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Courtesy of NAA:

Recently, Mexico has reported Tilapia Lake Virus (TiLV) on aquaculture farms in six states: Chiapas, Jalisco, Michoacán, Sinaloa, Tabasco and Veracruz. TiLV is a virus that poses a significant health threat worldwide to Nile tilapia, Oreochromis niloticus and hybrid tilapia (O. niloticus x O. aureus). Fifteen other countries currently report TiLV as being present: Ecuador, Egypt, Israel, Colombia, Malaysia, Mozambique, Philippines, Taiwan, Thailand, Uganda, India, Indonesia, Kenya, Peru, and Tanzania.

TiLV affects fingerling tilapia with reported death rates in affected populations as high as 90%. Older animals may have a lower mortality rate. Handling stress (i.e., moving fish between ponds) appears to be a significant risk factor for outbreaks. The virus survives in both fresh and brackish water. Direct fish to fish transmission is an important route of infection. There is no information on vertical transmission (parent to offspring).

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.

TiLV does not affect humans.

What Should I Do?
If you are a U.S. tilapia producer or grower:
Know your source of animals. Maintain biosecurity on your farm and educate farm employees about how to do this. 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. If you experience an unusual mortality event, contact your aquatic animal health expert or appropriate State Veterinarian’s office immediately.

If you import live tilapia into the United States:
Do not import tilapia from countries known to have TiLV without a health certificate stating that the fish are tested free of TiLV.  Know and trust your source of animals.

If you export live tilapia to other countries:
Discuss with your customers what import health requirements may be implemented if OIE lists TiLV. Canada has indicated they will implement health requirements for TiLV once listed by the World Organization for Animal Health (OIE).

For more information:
Read or download an OIE TiLV Disease Card:
http://www.oie.int/fileadmin/Home/eng/Internationa_Standard_Setting/ docs/pdf/Aquatic_Commission/A_TiLV_disease_card.pdf.

Watch two farm biosecurity webinars posted to the NAA website: http://thenaa.net/webinars/what-you-need-know-about-biosecurity and http://thenaa.net/webinars/how-design-your-biosecurity-plan.

Contact Dr. Kathleen Hartman, Aquaculture Program Leader, USDA APHIS Veterinary Services at 813-671-5230 ext 119 or kathleen.h.hartman@aphis.usda.gov.