Vibriosis

Vibriosis is also known Sea Gull Syndrome due to shrimp swimming at surface of pond (seagulls eat them). The etiological agents are wide variety of gram negative motile rod shape bacteria includes- V. harveyi, V. vulnificus, V. parahaemolyticus, V. alginolyticus. Most frequently found in hatcheries, but a big problem for young PL’s in ponds. All shrimp reared under stressful conditions are susceptible to vibriosis.

Clinical Signs: High mortalities in PL’s, young juveniles; moribund shrimp appear hypoxic and often come to the pond surface or edge; sea birds preying on shrimp; presence of luminescence in tanks.

Presumptive Diagnosis: A clinical sign includes large amounts of bacteria in hemolymph, slow clotting and melanosis of shell.

Confirmatory Diagnosis: Isolation/purification with appropriate media (TCBS).

Shrimp Vibriosis: commonly affected organs

• Cuticle
• Hepatopancreas (midgut gland)
• Lymphoid organ
• Antennal gland
• Heart and hemolymph
• Striated muscle

Hatchery Control:
Improve husbandry, especially in the areas of sanitation and disinfection, feed quality, water source purity, use of probiotics.

Grow-out Control: improve stocking handling to reduce stress, have feed in pond in advance of stocking, use of probiotics.