Inside the quarantine facility for shrimp with PCR testing lab to keep out viruses

Story and photos by SEAFDEC/AQD

 

Long before COVID-19 imposed mandatory quarantine and reverse transcription-polymerase chain reaction (RT-PCR) testing on travellers, a small building in a seaside town has been serving to regularly quarantine and test shrimp spawners for, not one, not two, but five viruses that plague shrimp farms.

The quarantine facility for incoming tiger shrimp (Penaeus mondon) spawners is part of the shrimp hatchery complex of the Southeast Asian Fisheries Development Center Aquaculture Department (SEAFDEC/AQD) in Tigbauan, Iloilo. Spawners are mother shrimp caught from the wild that each hold between 200,000 and 1 million eggs that hatch into larvae that develop into the fry stocked in ponds.

Inside the quarantine facility, individual spawners, usually sourced from Negros Occidental, are disinfected and allowed to rest in separate tanks in preparation for spawning. Each tank is covered in black canvas material to minimize the spread of droplets or aerosols.

“This is to prevent cross-contamination as well as isolate any potential carriers of pathogens,” said Dr. Leobert de la Peña, a scientist at SEAFDEC/AQD and head of its Research Division.

Pathogens are disease-causing organisms such as viruses that may be transmitted from spawners to their offspring, or through infected water, feed, and other surfaces. Undetected, they may wipe out all the stocks of shrimp farms in a matter of days.

To prevent catastrophic losses, SEAFDEC/AQD has taken a hardline approach through aggressive detection of pathogens from the spent spawners and larvae as well as tight biosecurity throughout the production cycle.

PCR testing

Across the highway is the research center’s PCR testing laboratory that pinpoints positive cases within a day. Once the mother shrimps have released their eggs that soon hatch into nauplii larvae, their tissue samples are tested for the notorious white spot syndrome virus (WSSV), monodon baculovirus (MBV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), yellow head virus (YHV), acute hepatopancreatic necrosis disease (APHND), and the parasite Enterocytozoon hepatopenaei (EHP).

“If the spent spawners tested positive for any presence of pathogens, they are disinfected with chlorine together with its nauplii and discarded,” explained Dr. de la Peña. “If they tested negative on the other hand, these nauplii would then be promptly stocked in larval rearing tanks.”

Once fry are stocked in completely enclosed larval rearing facilities, bacterial analyses of the water and fry are performed twice a week, and fry samples are subjected to periodic PCR testing at the postlarval (PL) stage before they reach PL 5, PL 10, and PL 15.

Tight biosecurity

Aside from testing measures, Dr. de la Peña also stated the importance of practicing strict biosecurity protocols and good aquaculture practices.

“We use ultraviolet (UV) light sterilized seawater for rearing the shrimp larvae. This goes the same for the aeration system which passes through the 0.45 micrometer cartridge filter,” he explained. Meanwhile, wastewater from the facility is thoroughly disinfected before being discharged.

Dr. de la Peña also shared that rubbing alcohol and foot baths are provided at the entrance of the quarantine facility housing the shrimp spawners so that hatchery staff and guests can disinfect themselves as humans can also be a source of contamination.

“These guests cannot be admitted into the facility for 48 to 72 hours if they previously visited an outside hatchery,” he added.

Moreover, visitors are also requested to take a shower and leave their belongings in a designated area to prevent the entry of pathogens. Visitors and staff are provided with scrub suits and boots to change into after they undergo the disinfection procedures.

These measures are in line with SEAFDEC/AQD’s Oplan Balik Sugpo Program initiative. Launched in 2017, the project aims to boost production of high-quality shrimp fry and in turn, revive the shrimp industry in the Philippines.