The source of AHPND infection can come from all shrimp production chains (hatchery to grow out). So it is necessary to ensure that before being released, the SPF-status fry and the ponds that will be used for farming are free from AHPND toxins.
“There was an incident in Kebumen-Central Java, around 2021, at the beginning of AHPND so our knowledge and experience were not like they are now. There was a pond that used a shallow well between 5 – 10 meters deep, the location was also on the coast. The pond experienced mass deaths suspected of being AHPND. Our shallow thinking at that time was that the cause was Vibrio parahaemolyticus so the total vibrio count had to be measured,” said Narendra Santika Hartana, Shrimp & Fish Health Manager – Animal Health & Lab Services PT Suri Tani Pemuka. Surprisingly, it turned out that the TVC was zero, green and yellow vibrio were zero. Even the total bacteria was low.
Narendra explained that the toxin produced by Vp AHPND is exotoxin. As long as the toxin exists in the environment, there does not need to be V parahaemolyticus bacteria around the pond area to cause AHPND symptoms. Therefore, detection of pirA pirB toxin in the pond map during the preparation period is no less important, even in some conditions more important than vibrio detection. In order to carry out further sanitation steps, to eliminate the toxin.
Furthermore, he continued, AHPND outbreaks can also be mitigated by identifying the source of infection risk. Surveillance conducted by ShrimpVet lab Vietnam shows that Acute hepatopancreatic necrosis disease (AHPND) can come from all shrimp production chains (hatchery – grow out). Blood worms, shellfish and squid have the risk of becoming intermediaries for AHPND with levels varying between 3.6% to above 40%. Even the transmission of AHPND from the hatchery could reach 53% of the population in 2019, although in 2019 it dropped to 2.9%.
Narendra stated, compared to the inlet section (22.2%), the largest reservoir of AHPND (65.2%) is in the sediment / mud of the map section to the outlet, so that in this section the greatest potential for exotoxins from vibrio accumulates. In wild crustaceans, sub soil mud (under the plastic layer in HDPE lined ponds) and map water and each of 8.6%, 2.3% and 1.8%.
