Some useful aspects on pond sediment PCR testing

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Some useful aspects on pond sediment PCR testing

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How to collect pond sediment for WSSV testing?

Collect about half-a-kilo of sub surface sediment sample after scraping off about top 4-6 inches of sediment from four to five points especially in the wet patches within the pond including the area near the sluice gate. Pool all the samples, mix thoroughly and send about half- a kg of sediment to the laboratory in zip-lock bag taking care to avoid air within the cover.

Should the sediment from all ponds in the farm be tested for WSSV?

If there was an incidence of WSD during the previous crop, it is advisable to carry out this test on all affected ponds. Testing sediment from an unaffected pond in the same farm located far from an affected pond may not be necessary. However, ponds adjacent to the WSD affected ones should be tested since possibilities of contamination of adjacent ponds are quite high.

Where to get the sediment tested for WSSV?

Pond sediment may be tested for WSSV at CIBA or a reputed laboratory that has capacity to carry out this test. Nucleic acid extraction from sediment is crucial because of PCR inhibitors.

How much time is required for testing sediment for WSSV?

For testing presence of WSSV in shrimp pond sediment, 7-8 hours would be required.

Based on the test results how to decide on starting new crop?

If the sediment is first step PCR positive for WSSV (OIE 2012), do not stock ponds.

Disinfect the pond and dry the pond thoroughly and get the testing done again.

If the sediment is nested PCR positive for WSSV, farmers may stock the pond after about 4-5 days, since the viral load is likely to reduce further to non-infective levels.

Source: CIBA (Central Institute of Brackishwater Aquaculture) – India

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