Home Economy Improving our African Swine Fever virus surveillance

Improving our African Swine Fever virus surveillance

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ALEKSANDARLITTLEWOLF-FREEPIK

It was a very helpful initiative by the Chairperson of the Senate Agriculture Committee, Senator Cynthia Villar, to call a public hearing on the African Swine Fever (ASF) vaccine last week. With it, we were able to focus our attention on the concerns surrounding the vaccine from Vietnam. For months now, stakeholders have heard about a significant importation of the vaccine, reportedly amounting to 3,000 doses, by a private sector firm. Allegedly, once the Food and Drug Administration (FDA) issues the importer a Certificate of Product Registry (CPR), those doses will be commercially sold to vaccinate the country’s pig inventory.

At the outset, we should feel good upon learning that perhaps we can get rid of the ASF virus sooner than expected. Unfortunately, there are ongoing concerns of the vaccine, which tell any country to take extra care before permitting its use.

Reports indicate that the vaccine had been used in Indonesia, Vietnam of course, and China. In all three, swine mortalities were observed, reportedly linked to the use of the vaccine.

The major concern can be traced to the source of the virus strain. The agent used to develop the Vietnamese vaccine was developed by USDA Agriculture Research Service (USDA/ARS). Called, the ASFV-G-ΔMGF, the agent was initially listed by the US regulator, in this case the USDA Animal and Plant Health Inspection Service (APHIS), under its Select Agent Regulatory Exclusions List. Such registration indicates it may be used for further research in the US and in this case to develop the ASF vaccine.

USDA/APHIS, however, delisted the ASF virus agents as these were evaluated to potentially pose a severe threat to animal health and animal products. However, Vietnam had already developed the vaccine and was getting started to commercialize the product.

I am for the vaccine if it is efficacious and safe to use. And this is why the regulator, the FDA with BAI (Bureau of Animal Industry), must conduct, or cause to conduct, randomized control trials on the Vietnamese vaccine. These trials must be conducted by professionals with no conflicts of interest. The stakes are large — our entire livestock industry.

These trials take some time, and there are protocols to follow to ensure the integrity of the trials. Moreover, the results of it must be publicly disclosed and reviewed by third party experts. That must happen first before a CPR is issued on the vaccine.

Critics have bewailed the poor performance of the country’s agricultural sector, especially during the administration of President Rodrigo Duterte. Of course, this can be explained by the African Swine Fever, which has nearly destroyed the industry. By 2019, we lost about 3 million heads of the country’s swine inventory and a third of a million of our breeders.

It used to be that the livestock industries (swine and poultry) had led the growth of the agricultural sector. Despite severe weather which dampened the contribution of the rice and corn industries to the gross value added of agriculture, the sector’s performance continued to float above a percent or two. But when ASF hit the country in 2019, that role dwindled, pulling down the economic performance of primary agriculture to about nil.

It would seem now that ASF would be with us for several decades. There are analysts who point out that it took Spain 30 years to get rid of the virus. When the disease hit us in 2019, it only decimated the swine industries of Luzon around the National Capital Region. A good part of the Visayas and Mindanao was spared.

Not anymore. It is affecting the entire country, except for a few island provinces with leaders passionate in conducting effective surveillance of the virus and closing its borders at the smell of it, like the governor of Cebu.

A SURVEILLANCE SYSTEM WANTING IMPROVEMENTSIn the meantime, the country must apply an effective surveillance system on the ASF virus. When the disease hit in 2019, the Agriculture department came out with several circulars on swine depopulation (AC No. 22 s. 2020), national zoning and movement plan (AC No. 2, s. 2022, amending AC No. 12, s. 2019), and the Bantay ASF Program (AO No. 7, s. of 2021).

That ASF had spread to many places in the country may be traceable to the current weak surveillance system that regulators use.

This surveillance approach is wanting for several reasons. One, it is reactive. Virtually blind with respect to the virus, regulators act when the clinical signs of the disease are observed, i.e., the pigs are dying or are sick. Two, confirmation of the presence of the disease is slow, with only a few animal disease diagnostic labs available. Three, samples used in verifying the disease are themselves carriers of the disease, risking the spread of the disease. Four, when regulators have to depopulate, they do so by zones, raising the cost to producers. Five, while producers are compensated, the amount is not readily available and below the cost of raising the sick pigs until they must be destroyed.

Incentives are all stacked in favor of just being quiet about the disease, which perpetuates the incidence.

Lastly, the implementors are few relative to the surveillance work done. This is why regulators allow a three-month validity of ASF clearances, which is just too long.

A FEW IDEAS TO IMPROVE OUR SURVEILLANCE SYSTEM1. We must use mobile PCRs or mPCRs to conduct on-site testing, instead of waiting to observe clinical signs of the presence of the virus. The onsite testing using mPCRs generates qualitative results, evidencing the sample tested has or does not have the virus. With this device, we manage the ASF disease by exception. The device is capable of producing onsite results in at most two hours after testing. Only those with positive results are to be confirmed and analyzed for the viral load and virulence of the virus.

2. We must deputize the municipalities/cities to conduct onsite testing. This solves the lack of manpower for surveillance.

3. Municipal/city LGUs deputized to implement the surveillance system may be allowed to charge fees to recover costs.

4. The provincial LGUs must be deputized to verify positive results of onsite testing in the province with qPCRs, following World Animal Health protocols. In some provinces like Batangas, the regional animal disease diagnostic labs may serve as verifiers of the disease.

5. Samples of positive results are transported in DNA and not biological form to avoid the spread of the disease.

6. Provincial LGUs must maintain a database of the incidence of the disease in the province.

7. An ICT application is to be developed to send the testing results in real time to the province. This allows a buildup of the disease to geomap the progress of the disease in the province.

Ramon L. Clarete is a professor at the University of the Philippines School of Economics.

Neil Banzuelo




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