Virus strikes Bulacan pond, kills 101,383 tilapia–report

The lethal Tilapia Lake Virus (TiLV) has arrived in the Philippines, killing 101,383 tilapia in a lone Bulacan-based pond in June, the Department of Agriculture (DA) said.

In a notification submitted to the World Organisation for Animal Health (OIE), Agriculture Assistant Secretary for Livestock Enrico P. Garzon said TiLV killed 101,363 tiliapia out of the 300,000 susceptible population in a Bulacan-based pond, representing a 33.78-percent mortality rate.

Garzon added the outbreak was confirmed last June 29 and has already been resolved by the DA on September 15.

“An unexplained daily mortality of tilapia fingerlings was observed in the nursery pond of a private farm after stocking on May 16, 2017. Elevated mortality after 15 days reached approximately 25 percent. Affected fish showed distended abdomen and bulging of the eyes,” he said in the notification dated November 23.

Garzon said on May 31, the DA collected samples from the affected farm and were submitted to the Fisheries Biotechnology Center (FBC) in Muñoz, Nueva Ecija.

“Semi-nested RT-PCR exhibited positive results using reported Tilapia Lake Virus [TiLV] primers. Other samples submitted to National Fisheries Laboratory- Fish Health of the Bureau of Fisheries and Aquatic Resources also showed positive results by insulated isothermal PCR [iiPCR],” he said.

The DA official added the laboratory results indicated that the “amplified 3 segment of the viral ENE [expression and nuclear retention element] has 94 to 95 percent nucleotide similarity to Israel TiLV strain.”

Garzon said the movement of fingerlings from the affected pond has been restricted and monitored. He added that the results of the last two samplings showed negative for TiLV.

On May 26 the Food and Agriculture Organization (FAO) of the United Nations warned countries of TiLV as it is considered a “lethal threat” to food security.

“The outbreak should be treated with concern and countries importing tilapia should take appropriate risk-management measures—intensifying diagnostics testing, enforcing health certificates, deploying quarantine measures and developing contingency plans,” the FAO said.

“Tilapia-producing countries need to be vigilant, and should follow aquatic animal-health code protocols of the World Organisation for Animal Health when trading tilapia. They should initiate an active surveillance program to determine the presence or absence of TiLV, the geographic extent of the infection and identify risk factors that may help contain it,” the FAO added.

The FAO said the TiLV poses no public health concern, but could decimate infected populations. The TiLV has been reported in at least five countries in three continents: Colombia, Ecuador, Egypt, Israel and Thailand, according to the FAO.

“Tilapia are the second most important aquaculture species in volume terms, providing food, jobs and domestic and export earnings for millions of people, including many smallholders,” it said.

“In 2015 world tilapia production, from both aquaculture and capture, amounted to 6.4 million tons, with an estimated value of $9.8 billion, and worldwide trade was valued at $1.8 billion,” the FAO added.