, Diagnosis an-&& of Shrimp Diseases - Central Institute of ...

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asophilic globular structures resembling viral inclusion bodies in the HP and LO, suddenand mass mortality, are the diagnostic features of THLN disease.Prevention rind control:NoneHepatopancreatic Parvo Virus (HPV)Nolure of infection:The HPV has been observed in the heptopancreas of cultured P. monodon and P.itldiczrs. However, the infected shrimps did not show any external signs of the disease.Further, the virus was not associated with any mortality. Gross signs of HPV may not bespecific, but in severe infections may include an atrophied HP, poor growth rate, anorexia andsecondary infections by pathogenic Vibrios. Only few samples (3-5 samples) of shrimpscollected during a 12 months period showed the presence of HPV, indicating the lowincidence of this virus in Indian shrimp farms.Patlzogenisis and diagnosis:Histopathologically, basophilic inclusion bodies of HPV can be seen in necrotic andatrophied hepatopancreatocytes. The HPV is a single stranded-DNA virus of 22-24 nm size.DIG-labeled HPV gene probes are also available for the sensiti;ediagnosis of HPV.Prevention and control:Avoid the occurrence of the disease by quarantine methods and destruction of theinfected stoclcs. There is no treatment for HPV.White Spot Disease (WSD)The nature if infection:The first incidence of White Spot Disease (WSD) in India was noticed in December1992 in P. monodon and P.indicus from a few seawater based farms near Tuticorin,Tamilnadu. Infected shrimps with prominent white spots on the cephalothorax region ofexoskeleton succumbed to death. The incidence was a localised one and did not cause alarmdue to the limited impact and localised nature. Since then for about one-and-half-years, therewas a temporary reprieve fiom the disease. However, during November 1994, the diseasestaged a comeback in the shrimp farming belts of Andhra .?radesh and Tamilnadu. Thevirulence of the disease was such that the cumulative mortality reached 100% after theappearance of clinical signs in most of the infected farms, within a period of 3-10 days.
Disease affected the shrimps of all ages and sizes, extensive to intensive farming conditionsand all range of salinities. 'The most i~nportant fact about the WSD is its wide range of hosts,i.e. it infects all cultured penaeids, crabs, lobsters and other crustaceans like copepods andamphipods. Acutely affected shrimps showed lethargy and anorexia. The moribund shrimpshowed up on the water surface and gathered on the edges of the pond. By September 1995,the disease spread to the shrimp farms in Kerala, Karnataka, Goa, Maharashtra, Gujarat,Orissa and West Bengal. The impact was so severe that it forced the closure of many farmscreating a total chaos in the Indian shrimp aquaculture industry. During the period 1994-1995alone, the shrimp loss due to the disease was about 15000 tonnes valued at Ks 500 crores.Even now, the shrimp farnls in the country are under the grip of this epizootic with changingvirulence.Patitogenesis and diagrzosis:The causative agent of the WSD was found to be a rod-shaped virus, the white spotvirus (WSV). This non-occluded, enveloped, nuclear virus infects shrimp tissues ofectoderamal and mesodermal origin.Typical clinical sign in infected shrimp is theappearance of white spots or0patches of 0.5 to 3mm in diameter on the inner surface of theexoslteleton.In many cases, moribund shrimps displayed reddish to pinkish colorationwitliout any white spots. Histologically, the infection is characterized by eosinophilic toprogressively more basophilic inclusion bodies in the hypertrophied nuclei of infected cells,due to the development and accumulation of intranuclear virions. Histopathological studydemonstrates that WSV targets various tissues originating from mesoderin and ectoder~n,particularly cuticular epidermis, gills, stoamch, lymphoid organs, he~natopoietic and antenna1gland. The disease could be diagnosed by histology and confirmed by TEM. New generationDNA based diagnostic tools like gene probes and PCR are also available for theasymptomatic detection of WSD.Though morphological features, histopathological response, and mode of infection aresimilar, the white spot disease has been named differently by various authors from differentcountries: rod-shaped nuclear virus of Penaeus japonicus (RV-PJ) and penaeid rod shapedDNA virus (PRDV) in Japan; systemic ectodermal and mesodermal baculovirus (SEMBV)and white spot syndrome virus (WSSV) in Thailand; hypodermal hematopoietic necrosisbaculovirus (WSBV) in China and white spot baculovirus (WSBV) and white spot disease(WSD) in Taiwan. The name white spot disease (WSD) for the disease, and white spot virus(WSV) for the pathogen has been used for the Indian strain.
Page 5 and 6: OVERVIEW OF STRATEGIES FOR PREVENTI
Page 7 and 8: in harmonizing aquatic animal healt
Page 9 and 10: SI-IRXMP DISEASES: GENEIL4L ASPECTS
Page 11 and 12: quantitative level of pathogen is i
Page 13: presence of prominent eosinophiiic
Page 19 and 20: BACTERIAL AND FUNGAL DISEASES OF SH
Page 21 and 22: Cause: The epibiotic bacteria stich
Page 23 and 24: PARASiTIC AND NON-INFECTIOUS IIISEA
Page 25 and 26: XOS-INFECTIOUS DISEASESNon-infectio
Page 27 and 28: INVESTIGATING SHRIMP DISEASES: OBSE
Page 29 and 30: lnay be a predisposing factor for b
Page 31 and 32: BACTERIOLOGICAL METHODSS.V. Alavand
Page 34 and 35: In place of ZMA, nutrient agar prep
Page 36 and 37: Interpretation: Positive reaction i
Page 38 and 39: Incubate at 37°C for 1-2 h.Examine
Page 40 and 41: Alkaligens: etc. are resistant. The
Page 42 and 43: Culture Media, Reagents and StainsC
Page 45 and 46: Differential characteristics of Vib
Page 47 and 48: Davidson's Alcohol Formatin Acetic
Page 49 and 50: Paraffin cold impregnationXylene an
Page 51 and 52: ProcedureDe-paraffinise the slid'c
Page 53 and 54: Biochemistry of Nucleic Acids with
Page 55 and 56: DNA e.rl1i6it.v base equivuleizcc!E
Page 57 and 58: hydrolyzed by dilute alkali. The su
Page 59 and 60: Polymerase Chain Reaction (PCR) is
Page 61 and 62: a number of viral, bacterial and pa
Page 63 and 64: from 15-30 bases. Negative controls
Page 65 and 66:
PCR Primers for Indian WSVTwo sets
Page 67 and 68:
ANTIOXIDANTS IN MANAGEMENT OF OXIDA
Page 69 and 70:
Many potent chemical carcinogens ar
Page 71 and 72:
cells. It has been shown that possi
Page 73 and 74:
AFB, induced ~nutagenesis in Salmon
Page 75 and 76:
FIGURE 2. An overview of oxygen rad
Page 77 and 78:
were responsible for production los
Page 79 and 80:
for Asiatic region. The participati
Page 81 and 82:
charge of the DNA fragment. The neg
Page 83 and 84:
European countries have in place th
Page 85:
irth to a new concept to treatment
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