A review on White Spot Disease in penaeid ... - Middle East - OIE

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Histopathological findings• The histopathology of WSD in moribund shrimps collected duringoutbreaks is distinctive and can be used for preliminary confirmationof an initial diagnosis. However, additional tests such as PCR, in situDNA hybridisation, Bioassy, transmission electron microscopy arerequired for final confirmation (OIE manual of aquatic 2009).• The major targets of WSSV infection are tissues of ectodermal andmesodermal embryonic origin, especially the cuticular epitheliumand subcuticular connective tissues .• Although WSSV infects the underlying connective tissue in theshrimp hepatopancreas and midgut, the hepatopancreatic tubularepithelial cells of these two organs are of endodermal origin, andthey do not become infected.•• Moribund Shrimps with WSD, have systemic viral infection leading tonecrosis of tissues of ectodermal and mesodermal origin.In the histopathological findings in WSD out break in L.vannamei ,in2008( Iran-Khuzestan province)reported by Afsharnasab M. et al.(2009), the subcuticular epithelium of stomach provides excellentview of Cowdry type A inclusion bodies characterized by marginatedchromatin separated from nucleoplasm. (Fig. 9).In the out break ofWSD in P.indicus farms in 2005 (Iran-Boushehr province) reported byAfsharnassab M. et al.(2006)same histological finding were seen inthe moribund shrimp.• Histological signs of WSSV infection include enlarged nuclei in tissuesof ectodermal and mesodermal origin and the most convenienttissue for diagnosis is the subcuticular epithelium.Infection andnecrosis are seen in cuticular epithelial cells and connective tissuecells of the stomach, carapace and gills.• Infection is also seen in the antennal gland epithelium, lymphoidorgan sheath cells, haematopoietic tissues , and in fixed phagocytesof the heart .• Infected cells typically have hypertrophied (enlarged) nucleicontaining a single intranuclear inclusion that are initially eosinophilicand (as an artifact of fixation in Davidson’s fixative solution) areseparated by a clear halo from the marginated chromatin. These areknown as Cowdry type A inclusions;• They are intranuclear, eosinophilic, amorphous and surrounded bya clear halo beneath the nuclear membrane but later, inclusionsbecome lightly to deeply basophilic and fill the entirenucleus(LightnerD.V. 1996,OIE Manual of Aquatic 2009).Above. L.vannamei .Iran. The cuticular epithelium is separatedfrom the connective tissue and large basofilic inclusion bodies(arrows)are centronuclear and segregated from the membrane.With the progress of infection the inclusion bodies wereseparated by a halo 'from the marginal chromatin .(H&E 100X)Source:M.Afsharnassab
Histopathological findingsCowdry type A inclusion bodies are intranuclear, eosinophilic, amorphousand surrounded by a clear halo beneath the nuclear membrane but later,inclusions become lightly to deeply basophilic and fill the entirenucleus(LightnerD.V. 1996,OIE Manual of Aquatic 2009).Left. IntranuclearIBs characteristicof WSSVinfection(arrow)inthe haemapoeitictissue cells ofL.vannamei in Iranshowing signs ofWSSV(H&E 100X).Source:M.Afsharnasab.Above. Intranuclear IBs characteristic of WSSV infection(arrow)in thegill tissue cells of L.vannamei in Iran showing signs of WSSV(H&E 100X).Source: M.Afsharnasab.Left. Intranuclear IBscharacteristic ofWSSVinfection(arrow)inthe heart tissue cellsof L.vannamei in Iranshowing signs ofWSSV(H&E 100X).Source:M.Afsharnasab.**Left.Penaeus vannamei.Hypertrophied nucleiwithin sub-cuticularepithelium. Notegranular eosinophillicstaining (*) within somenuclei and densehaemotoxylinstaining in others(arrows). H&E stain.Scale = 10μm.And (below left)Penaeus vannamei.WSSV particlesdeveloping withinnucleus of infectedcuticular epithelial cell.TEM. Scale = 1μm.Source:EuropeanCommunity ReferenceLaboratory forCrustacean Diseasesleaflet 2008
Page 1: Ali Khatibi Tabar D.V.MDepartment o
Page 4 and 5: Aetiology• The causative agent of
Page 6: World Distribution• Prior to 1992
Page 12 and 13: Environmental stressors• Disease
Page 14 and 15: Immunostimulants & vaccine• The c
Page 16 and 17: Clinical & gross signs• Infected
Page 18 and 19: Mortality
Page 20 and 21: White spots
Page 24 and 25: Histopathological findings12Histolo
Page 26 and 27: Laboratory methods• Diagnostic La
Page 28 and 29: PCR result of assessing the prevale
Page 30 and 31: Differential diagnosis of virus-ind
Page 32 and 33: Farm level biosecurity of WSSV• P
Page 34 and 35: Preventing the entry of WSSV in to
Page 36 and 37: Disease outbreak & its control• Q
Page 38 and 39: EradicationsEradication may not be
Page 40 and 41: Control & MitigationIf infection is
Page 42 and 43: Code of Practice 1388/44/01(summari
Page 44 and 45: Code of Practice 1388/44/01(summari
Page 46 and 47: DiscussionCurrent achievements and
Page 48: Thank You For Your Attention !

A review on White Spot Disease in penaeid ... - Middle East - OIE

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