1Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030, Kuala Nerus, Terengganu, Malaysia
2Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan
3International Program in Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan
4Animal and Plant Disease Control Center of Yunlin County, Yunlin, 640201, Taiwan
5National Museum of Marine Biology and Aquarium, Checheng, Pingtung, 94450, Taiwan
6Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan
7Institute of Marine Ecology and Conservation, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan
8Southern Taiwan Fish Diseases Research Center, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan
*Corresponding Author: M.A. Tsai, Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, 91201, Taiwan, Email: william878588@gmail.com
The high mortality rate and stunted growth of marine shrimp in the farm have raised concerns about the outbreak of co-infection involving Enterocytozoon hepatopenaei (EHP) and white spot syndrome virus (WSSV), which could lead to significant economic loss. In a mixed-culture farm consisting of Scylla serrata and Peneaus vannamei located in Yunlin Country, Taiwan, were reported mortality cases on culture animals.
Based on clinical signs, histology and molecular analyses, the disease was diagnosed in this study. In the histopathology examination, infected organs, such as the carapace and gills, were stained with hematoxylin and eosin (H and E), then observed under microscope. For the molecular analysis, SalI DNA fragment (WSSV) and spore wall protein (SWP) gene (EHP) were targeted to detected the pathogen in animal host.
The cumulative mortality data for this co-infection indicates that S. serrata (1.5% mortality) exhibits higher susceptibility compared to P. vannamei (>99% mortality). Phylogenetic tree analysis reveals that the spore wall protein (SWP) gene of EHP and the SalI DNA fragment of WSSV strain extracted from S. serrata are genetically similar to those extracted from Peneaus spp., indicating the potential for cross-species infection. Histopathological examination of lesion tissue observed the presence of WSSV basophilic intranuclear inclusion bodies in the carapace tissue and gill fragments of S. serrata. The source of the disease outbreak is highly suspected to be the feed used, which consisted of raw shrimp and fish. This study provides the first documented case of natural EHP infection with co-infection of WSSV in S. serrata.
Enterocytozoon hepatopenaei, Marine mud crab, Natural infection, White spot syndrome virus
