Wednesday, February 21, 2024

Researchers focusing on six unique strains of African swine fever

By Elizabeth Bobenhausen Poultry Times staff ebobenhausen@poultrytimes.com

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GAINESVILLE, Ga. — Along with the many other viruses the USDA follows, there is another virus that has the attention of agriculture producers around the world. The virus is called African swine fever (ASF). The USDA describes the virus as “a highly contagious and deadly viral disease affecting both domestic and feral swine of all ages.”

ASF is not spread to humans and is not a threat to food security. The virus is located in many countries such as the Dominican Republic, Haiti, China, Mongolia, Vietnam and the European Union. The United States has not had any cases of ASF. Symptoms of African swine fever is high fever, decreased appetite, weakness, skin lesions, red blotchy skin, loose stool, vomiting, difficulty breathing and coughing.

In November, the USDA Agricultural Research Service stated that researchers have recategorized and reduced the amount of virus strains from 25 to six genotypes. Since this development, scholars have found they can classify ASF virus isolates, and this will change the game for vaccine manufacturing.

Senior ARS scientist Douglas Gladue said, “previously, 25 different virus genotypes were identified across the globe. Our research team recently re-evaluated all the publicly available virus DNA sequence and found that the majority of genotypes (genetic makeup) originally identified as novel were not correctly identified nor compared to already existing ASFV virus genotypes. Based on this analysis, there are actually fewer unique genotypes than the ASF research community believed, and that means that there is less diversity of ASFV affecting communities across the globe. This information is important as it may reduce the number of vaccines previously thought to be needed to protect against all ASFV genotypes.”

For reducing the risk of ASF, and most other viruses, biosecurity remains a best line of defense. The USDA gives tips to protect swine from exposure, such as:

· Update your biosecurity plan and start ongoing training for personnel

Your site’s biosecurity manager is responsible for developing and updating an enhanced written biosecurity plan with the help of your herd veterinarian.

This person is accountable for training and communicating biosecurity measures in a language each person who enters the site can understand.

The biosecurity manager and key personnel need to be trained themselves about biosecurity measures to keep the virus out.

· Restrict access to your production site

Limit your site’s entry points and protect each with lockable gates. Lock buildings when no one is present.

Establish a perimeter buffer area (PBA) to serve as an outer barrier around buildings and limit movement of the virus near animals. Designate a clearly marked parking area outside the PBA. People and vehicles moving through PBA access points must follow cleaning, disinfection, and other biosecurity measures.

Create 1 or more line(s) of separation (LOS) as a control boundary to prevent movement of the virus into animal areas.

· Enhance employee biosecurity practices

Limit access only to people who are essential to your production site.

Ensure everyone crossing the LOS arrives showered and wearing clean clothing and shoes. All individuals crossing the LOS should sign an agreement to follow biosecurity plan rules.

Require those crossing a LOS access point to complete an entry logbook. Make sure that the logbook is monitored and information is maintained.

· Ensure strict protocols for animal movement

Ensure pigs and semen, if applicable, come from documented sources and are verified as free of foreign animal diseases. Even then, no other animals can be introduced onto the site for at least 7 days before moving animals to another pork production site with susceptible animals.

Make sure animals leaving the production site can only move in 1 direction across any line of separation at a time. You must have a contingency plan for interrupted animal movement.

Clean and disinfect contaminated areas.

· Prevent feed contamination and control wildlife, rodents and flies

Ensure that grain and feed are delivered, stored, mixed, and fed in ways to prevent contamination. Clean up and dispose of feed spills immediately to discourage wildlife.

Make sure your facilities are designed to prevent all animals, including birds, from crossing into secure areas and contacting pigs.

Maintain those areas and ensure that everyone works to support the documented rodent and fly control programs.

· Put in place proper carcass disposal and manure management practices

Dispose of dead animals so they don’t attract the attention of wildlife, rodents, and other scavengers.

Ensure rendering vehicles don’t enter the PBA.

Manure should be removed to prevent exposure of your herd to disease agents. Have a plan where to store manure onsite if it cannot be moved offsite due to an outbreak.

The USDA also offers seven biosecurity statements to protect swine:

1. Limit on-farm traffic

The fewer people and vehicles on the farm, the better.

2. Discuss prevention practices regularly

Everyone needs to understand and follow the rules.

3. Shower-in/shower-out

People can bring the virus onto your farm as it can live on clothing, shoes, and equipment. Remove clothing and accessories on a designated dirty side and dress in laundered items on the clearly marked clean side before entering or exiting restricted animal areas.

4. Wear clean coveralls and boots at each site

Because the virus can stay on clothing, this step limits disease spread for anyone moving between sites.

5. Don’t eat in animal areas

The virus can survive for months in pork and pork products and be a source of spread. Keep all outside food products away from animals.

6. Wash all on-farm equipment and vehicles

The virus can stay on vehicles and equipment. Follow specific cleaning and disinfection protocols for all vehicles entering or leaving your site.

7. Ask visitors about recent international travel

Don’t let anyone who has been in an African swine fever-affected country onto your farm for at least 5 days after returning to the United States

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