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February 3, 2016

Australia

Vibrio Outbreak

 

OIE, the World Organization for Animal Health, a reference organization responsible for improving animal health worldwide, has reported on a new shrimp disease outbreak in Queensland, Australia.

 

Mortalities of farmed Penaeus monodon have been observed in some ponds at several farm sites.  An event in late 2015 did not meet requirements for immediate notification; however, a January 2016 event did, and both events are reported here.  Affected animals range from 35 to 95 days post stocking.  Mortality rates have varied from negligible to approximately 90%.  Hepatopancreatitis has been associated with affected shrimp.

 

The histopathology of the hepatopancreas in affected animals is consistent with that described for acute hepatopancreatic necrosis disease (AHPND); however, the disease does not meet the case definition for AHPND provided in the draft OIE Aquatic Code chapter that has been circulated to OIE members.

 

Current diagnostic information on the disease is described below:

 

• A member of the Vibrio harveyi clade has been isolated from affected shrimp.

Vibrioparahaemolyticus has been excluded.

 

• PCR tests (AP3 and AP4 assays) of the bacterial isolates from affected shrimp were positive

for PirA and PirB toxin genes.  AP1 and AP2 assays were negative (positive in control AHPND

samples from Asia), indicating absence of the pVA1 plasmid associated with AHPND.

 

• Preliminary whole genome sequence analysis indicates that the PirA and PirB toxin genes may

be integrated into the genome of the bacterial isolate.

 

• Laboratory investigations are continuing to complete whole genome sequence analysis and

identify the bacterial isolate.  Bioassays are being considered to confirm pathogenicity of theisolate.  A national survey will be undertaken to determine the distribution of the disease.

 

Source of the Outbreak: Unknown or inconclusive.

 

Measures Applied: Disinfection/Disinfestation, Quarantine, Surveillance.

 

Report's Author: This report (in English, French and Spanish) was submitted to OIE on February 2, 2016, by Dr. Mark Schipp, Chief Veterinary Officer, P.O. Box 858, Canberra, Act 2601 Canberra, Australia (phone +61 262 724 644, fax +61 262 723 150).

 

Information: OIE (the World Organization for Animal Health), 12, rue de Prony, 75017 Paris, France (phone 33-(0)1-44-15-18-88, fax 33–(0)1-42-67-09-87, email oie@oie.int, website http://www.oie.int).

 

Source: Email to Shrimp News International.  Subject: OIE Alert Hepatopancreatitis in Prawns.  February 3, 2016.

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