Hepatopancreatic microsporidiosis caused by Enterocytozoon hepatopenaei (EHP) is currently one of the main diseases of concern affecting the international shrimp farming industry. Originally limited to some countries in Asia , EHP or a closely related species has also been documented in Venezuela in 2016.
This disease is relevant not only because it causes mortality , but also because it contributes to slow growth and can make the shrimp more susceptible to other, secondary infections. Although direct transmission from shrimp to shrimp is a known fact (i.e., via cannibalism or ingestion of spores shed in the feces), there is l imited information regarding alternative modes of transmission or the existence of potential vectors or reservoirs. EHP was originally discovered in Penaeus monodon , but Penaeus (Litopenaeus ) vannamei and crayfish (Procambarus clarkii) are also very susceptible. Additionally, it has been shown experimentally that the infection can be passed from Penaeus (L .) vannamei onto Penaeus (L .) stylirostris.
There are indications that hepatopancreatic microsporidiosis is spreading in the Americas. During 2023, our laboratory confirmed the presence of microsporidian infections affecting the hepatopancreas of shrimp in other countries aside from Venezuela. We do not know yet how closely related this microsporidian is to EHP. However, conventional H&E histology has revealed the presence of lesions diagnostic of the disease, and it is s imilar enough to be detected by current EHP PCR and qPCR protocols. The parasite is also recognized by a gene probe designed for detection of EHP by in situ hybridization assays. Ongoing research comparing genomic sequences will reveal the level of relatedness with EHP.
Hepatopancreatic microsporidiosis is a high-risk disease . Since current molecular methods are adequate at detecting the parasite, avoidance by exclusion should be implemented whenever possible to avoid further spread in this continent.