Complete details about EHP in shrimp pond.

Hello everyone:

        Today we will see about important disease occurs in shrimp farming called EHP. EHP, white spot syndrome, Vibrio, white gut, white fecal disease. These are incurable.

        Hepatopancreatic microsporidiosis is a disease caused by Enterocytozoan hepatopenaei, we called it as EHP. It is a microsporidian parasites and have intracellular action on host cell. It penetrates into the host cell and start multiplication.

          It is first discovered in P.monodon in Thailand in 2004, but it causes severe loss and wide spread from 2009.

Symptoms:

          By physical observation, we can't detect EHP in shrimp. We thought like, yes our shrimp grows well, no problem, but EHP shows it's work after some DOC. If your shrimp affected with EHP means, huge size variation occurs on the population. Shrimp grows very slowly. Farmers have a general doubt, before stocking we checked EHP for the seeds, at the time negative results came but how it affects? How it is possible?

            Remember that, in certain early stages of shrimp, this parasites does not proliferate in certain amount. So the PCR results is negative. EHP will detected on certain later stages of shrimp. This is the main problem. So we have check some often times for the presence of EHP in shrimps after stocking. If the shrimps affected with EHP, it increases the FCR. Lot of chance for feed wastage. It leads to affect in another water quality like Ammonia,pH and nitrite. Empty gut, soft shells also occurs in shrimps.

 How EHP enters into the pond?

Improper pond preparation.(if previous crop is affected by any disease, we have properly dry and disinfect the pond for next crop).

Improper biosecurity in farm.( Remember that biosecurity is the important one in farm).

Improper checking the quality of seeds during purchasing.

How it enters into hatchery?

    In broodstock management, we give high protein feed with polychaetes, clams to the shrimp.

    EHP is a parasite, it is mostly found in these live organism which is used as a feed in hatchery. There may be a one of the chance for contamination. So, it is better to give the food after heating or prevents the use of live animal for feed or frozen the food or radiate the food before application. It may reduce the parasite. The news told Artemia, mollusks, polychaetes are positively reported for EHP. Like vibrio, EHP also well proliferate in high saline condition. The Marine water must properly disinfected.

How it spread to other shrimps?

    EHP is generally enters into host by oral and fecal matter or directly affect the hepatopancreas. In hepatopancreas, it causes lesions and reduce the activity. In hatchery, if an animal is affected with EHP, the fecal matters released by the affected animal causes infection to other shrimps.

EHP is a spore forming parasite.

           Spores enters into the target host cell.

       Insert it's spore into target host cells cytoplasm

         New spores matures inside the cytoplasm by   nucear division.

     Spore cells matures, bursts, release the matured spores.

Infect the other cell... likewise spread into all cell...

Spores also excreted through fecal matter of the affected shrimp. It easily affect the entire population.

But in different salinities may affect the duration of spore formation of EHP. High saline and high hardness condition is favourable for EHP. Because, Ca is important for conducting cell events in EHP.

Low infection does not cause mortality or lesions.

EHP also associate with other disease like AHPND and white feces syndrome in vannamei.

In high proliferated condition causes other opportunistic bacterias to grow. By this triggeration also leads to WFD.

High pH also promotes faster extrusion of spores.

In hatchery, we have to properly maintain biosecurity measures, proper cleaning and disinfecting the eggs. It prevents the vertical transmission of disease. If you are maintains nursery, before going to stock in growout , you have to check the EHP one time.Proper pond management, proper biosecurity measures, proper sampling, proper selection of seeds, proper pond preparation is the important thing to prevent this infection.