Major Diseases of Brackishwater Species


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Major Diseases of Brackishwater Species
Shrimp 1. Disease Name: Necrosis of appendages
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon Symptoms: The tips of walking legs, swimmerets and uropods undergo necrosis and become brownish black. The setae, antennae and appendages may be broken and melanized. Cause: The epibiotic bacteria such as Vibrio spp., Pseudomonas spp., Aeromonas spp. and Flavobaterium spp. Diagnosis: Based on gross signs and symptoms Prevention: Maintain good water quality. Stock shrimp at optimum density. Avoid unnecessary handling of the shrimps, which may lead to injuries and necrosis. Control: Induce moulting by applying 5-10 ppm teaseed cake. Data Source: Shrimp Diseases, Their Prevention and Control, CIBA Bulletin-3 (1995) Photo: Dr. S.V. Alavandi, Senior Scientist, AAHED

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2. Disease Name: Monodon Type Baculovirus (MBV)
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Shrimps lethargic with surface and gill fouling. The virus affects all life stages. Disease severe in postlarvae and senescent adults. High cumulative mortalities.
Cause: Type A Baculovirus
Diagnosis: Tentatively diagnosed by microscopic demonstration of single or multiple spherical intranuclear occulsion bodies in fresh squash preparations of hepatopancreas under phase contrast microscope or by staining with 0.1% malachite green (darkly stained intr
Prevention: Use MBV free stock for culture purpose. MBV infections are well tolerated by P. monodon until the environmental conditions are not hostile. Hence, it is essential to maintain good water quality by increased water exchange in order to minimise risks of s
Control: Not known. Destroy affected shrimp by burning or burying them after mixing with lime away from the culture facility.
Data Source: Shrimp Diseases, Their Prevention and Control, CIBA Bulletin-3 (1995)
Photo: Dr. S.V. Alavandi, Senior Scientist, AAHED

