Dahuanong Pei Zhangfu: With the aid of molecular biology testing, ASF prevention and resumption of production can be smoother

African Swine Fever(ASF) has been in China for over a year, and everyone is working on itsprevention and control every day. But have you ever thought about the aspectsthat might not be in place, or the details that you might have overlooked? OnOctober 14-15, at the 2019 Joint Annual Academic Meeting of the GuangxiVeterinary Association, Guangxi Society of Veterinary Medicine, and theInfectious Diseases Branch of the Guangxi Society of Veterinary Medicine, Dr.Pei Zhangfu from the South China Testing Center of Zhaoqing Dahuanong BiologyMedicine Co., Ltd. (hereinafter referred to as "Zhaoqing DHN") sharedthe details of detection and monitoring in the application of ASF preventionand control.

Testing helpsto interrupt the transmission pathways, and pig farms need to monitor sevenaspects of work.

   Viruses are invisible to the naked eye, but with the aid of testingmethods, they can be detected in detail. By utilizing molecular biology testingmethods, one can assess the effectiveness of the disinfection and cleaning workon pig farms. Pathogen transmission routes such as transportation vehicles(including sale pigs vehicles, transfer pigs vehicles, manure trucks, feedtrucks, and material procurement vehicles), personnel (on-site personnel andoutsiders), items (feed, water, semen, and all other items), and vectors(ticks, flies, mosquitoes, rats, cats, dogs, and other creatures) can becontrolled by testing methods to guard every "gate" leading to thepig farm.

For pig farms that have not had AfricanSwine Fever, all means are being used to keep pathogens out. The disinfectionand cleaning work has been greatly improved compared to before the outbreak,but how to judge the effectiveness of the disinfection and cleaning? Dr. PeiZhangfu believes that pig farms need to monitor data in seven major areas:

1.Records of environmental disinfection andtesting in the pig farm.

2.Random inspections after disinfection andbathing of personnel entering the site.

3.Records of harmless treatment of deadpigs and garbage, and pig sales procedures.

4.Records of disinfection of the pig exitplatform.

5.Records of disinfection measures andprocedures for materials entering the site.

6.Testing and records of feed and drinkingwater on-site.

7.Records of vehicle disinfection measures,procedures, and records.

Pig farms that have had problems not onlyneed to do a good job in disinfection and cleaning but also need to stabilizethe farm as soon as possible. Dr. Pei Zhangfu summarized some cases of failed"tooth extraction" clearance in pig farms and analyzed the mainreasons as follows:

1.Routine ASF testing throughout the farmis not standardized.

2.Latent period pig herd testing andclearance are not timely, causing the spread of latent period hiddenvirus-carrying pigs.

3.Only individual sick pigs are cleared; itshould be changed to clear entire rows, units, or buildings.

4.Comprehensive prevention and controlmeasures focusing on biosecurity are not taken.

5.The pig farm is located in an outbreakarea with severe surrounding epidemics and high pressure of virus infection.

   Earlydetection and early treatment, testing is an effective guarantee for resumptionof production.

   For pig farms that have beenaffected, early detection and timely response can reduce losses. Dr. PeiZhangfu introduced the test results of infection status at different times:

According to Dr. Pei Zhangfu, to ensure theaccuracy of test results, attention to detail is crucial:

1.Saliva Testing: Fresh samples are required, and the sampling time should notexceed 2 hours. It is crucial not to freeze and thaw the samples.

2.Nasal Swab Samples: Care must be taken during sample processing to avoid mixingsamples, as the detection rate is lower than that of saliva.

3.Blood Samples: They have the highest detection rate, but universal testing islabor-intensive and not easy to operate. It is particularly important to notethat the virus load in blood is high; blood should not be allowed to drip onthe floor. Additionally, there should be diligent and responsible staff readywith dry cotton to stop bleeding for pigs that have been bled.

For pig farms that are resumingproduction, conducting monitoring is a crucial guarantee that the investmentwill not be wasted. Pei Zhangfu stated that monitoring and testing work must bewell-managed before, during, and after the resumption of production. Beforeresuming production, it is necessary to sample and self-test based on theincubation period of ASFV, focusing on the key and critical points of the pigfarm. At the same time, assist the government or take the initiative to conductASF testing and screening every two weeks for villages within a 3-kilometerradius to ensure that there is no residual ASFV in the farm and no ASFepidemics within a 3-kilometer radius around the farm.

After resumingproduction, it is necessary to monitor the environmental sampling points withinthe pig farm, including pig houses, hardened roads, soil, manure pits, incomingmaterials, feed, water quality, personnel clothing, and kitchens. At the same time,after resuming production, conduct ASF virus pathogen testing throughmulti-site and multi-time sampling every two weeks. Pei Zhangfu believes thatafter resuming production, it is essential to closely monitor the health statusof the pig herd, investigate suspicious epidemics from three aspects:epidemiology, clinical symptoms, and autopsy symptoms, to achieve earlydetection, early diagnosis, and early treatment.

Of course, accurate test results depend onhigh-quality testing kits. Dr. Pei Zhangfu introduced that the Zhaoqing DHNdiagnostic reagent workshop was established in 2017 and has now built adiagnostic reagent production workshop with a purification area of 400 squaremeters, meeting the requirements of veterinary GMP. Currently, there is oneimmunological Class A production line for diagnostic products, which has passedthe GMP static acceptance, and it is expected to obtain molecular biology ClassA production qualifications within the year. At that time, it will become thefirst diagnostic reagent workshop in China with dual Class A production linesfor diagnostic products, with an annual production capacity of 200,000 boxes.

   With the support of high standards and advanced equipment, theAfrican Swine Fever (ASF) fluorescent PCR detection kits produced by Zhaoqing DHNare of high quality, showing good detection effects on various samples such asnasal swabs, saliva, and blood. Dr. Pei Zhangfu revealed that the detection kitis suitable for multiple testing scenarios, including large-scale slaughteringand food processing enterprises, large-scale feed enterprises and breedingcompanies, as well as small-scale slaughtering and food processing businesses.Many well-known domestic companies such as Wens Food Group, Shuanghui, andJiangxi Master Zhu are using it. It is understood that Zhaoqing DHN cancustomize testing plans according to the conditions of various testingscenarios, carry out monitoring, and provide on-site testing services.