THE PREVALENCE OF HEPATOPANCREATIC MICROSPORIDIOSIS CAUSED BY Enterocytozoon hepatopenaei IN Penaeus vannamei FARMS OF TAMIL NADU, INDIA

Shrimp aquaculture is a commercially important major food producing sector globally. India is one of the major producers of P.vannamei with the present annual production of 5,63,000 tonnes. The contribution of Tamil Nadu state in the Indian shrimp production is about 32,000 tonnes during the year 2017.  Shrimp farming practices are hampered by the outbreaks of various existing and emerging diseases from time to time. Hence, periodic surveillance of the diseases is important to understand their prevalence and to develop suitable management measures for their prevention and treatment for profitable and sustainable shrimp farming.

A state-wide disease surveillance was undertaken to screen for the OIE listed pathogens and other pathogens of commercial importance in the P.vannamei farms of Tamil Nadu, India. This study was undertaken in Tiruvallur and Nagapattinam districts of Tamil Nadu with intensive shrimp farming activity during the period from September 2016 to December 2018. Samples of P.vannamei postlarvae (128), and juveniles/adults (551), soil (237) and white faeces (60) from shrimp ponds were collected. Screening was done by PCR for diseases caused by White spot syndrome virus (WSSV), Infectious hematopoietic necrosis virus (IHHNV), Shrimp hemocyte iridescent virus (SHIV), Infectious myonecrosis (IMNV) and Enterocytozoon hepatopenaei (EHP).  Microbiological analysis and PCR were carried out for the diagnosis of Acute hepatopancreatic necrosis disease (AHPND), and white faeces syndrome (WFS).                                                       

The results of the study showed that, among the total number of 976 samples screened, the overall prevalence of EHP was the highest (17.11%) followed by WSSV (3.073%) and IHHNV (0.1%). The highest prevalence of EHP was recorded in the white faeces followed by soil samples   (Table 1 and Fig 1). EHP causes hepatopancreatic microsporidiasis in P.vannamei resulting in reduced growth and associated production, economic losses in shrimp farming operations. Hence, adoption of suitable management measures for the prevention of the disease through selection of disease-free postlarvae and live feed,  maintaining the health of shrimp following good water and feed quality management would help for a successful and sustainable aquaculture.