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3. Disease Name: White Spot Disease (WSD)
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Infected shrimps show generalized signs of disease such as rapid reduction in feed consumption, and during the initial stages of infection, minute white spots of up to 2mm diameter appear on the head (cephalothorax) and tail. Subsequently they spread all
Cause: White-spot syndrome is caused by a double stranded DNA virus, called as whitespot virus (WSV) or white-spot syndrome baculovirus (WSSB) complex or systemic ectodermal and mesodermal baculovirus (SEMBV).
Diagnosis: WSD can be presumptively identified by microscopic examination of tissue impression smears stained by Geimsa's stain. These preparations reveal extensive damage and presence of viral inclusions in the cuticular epidermis, gills, lymphoiod organ and gut wa
Prevention: So far, no control measures are known. Only integrated management involving quarantine, routine screening of shrimp for viral infection and good husbandary practice could avoid the disease. Infected stock must be properly disposed by incineration or buryi
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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4. Disease Name: Infectious Hepatopancreatic and Lymphoid Organ Necrosis (IHLN)
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: The infected shrimps exhibited light pinkish to yellowish discolouration of the cephalothorax region and were most often associated with fouling by ciliate protozoa such as Zoothamnium. The hepatopancreas of affected shrimp was highly decayed (necrotic) a
Cause: The primary cause of the disease is attributed to viral etiology
Diagnosis: Presumptive diagnosis of IHLN could be achieved based on the gross clinical signs and symptoms and confirmed by histopathological examination. The hepatopancreas shows multifocal necrosis, marked by haemocytic infiltration and encapsulation resulting in
Prevention: Although viral etiology was the primary cause of the disease, secondary bacterial infection and environmental degradation caused mass mortality of shrimp in the affected ponds. Some of the water quality parameters such as total suspended solids, chemical
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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5. Disease Name: Hepatopancreatic parvo-like virus (HPV) disease
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Affected shrimps show generalized signs of disease such as reduced feeding, poor growth rate, body surface and gill fouling with ciliates, occasional opacity of abdominal muscles, and atrophy of hepatopancreas.
Cause: HPV is caused by a small (22-24nm size) DNA virus.
Diagnosis: HPV can be diagnosed by histopathological demonstration of single prominent basophilic (pinkish) intranuclear inclusion bodies in the hypertrophied hepatopancreatic tubule epithelial cells by haematoxylin and eosin staining method. The host cell chromatin
Prevention: HPV infection could be avoided by quarantine and screening for pathogen.
Control: No control measures are known.
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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6. Disease Name: Systemic vibriosis
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Infected shrimps show opaque Abdominal musculature, pale gill filaments, melanised (black) ventrolateral edges of the carapace, flared up gill covers (branchiostegites) popularly known as German helmets, blisters on the shell, brownish to black cuticular
Cause: Systemic vibriosis can be caused by bacteria such as Vibrio alginolyticus, V. parahaemolyticus, V. anguillarum, V. vulnificus, V. damsella, V. fluvialis and V. mimicus
Diagnosis: Diagnosis of vibriosis is usually based on gross clinical signs and symptoms and confirmed by isolation of bacteria by microbiological techniques. Haemolymph of affected shrimp contains numerous bacteria and upon culture, yield Vibrio spp. on the culture
Prevention: Maintenance of good water quality to reduce bacterial counts in the culture system will be of immense help in reducing incidence of bacterial infection in hatcheries and culture ponds. However, methods employed to obtain quality water in the culture p
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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7. Disease Name: Luminescent bacterial disease
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Eggs, larvae, post-larvae, juveniles and adults of shrimps may suffere from luminescent bacterial disease. Affected shrimp larvae become weak and opaque and exhibit greenish bioluminescence under darkness. The luminescent bacterial disease may lead to com
Cause: Luminescent bacteria such as Vibrio harveyi and V. splendidus.
Diagnosis: The disease can be diagnosed based on gross signs and symptoms. Microscopic examination of infected larval shrimp would reveal large number of swarming bacteria in the haemocoel. Bacteria could be readily isolated on common culture media, such as Zobell'
Prevention: Daily exchange of 80-90% water in the hatchery and maintenance of good water quality by physical or chemical methods will help in reducing bacterial counts and incidence of bacterial infection. The hatchery facilities must be disinfected. Disinfection
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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8. Disease Name: Larval mycosis
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon Symptoms: Infected eggs do not hatch. The eggs and larvae are weak and appear whitish. Mortalities may reach 100% within two days. Upon infection, the fungal mycelium replaces the larval tissues and ramifies into all parts of the body and protrudes out of the bo
Cause: Larval mycosis is caused by filamentous fungi of genus Lagenidium spp. and other filamentous fungi such as Sirolpidium spp. and Haliphthoros spp. are also often associated in cases of larval mycosis.
Diagnosis: The fungus can be identified by microscopic examination of affected protozoea and mysis stages, which would reveal filamentous fungal mycelia in the body cavity of affected larvae. Fungi could be identified depending upon the morphology of discharge tube,
Prevention: General hatchery management practices such as use of UV sterilised and filtered seawater, adequate water exchange, etc. must be strictly adhered to. Use of antifungal agents during infection should be discouraged. Rearing water, equipment used in the ha
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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9. Disease Name: Protozoan fouling
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Mild infestations usually do not harm the shrimp. Heavily infested shrimps are restless, appear near the surface and periphery of the pond and show generalized signs of disease such as lethergy, lack of appetite and occasional opacity of abdominal muscle
Cause: The most common cilliate fouling is caused by Zoothamnium spp. other protozoa such as Vorticella spp., Epistylis spp., Acineta spp. etc. are also often involved in epibiotic fouling especially in culture facilities that are poorly managed.
Diagnosis: Microscopic examination of shrimp larvae or scrapings from exoskeleton or wet mount preparations of gills of cultured shrimp reveal the identity of protozoa.
Prevention: Treatment with 15 to 20 ppm of formalin for 5 to 10 days depending on the extent of fouling and efficacy is usually advocated in ponds. However, primary cause of fouling must be understood before the treatment. In hatchery tanks, 25 to 250 ppm formalin t
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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10. Disease Name: Microsporidosis (Cotton shrimp disease or milk shrimp disease or cooked shrimp or roe shrimp)
Species General Name: Tiger Shrimp Species Scientific Name: Penaeus monodon
Symptoms: Infected shrimps appear opaque and cooked. Gradual and low levels of mortalities are observed in the affected ponds.Microsporida invade and replace host tissues such as gills, muscles, heart, gonads and hepatopancreas, and cause necrosis of the infected t
Cause: Microsporida such as Thelohania spp., Nosema spp., and Pleistophora spp.
Diagnosis: Microsporidial infection can be diagnosed by demonstration of microsporidian spores in the affected tissues by simple tissue impression smears under the microscope. Geimsa stained preparations also reveal the microsporidia upon microscopic examination.
Prevention: Not Known
Control: Not known
Data Source: Shrimp Diseases: Symptoms, Causes, Diagnosis, Prevention and Contro, CIBA Extension Series No.19 (2000)l

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Major Diseases of Brackishwater Species