Disease & Pathologyhigh Threat Level

Monodon Baculovirus (MBV) — Comprehensive Pathology & Treatment Protocol

Dr. K. S. Murthy(ICAR-CIBA Senior Aquatic Pathologist)
6 min read
Verified ICAR-CIBA Protocol

1. Clinical Overview & Background

Monodon Baculovirus (MBV) is caused by Penaeus monodon-type Baculovirus (PmNPV). It represents a HIGH-risk threat to commercial shrimp and fish farming operations across India.

Outbreaks are frequently triggered by sudden environmental stress, such as heavy rainfall, water temperature fluctuations exceeding 3°C within 24 hours, or sudden drops in dissolved oxygen below 3.5 mg/L.

Early diagnosis and strict biosecurity protocols are critical to halting transmission across adjacent ponds in the cluster.

2. Symptoms & Field Diagnostic Signs

Inspect pond stock daily using checktrays and cast nets. Look for these primary clinical indicators:

Reduced feeding and lethargy
Yellowish-brown discolouration of hepatopancreas
Poor growth and moulting difficulties
Polyhedra inclusions visible in hepatopancreas cells (histology)

3. Pathogen Agent & Vector Characteristics

Causative Agent: Penaeus monodon-type Baculovirus (PmNPV)

Primary vectors include wild crabs, aquatic birds, un-sterilized cast nets, contaminated intake water, and infected post-larvae (PL) batches from non-SPF hatcheries.

4. Step-by-Step Action Protocol

01

Immediately isolate affected ponds and stop water exchange with neighboring culture ponds.

02

Reduce daily feed rations by 50% to prevent organic loading and toxic ammonia accumulation.

03

Increase continuous aeration to maintain Dissolved Oxygen (DO) strictly above 5.0 mg/L.

04

Apply recommended disinfectant or therapeutic probiotic dosage as prescribed by an aquatic health specialist.

05

If mass mortality exceeds 20% in 48 hours, conduct emergency harvest of viable stock to recover costs.

Specific Treatment Note: No direct cure. Improve water quality; reduce stress. Apply vitamin C and immunostimulants to boost host resistance.

5. Water Parameters & Dosage Benchmarks

Parameter / ItemRecommended ValueOperational Importance
Target Salinity Range15 – 25 pptOsmo-regulatory stress reduction
Critical DO Threshold> 5.0 mg/LPrevents stress-induced immune suppression
Water pH Stability7.5 – 8.3Controls toxic un-ionized ammonia spikes
Disinfectant Dosage (Emergency)20–30 ppm Active ChlorineComplete pond water sterilization post-harvest

6. Long-Term Biosecurity & Preventive Measures

  • Screen broodstock and post-larvae by PCR
  • Maintain optimal water quality — avoid ammonia spikes
  • Reduce organic load in pond bottom

7. Frequently Asked Questions

Q: Can Monodon Baculovirus spread to neighboring ponds through birds or equipment?

Yes. Aquatic birds, cast nets, boots, and unsterilized aeration equipment act as mechanical vectors carrying the pathogen between ponds.

Q: Is it safe to consume shrimp harvested during an outbreak?

Yes, shrimp pathogens like WSSV and AHPND are specific to crustaceans and pose zero health risk to humans.

Q: How long should a pond remain dry before restocking after an infection?

Ponds should undergo sun-drying for 10–14 days until soil cracks, followed by quicklime treatment at 200–300 kg/acre.

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