Kamis, 01 September 2011

Shrimp Disease: Disease Yellowhead

Shrimp Disease: Disease Yellowhead

Cause: Yellow Head Virus (YHD), corona-like RNA virus (genus Okavirus, family Ronaviridae and the order Nidovirales)

Bio - Ecology of Pathogens:
• Krustase sensitive to infection with this virus include: Penaeus monodon, P. merguensis, P. semisulcatus, Metapenaeus ensis, Litopenaeus vannamei, etc..
• Shrimp black tiger shrimp is a very sensitive species, in acute cases can result in the death of up to 100% within 3.5 days since the first clinical symptoms appear.
• Transmission occurs horizontally through the water shrimp or cannibalism to feed a sick or infected.
• Post larvae (PL) shrimp aged <15 days relative resisters against infection with this virus compared with 20-25 days old PL or juveniles.
• The molecular (DNA sequencing) from products of reverse-transcription polymerase chain reaction (RT-PCR) of yellow head virus have similarities to the gill-associated virus (Gav), although different species or strains.


Clinical Symptoms
• Juvenil measuring between 5-15 grams of shrimp have a high appetite (abnormal) for several days, for the next stop (reject) eat all of a sudden.
• About 3 days after refusing to eat, began mass death
• Shrimp are dying gathered near the water surface or to the side of the pond dike / embankment
• Gills are white, yellow or brown
• yellowish cephalothorax, while other body parts pale

This disease can cause mass death within 2-4 days

Diagnosis:
Polymerase Chain Reaction (PCR)

Control:
• Use the fries are really free YHV / SPF
• Maintain the health status of shrimp in order to always prime through feeding the right amount and quality
• Maintain the environmental quality of cultivation so as not to cause stress for shrimp


• Perform harvesting in the pond / pool at the time of occurrence of the disease, early harvesting can reduce but not eliminate economic losses only.
source: Ministry of Maritime Affairs and Fisheries of Indonesia, Directorate General of Aquaculture, Fish and Environmental Health Directorate, 2010

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