Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

HEPATOPANCREATIC MICROSPORIDIOSIS IN THE AMERICAS

 Carlos R. Pantoja*, Hung Nam Mai, Roberto Cruz-Flores ,  Sara Lynn, Maia Koliopolus  and Arun  K. Dhar

 

 Aquaculture Pathology Laboratory

 School of Animal and Comparative Biomedical Sciences

 The University of Arizona

 Tucson, Arizona 85721

 cpantoja@arizona.edu

 



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.