommended to support the shrimp producers in the management of their farms and in the implementation of biosecurity protocols to prevent and control WSSV. Prevalence of WSSV in Costa Rica must be determined, and further longitudinal studies of environmental variations that favor WSSV replication should be carried out. In addition, molecular and histopathological techniques must be applied to detect presence of WSSV and the pathological changes it induces at the cellular level.