Loose shell syndrome of farmed Penaeus monodon in India is caused by a filterable agent

Abstract

Loose shell syndrome (LSS) of farmed black tiger shrimp Penaeus monodon has been reported from Indian shrimp farms since 1998 and is recognized as a major disease problem causing significant economic loss to the shrimp aquaculture sector. Unlike the rapid mortalities associated with viral pathogens such as white spot syndrome virus and yellow head virus, progression of LSS is gradual, leading to low-level progressive mortalities. The signs of LSS include a flaccid spongy abdomen due to muscular dystrophy, space between the exoskeleton and muscle, and a shrunken hepatopancreas. The feed conversion efficiency is reduced, and shrimp have poor meat quality, caused by impairment of the hepatopancreatic functions such as digestion and absorption as evidenced by the atrophy of the hepatopancreas. Histopathological investigations on LSS-affected shrimp showed shrinkage of extensor and flexor muscles with occasional hemocytic infiltration. The hepatopancreas showed inflammation of hepatopancreatic tubules with enlargement of intertubular spaces, hemocytic infiltration, and low levels of lipid reserves in the R cells. In advanced stages of LSS, many tubules were in highly necrotic condition with a sloughed epithelium, reflecting the dysfunction of the digestive gland. LSS could be induced in healthy tiger shrimp by challenge studies using membrane-filtered LSS-affected shrimp tissues, suggesting involvement of a filterable infectious agent.

Loose Shell Syndrome (LSS) in Litopenaeus vannamei grow-out Ponds and its Effect on Growth and Production

“…The loose shell syndrome characterized by a flaccid spongy abdomen due to muscular dystrophy, lethargic and flaccid. The exoskeleton forms a sort of loose covering over the abdominal musculature, with a gap between the muscle and shell in P. monodon by [1,2,[8][9][10]. In the present study the same symptoms were found in L. vannamei, where the LSS infected shrimps became sluggish, soft exoskeleton, gab between muscle and shell, pigmented hapatopancreas and microbes fouling on the exoskeleton.…”

“…This is due to the poor bottom conditions of the ponds. The affected shrimp has a soft carapace with a gap between the muscle tissue and exoskeleton, shrunken hepatopancreas [1].…”

First incidence of loose-shell syndrome disease in the giant tiger shrimp Penaeus monodon from the brackish water ponds in Bangladesh

“…LSSD was first reported in India in 1998, and the incidence of this disease has increased every year (Alavandi et al 2007). LSSD was prevalent in Tamil Nadu, Andhra Pradesh, Orissa, Gujarat, Kerala, and west Bengal of India (Alavandi et al 2008;Loka et al 2012). The incidence of LSSD was reported in approximately 14-23% of shrimp farms in Tamil Nadu during -1999(Mayavu et al 2003Alavandi et al 2008) and incurred a loss of ∼9.125 million USD in 2006 (Alavandi et al 2008).…”

“…LSSD was prevalent in Tamil Nadu, Andhra Pradesh, Orissa, Gujarat, Kerala, and west Bengal of India (Alavandi et al 2008;Loka et al 2012). The incidence of LSSD was reported in approximately 14-23% of shrimp farms in Tamil Nadu during -1999(Mayavu et al 2003Alavandi et al 2008) and incurred a loss of ∼9.125 million USD in 2006 (Alavandi et al 2008). Together with the WSSD, LSSD has caused severe economic losses for penaeid shrimp farms in north coastal Andhra Pradesh and east Godavari district in India (Loka et al 2012).…”

Horizontal Gene Transfers with or without Cell Fusions in All Categories of the Living Matter

“…An abbreviated listing of Shrimp and Prawn viruses: Baculovirus [99a]; Dicistroviruses [100]; Hepatopancreatic parvovirus [99b, 101]; Taura syndrome virus [102][103][104]; Yellow head nidovirus [105]; Gill-associated and yellow head okavirus [106]; Whispovirus. White spot syndrome virus [107][108][109][110]; Loose shell syndrome virus [111]; Crustacean antiviral immunity [112].…”