How Does African Swine Fever Spread? These Areas and Farms Need Close Attention
Recently, due to the impact of African swine fever, pork prices across the country have also been rising, and many pig farmers have been affected as well. So what are the transmission routes of African swine fever? Which areas and farms need close attention?
I. Pathogen Transmission Routes
The transmission routes of African swine fever are mainly infection through the mouth via contact with or consumption of items contaminated with the African swine fever virus, or infection through the blood-sucking of insects. It can spread through the air over short distances. Contaminated feed, swill, leftovers and meat scraps, pens, vehicles, equipment and clothing can all indirectly transmit this disease. Ticks can transmit it through mating, and can also transmit it vertically. In addition, blood-sucking insects, such as mosquitoes and horseflies, can transmit the African swine fever virus from infected pigs to healthy pigs through bites.
The possible routes by which African swine fever was introduced into China carry the highest risk through international trade and personnel exchanges carrying meat products contaminated with the virus. In addition, the introduction of breeding stock and wild boar activity may also cause the introduction of the epidemic.
International trade and personnel exchanges. As China's reform and opening up continues to expand and its level of economic development continues to rise, the number of foreign tourists entering China or Chinese tourists traveling overseas has been increasing year by year. Inbound tourists, returning personnel and international parcels may carry contaminated pork or pork products from epidemic countries into the country; if the food waste from international flights, ships and other aircraft or vessels from epidemic countries is not treated, and is consumed by domestic pigs after contact, it may also trigger an epidemic. In the history of African swine fever epidemics, cases of cross-border transmission caused in this way are very common. The epidemic in Eastern Europe was brought in by an international cargo ship docked in Georgia; at the time, the ship carried swill contaminated with African swine fever, which was fed to pigs near the port.
Introduction of breeding stock. This is one of the important routes of introduction. Virus-carrying breeding pigs can carry the virus latently and enter the country along with the introduction of breeding stock. The African swine fever virus can survive for a long time in frozen boar semen, and can be transmitted to sows along with artificial insemination, causing an outbreak of the epidemic.
Wild boar activity. China has a vast territory and abundant wild boar resources, especially in areas bordering Russia, where there are biological corridors. Wild boars can move back and forth near the border between the two countries. Once an epidemic occurs on the Russian border, the risk of introduction into China through wild boar activity is also very high.
II. Risk Areas After an epidemic occurs, based on the principles of spatiotemporal proximity and risk priority, the following areas must receive close attention:
Key areas: Beijing, Tianjin, Hebei, Inner Mongolia, Liaoning, Jilin, Heilongjiang, Gansu, Xinjiang, etc.
III. Farms That Need Close Attention
1. Farms with recently dead or sick pigs, especially sites with pigs showing weakness, reduced feed intake, listlessness, high fever, or increased secretions from the eyes, nose and mouth. 2. Those that have recently purchased live pigs without origin quarantine inspection or from unclear sources. 3. Those that feed swill, especially swill that has not been cooked. 4. Those with poor biosecurity levels, such as pigs raised outdoors, pens without disinfection facilities/measures, and farms close to major traffic routes. 5. Those where pig dealers from key areas have recently entered to buy pigs, or where there has recently been buying and selling activity at live pig trading markets, etc.