The Summary of Main Shrimp Diseases in Asia

Author:Lachance Time:2022-08-02 Hits:
 

 1. Acute Hepatopancreatic Necrosis Disease (AHPND)

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Acute hepatopancreatic necrosis disease (AHPND), also called early mortality syndrome (EMS), is a recently emergent shrimp bacterial disease that has resulted in substantial economic losses since 2009. AHPND is known to be caused by V. parahaemolyticus that contains Pir A&B toxic genes which mainly infects P. vannamei and P. monodon.  The main outbreak area is in Asia, including China, Indonesia, Malaysia, Philippines, Thailand and Vietnam.

Pathogens: V. parahaemolyticus containing Pir A&B toxic genes

  • Symptoms:

Suddenly mass mortality which can up to 100%

Shrimp are susceptible to be infected during DOC 20-30 days 

Mainly attacking and gut-related tissues and organs

  • Possible reasons:

Over feeding, 

Bad quality of PL

Water quality,

Low feed quality

Eutrophication of water or algae crash

  • Prevention:

Improve the hygiene of hatchery

Screening good quality of PL and broodstock

Reasonable feeding amount

Proper density of PL for different farming way


2. Enterocytozoon Hepatopenaei (EHP)

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  • Introduction:generally EHP does not cause the death of shrimp, but will affect the growth rate of shrimp. It can be detected by PCR, and at the same time, the faeces of broodstock are supposed to be tested. EHP is very common in Asia, including Malaysia, China, Thailand,Vietnam, Indonesia and India.

  • Pathogen:

Microsporidian parasite, the size of mature spores is 1.1±0.2~0.6-0.7±0.1μm.

  • Symptoms:

Size of the same batch PL varies a lot

 “slim”

Growth rate slow 

  • Prevention:

Enhance the bio-security of hatcheries, recent studies have found that dragonfly larvae can carry EHP, and these mature spores can also infect shrimp. 

Live bait is not fed and thoroughly disinfected the pond. 

Good pond management, such as removing the organic matter at the bottom of the pond, Generally speaking, the organic matter at the bottom of the pond may contain spores. Once the shrimp is sub-healthy, it may be infected and thoroughly disinfected during the growing period.

Pay attention to the pond management and discharge the pollutants in the pond in time.


3. White spot syndrome virus (WSSV)

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Introduction: 

White spot syndrome virus (WSSV) has a worldwide distribution and is considered one of the most pathogenic and devastating viruses to the shrimp industry.First reported in Taiwan in 1992, it has since spread throughout the whole asia. 

Pathogen: White spot virus

  • Symptoms:

Dramatically decline in feeding, lethargy, high mortality, up to 100% mortality within 3-10 days.

Separation of shell and meat and white spots on the shell, most of white spots are on the inner surface of the carapace, due to the diffu sion of surface pigments.

The color of dying Shrimp is from pink to reddish-brown

  • Prevention methods:

Screening of broodstock, larvae and PL

Avoid drastic changes in water quality

Try not to feed fresh bait or live feed (especially crustaceans, which are more likely to infect each other)

Avoid stress

Reduce the amount of water changes to prevent the introduction of viruses or virus-carrying animals

Thorough disinfection of ponds infected with virus to completely remove infected shrimpand virus carriers

Disinfect all equipments


4. Running Mortality Syndrome(RMS)

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Introduction: RMS was found in India in 2011, but it is non-infectious, often accompanied by high levels of Vibrios, especially V. parahaemolyticus and V. cyanobacteria

Pathogen: has not confirm, may be caused by overfeeding, deterioration of water quality and ultra-high density, etc.

  • Symptom:

Microscopic examination of intestinal contents found that it contained hepatopancreatic cells, and white or yellow feces were found in the intestines

The pigment of the hepatopancreas increases, and the body color changes from reddish to dark red

The clotting time of hemolymph is increased

High mortality, high percentage of B and R cells in the hepatopancreas in the early stage of disease

Occurs mostly during the inter-molt period

  • Prevention:

In the early stage of outbreak, remove dead shrimp

Reduce stock density and harvest in batches

Reduce the feeding amount

Polyculture between fish and shrimp 

Buy high-quality healthy shrimp PL, good feeding management

Improved bio-security measures


All in all, for the shrimp farming, prevention is better than cure, and prevention is the best way. Shrimp farming is a systematic job, if farmers want to achieve high yield, they must maintain good water quality, reasonable feeding and healthy shrimp.


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