White Spot Disease is a highly dreaded disease among shrimp farmers, especially in intensive shrimp farm areas, such as the northern coast of Java, Indonesia. This disease is caused by the White Spot Syndrome Virus (WSSV), which comes from the Nimaviridae family and Whispovirus genus (Rukisah et al. 2019). WSSV is often found among vannamei and giant tiger shrimp farms, especially in farming conditions with fluctuating temperature and poor salinity (Lantu 2010).
White Spot Disease infects shrimps in the Post Larva (PL) 40g stage and results in 100% lethality 3-10 days after clinical symptoms (Rahma et al. 2014) The virus spreads rapidly both vertically (from shrimp to larva) and horizontally (via water, sediments, feed, and pests (Kono et al. 2004).
Shrimp infected with WSSV can be detected from loss of appetite, darkened body, white spots on its carapace, swimming in groups near the water surface, reduced activity, and disturbed intestinal microbiota (Yanti et al. 2017, Aulia et al. 2019). White spots first appear in the 5th and 6th cephalothorax segment from the abdomen which then spread to the shrimp's whole body (Kilawati dan Maimunah 2015).
Early detection of WSSV helps to prevent the spread and subsequently large scale farm loss. Identification can be done through morphological observation or molecular tests such as Polymerase Chain Reaction (PCR),to%20the%20offered%20template%20strand.) (Yanti et al. 2017).
Why is WSSV becoming an issue in shrimp farming?
WSSV has long been an issue for shrimp farmers. This disease not only has a severe influence on the shrimp that are farmed, but it also has an economic cost.
Rapid Spread Rate
WSSV is extremely contagious and spreads rapidly through water, equipment, feed, direct contact with sick shrimp, and even birds that eat shrimp.
No Specific Medicine
There is currently no specific medicine to treat WSSV. Therefore, farmers should focus on disease handling to prevent the disease from occurring.
High mortality rate
WSSV causes mass mortality on shrimp rapidly, sometimes within 6-11 days after clinical symptoms appear. In certain cases, infected shrimp may die within 3-10 days after symptoms appear. Shrimp mortality rates might exceed 100% if the water quality in the pond is poor.
Impacting Shrimp Production
WSSV has an influence on shrimp productivity since its high mortality rate lowers the quantity of harvests and causes large losses for farmers.
How to Handle WSSV or White Spot Disease?
If shrimp in a farm has been infected with WSSV, the farmer may partially harvest them and separate healthy and infected shrimp. Shrimp with light WSSV infection might still survive with slowed growth. Further outbreak might occur in poor pond water conditions, which cause stress to shrimp (Rukisah 2019).
There has not been any effective treatment against WSSV, but a research by Citarasu et al. (2006) discovered that feed containing some herbal plants (C. dactilon, Aegle marmelos, T. cardivolia, P. kurooa and E. alba) or 0.4% honey (Widanarni et al. 2019) may increase immune response and resistance in vannamei shrimp against WSSV.
WSSV or White Spot Disease Prevention
White spot disease prevention can be done directly or indirectly. Direct prevention involves the use of SPF/SPR shrimp stocks, proper farming management which implements biosecurity, and avoiding the use of live feed. Indirect prevention includes regular farm monitoring (Rukisah et al. 2019).
About the author
The author of this article is Shofii Amaliah Putri, a graduate of the Aquaculture Department of IPB University from Tuban, East Java. She's deeply passionate about health and disease prevention in aquatic animals.
References
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