It is related to fish health management.

1. AN ASSIGNMENT ON WHITE SPOT SYNDROME
PRESENTED BY
MD. IMRAN ALI SHAKH
MS in Fisheries Technology and Quality contro
l

2. Introduction
White-spot syndrome virus (WSSV) is the most economically
important viral disease to impact global shrimp farms.
 An acute disease that are the DNA type virus disease.
WSSV infection often results in 100% mortality among affected
populations within a 3 to 10 days .
Because of its economic importance and designation as
notifiable pathogen

3. History
1992
The first reported
epidemic due to this
virus is from Taiwan
1994
It was found i Thailand,
India and Malaysia,
Bangladesh
1993
It was first found in
China than Japan and
Korea in the same
year,
1995
It was reported in the
United States

4. History
1996
In Bangladesh the
disease spread to
Khulna region
1999
It was outbreaks in
Mexico
1998
It was take place in
Central and South
America
2016
The virus was detected
in Queensland,
Australia in November

5. Causative agent (WSS)
 The causative agent of White spot syndrome (WSS) is white
spot syndrome virus (WSSV),
White spot syndrome virus (WSSV) is a double stranded DNA
virus, which belongs to the family Nimaviridae, genus
Whispovirus .
The disease is highly lethal and contagious, killing shrimp
quickly.

6. Structure of DNA Virus
WSSV is a rod-shaped ,double standard,
DNA virus,and the size of the enveloped
viral partical have been reported to be
210–420 nm long and 70–167 nm in
diameter.
The nucleo capsid core is 120–20 nm
long and the diameter is 95–165nm.
The virus has an outer lipid bilayer
membrane envelope, sometimes with a tail
-like appendage at one end of the virion.

7. Mode of transmission
The horizontal transmission of disease is usually via
cannibalism of sick or dying prawns, or directly through
contaminated water.
Vertical transmission occurs from infected bloodstock
Vectors of the virus include rotifers, marine mollusks including
the copepods, non-crustacean arthropods and insect larvae are a
lso responsible for disease transmission.
Birds can also transmit the disease from pond to pond by relea
sing caught prawns over neighboring ponds.

8. White patches develop within several days
100% mortality within 3-10 days
White spot under the carapace
Sign and symptoms

9. Reduce
preening
Low response
to stimulus and
loose cuticle
Cont’d
….
Infected shrimp is
found together near
the pond edge.
Dark reddish or
pink coloration on
body surface.
Circular white
spots or patches
of 0.5-3.0 mm in
diameter.
Loss of carapace

10. Economics Consequences of WSS Virus
2700M
US $2
40K
In India
Since 1992, shrimp aquaculture, India’
s earnings have gone down to a loss
amount of 2700 million
In Bangladesh
In 1994, affecting approximately 90%
of extensive shrimp farms and causin
g a 20% drop in national shrimp produ
ction
In China
After the first outbreak in 1992, it
reduced the production over 70%
resulting in a production loss over
US $2 billion in three years.
.

11. Economics Consequences of WSS Virus
US $1
billion
US $1.6
billion
40K
In Thailand
In 1994 their production reduced
to 2,65,000 tonnes or US $1.6 billi
on by value.
In Indonesia
In 1992 their production dropped resul
ting losses of US $1 billion through
ten years.
In Ecuador
In 1999 and from that time
production decreased over 60% in
two years, resulting in losses of over
US $1 billion

12. Table : Economic loss of Shrimp production due to disease(WSS)

13. Diagnosis
Clinical diagnosis PCR(polymerase Chain Reaction Histopathology

14. Prevention
 Pond must drying well before pond preparation.
Liming and disinfectant must use before stocking of shri
mp.
Specific pathogen free stocking and at optimum densities
.
Good management practices are maintained for preventi
on of WSS(White Spot Syndrom).

15. Recommendation
One should destroy full stock of infected shrimp.
Shrimp should rear with extreme care.
Use good quality of diet throughout its life cycle.
Water temperature (>29°C) should maintain for resis
tance to WSSV (White Spot Syndrome virus).

16. Conclusion
Most emergent disease cause rapid mortality.
 Better management practice are the only way to get
remedy .
Farmers concern on WSSV and strictly follow the
regulations of GAP.