Aquaculture North America

USDA issues fact sheet on tilapia virus

July 13, 2017
By US Department of Agriculture's (USDA)

A healthy tilapia. The TiLV virus has not been detected in fish farms in the United States 'TiLV: What you need to know'

The United States Department of Agriculture (USDA) today released a fact sheet on a deadly virus affecting the tilapia industry in seven countries. While the virus has not been detected in fish farms in the United States, USDA’s National Institute of Food and Agriculture issued the following advisory as a precaution. Aquaculture North America is publishing it in its entirety:

TiLV: Significance for US Tilapia Industry

Tilapia Lake Virus (TiLV) is a virus that poses a significant health threat worldwide to Nile tilapia, Oreochromis niloticus and hybrid tilapia (O. niloticus x O. aureus). TiLV is in the influenza virus family, Orthomyxoviridae. The World Organization for Animal Health (OIE) is reviewing TiLV to include on its finfish disease list because of the impact it has had on global tilapia production, and the high risk of the virus being moved by infected fish.


TiLV: Disease

  1. TiLV affects fingerling tilapia with reported death rates in affected populations as high as 90%.
  2. Older animals may have a lower mortality rate.
  3. Handling stress (i.e., moving fish between ponds) appears to be a significant risk factor for outbreaks.
  4. The virus survives in both fresh and brackish water.
  5. Direct fish to fish transmission is an important route of infection.
  6. There is no information on vertical transmission (parent to offspring).
  7. TiLV mainly affects tilapia eyes, brain and liver.
  • Eyes may be cloudy, bulging or shrunken
  • Skin lesions may be present
  • Fish may be slow-moving and off feed

     8. TiLV does not affect humans.

What Should I Do? I’m a U.S. Tilapia Producer or Grower

  1. Know your source of animals.
  2. Maintain biosecurity on your farm and educate personnel about how to do this.
  3. Do not bring other fish without a health certificate or tilapia products onto the farm. Ask your aquatic animal health expert about testing for TiLV.
  4. If you experience an unusual mortality event, contact your aquatic animal health expert or the State Veterinarian’s office immediately.

My Business Imports LIVE Tilapia into the U.S.

  1. Do not import tilapia from countries known to have TiLV without a health certificate stating that the fish are tested free of TiLV.
  2. Know and trust your source of animals.

My Business Exports LIVE Tilapia to other countries

  1. Discuss with your customers what import health requirements may be implemented if OIE lists TiLV.
  2. Canada has indicated they will implement health requirements for TiLV once listed by the OIE.

For more information

OIE TiLV Disease Card:

UN’s Food and Agriculture Organization TiLV Worldwide Alert:

Who to Contact

  1. Your aquatic animal health expert
  2. State veterinarian

APHIS Veterinary Services

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